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NOTABLE SCIENTISTS

A TO Z OF SCIENTISTS IN SPACE AND ASTRONOMY

DEBORAH TODD AND JOSEPH A. ANGELO,JR. A TO Z OF SCIENTISTS IN SPACE AND ASTRONOMY

Notable Scientists

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Todd, Deborah. A to Z of scientists in space and astronomy / Deborah Todd and Joseph A. Angelo, Jr. p. cm.—(Notable scientists) Includes bibliographical references and index. ISBN 0-8160-4639-5 (acid-free paper) 1. Astronomers—Biography. 2. Space sciences—Biography. I. Angelo, Joseph A. II. Title. III. Series. QB35.T63 2005 520'.92'2—dc22 2004006611

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This book is printed on acid-free paper. “I know nothing with any certainty, but the sight of stars makes me dream.” —Vincent Van Gogh

“All of us are truly and literally a little bit of stardust.” —William Fowler

To the loves on this very tiny planet who have sprinkled their stardust into my life and believed in my dreams. To Jason, my original and brightest star. To A from T. To Rob, as always, with love. To Jenny. To Gregg, thank you for everything. To Rusty, our beloved star. To Mom and Dad. To my Sister. Out of stardust comes poetry... To Jeb, for the music and art. To Omar, my favorite poet of all time. —Deborah Todd

To my special friend, Michael Joseph Hoffman, his brother, Daniel, and all the other wonderful children of planet Earth who will inherit the stars. At just three years old, with the same unquenchable curiosity that inspired so many of the interesting people in this book, Michael asked me: “Where does the Sun go at night?” This book is written to help him discover an incredible universe that is now both a destination and a destiny through space technology. —Joseph A. Angelo, Jr. CONTENTS

List of Entries ix Acknowledgments xi Introduction xiii

Entries A to Z 1

Entries by Field 286 Entries by Country of Birth 289 Entries by Country of Major Scientific Activity 291 Entries by Year of Birth 293 Chronology 295 Bibliography 299 Index 305 LIST OF ENTRIES

Adams, John Couch Boltzmann, Ludwig Fleming, Williamina Paton Adams, Walter Sydney Bradley, James Stevens Alfonso X Brahe, Tycho Fowler, William Alfred Alfvén, Hannes Olof Gösta Braun, Wernher Magnus von Fraunhofer, Joseph von Alpher, Ralph Asher Bruno, Giordano Galilei, Galileo Alvarez, Luis Walter Bunsen, Robert Wilhelm Galle, Johann Gottfried Ambartsumian, Viktor Burbidge, Eleanor Margaret Gamow, George Amazaspovich Peachey Giacconi, Riccardo Anderson, Carl David Campbell, William Wallace Gill, Sir David Ångström, Anders Jonas Cannon, Annie Jump Goddard, Robert Hutchings Arago, Dominique-François- Cassini, Giovanni Domenico Hale, George Ellery Jean Cavendish, Henry Hall, Asaph Aratus of Soli Chandrasekhar, Halley, Sir Edmund Argelander, Friedrich Wilhelm Subrahmanyan Hawking, Sir Stephen August Charlier, Carl Vilhelm Ludvig William Aristarchus of Samos Clark, Alvan Graham Herschel, Caroline Lucretia Aristotle Clausius, Rudolf Julius Herschel, Sir John Frederick Arrhenius, Svante August Emmanuel William Aryabhata Compton, Arthur Holly Herschel, Sir William Baade, Wilhelm Heinrich Copernicus, Nicolas Hertz, Heinrich Rudolf Walter Curtis, Heber Doust Hertzsprung, Ejnar Barnard, Edward Emerson Dirac, Paul Adrien Maurice Hess, Victor Francis al-Battani Doppler, Christian Andreas Hewish, Antony Bayer, Johannes Douglass, Andrew Ellicott Hohmann, Walter Beg, Muhammed Taragai Drake, Frank Donald Hubble, Edwin Powell Ulugh Draper, Henry Huggins, Sir William Bell Burnell, Susan Jocelyn Dyson, Sir Frank Watson Jeans, Sir James Hopwood Bessel, Friedrich Wilhelm Eddington, Sir Arthur Stanley Jones, Sir Harold Spencer Bethe, Hans Albrecht Ehricke, Krafft Arnold Kant, Immanuel Bode, Johann Elert Einstein, Albert Kapteyn, Jacobus Cornelius Bok, Bartholomeus Jan Euler, Leonhard Kepler, Johannes

ix x A to Z of Scientists in Space and Astronomy al-Khwarizmi, Abu Olbers, Heinrich Wilhelm Schwabe, Samuel Kirchhoff, Gustav Robert Matthäus Heinrich Korolev, Sergei Pavlovich Oort, Jan Hendrik Schwarzschild, Karl Kuiper, Gerard Peter Penzias, Arno Allen Secchi, Pietro Angelo Lagrange, Comte Joseph-Louis Piazzi, Giuseppe Shapley, Harlow Laplace, Pierre-Simon, Pickering, Edward Charles Sitter, Willem de Marquis de Planck, Max Karl Slipher, Vesto Melvin Leavitt, Henrietta Swan Plato Somerville, Mary Fairfax Lemaître, Abbé-Georges- Ptolemy Stefan, Josef Édouard Reber, Grote Tereshkova, Valentina Leverrier, Urbain-Jean-Joseph Rees, Sir Martin John Tombaugh, Clyde William Lippershey, Hans Rossi, Bruno Benedetto Tsiolkovsky, Konstantin Lockyer, Sir Joseph Norman Russell, Henry Norris Eduardovich Lowell, Percival Ryle, Sir Martin Urey, Harold Clayton Messier, Charles Sagan, Carl Edward Van Allen, James Alfred Michelson, Albert Abraham Scheiner, Christoph Wilson, Robert Woodrow Newcomb, Simon Schiaparelli, Giovanni Wolf, Maximilian Newton, Sir Isaac Virginio Zwicky, Fritz Oberth, Hermann Julius Schmidt, Maarten ACKNOWLEDGMENTS

he creation of the universe took a matter of the change you made in my computer situation, Tseconds. The creation of this book took but I guess honestly I am liking it more and more somewhat longer. These acknowledgments are to every day, and my computer and I have both thank those wonderful people who helped de- been virus free since the switch! I know—you velop it from its original flicker of light into the told me so. Thank you. shining example of the completed collaboration To Roger Eggleston for his great research, at that it is today. First and foremost: to Chris Van a moment’s notice, with a smile. To Elizabeth Buren, who is now living the life of his dreams in Eggleston for always smiling and always believ- a land far, far away, thank you for working us ing in this project and me. Thank you to both through the spark phase and into the realm of re- of you for your always-present support. Who’s in ality; to Margo Maley Hutchison for picking charge? I know! things up in the middle of it all with kindness and Special thanks to Kasey Arnold-Ince for her grace; to Kimberly Valenti for taking it the final research skills, Heather Lindsay for her photo mile—the hardest part of the journey—you are expertise on both books, Gregg Kellogg for again deeply appreciated; and to Bill Gladstone for in- discussing biography candidates with me and the sisting that I meet your “first writer,” because we multitude of offers to help, and Curtis Wong for both live in the same county—thank you for in- always asking how my book was coming along troducing me to someone who has surely become and the many varied discussions we had on this a lifelong friend, and now part-time collaborator. topic and others. To Ed Addeo, a fabulous friend, and an Thank you to John Newby, who continues equally wonderful writer. Your help was above the mantra “Keep moving forward.” I am glad and beyond the call of duty and/or friendship. you were passing through. You are a collection You kept me afloat and made this book possible. of very special stardust. And to think we did it all without being in the Thank you to Matt Beucler. You know why, same room, except of course for those occasional coach. lunches that kept us going and kept me sane. A special thank you to the editorial staff at Thank you, thank you, thank you. Facts On File, especially Frank Darmstadt, for To Rob Swigart for the use of your office, pulling the project through and helping bring it your house, your kitchen, your desk, your other to completion with patience and understanding desk in the library and that wonderful chair, and through cancer, physical disabilities, and the your apartment in Paris. I’m still not sure about passing away of loved ones, and Laura Magzis,

xi xii A to Z of Scientists in Space and Astronomy for an excellent copyediting job. To Joe Angelo This book could not have been prepared with- for his expertise, dedication, and years of expe- out the generous support and assistance of Ms. rience in this book-writing process that proved Heather Lindsay, curator of the Emilio Segrè invaluable in getting it completed. Visual Archives (ESVA) of the American To my sister, Drena Large, I simply say Institute of Physics (AIP). Special thanks also go “Thanks, Sis” for being the great listener and to the staff at the Evans Library of Florida Tech, problem solver that you are. You didn’t know it, whose assistance in obtaining obscure reference but you helped tremendously. materials proved essential in the success of this Thank you to Jennifer Omholt. You prove project. Finally, a special thanks is extended to to me daily that laughter is the best medicine. the editorial team at Facts On File, particularly Thanks for listening and for the perspective. executive editor Frank K. Darmstadt, who kept My fondest thank you to Jeb Brady, for be- a steady hand at the wheel while the draft ing an amazing collection of stardust and for manuscript traveled through uncharted, often continuing to shine brilliantly. Thank you for turbulent, waters. introducing me to the concept of “Life on Planet —Joseph A. Angelo, Jr. Ziploc.” You make me laugh. I love you. Finally, thank you to my son, Jason Todd, the star that forever shines brightest in my universe. —Deborah Todd INTRODUCTION

he best thing about writing a book on the cannot deny that we are all inexplicably con- TA to Z of Scientists in Space and Astronomy nected to this tiny planet and to the place it oc- is discovering that many of the most amazing cupies in a vast space that we are still striving contributions were made by ordinary people who to understand. loved gazing at the stars. Musicians, philoso- Our unquenchable thirst for knowledge in phers, priests, physicians, people who came from the galaxy and the universe has propelled us into impoverished backgrounds, and those with un- space, traveling in search of answers. We have told wealth, have all contributed to our under- sent new kinds of ships into a new unexplored standing of what we see when we look into the territory, gathering samples and pictures from night sky, and where we fit into the scheme of places that are too far away for any human to things. Astronomy, unlike any other field, can travel, yet. And just in case, hoping that we be and has been significantly affected by ama- might not be alone, we beckon a response from teurs. The stars are for everyone. any other travelers who might be out there also Throughout time, the stars have guided peo- exploring. ple in all walks of life in a variety of ways—to This book was written to introduce you to navigate ships, determine when wars should be some of the inspiring people who have dedicated waged, decide when marriages should take place themselves to this field and have made it possi- (and to whom one should be married), where ble for us to learn more. Many have given their buildings should be erected, and when fields lives to their studies, and far too many have lost should be planted and harvested. Astronomy their lives for their beliefs. Some pursued find- and astrology were once a single discipline, and ing answers in the stars as a hobby over a life- important aspects in medical care. Even today, time. Others made great contributions during a the medical profession admits that emergency short period of time, and then left the field to rooms get a little crazy during full moons. And pursue other interests. Yet their commonality is of course there is the term lunatic, which comes one that we all share—the wonder of looking up from the Latin luna, “the Moon.” at the night sky. At least once during your life- Astronomy has allowed us to standardize our time, look through a telescope at the Moon, or clocks and our calendars, and has provided us a star, or a comet, or a planet. And when you with some sense of order in our very busy lives. do, remember that even Galileo could not have And as our bodies and internal clocks work in seen the wonders that you can see. It would have time with solar and lunar and stellar events, we been beyond his wildest dreams.

xiii xiv A to Z of Scientists in Space and Astronomy

ENTRIES most important, work and contributions to the The entries in this book run the gamut from rel- study of space and/or astronomy. Where there is atively unknown amateurs to the most highly re- a name listed in SMALL CAPS within the body of garded scientists in astronomy, cosmology, and the biography, that name will be listed as its own physics. If there were more time and more space, biography within the book. there would be many, many more worthy people included in this book. Perhaps future editions CROSS-REFERENCES AND BIBLIOGRAPHY will have further additions. Following the alphabetical entries are a number Each entry here is arranged in alphabetical of cross-reference indexes. The Chronology lists order by surname or, in the case of the ancients, entrants by the periods in which they lived. They by the name by which they are most commonly are also grouped by birth dates in the Year of Birth known (for example, Ptolemy). In the instances section, plus by Country of Birth, Scientific Field, of those whose names have had many different and Country of Scientific Activity. spellings, a variety of spellings have also been An extensive bibliography lists resources included. Following the name, you will find birth used in the research of this book, including both and death dates, nationality, and field of spe- printed material and Web sites. As you whet cialization. your appetite reading about these extraordinary The biographies are typically 750 to 1,200 people, you are invited to use these resources as words, usually containing some information a starting place to help you learn more about sci- about the subjects’ childhood and family back- entists in space and astronomy. ground, and exploring influences, progression into the field, educational background, and, —Deborah Todd

that “the irregularities of the motion of Uranus” ᨳ Adams, John Couch had him questioning “whether they may be at- (1819–1892) tributed to the action of an undiscovered planet British beyond it.” His studies, and later his work, kept Astronomer, Mathematician Adams busy, but he planned on “investigating, John Couch Adams, a brilliant scientist often as soon as possible after taking my degree” (an- described as shy, reserved, and even self-effacing, other two years away), the possible explanation is best known as a central figure in a scientific for the planet’s orbit, believing that he would fiasco that sparked an international debate, pit- then “if possible . . . determine the elements of ted nations against one another, and brought the its orbit, etc. approximately, which would prob- world of astronomy out of academia and into the ably lead to its discovery.” life of the average citizen. Adams’s involvement Unfortunately, life got in the way, protocol in the missed discovery, and subsequent codis- got in the way, and ineffective tools and people covery, of the planet Neptune became one of the got in the way. The chain of events that took most important events in the history of astron- place between Adams’s documented idea in July omy, from both a scientific and a political point 1841, in which he suspected the existence of an- of view. other planet, to his computations of the planet’s Born in 1819, the son of a farmer, Adams location, to the actual discovery of the planet in reportedly showed great mathematical ability September 1846, was a slow and painful pro- from the time he was young, and at the age of gression. The time span of more than 5 years al- 16 calculated the time of an upcoming solar lowed plenty of time for outside forces and peo- eclipse. Four years later, in October 1839, Adams ple to complicate matters, and the result was a became a student at St. John’s College in full-blown scandal. The idea that “he who pub- Cambridge, a town that Adams stayed tied to for lishes first gets the credit,” which was the pro- the rest of his life. tocol of the time, did not help Adams either. Shortly after the discovery of Uranus by SIR The professional positions and personal obliga- WILLIAM HERSCHEL, astronomers discovered a tions of the people involved further complicated baffling problem with that planet’s orbit. Adams, the events that followed. in his second year of college, suspected that the In 1841 Adams was a second-year student problem was another planet, writing in 1841 convinced that there was another planet beyond

1 2 Adams, John Couch completed computations for the location of the planet, and shared his theory with the Astronomer Royal, Sir George Airy. But Airy disagreed, and thought that the problems with the orbit were related to the inverse square law of gravitation, in which gravitation begins to break down over large distances. Airy’s dismissal of the computations, compounded by new teaching responsibilities, kept Adams from pursuing his theory. Despite the setbacks, Adams had a brilliant mind, and although he was not what anyone would ever call aggressive, he was persistent about calculating the planet’s position. Adams requested additional data on Uranus from Greenwich. Through the director of the Cambridge Observ- atory, Professor James Challis, Adams requested additional data from Airy in Greenwich, and in February 1844, the information was sent. The British astronomer John Couch Adams, who is DOMINIQUE-FRANÇOIS-JEAN ARAGO, the cocredited with the mathematical discovery of the director of the Paris Observatory, was also in- planet Neptune in the 19th century.From 1843 to terested in Uranus’s orbital problems, and he 1845, he investigated irregularities in the orbit of Uranus and used mathematical physics to predict also thought another planet might be in- the existence of a planet beyond. However, his volved. In June 1845 he requested that one of work was ignored in the United Kingdom until his astronomers, URBAIN-JEAN-JOSEPH LE Urbain J. J. Leverrier made similar calculations that VERRIER, work on the solution to find this allowed Johann Galle to discover Neptune on September 23, 1846. (Courtesy of AIP Emilio Segrè planet. Arago did not know about Adams’s Visual Archives) work, and Airy did not know that Arago was looking for a planet. By September Adams’s calculations were Uranus. He was overworked with his studies, but complete, and included the location of the still reportedly spent hours by candlelight, work- planet, its mass, and its orbit. Adams personally ing through the night on mathematical compu- took his findings to show Airy, but Airy was tations to pinpoint the planet’s location. While away in France, so Adams left a letter of intro- this was unknown to the rest of the world at the duction written on his behalf by Challis. time, Adams was the first person to use Newton’s Despite the fact that it was common for people theory of gravitation as a basis for calculating the from all walks of life to write to and drop in on position of a planet. the Astronomer Royal, Adams’s behavior of Two years later, in 1843, Adams graduated showing up without an appointment is often with extraordinarily high marks from Cambridge, highly criticized and cited as a contributing receiving the award of First Smith’s Prizeman factor to the fiasco. and a fellowship at Pembroke College. He soon The following month, Airy wrote to Challis became a curator of the Cambridge Observatory, saying that he would see Adams, and Adams and his career was underway. In October he traveled once again without an appointment to Adams, John Couch 3 see the astronomer. When he arrived, Mrs. Airy certain, success appeared very doubtful,” wrote told Adams that her husband was out, so he left Challis, but on July 29, he started the search by his card saying that he would return later in the recording stars in the area, which he would have day. She forgot to give the card to Airy, and when to observe and reobserve over several different Adams returned as promised in the afternoon, he evenings, to compare locations and see if one was told that the family was having dinner, which had moved. Since Challis did not have a cur- they did every afternoon at 3:30, and he was rent star map at the observatory, he could not turned away again. Adams left his papers for make quick comparisons. He made his second Airy to review, and returned to Cambridge. observation on July 30, his third on August 4, Airy still questioned Adams’s theory, even and his final observation on August 12, then after looking at his calculations and explana- started comparing his data. Unfortunately, he tions, and later wrote to him asking specifically only looked at the first 39 stars he recorded on whether the new planet could explain some of August 12 when he made the comparisons to the the discrepancies of Uranus’s orbit. Many think July 29 data. It was the 49th “star” that later that Adams was bothered by the question be- proved to be the planet, but Challis stopped his cause he thought it was missing the point—he comparisons before finding this result. had identified a planet and gave complete and In late August 1846 Hershel, who believed thorough calculations. For whatever reason, in the existence of the planet, suggested to a Adams did not write back. friend with a telescope that they could probably In November 1845 LeVerrier published a pa- see the planet just by looking for it in the sug- per stating that Jupiter and Saturn definitely did gested location. His friend, William Dawes, de- not cause Uranus’s orbit, insisting that another cided that the telescope he owned was not ade- factor had to be involved. On June 1, 1846, he quate enough, and searching for it would be a published another paper, this time stating with waste of time. certainty that another planet beyond Uranus As it turned out, LeVerrier had the same was the only possible explanation for Uranus’s idea. On August 31 he published a paper with orbit. Airy got a copy of LeVerrier’s paper on the planet’s orbit, mass, and angular diameter, June 23, and wrote to him asking the same ques- and suggested that using the data, they could tion he had asked Adams approximately six look at the stars in this location, find the one months earlier. This put Airy in the possession that was a disc rather than a point of light (plan- of information making him the only one who ets are disc-shaped in a telescope), and quickly knew that Adams and LeVerrier were working find the planet. on the same prediction, and that they in fact On September 2 Adams sent Airy new com- came to the same conclusion. Airy told neither putations with a more precise location of the of them about the other’s work. On June 29 Airy planet. Meanwhile, Dawes wrote to a friend, received LeVerrier’s reply. With this information, William Lassell, asking if he would use his larger he met with Challis and another astronomer, SIR telescope to help look for it. But Lassell had a JOHN FREDERICK WILLIAM HERSCHEL (son of Sir badly sprained ankle and could not get around, William Herschel, discoverer of Uranus) to dis- so he gave the letter to his maid for safekeeping cuss the “extreme probability of now discover- while he recovered. She promptly lost the let- ing a new planet in a very short time . . .” ter, so Lassell never looked. “It was so novel a thing to undertake ob- On September 10 Herschel gave a speech servations in reliance upon merely theoretical at a British Association event, in which he deductions; and that while much labour was discussed his belief in the new planet, and at 4 Adams, John Couch which Adams was scheduled to present a paper since they were the first to know about the on his findings. As if things could not become planet, it was a British discovery. The French a more dreadful comedy of errors, it turns out government, absent in helping LeVerrier look that there was some confusion as to the sched- for the planet, suddenly decided it was time to uled date of the presentation, and Adams arrived take action, so it claimed ownership of the dis- at the session the day after it closed. covery. And the Germans, who were the first LeVerrier’s experience in getting the French to actually see the planet, received no credit at government to search for the planet soon be- all. gan to resemble Adams’s experience with the Additional investigations revealed that British government: Interest was lacking. So, on “LeVerrier’s planet” had been observed and cat- September 18 he wrote to the astronomer JOHANN alogued by other, earlier astronomers, including GOTTFRIED GALLE at the Berlin Academy, giving Galileo Galilei on December 28, 1612, and him the calculations and asking him to search January 27 and 28, 1613, who observed that it with his telescope. Galle and his assistant, had traveled but did not pursue it as a planetary Heinrich d’Arrest, received LeVerrier’s letter on discovery. The French astronomer Joseph- September 23, and since they had a telescope Jérôme Le Français de Lalande recorded it as a and new star maps success seemed likely. star on May 8 and 10, 1795, as did Herschel on Within the hour, the planet was found. Galle July 14, 1830, and the Scottish-German as- immediately wrote to LeVerrier, “Monsieur, the tronomer Johann von Lamont on October 25, planet of which you indicated the position really 1845, and September 7 and 11, 1846. exists.” To add to the debate, American scientists Back in England, Challis finally received a attacked both Adams and LeVerrier, saying copy of LeVerrier’s August 31 paper, and he did that their calculations of the planet’s orbit some more observations. This time he actually were so far off (which they were) that its dis- saw that one of the stars was a disc, but he pre- covery was purely a coincidence. None of this ferred to confirm that it was really a planet by seemed to really affect the mild-mannered observing and comparing movement, which Adams, who simply did not get embroiled in would take time, so he did nothing. any of it. To the surprise of everyone involved, on In 1847 John Herschel invited both Adams October 1 London’s prestigious newspaper The and LeVerrier to meet with him at his home in Times announced Galle’s sighting of “LeVerrier’s Kent. Despite the insistence by the British gov- planet.” Challis immediately looked through his ernment that Adams had discovered the planet, telescope again and confirmed that the disc he Adams himself apparently never made that saw on July 29 had moved. By October 3 the claim, and it is considered common knowledge scandal had begun. that he was never bitter about any of it. He was, Herschel informed the public that Adams instead, a great admirer of LeVerrier’s, and upon had made the same prediction earlier than meeting at Herschel’s, the two apparently be- LeVerrier. The humble Adams was called upon came good friends. to confirm the time and nature of his computa- Adams survived the great fiasco, and both tions, and Airy and Challis had to explain them- he and LeVerrier became recognized as the selves to the press and the public in light of codiscoverers of the new planet, named Neptune. Adams’s virtually ignored, yet significant, work. Adams went on to participate in other signifi- Naturally, the British government wanted cant astronomical work, including computa- the credit for the finding, and so it claimed that tions on the acceleration of the Moon, and the Adams, Walter Sydney 5 relationship of the Leonids (meteors that originate from a region in the “head” of the constellation Leo) with a comet. In 1848 Adams received the coveted Copley Medal from the Royal Society of London, and in 1859 he became the Lowndean Professor of Astronomy and Geometry at Cambridge University. He stayed in this position for the next 32 years. In 1861 he succeeded Challis as the director of the Cambridge Observatory, and later served two terms as president of the Royal Astronomical Society. Adams passed up two very deserved opportunities for fame. He declined Airy’s job as Astronomer Royal when Airy retired, and he refused a knighthood offered by Queen Victoria because he apparently could not afford to keep up the standard of living of a knight. Adams married Eliza Bruce (descendant of Scottish king Robert Bruce) in 1863. He retired from Cambridge in 1891 and died in 1892. In 1895 a memorial was placed in Westminster Abbey near the memorial to Newton, and many Astronomers Walter Sydney Adams (left), James Hopwood Jeans (center), and Edwin Powell Hubble believe that Adams was the greatest English as- (right) relax for a moment outdoors in spring 1931 at tronomer and mathematician since SIR ISAAC the Mount Wilson Observatory, in the San Gabriel NEWTON. Adam’s memoir, which included the Mountains about 30 kilometers northwest of Los story of his predictions, was published at some Angeles, California. Adams specialized in stellar spectroscopy and served as the director of Mount point during his life, under the title An explana- Wilson from 1923 to 1946. (Courtesy AIP Emilio tion of the observed irregularities in the motion of Segrè Visual Archives) Uranus, on the hypothesis of disturbances caused by a more distant planet; with a determination of the mass, orbit, and position of the disturbing body. A for determining stellar distances. In 1915 his crater is named in honor of Adams on the sur- spectral studies of Sirius B led to the discovery face of the Moon. of the first white dwarf star. From 1923 to 1946 he served as the director of the Mount Wilson Observatory in California. ᨳ Adams, Walter Sydney Walter Adams was born on December 20, (1876–1956) 1876, in the village of Kessab, near Antioch in American northern Syria, to Lucien Harper Adams and Astronomer Dora Francis Adams, American missionaries from New Hampshire. This area of Syria, where Walter Sydney Adams specialized in stellar Adams spent the first nine years of his child- spectroscopic studies and codeveloped the im- hood, was then under Turkish rule as part of the portant technique called spectroscopic parallax former Ottoman Empire. By 1885 his parents 6 Adams, Walter Sydney had completed their missionary work and re- At Mount Wilson, Adams was closely in- turned home to the United States. volved in the design, construction, and opera- As a student at Dartmouth College, Adams tion of the observatory’s initial 60-inch (1.5-m) earned a reputation as a brilliant undergraduate. reflecting telescope, and then the newer 100- He selected a career in astronomy as a result inch (2.5-m) reflector that came on line in of his courses with Professor Edwin B. Frost 1917. Starting in 1914 he collaborated with (1866–1935). Adams graduated from Dartmouth the German astronomer Arnold Kohlschütter in 1898 and then followed Frost to the University (1883–1969) in developing a method of estab- of Chicago’s Yerkes Observatory. While learning lishing the surface temperature, luminosity (the spectroscopic methods at the observatory, Adams amount of radiation a star emits), and distance also continued his formal studies in astronomy of stars from their spectral data. at the University of Chicago, where, in 1900, In particular, Adams showed how it was he obtained a graduate degree. The famous possible for astronomers to distinguish between American astronomer GEORGE ELLERY HALE a dwarf star and a giant star simply from their founded this observatory in 1897, and its 40-inch spectral data. As defined by astronomers, a refractor telescope was the world’s largest. As a dwarf star is any main sequence star, while a young graduate, Adams had the unique oppor- giant star is a highly luminous one that has de- tunity to work with Hale as he established a new parted the main sequence toward the end of its department devoted to stellar spectroscopy. This life and swollen significantly in size. Giant stars experience cultivated Adams’s lifelong interest typically have diameters from 5 to 25 times the in stellar spectroscopy. diameter of the Sun and luminosities that range From 1900 to 1901 Adams studied in Munich, from tens to hundreds of times the luminosity Germany, under several eminent German as- of the Sun. Adams showed that it was possible tronomers, including KARL SCHWARZSCHILD. He to determine the luminosity of a star from its then returned to the United States and worked spectrum. This allowed him to introduce the at the Yerkes Observatory on a program that important method of “spectroscopic parallax” measured the radial velocities of early-type stars. whereby the luminosity deduced from a star’s In 1904 he moved with Hale to the newly es- spectrum is then used to estimate its distance. tablished Mount Wilson Observatory, in the San Astronomers have estimated the distance of Gabriel Mountains about 19 miles (30 km) many thousands of stars with this important northwest of Los Angeles, California. Adams be- method. came assistant director of this observatory in Adams is perhaps best known for his work 1913, and served in that capacity until 1923, involving Sirius B, the massive but small com- when he succeeded Hale as director. panion to Sirius, the Dog Star—the brightest Adams married his first wife, Lillian Wickham, star in the sky after the Sun. in 1910. After her death 10 years later, he mar- The German mathematician and astronomer ried Adeline L. Miller in 1922, and the couple FRIEDRICH WILHELM BESSEL first showed in 1844 had two sons, Edmund M. and John F. Adams. that Sirius must have a companion and he even From 1923 until his retirement in 1946, Adams estimated its mass to be about the same as that served as the director of the Mount Wilson of the Sun. In 1862 the American optician Observatory. Following his retirement on January ALVAN GRAHAM CLARK made the first telescopic 1, 1946, he continued his astronomical activi- observation of Sirius B, sometimes called the ties at the Hale Solar Laboratory in Pasadena, Pup. Their preliminary work set the stage for California. Adams to make his great discovery. Alfonso X 7 In 1915 Adams obtained the spectrum of home in Pasadena, California, on May 11, 1956. Sirius B—a very difficult task due to the bright- His numerous honors and awards for his con- ness of its stellar companion, Sirius. The spec- tributions to astronomy include the Henry tral data indicated that the small star was Draper Medal of the National Academy of considerably hotter than the Sun. A skilled as- Sciences (1918), the Gold Medal of the Royal tronomer, he immediately realized that such a Astronomical Society (1917), and the Bruce hot celestial object, just eight light-years dis- Gold Medal from the Astronomical Society of tant, could remain invisible to the naked eye the Pacific (1928). He became an associate of only if it was very much smaller than the Sun. the Royal Astronomical Society in 1914 and a Sirius B is actually slightly smaller than Earth. member of the National Academy of Sciences Assuming all of his observations and reasoning in 1917. were true, Adams reached this important conclusion: Sirius B must have an extremely high density, possibly approaching 1 million times ᨳ Alfonso X (Alfonso el Sabio, the density of water. Alfonso the Learned, Alfonso the Wise) So in 1915 Adams made astronomical his- (1221–1284) tory by identifying the first “white dwarf”—a Spanish small, dense object that is the end product of Astronomer, Historian stellar evolution for all but the most massive stars. A golf ball–sized chunk taken from the Alfonso X, dedicated to creating a Spanish- central region of a white dwarf star would have language encyclopedia filled with the knowl- a mass of about 35,000 kilograms—that is, 35 edge of all of mankind, and particularly com- metric tonnes, or some 15 fully-equipped sport mitted to the study of astronomy, became an utility vehicles. important figure in this scientific field during Almost a decade later, Adams parlayed his his reign (1252–84) as king of León and Castile. identification of this very dense white dwarf star. Armed with the power and money to attract He assumed a compact object like Sirius B the most brilliant minds in the known world, should possess a very strong gravitational field. Alfonso ordered and oversaw the creation of He further reasoned that according to A LBERT astronomy-based texts and tables that became EINSTEIN’S general relativity theory, Sirius B’s the definitive work on the subject for three strong gravitational field should redshift any light it emitted. Between 1924 and 1925 he suc- centuries. cessfully performed difficult spectroscopic meas- Astronomy and astrology were disciplines urements that detected the anticipated slight that were so closely intertwined during this era redshift of the star’s light. This work provided that they were not considered two separate other scientists with independent observational fields of study. The Moon and stars were con- evidence that Einstein’s general relativity theory sulted for a variety of practical purposes, in- was valid. cluding religion, timekeeping, medicine, and Adams also conducted spectroscopic inves- navigation. Accurate and complete texts, tigations of the Venusian atmosphere in 1932, charts, and tables were essential to govern these showing that it was rich in carbon dioxide (CO2). important matters, and the key to creating the He retired as director of the Mount Wilson definitive source was to amass the largest quan- Observatory in 1946, but continued his research tity of information and then turn it into the at the Hale Laboratory. He died peacefully at most accurate translations. 8 Alfvén, Hannes Olof Gösta

These translations required experts in both PTOLEMY’S celestial spheres were explained in the languages and the subject matter. Whether great detail in this text. Due to the complexity the document was in Arabic, Greek, or Latin, of the Ptolemaic system, in which the planets, each was to be translated into Spanish. Aside Sun, and Moon each existed in their own cir- from simply transferring the information from cle, each circled the Earth, and most required one language to another, translators were re- additional circles to explain their motion, quired to correct and update the mathematical Alfonso X was so perplexed by Ptolemy’s ex- computations. Experts in astronomy and geom- planation that he is quoted as saying, “Had I etry were essential to this process. It is said been present at the creation, I would have given Alfonso X brought together more than 50 of the some useful hints for the better ordering of the greatest minds from around the world to work Universe.” on just one of these translations. Because of his dedication to astronomy and The most significant work to come out of the decree to amass the definitive collection of this regime was the Alfonsine Tables. These ta- texts, Alfonso X is responsible for the survival bles were calculations that, using Alfonso’s year of information from the ancient texts, which al- of coronation as the base year, gave exact rules lowed their introduction to European society to compute the position of any of the planets and helped fuel the scientific advancements that at any time. Derived from the Arabian Toledo began during the Renaissance and continue to Tables, created in the middle of the 11th cen- this day. tury by Abu Ishaq Ibrahim Ibm Yahya al- Zarqali (better known by his European name of Arzachel), the Alfonsine Tables resolved some discrepancies of the earlier tables and were the ᨳ Alfvén, Hannes Olof Gösta “holy grail” of astronomical tables for the next (1908–1995) 300 years. Swedish It is estimated that the Alfonsine Tables Physicist, Space Scientist, Cosmologist were completed sometime between 1252 and 1280, and it is known for certain that they Hannes Alfvén developed the theory of magne- reached Paris in 1292, staying in use well into tohydrodynamics (MHD), the branch of physics the mid-1500s. NICOLAS COPERNICUS learned that helps astrophysicists understand sunspot about the Alfonsine Tables while studying at formation and the magnetic field-plasma inter- the university in Krakow, and he used them in actions (now called Alfvén waves in his honor) his computations as he developed his theories taking place in the outer regions of the Sun and of a heliocentric universe. With Copernicus’s other stars. For this pioneering work and its ap- calculations, a new set of tables, the Prutenic plications to many areas of plasma physics, he Tables, were developed in 1551 by Erasmus shared the 1970 Nobel Prize in physics. Reinhold, and these became the new standard Hannes Olof Gösta Alfvén was born in in astronomy. Norrköping, Sweden, on May 30, 1908, to In 1280 another huge undertaking was Johannes Alfvén and Anna-Clara Romanus, completed, the publishing of Libros del Saber de both practicing physicians. He began his higher Astronomia, in which all of the known stars were education at the University of Uppsala in 1926, identified and listed with their coordinates. and obtained his Ph.D. in philosophy in 1934. Astronomical instruments were described, a va- That same year, he received an appointment to riety of clocks were identified and detailed, and lecture in physics at the University of Uppsala. Alfvén, Hannes Olof Gösta 9 and joined the University of California at San Diego as a visiting professor of physics, a position he held until 1991, when he retired. In 1970 he shared the Nobel Prize in physics with the French physicist Louis Néel (1904–2000). Alfvén received his half of the prize for his fundamental work and discoveries in MHD and its numerous applications in various areas of plasma physics. Alfvén is best known for his pioneering plasma physics research that led to the creation of the field of magnetohydrodynamics—the branch of physics concerned with the interactions between plasma and a magnetic field. Plasma is an electrically neutral gaseous mixture of positive and negative ions. Physicists often refer to plasma as the fourth state of matter, because the plasma behaves quite differently from solids, liquids, or gases. In the 1930s Alfvén went against conventional beliefs in classical electromagnetic theory. He boldly proposed a theory of sunspot formation centered on his hypothesis that under cer- The Swedish physicist and Nobel laureate Hannes tain physical conditions a magnetic field can be Alfvén developed the theory of magnetohydrodynamics locked or “frozen” in a plasma. He built upon (MHD). This important branch of physics allows astrophysicists to study sunspot formation and the this hypothesis and further suggested in 1942 magnetic field–plasma interactions that take place in that under certain conditions—as found, for ex- the outer regions of the Sun and other stars. He ample, in the Sun’s atmosphere—waves can appears here at a press conference after being propagate through plasma influenced by mag- announced as a co-winner of the 1970 Nobel Prize in physics. (AIP Emilio Segrè Visual Archives) netic fields. Today solar physicists believe that at least a portion of the energy heating the solar corona is due to action of these waves, Alfvén He married Kerstin Maria Erikson in 1935, and waves, propagating from the outer layers of the the couple had five children: one son and four Sun. daughters. Much of Alfvén’s early work on MHD In 1937 Alfvén joined the Nobel Institute and plasma physics is collected in the books for Physics in Stockholm as a research physicist. Cosmical Electrodynamics (1948) and Cosmical Starting in 1940, he held a number of positions Electrodynamics: Fundamental Principles, coau- at the Royal Institute of Technology in thored in 1963 with the Swedish physicist Carl- Stockholm. He served as an appointed profes- Gunne Fälthammar (born 1931). sor in the theory of electricity from 1940 to In the 1950s Alfvén again proved to be a 1945, professor of electronics from 1945 to scientific rebel when he disagreed with both 1963, and professor of plasma physics from 1963 Steady State cosmology and Big Bang cosmology. to 1967. In 1967 he came to the United States Instead, Alfvén suggested an alternate cosmology 10 Alpher, Ralph Asher based on the principles of plasma physics. He radiation in space, the existence of which was used his 1956 book, On the Origin of the Solar suggested some 41 years earlier by the young System, to introduce his hypothesis that the Ph.D. student Ralph Alpher. Known for the con- larger bodies in the solar system were formed by cept that would eventually be dubbed the big the condensation of small particles from pri- bang theory, Alpher was the first person to de- mordial magnetic plasma. He further pursued vise the equations that explained the origin of such electrodynamic cosmology concepts in his the universe. 1975 book, On the Evolution of the Solar System, Ralph Alpher was born in 1921 to Samuel which he coauthored with Gustaf Arrhenius. and Rose Alpher, and by the time he was 16, in Alfvén also developed an interesting model 1937, the inquisitive young man was ready to of the early universe in which he assumed the leave his family’s home in Washington, D.C., to presence of a huge spherical cloud containing study science at college. But it was the Great equal amounts of matter and antimatter. This Depression, and Alpher’s dream to study at the theoretical model, sometimes referred to as Massachusetts Institute of Technology (MIT) on Alfvén’s antimatter cosmology model, is not cur- a full scholarship was vanquished when the rently supported by observational evidence of scholarship was inexplicably rescinded. So, the large quantities of annihilation radiation—the perseverant Alpher did what he thought would anticipated by-product when galaxies and anti- best accomplish his goals. He enrolled in night galaxies collide. So while contemporary astro- school at George Washington University. physicists and astronomers generally disagree Working during the day as a secretary to with his theories in cosmology, Alfvén’s work in earn enough money for school, books, and food, magnetohydrodynamics and plasma physics re- Alpher spent the next six years as an under- mains of prime importance to scientists engaged graduate, first studying chemistry, then switch- in controlled thermonuclear fusion research. ing to physics. Science had taken hold of Alpher After retiring in 1991 from his academic po- and would not let go. Acknowledging that there sitions at the University of California at San was much more he wanted to learn and accom- Diego and the Royal Institute of Technology in plish, Alpher spent the next two years working Stockholm, Alfvén enjoyed his remaining years toward his master’s degree, and then, in 1945, by commuting semiannually between homes in he jumped into the doctorate program. the San Diego area and Stockholm. He died in Alpher’s thesis adviser was the renowned ex- Stockholm on April 2, 1995, and is best re- Soviet scientist GEORGE GAMOW, who had the membered as the Nobel laureate theoretical perfect project for Alpher. Gamow had given a physicist who founded the important field of lot of thought to what might have happened at magnetohydrodynamics. the beginning of time to create the elements, but he had dedicated little time to work on the problem. Under Gamow’s supervision, Alpher was to ᨳ Alpher, Ralph Asher figure out the origin of the elements for his the- (1921– ) sis. To narrow it down, Gamow suggested that American Alpher not worry about the exact instant the Physicist, Cosmologist universe was created, but rather look at what was happening when things started to stabilize and In 1989 the National Aeronautics and Space cool down to the point of containing radiation Administration (NASA) launched a $150 mil- and ylem, the Greek term Gamow assigned to lion satellite to investigate cosmic background the concept of the primordial soup of life. Alpher, Ralph Asher 11 Alpher worked on the timing and the published in Nature, a British scientific journal. mechanics, considering first how neutrons had This paper suggested that the best way to prove existed and then radioactively decayed into pro- the theory was to look into space for the radia- tons, electrons, and neutrinos; expanding, cool- tion that still existed from the event that oc- ing, combining, creating the universe and all of curred 15 billion years ago. The radiation, they the elements in it, all of which happened within insisted, would be within a blackbody spectrum the first five minutes of creation. These were that would show up at about 5 kelvins (K), ap- concepts that no previous scientist had even proximately 450 degrees below zero Fahrenheit. considered explaining. The simple math for the proof boiled down to Gamow was interested in making certain this: The amount of radiation divided by the that Alpher’s work would get as much attention amount of matter that existed immediately af- as possible. Since alpha, beta, and gamma are the ter the big bang is equal to the amount of radi- first three letters of the Greek alphabet, Gamow ation divided by the amount of matter that ex- made a play on words to give Alpher’s work a ists now. This equation took Herman and memorable title. By adding another scientist’s Alpher an entire summer to devise, calculate, name to the paper, HANS ALBRECHT BETHE, he and substantiate. could call it the Alpher, Bethe, Gamow theory. Alpher’s biggest problems were twofold. Bethe refused to take credit for work he had not First, a highly respected group of notable scien- done, but Gamow included his name on the pa- tists had an entirely different view on how the per anyway, and the publicity idea worked. universe worked. These “steady-state” physicists Gamow sent the paper to The Physical Review for included Fred Hoyle, who, ridiculing Alpher, publication, and the article was printed on April came up with the term “big bang.” The second 1, 1948. This became the hottest topic in the problem involved the technology, or lack of it, history of astronomy. available at the time. Alpher and Herman sim- With Alpher’s thesis public, the idea that ply could not get their results verified because the universe was created by a superhot explosion background radiation in space, they were told, caused a scientific stir of great proportions. could not be measured. Despite their exhaustive Alpher’s next task was to defend the work in his efforts to find a way, they came up with no help. oral exam, which under normal circumstances In 1955 Alpher and Herman left academia would take place in front of a handful of faculty to earn a living in the corporate sector. Herman members. In this case, however, Alpher showed worked for General Motors, and Alpher went to up to an audience of about 300 people, includ- General Electric (GE). Alpher wrote hundreds ing the press and some of the most important of papers for GE, but he and Herman wrote physicists of the time. When Alpher was asked only four more research papers together on how long the big bang took, and he responded their theory. In time, their revolutionary ideas about 300 seconds, he became instant fodder for were forgotten. headlines and cartoons, and the recipient of all Technology changed dramatically over the kinds of mail offering help for his soul because, next nine years. By 1964, two scientists, A. G. as he said, “I had dared to trample on their con- Doroschkevich and Igor Novikov, took up cept of Genesis.” Alpher and Herman’s cause in a paper they pub- This kind of notoriety required more work lished, suggesting a search for blackbody radia- immediately. Alpher teamed up with a col- tion. But no one seemed interested in the topic. league, Robert Herman, and the two wrote and At the same time, two other scientists, both published 18 more papers, the first of which was radio astronomers working for Bell Laboratories, 12 Alvarez, Luis Walter were testing a horn-shaped antenna hoping to Background Explorer. The satellite found exactly measure radio waves and echoes from satellites, what it was looking for—cosmic background when they were plagued with a background mi- radiation—precisely at 2.7° K, radiation ema- crowave noise that they could not get rid of no nating from everywhere. matter what adjustments they tried. What actu- Today, Alpher is a distinguished research ally happened was that they had stumbled upon professor at Union College in New York. He is the blackbody radiation Alpher and Herman the administrator of the university’s Dudley predicted in their early work. Instead of getting Observatory, which has a mission to “support re- rid of the noise, ARNO ALLEN PENZIAS and search in astronomy, astrophysics, and the his- ROBERT WOODROW WILSON ended up discover- tory of astronomy.” Ralph Alpher is part of its ing cosmic microwave background radiation— living history. at 3.5 K, instead of the 5 K that Alpher and Herman had suggested. Penzias and Wilson’s discovery was published ᨳ Alvarez, Luis Walter in 1965, and almost immediately ended the de- (1911–1988) bate between the steady-state and the Big Bang American theorists. This proved that the Big Bang theory Physicist was correct and sparked the birth of cosmology as a dedicated science. But everyone seemed to have Luis Walter Alvarez, a Nobel Prize–winning forgotten the fact that Alpher, Herman, and physicist, collaborated with his son, Walter, a Gamow had predicted and calculated this radia- geologist, to rock the scientific community in tion 17 years earlier, when radio astronomy was in 1980 by proposing an extraterrestrial catastro- its infancy and this kind of proof was impossible. phe theory. Called the “Alvarez hypothesis,” this The three original scientists began a writing popular theory suggests that a large asteroid campaign to reinform the scientific community struck Earth some 65 million years ago, causing of the hot debate that evolved around the orig- a mass extinction of life, including the dinosaurs. inal predictions in 1948, but no one was inter- Alvarez supported the hypothesis by gathering ested and they received little response. Although interesting geologic evidence—namely, the dis- Alpher and Herman did eventually receive the covery of a worldwide enrichment of iridium in Magellanic Premium Award from the American the thin sediment layer between the Cretaceous Philosophical Society in 1975 for their discov- and Tertiary periods. The unusually high ele- eries, they were not included in the most im- mental abundance of iridium has been attributed portant recognition a scientist can achieve. In to the impact of an extraterrestrial mineral 1978 Penzias and Wilson won the Nobel Prize source. The Alvarez hypothesis has raised a great in physics for their discovery of cosmic mi- deal of scientific interest in cosmic impacts, both crowave background radiation. as a way to possibly explain the disappearance Alpher’s Big Bang theory is considered one of the dinosaurs and as a future threat to planet of the Top Ten Astronomical Triumphs of the Earth that might be avoidable through innova- Millennium, according to the American Physical tions in space technology. Society News. He has been called by his col- Luis Alvarez was born in San Francisco, leagues “arguably one of the most important sci- California, on June 13, 1911, to Walter C. Alvarez, entists of the century.” a prominent physician, and Harriet Smyth In 1989 Alpher and Herman were honored Alvarez. In 1925 the family moved from San guests at the launching of COBE, NASA’s Cosmic Francisco to Rochester, Minnesota, so his father Alvarez, Luis Walter 13 enthusiasm and passion that remained for a lifetime. In rapid succession, he earned his bachelor’s degree (1932), master’s degree (1934), and Ph.D. in physics (1936) at the University of Chicago. He married Geraldine Smithwick in 1936, and they had two children: a son (Walter) and a daughter (Jean). Almost two decades later, in 1958, Luis Alvarez married his second wife, Janet L. Landis, with whom he had two other children: a son (Donald) and a daughter (Helen). After obtaining his doctorate in physics from the University of Chicago in 1936, Alvarez began his long professional association with the University of California at Berkeley. Only World War II disrupted this affiliation. Alvarez conducted special wartime radar research at the Massachusetts Institute of Technology in Boston from 1940 to 1943. He then joined the atomic bomb team at Los Alamos National Laboratory in New Mexico (1944–45). He played a key role in the development of the first plutonium im- plosion weapon. During the Manhattan Project, Alvarez had the difficult task of developing a reliable, high-speed way to multipoint-detonate The Nobel laureate physicist Luis Walter Alvarez the chemical high explosive used to symmet- collaborated with his geologist son Walter to rock the rically squeeze the bomb’s plutonium core into scientific community in 1980 when they proposed an extraterrestrial catastrophe theory. Also called the a supercritical mass. During the world’s first “Alvarez hypothesis,” their popular version of an atomic bomb test, called Trinity, on July 16, ancient catastrophe suggests that a large asteroid 1945, near Alamogordo, New Mexico, Alvarez struck Earth some 65 million years ago, causing the flew overhead as a scientific observer. He was mass extinction of most living creatures, including the dinosaurs. Luis Walter Alvarez received the 1968 the only witness to precisely sketch the first Nobel Prize in physics for his outstanding experimental atomic debris cloud as part of his report. He also work in nuclear particle physics. (Ernest Orlando served as a scientific observer onboard one of Lawrence Berkeley National Laboratory, courtesy AIP the escort aircraft that accompanied the Enola Emilio Segrè Visual Archives) Gay—the B-29 bomber that dropped the first atomic weapon on Hiroshima, Japan, on August 6, could join the staff at the Mayo Clinic. During 1945. his high school years, Luis spent the summers After World War II Alvarez returned to the developing his experimental skills by working as University of California at Berkeley and served an apprentice in the Mayo Clinic’s instrument as a professor of physics from 1945 until his re- shop. He initially enrolled in chemistry at the tirement in 1978. His fascinating career as an ex- University of Chicago, but quickly embraced perimental physicist involved many interesting physics, especially experimental physics, with an discoveries that go well beyond the scope of this 14 Alvarez, Luis Walter book. Before discussing his major contribution Tertiary period (symbol T). A thin (approximately to modern astronomy, however, it is appropri- 1 centimeter) clay strip separated the two lime- ate to briefly describe the brilliant experimen- stone layers. tal work that earned him the Nobel Prize in According to geologic history, as this lay- physics in 1968. Simply stated, Alvarez helped ered rock specimen formed eons ago, the di- start the great elementary particle stampede nosaurs flourished and then mysteriously passed that began in the early 1960s. He did this by into extinction. Perhaps the thin clay strip developing the liquid hydrogen bubble chamber contained information that might answer the into a large, enormously powerful research in- question of why the great dinosaurs suddenly strument of modern high-energy physics. His in- disappeared. Alvarez and Walter carefully ex- novative work allowed teams of researchers at amined the rock and were puzzled by the pres- Berkeley and elsewhere to detect and identify ence of a very high concentration of iridium many new species of very-short-lived subnuclear in the peculiar sedimentary clay. Here on particles—opening the way for the development Earth, iridium is quite rare and typically no of the quark model in modern nuclear physics. more than about 0.03 parts per billion are When an elementary particle passes through normally found in the planet’s crust. Soon the chamber’s liquid hydrogen (kept at a tem- geologists discovered this same iridium en- perature of –250 degrees Celsius), the cryogenic hancement (sometimes called the “iridium fluid is warmed to the boiling point along the anomaly”) in other places around the world in track that the particle leaves. The tiny telltale the same thin sedimentary layer (called the KT trail of bubbles is photographed and carefully boundary) that was laid down about 65 million computer-analyzed by Alvarez’s device. Nuclear years ago—the suspected time of a great mass physicists then examine these data to extract extinction. new information about whichever member of Since iridium is so rare in Earth’s crust and is the “nuclear particle zoo” they have just cap- more abundant in other solar system bodies, the tured. Alvarez’s large liquid-hydrogen bubble Alvarez team postulated that a large asteroid— chamber came into operation in March 1959, about 6 miles (10 km) or more in diameter— and almost immediately led to the discovery of had struck prehistoric Earth. This cosmic col- many interesting new elementary particles. In a lision would have caused an environmental quite appropriate analogy, Alvarez’s hydrogen catastrophe throughout the planet. Alvarez rea- bubble chamber did for elementary particle soned that such a giant asteroid would largely physics what the telescope did for observational vaporize while passing through Earth’s atmos- astronomy. phere, spreading a dense cloud of dust particles Just before his retirement from the University including large quantities of extraterrestrial irid- of California, Luis Alvarez became intrigued by ium atoms uniformly around the globe. The a very unusual geologic phenomenon. In 1977 Alvarez team further speculated that after the his son Walter (born 1940) showed him an in- impact of this killer asteroid, a dense cloud of teresting rock specimen that he had collected ejected dirt, dust, and debris would encircle the from a site near Gubbio, a medieval Italian town globe for many years, blocking photosynthesis in the Apennine Mountains. The rock sample and destroying the food chains upon which was about 65 million years old and consisted of many ancient animals depended. two layers of limestone: one from the Cretaceous When Alvarez published this hypothesis in period (symbol K, after the German word 1980, it created quite a stir in the scientific com- Kreide for Cretaceous) and the other from the munity. In fact, the Nobel laureate spent much Ambartsumian, Viktor Amazaspovich 15 of the last decade of his life explaining and de- ᨳ Ambartsumian, Viktor Amazaspovich fending his extraterrestrial catastrophe theory. (1908–1996) Despite the geophysical evidence of a global irid- Armenian ium anomaly in the thin sedimentary clay layer Astrophysicist at the KT boundary, many geologists and pale- ontologists still preferred other explanations Viktor Ambartsumian founded the Byurakan concerning the mass extinction. While still con- Astrophysical Observatory in 1946 on Mount troversial, the Alvarez hypothesis emerged from Aragatz, near Yerevan, Armenia. This facility the 1980s as the most popular explanation of the served as one of the major astronomical obser- dinosaurs disappearance. vatories in the former Soviet Union. Shortly after Alvarez’s death, two very in- Considered the father of Russian theoretical as- teresting scientific events took place that gave trophysics, he introduced the idea of stellar as- additional support to the extraterrestrial catas- sociation into astronomy in 1947. His major trophe theory. First, in the early 1990s, a ring theoretical contributions to astrophysics in- structure 112 miles (180 km) in diameter, called volved the origin and evolution of stars, the na- Chicxulub, was identified from geophysical data ture of interstellar matter, and phenomena as- collected in the Yucatán region of Mexico. The sociated with active galactic nuclei. Chicxulub crater has been age-dated at 65 mil- Ambartsumian was born on September 18, lion years. The impact of an asteroid 10 kilo- 1908, in Tbilisi, Georgia (then part of the czarist meters in diameter would have created this Russian Empire). His father was a distinguished very large crater, as well as caused enormous Armenian philologist—a teacher of classical tidal waves. Second, a wayward comet called Greco-Roman literature—so young Viktor was Shoemaker-Levy 9 slammed into Jupiter in July exposed early in life to the value of intense in- 1994. Scientists using a variety of space-based tellectual activity. When he was just 11 years old, and Earth-based observatories studied how the he wrote the first two of his many astronomical giant planet’s atmosphere convulsed after get- papers: “The New Sixteen-Year Period for ting hit by a cosmic “train” of chunks, about 20 Sunspots” and “Description of Nebulae in kilometers in diameter, of this fragmented Connection with the Hypothesis on the Origin comet that plowed into the southern hemi- of the Universe.” His father quickly recognized sphere of Jupiter. The comet’s fragments de- his son’s mathematical talents and aptitude for posited the energy equivalent of about 40 mil- physics and encouraged him to pursue higher ed- lion megatons of trinitrotoluene (TNT), and ucation in St. Petersburg (then called their staccato impact sent huge plumes of hot Leningrad), Russia. In 1925 Ambartsumian en- material shooting 1,000 kilometers above the rolled at the University of Leningrad. Before re- visible Jovian cloud tops. ceiving his degree in physics in 1928, he pub- About a year before his death in Berkeley, lished 10 papers on astrophysics. From 1928 to California, on August 31, 1988, Alvarez pub- 1931, he did his graduate work in astrophysics at lished a colorful autobiography entitled Alvarez, the Pulkovo Astronomical Observatory. This his- Adventures of a Physicist. In additional to his toric observatory near St. Petersburg was founded 1968 Nobel Prize in physics, he received nu- in the 1830s by the German astronomer Friedrich merous other awards, including the Collier Georg Wilhelm von Struve (1793–1864) and Trophy in Aviation (1946) and the National served as a major observatory for the Russian Medal of Science, personally presented to him (Soviet) Academy of Sciences until its destruc- in 1964 by President Lyndon Johnson. tion during World War II. 16 Anderson, Carl David During the short period from 1928 to 1930, explosions at the centers of these particular Ambartsumian published 22 astrophysics papers galaxies. The English translation of his influen- in various journals, while still a graduate student tial textbook, Theoretical Astrophysics, appeared at Pulkovo Observatory. The papers signified in 1958 and became standard reading for as- the emergence of his broad theoretical research tronomers-in-training around the globe. interests, and his scientific activities began to His fellow scientists publicly acknowledged attract official attention and recognition from Ambartsumian’s technical contributions and the Soviet government. At age 26, Viktor leadership by electing him president of the Ambartsumian was made a professor at the International Astronomical Union (1961–64) University of Leningrad, where he soon organ- and president of the International Council of ized and headed the first department of astro- Scientific Unions (1970–74). His awards in- physics in the Soviet Union. His pioneering cluded the Janssen Medal from the French academic activities and numerous scientific pub- Academy of Sciences (1956), the Gold Medal lications in the field eventually earned him the from the Royal Astronomical Society in London title of “father of Russian (Soviet) theoretical (1960), and the Bruce Gold Medal from the astrophysics.” Astronomical Society of the Pacific (1960). Ambartsumian served as a member of the On August 12, 1996, this eminent Armenian faculty at the University of Leningrad from 1931 astrophysicist died at the Byurakan Observatory. to 1943, and was elected to the Soviet Academy He is best remembered for his empirical ap- of Sciences in 1939. During World War II, drawn proach to complex astrophysical problems deal- by his heritage he returned to Armenia (then a ing with the origin and evolution of stars and republic within the Soviet Union). In 1943 he galaxies. He summarized his most important held a teaching position at Yerevan State work in the paper “On Some Trends in the University, in the capital city of the Republic of Development of Astrophysics,” published in the Armenia. That year he also became a member Annual Review of Astronomy and Astrophysics, of the Armenian Academy of Sciences. In 1946 volume 18, 1980. he organized the development and construction of the Byurakan Astrophysical Observatory. Located on Mount Aragatz, this facility served ᨳ Anderson, Carl David as one of the major astronomical observatories (1905–1991) in the Soviet Union. Ambartsumian served as American the director of the Byurakan Astrophysical Physicist Observatory and resumed his activities investigating the evolution and nature of star systems. Carl David Anderson began his studies in sci- In 1947 he introduced the important new ence in 1923 at the California Institute of concept of stellar association—the very loose Technology as an electrical engineering student. groupings of young stars of similar spectral type But he soon discovered physics and changed dis- that commonly occur in the gas- and dust-rich ciplines, and eventually changed the world with regions of the Milky Way Galaxy’s spiral arms. a scientific discovery that has been called one of He was the first to suggest the notion that in- the most momentous of the century. terstellar matter occurs in the form of clouds. Born in New York City on September 3, Some of his most important work took place in 1905, Anderson was the only child of Carl 1955, when he proposed that certain galactic ra- David Anderson and Emma Adolfinja Ajaxson, dio sources indicated the occurrence of violent Swedish immigrants. The family moved to Los Anderson, Carl David 17 Angeles, California, when Anderson was seven, would lead to some insights and discoveries in this and he lived with his mother following his par- new frontier. ents divorce soon after the move. Following an Anderson’s responsibility was to head up the education in public schools, Anderson enrolled research with the Wilson chamber, a cylindrical at a new college in Pasadena, the California glass “cloud chamber” filled with water vapor- Institute of Technology (Caltech), in 1923, and saturated gas. According to Pickering, “the pres- soon became a student of Robert Millikan, who sure is dropped suddenly so that the gas expands in December 1923 was honored for his work on and cools to a supersaturated state.” When an the elementary charge of electricity and on the ionized particle passes through the cylinder, a photoelectric effect, as a Nobel laureate in visible path of water droplets appears along its physics. path, which is photographed and analyzed by the It was Millikan who kept Anderson at scientific team. Caltech after his graduation in 1927. Despite the Anderson needed to improve the conditions fact that Anderson had applied and been ac- of the Wilson chamber, for which Wilson won a cepted for a fellowship in doctoral studies at the Nobel Prize in 1927, and decided to build a newer University of Chicago under Millikan’s sugges- version that had the effect of dropping the pres- tion to get experience someplace other than sure much faster with the help of a piston and a Caltech, Millikan decided that he wanted the vacuum, changing the vapor to include a mixture bright student to stay and work with him on cos- of alcohol and water, and boosting the electro- mic rays. Since this subject was the one Anderson magnetic power to bend the path of ionized par- most wanted to pursue, he obliged, and worked ticles. This was a key both to getting better pho- on research and experiments under Millikan’s tographs and to finding the polarity of the direction at Caltech. particle’s charge. When the new experiments with From 1927 to 1930, Anderson was a teach- the modified chamber also included Pickering’s ing fellow at the university while working on his Geiger counter readings of when a particle was doctoral dissertation. In 1930 he received his present, Anderson ended up with more data, but Ph.D. magna cum laude, again in physics engi- also with new results that caused great concern. neering, with a thesis on the space distribution of It appeared that the particles were negatively photoelectrons ejected from various gases by X- charged and positively charged. Electrons, of rays. For the next three years, he worked with course, could only be negative. Millikan as a research fellow, excited about the Anderson added one more modification to his possibility to delve into the world of gamma rays, Wilson chamber, a lead plate that would slow of which little was known. It was during this time, down the rate of speed as a particle passed through in 1932, that Anderson made a discovery that it, and therefore determine the direction the par- would soon earn him the coveted Nobel Prize. ticle traveled. He then photographed a particle Cosmic radiation was relatively new ground that was absolutely a positively charged electron for Millikan and his researchers. A young as- traveling upward through the cylinder. This was tronomer named PAUL ADRIEN MAURICE DIRAC no longer cause for concern; it was instead the dis- had suggested that positive and negative states covery of a lifetime. Reported in the Proceedings should exist for all matter, but not much was un- of the Royal Society in 1932, the newly discovered derstood about it, and Milliken was extremely positron became one of the first new fundamen- curious. He assembled a team of researchers, in- tal particles. Anderson had discovered antimatter. cluding William Pickering, Victor Neher, and Anderson still wanted more. Despite the fact Anderson, to oversee a group of experiments that that his research was taking place during the Great 18 Ångström, Anders Jonas Depression, when funding was virtually nonexist- lant. From 1941 though 1945, he participated in ent, he wanted to see what else he could find at research for the Office of Scientific Research and different altitudes and latitudes. Anderson enlisted Development, the National Defense Research the help of graduate student Seth Neddermey to Committee, and even traveled to Normandy, perform what became known as the Pike’s Peak France, to observe rockets in use. experiment, in which they, with great difficulty Anderson added a family to his life in 1946 and many setbacks, took their Wilson chamber to when, at age 41, he married Lorraine Bergman an elevation of 14,000 feet and spent six weeks and adopted her three-year-old-son Marshall photographing particles. Nearly 10,000 photo- David. From 1947 to 1948 he was president of graphs later, Anderson had made his next great the American Academy of Arts and Sciences. discovery, a new particle called the muon (origi- In 1949 two more honors were bestowed upon nally called the mesotron, then the mu meson, him: an honorary degree from Temple University then shortened to simply muon). For his work dur- and a new son, David Anderson. ing his early years in physics, Anderson received In his remaining years at Caltech, Anderson his first award in 1935, the Gold Medal of the continued teaching, conducting individual re- American Institute of the City of New York. search, and receiving awards for the work that was In 1936, at the age of 31, this assistant pro- the foundation of cosmic physics. He earned the fessor from Caltech borrowed $500 from Millikan John Ericsson Medal of the American Society of to go to Sweden to accept his next award, the Swedish Engineers in 1960, and joined President Nobel Prize in physics, following in the footsteps Kennedy at a special White House dinner held of his mentor. Anderson was corecipient of the in 1962 in honor of the Nobel laureates. The award that year with VICTOR FRANCIS HESS following year brought an honorary degree from (1883–1964) who discovered cosmic radiation. In Gustavus Adolphus College, and his member- presenting the award, the Nobel Committee for ship in the National Academy of Sciences be- Physics applauded Anderson for “finding one of came a chairmanship of the Physics section in the building stones of the universe, the positive 1963, a position he held for three years. electron.” Anderson used half of his nearly Anderson retired from Caltech in 1970, $20,000 prize money to pay for his ill mother’s leaving behind his positions as chairman of the medical bills, and invested the rest in real estate. freshman admissions committee and chairman In 1937 Anderson became an associate proof the Physics, Mathematics, and Astronomy di- fessor at Caltech, and the same year received the visions, which he had occupied for the prior Elliott Cresson Medal of the Franklin Institute, as eight years. In 1976 Anderson was named pro- well as an honorary degree from Colgate fessor of physics emeritus of the Caltech Board University. The following year, he was elected to of Trustees. He died on January 11, 1991, at the the National Academy of Sciences. Anderson be- age of 85 following a brief illness. came a full professor of physics at Caltech in 1940, and in 1945 won the Presidential Certificate of Merit. ᨳ Ångström, Anders Jonas During World War II Anderson was in- (1814–1874) volved in several projects to benefit the U.S. Swedish government. He turned down the position of Physicist, Astronomer director of the atomic bomb project, but later helped the U.S. Navy, through Caltech, to de- This famous 19th-century Swedish physicist velop a stable and reliable solid rocket propel- and solar astronomer performed pioneering Ångström, Anders Jonas 19 spectral studies of the Sun. In 1862 Ångström chaplain for the timber industry. Anders studied discovered that hydrogen was present in the so- physics and astronomy at the University of lar atmosphere and went on to publish a de- Uppsala—founded in 1477, the oldest of the tailed map of the Sun’s spectrum, covering Scandinavian universities—and graduated in other elements present as well. A special unit 1839 with his doctorate. Upon graduation, of wavelength, the angstrom (symbol Å), now Ångström joined the university faculty as a lec- honors his accomplishments in spectroscopy turer in physics and astronomy. For more than and astronomy. three decades, he remained at this institution, Anders Jonas Ångström was born in Lögdö, serving it in a variety of academic and research Sweden, on August 13, 1814. His father was a positions. In 1843 he became an astronomical observer at the famous Uppsala Observatory— the observatory founded in 1741 by Anders Celsius (1701–44). In 1858 Ångström became chairperson of the physics department and remained a professor in that department for the remainder of his life. Ångström performed important research in heat transfer, spectroscopy, and solar astronomy. With respect to his contributions in heat transfer phenomena, he developed a method to measure thermal conductivity by showing that it was proportional to electrical conductivity. He was also one of the 19th-century pioneers of spectroscopy. Ångström observed that an electrical spark produces two superimposed spectra. One spectrum is associated with the metal of the electrode generating the spark, while the spectrum is from the gas through which the spark passes. He applied LEONHARD EULER’s resonance theorem to his experimentally derived atomic spectra data and discovered an important principle of spectral analysis. In his paper “Optiska Undersökningar” (“Optical investigations”) presented to the Swedish Academy in 1853, Ångström reported that an incandescent (hot) gas emits light at precisely the same wavelength as it absorbs light when it is cooled. Portrait of Anders Ångström as a young scientist. This This finding represents Ångström’s finest re- famous 19th-century Swedish physicist and solar astronomer performed pioneering spectral studies of search work in spectroscopy, and his results an- the Sun. In 1862 he discovered that hydrogen was ticipated the spectroscopic discoveries of GUSTAV present in the Sun’s atmosphere and published a ROBERT KIRCHHOFF (1824–87) that led to the detailed map of the solar spectrum, covering other subsequent formulation of Kirchhoff’s laws of elements present as well. (AIP Emilio Segrè Visual Archives) radiation. 20 Arago, Dominique-François-Jean Ångström was also able to demonstrate the yellow-green light. He was a member of the composite nature of the visible spectra of various Royal Swedish Academy (Stockholm) and the metal alloys. His laboratory activities at the Royal Academy of Sciences of Uppsala. In 1870 University of Uppsala gave Ångström the hands- Ångström was elected a fellow of the Royal on experience in the emerging field of spec- Society in London, and in 1872 received its troscopy necessary to accomplish his pioneering prestigious Rumford Medal. Ångström died on observational work in solar astronomy. June 21, 1874, in Uppsala. By 1862 Ångström’s initial spectroscopic investigations of the solar spectrum enabled him to announce his discovery that the Sun’s at- ᨳ Arago, Dominique-François-Jean mosphere contained hydrogen. In 1868 he pub- (1786–1853) lished Recherches sur le spectre solaire (Researches French on the solar spectrum), his famous atlas of the Mathematician, Astronomer, Physicist, solar spectrum, containing his careful measure- Politician ments of approximately 1,000 Fraunhofer lines. Unlike other pioneering spectroscopists—for Dominique-François-Jean Arago, born in 1786 example, ROBERT WILHELM BUNSEN (1811–99) just before the French Revolution, became one and Gustav Kirchhoff—who used an arbitrary of the most renowned scientists ever to come out measure, Ångström precisely measured the cor- of Napoleon’s famous Parisian school, École responding wavelengths in units equal to one Polytechnique. ten-millionth of a meter. Ångström’s map of the Arago was a mathematician first in his ca- solar spectrum served as a standard of reference reer, but a lover of science foremost. In 1809, at for astronomers for nearly two decades. In 1905 the age of 23, he became a full mathematics pro- the international scientific community honored fessor at the École Polytechnique with an ap- his contributions by naming the unit of wave- pointment as chair of analytical geometry. This length he used the “angstrom”—where one same year, he was also elected into the Académie angstrom (symbol Å) corresponds to a length of des Sciences. His career was firmly set in place 10–10 meter (one ten-millionth of a millimeter). at this early age, and within two years, he was Physicists, spectroscopists, and microscopists entrenched in scientific discovery. use the angstrom when they discuss the visible Light and optics theories were fascinating to light portion of the electromagnetic spectrum. Arago’s brilliant mind, and in 1811 he began to The human eye is sensitive to electromagnetic contemplate the theories of polarization, how radiation with wavelengths between 4 and 7 ϫ light rays have different characteristics when 10Ϫ7 meter. Since these numbers are very small, they travel in different directions when re- scientists often find it convenient to use the flected. Using quartz crystals, he conducted angstrom in their communications. For exam- experiments on light that resulted in the dis- ple, the range of human vision can now be ex- covery of chromatic polarization. Arago was pressed as ranging between 4,000 and 7,000 contacted by another scientist, Thomas Young, angstroms (Å). who, using Arago’s work, proposed the first In 1867 Ångström became the first scientist transverse wave light theory. Another contem- to examine the spectrum of the aurora borealis, porary, Augustine Fresnel, also wrote Arago commonly known as the Northern Lights. Because about wave optics, and by 1815 Fresnel presented of this pioneering work, his name is sometimes his theory, La diffraction de la lumière, to the associated with the aurora’s characteristic bright Académie. Despite opposition, Arago completely Arago, Dominique-François-Jean 21 backed Fresnel’s theory, which was in direct pay Daguerre and Niepce’s son for the rest of their conflict with the better-known corpuscular the- lives to continue their work on the process. By ory of light, in which light is made up of parti- 1874 the highly developed plates and solutions cles, as explained by SIR ISAAC NEWTON. Thanks were capable of taking pictures at the very fast rate in part to Arago’s belief in Fresnel’s theories, of 1/25 of a second, and astronomer Pierre-Jules- they were finally proven to be correct. César Jannsen (1824–1907), codiscoverer of he- In 1820 Arago became one of many scien- lium in 1868, took the first series of continuous tists who became enthralled with the newly photographs of the transit of Venus. Before the published theory of electromagnetism. Arago end of the century, cinematography was created took simple steps to create an experiment in from this same technology. which he ran a current through a wire and at- The discovery of Neptune, in 1846, is as tracted iron filings to the current, creating the tied to Arago as it is to JOHN COUCH ADAMS, first electromagnet. His next major interest was Sir George Airy, and URBAIN-JEAN-JOSEPH LE in sound waves. In 1822 Arago worked with VERRIER. Arago suspected in 1845 that the Gaspard de Prony in a cannon-firing experi- anomalies in Uranus’s orbit were cause by an as- ment to attempt to determine how fast sound yet-undiscovered planet. Arago assigned the task traveled through air. of finding the planet to LeVerrier, who published In 1824 Arago experimented with suspend- his papers before Adams and won credit for the ing a magnetized needle above a copper disk, and new planet, which Arago participated in nam- noticed that when the copper moved, the nee- ing. When the great scandal took place over the dle moved. This was the basis for Faraday’s 1831 ownership of discovery, all of France, especially discovery of electromagnetic induction. The fol- Arago, staunchly defended LeVerrier’s claim. lowing year, in 1825, Arago was awarded the Arago’s work with light and optics con- Royal Society Copley Medal, and his experi- tributed to the creation of instruments that en- mentation continued, this time taking him into abled photographic study of planets and stars, the realm of compressing gases. His early work, and the ability to begin to measure their color along with that of Faraday and others, con- and radiation. Measuring and comparing the tributed to the foundation of work that contin- brightness of stars through photometry was a ued until 1906, which identified the critical theory first introduced in 1729 by Pierre Bouguer temperature that would liquefy each of the in his paper Essai d’optique sur la gradation de la permanent gases. lumière.SIR JOHN FREDERICK WILLIAM HERSCHEL Arago’s active interest in scientific discovery was the first astronomer to create a photometer, had far-reaching consequences. In 1816 Nicéphor in 1836, and although improvements were made Niepce started work on a solution to making light- during the next decade, many problems re- sensitive chemicals that would create a permanent mained with the glass, or the prisms, and the photograph, which he originally wanted to use for methods used to work the photometer. In 1850 lithography. Ten years later, Niepce created a so- Arago’s knowledge of polarization led to the lution that worked on an eight-hour exposure. He solution when he suggested using a single object invited the French painter Louis Daguerre to join glass and two Nicol prisms as a basis for him, and when Niepce died in 1833, Daguerre comparing brightness. Astronomers EDWARD continued the work. Eventually he began to use CHARLES PICKERING (1846–1919) and Karl silver iodide and mercury vapor on the plate, with Friedrich Zöllner (1800–60) made a slight ad- a hyposulphite of soda solution. Arago stepped in justment of the prisms and glass, and by 1860 and insisted, in 1839, that the French government the photometer was perfected. Zöllner then 22 Aratus of Soli began using the instrument for a new purpose, and year to year, plus the description of the paths to measure the light reflected by planets. that were traveled in orbit, were all explained The matter of light waves was one that mathematically in an elaborate scheme of spheres stayed with Arago throughout his lifetime. In within spheres, each system of spheres inde- 1838 he worked on the theory of an experiment pendent of the others. involving the comparison of the speed of light Aratus of Soli was not an astronomer or a through air versus water versus glass, but there scientist as we would classify these roles today, were problems actually conducting the experi- but his contribution to astronomy was one of the ment. In 1850 experimentation could finally be- greatest from ancient times, and had an impact gin, but Arago’s age and failing eyesight meant on the works of Hipparchus and, eventually, that his colleagues Léon Foucault and Hippolyte PTOLEMY, centuries later. Fizeau would have to carry out the work. Based Aratus was a Stoic who lived at the court of on his specifications, the two proved his theory the Stoic king, Antigonus Gonatus of Macedonia. of light, in which the velocity of light decreases It is estimated that sometime around 270 B.C.E., as it passes through a denser medium. Arago died Aratus wrote the poem Phaenomena, which ex- shortly thereafter. plained the work of Eudoxus, not in detailed During his lifetime, Arago became a politi- mathematical terms, but rather in simple verse, cal figure campaigning for liberal reform in the making the information more accessible to French government. He was appointed as minis- everyone. This document gave the positions of ter of war and marine, and is credited for elimi- the stars, their risings and settings, and descrip- nating slavery throughout the colonies. He has tions of 44 constellations, all under the pretense been honored for his lifetime contribution to sci- of a poem. ence in many ways. Several Parisian streets bare Hipparchos was the next astronomer to his name, and he is one of 72 scientists com- work with Aratus’s poem, in the first century memorated with a plaque in the Eiffel Tower. B.C.E. The next great astronomer to come along, The Moon and Mars each have a crater named Ptolemy, also used the text as a basis for his Arago. work, and expanded the number of constellations to 48. Phaenomena was considered such an impor- ᨳ Aratus of Soli tant work that it transcended time. It was trans- (ca. 315–ca. 245 B.C.E.) lated from Greek into Latin and remained one Greek of the predominate textbooks on astronomy well Writer into the 16th century.

Prior to the famous publication of Phaenomena, by Aratus of Soli, the texts of astronomy in an- ᨳ Argelander, Friedrich Wilhelm August cient Greece were mostly concerned with ex- (1799–1875) planations of the spherical nature of the homo- German centric system, as detailed by Eudoxus of Cnidos, Astronomer who died approximately 35 years before Aratus was born. The ordering of the heavens and the This 19th-century German astronomer investi- nature of their movement in relationship to the gated variable stars and compiled a major tele- Earth and Sun, the reasoning behind why the scopic (but prephotography) survey of all the stars stars moved from east to west, month to month, in the Northern Hemisphere brighter than the Argelander, Friedrich Wilhelm August 23 ninth magnitude. From 1859 to 1862 Argelander was completed in 1832. This beautiful and ver- published the four-volume star catalog entitled satile observatory served as the model for the Bonner Durchmusterung (Bonn survey), an amaz- Pulkovo Observatory constructed by Friedrich ing compendium containing more than 324,000 Georg Wilhelm von Struve (1793–1864) near stars. St. Petersburg (Leningrad) for use as the major Friedrich Argelander was born on March 22, observatory of the Imperial Russian Empire. 1799, in the Baltic port of Memel, East Prussia Argelander summarized his work on stellar (now Klaipeda, Lithuania). His father was a motions in the 1837 book About the Proper wealthy Finnish merchant and his mother a Motion of the Solar System. His work in Helsinki German. He studied at the University of ended in 1837 when Bonn University in his na- Königsberg in Prussia, where he was one of tive Prussia offered him a professorship in as- FRIEDRICH WILHELM BESSEL’s most outstanding tronomy that he could not refuse. The offer in- students. In 1820 Argelander decided to pursue cluded construction of a new observatory at astronomy as a career after becoming Bessel’s as- Bonn, financed by the German crown prince sistant at the Königsberg Observatory. Friedrich Wilhelm IV (1795–1861), who be- Argelander received his Ph.D. in astronomy came king in 1840. Argelander was a personal in 1822 from the University of Königsberg. His friend of Friedrich Wilhelm IV, having offered doctoral dissertation involved a critical review the crown prince refuge in his own home in of the celestial observations made by John Memel, following Napoleon’s defeat of the Flamsteed. Argelander’s academic research in- Prussian army in 1806. terest in assessing the observational quality of The new observatory in Bonn was inau- earlier star catalogs so influenced his later gurated in 1845. From then on, Argelander professional activities that the hardworking as- devoted himself to the development and pub- tronomer would eventually develop Bonner lication of his famous star catalog, Bonner Durchmusterung, his own great catalog of Northern Durchmusterung, which was published between Hemisphere stars. 1859 and 1862. Argelander and his assistants In 1823 Bessel’s letter of recommendation worked very hard measuring the position and helped Argelander secure a position as an ob- brightness of 324,198 stars in order to compile server at the newly established Turku (Åbo) the largest and most comprehensive star cata- Observatory in southwestern Finland (then an log ever produced without the assistance of autonomous grand duchy within the Imperial photography. Argelander’s enormous work Russian Empire). Here, the young astronomer listed all the stars observable in the Northern poured his energies into the study of stellar mo- Hemisphere down to the 9th magnitude. In tions. Unfortunately, a great fire in September 1863 Argelander founded the Astronomische 1827 totally destroyed Turku, the former capital Gesellschaft (Astronomical Society), whose mis- of Finland, halting Argelander’s work at the ob- sion was to continue his work by developing a servatory. Following this catastrophe, the entire complete celestial survey using the cooperation university community moved from Turku to the of observers throughout Europe. new Finnish capital at Helsinki. Friedrich Argelander died in Bonn on In 1828 the university promoted Argelander February 17, 1875. His assistant and succes- to the rank of professor of astronomy and also sor, Eduard Schönfeld (1828–91), extended gave him the task of designing and constructing Argelander’s astronomical legacy into the skies a new observatory. Argelander found a suitable of the Southern Hemisphere by adding an- site on a hill south of Helsinki and construction other 133,659 stars. Schönfeld’s own efforts 24 Aristarchus of Samos ended in 1886, but other astronomers continued without the benefit of instruments or trigonom- Argelander’s quest. In 1914 the Cordoba etry. He calculated that the Sun was 20 times Durchmusterung (Cordoba Survey) appeared, the size of the Moon, and 20 times as far from containing the position of 578,802 Southern the Earth as the Moon. Through modern as- Hemisphere stars measured down to the 10th tronomy we know that his calculations were off magnitude, as mapped from the Córdoba obser- by an order of magnitude, but the fact that he vatory in Argentina. This effort completed the was even able to make this kind of measurement huge systematic (pre-astrophotography) survey was of great importance to science. of stars begun by Bessel and his hardworking as- Through the writings of the Roman archi- sistant Argelander nearly a century before. tect Vitruvius (90–20 B.C.E.), we get some indication of Aristarchus’s importance in this field of study. He mentions Aristarchus among ᨳ Aristarchus of Samos others in acknowledging their contribution (ca. 320–ca. 250 B.C.E.) to mathematical principles and inventions Greek (Aristarchus is also credited for inventing a Mathematician, Astronomer bowl-shaped sundial). It is through the works of Archimedes In the mid-1600s, NICOLAS COPERNICUS revealed (287–12 B.C.E.) and Plutarch (45–125) that his revolutionary idea of a heliocentric universe. Aristarchus’s theory of a heliocentric system can While Copernicus remains one of the most be found. While a critic of Aristarchus’s notion renowned astronomers of all time, it was the that the Sun, not the Earth, is the center of the Greek astronomer and mathematician Aristarchus, universe, Archimedes makes it clear that born on the island of Samos, who first intro- Aristarchus gets the credit for being the first to duced the concept that the Earth revolved propose such an idea, as well as the first to sug- around the Sun, some 17 centuries before gest that the universe is enormous, much larger Copernicus was born. than ever believed. Plutarch’s writings show that Little has been found through the ages about Aristarchus also believed that, despite how it Aristarchus’s work. It is believed that he studied might appear that the stars rotate around the under Strato of Lampsacus at ARISTOTLE’s Lyceum Earth, the truth was actually that the Earth in Alexandria, sometime after 287 B.C.E. Several rotated on its axis. authors of other treatises have referred to his work, Aristarchus’s work was key in introducing giving some historical perspective on his contri- the concept of mathematical astronomy. Like bution to both astronomy and mathematics, as many astronomers in the centuries to come, this well as the opinions of his work during the time. student of the cosmos suffered from criticism The only remaining text found to date writ- that his outrageous theories denied both math- ten by Aristarchus is a document entitled ematical and religious known “truths.” Treatise on the Sizes and Distances of the Sun and Moon. The significance of this piece has noth- ᨳ Aristotle ing to do with whether the Sun or the Earth is (384–322 B.C.E.) the center of the universe, but rather with the Greek fact that he reasoned, through mathematics and Philosopher observation of reflected sunlight on the surface of the Moon, a method to determine the rela- Aristotle’s approach to astronomy differed little tionships between the Moon, Earth, and Sun from his approach to all of the other fields of Aristotle 25 knowledge he pursued. He looked at everything, of the Academy. Dedicated to learning, he be- including the universe, as an organism. His ideas gan a personal journey of acquiring and collect- on the order of the heavens were just a small ing knowledge, writing down his observations part of the volumes he amassed for the purpose and thoughts on topics ranging from biology and of teaching, and like the rest of Aristotle’s phi- zoology, to logic and politics. He left Athens and losophy, his views on astronomy went unchal- traveled first to Assos, where he married Pythias, lenged for centuries. the niece and adopted daughter of the ruler The son of a medical doctor named Hermias of Atarneus, and had a daughter also Nicomachus and his wife Phaestis, Aristotle was named Pythias. He went on to Lesbos, then to born in 384 B.C.E. in the northern Greek city of Macedonia in 343, staying at the court of King Stagirus. As the son of a physician, Aristotle was Philip, son of Amyntas III. During his stay in destined to learn about organisms and how liv- Macedonia, Aristotle endured the death of his ing beings worked, because the practice of med- wife, and eventually met Herpyllis, with whom icine at the time was handed down from father he had a son, Nicomachus. When internal po- to son as sacred, secret knowledge. But his par- litical problems arose, Aristotle supported the ents died when he was about 10 years old, and views of Philip’s son, Alexander, who soon be- his travels and instruction with his father, who came King Alexander the Great. Alexander was the personal physician to Amyntas III, the supported the works of the university, and asked king of Macedonia, came to an end. Aristotle Aristotle to start another university of his own was thereafter raised and educated in rhetoric, in Athens. poetry, writing, and Greek by Proxenus of In 335 B.C.E. Aristotle founded the Lyceum, Atarneus. bringing with him all of the writing he had ac- By the time Aristotle was 17, he was ready cumulated over the years. The Lyceum became for higher education, and went to study at the famous for its teachings and discussions, which institution that PLATO founded 20 years earlier, often took place between students and instruc- the Academy in Athens, named after the Greek tors as they walked around the school, causing landowner Academus. Eudoxus (ca. 400–347 it to be referred to as the Peripatetic school, B.C.E.) was acting head of the university when meaning “walking about.” Plato traveled for political purposes, giving Aristotle believed that “a man could not Aristotle direct exposure to Eudoxus’s work. claim to know a subject unless he was capable Aristotle’s philosophy soon began to be no- of transmitting his knowledge to others, and he ticed, and Plato consistently referred to his fa- regarded teaching as the proper manifestation of mous student as “the intelligence of the knowledge.” Aristotle’s knowledge, in addition school.” to politics, psychology, economics, logic, zoology, Aristotle’s primary philosophy was based ethics, poetry, rhetoric, and theology, included in nature, and he believed that everything astronomy, meteorology, chemistry, geography, could easily, and logically, be explained through physics, and metaphysics, many of which did not observation. It was this application of logic to exist as fields of study until he created them. his observations that made it possible for There were some underlying philosophical Aristotle to devise such convincing explana- concepts that led to his overall view of how the tions that his ideas became intellectually irre- universe worked; and the logic that he imple- proachable. mented and applied to all science had to follow. In 347 B.C.E., upon Plato’s death, Aristotle First, Aristotle was a theoretical scientist. His was not named to succeed his teacher as the head ideas were based on philosophical speculation, 26 Aristotle never on scientific measurement, and were ter, there were now 55 concentric spheres, all at- somewhat guided by the knowledge and culture tached, all rotating at different velocities, work- of the time. His place was to give these theories ing in the complex way that an organism works. a sense of order. Additionally, Aristotle did not Aristotle also used this system to explain why believe in the mathematical concept of “infi- stars twinkled. It was the movement of the nite.” Logic prevailed, and he ordered astronomy spheres, he concluded, that caused friction and around the fact that the universe was finite. heated the air around a star, “particularly in the His works On the Heavens and On Physics part where the sun is attached to it,” and that were two of the main texts concerning Aristotle’s friction explained why a star shines. order of the universe. Having studied under To address the issue of motion, Aristotle cre- Eudoxus, Aristotle expounded on the work of his ated another explanation. Since everything that teacher regarding the spherical definition of the is in motion has to be set in motion, Aristotle planets, Earth, Moon, Sun, and stars. He be- created the existence of a Prime Mover, respon- lieved that all of these were shaped like spheres, sible for the initial movement of all of nature. and that all existed in spheres, because spheres He argued that this Prime Mover exists in the are the perfect shape. It was in fact logical, and outermost sphere of the universe, that it causes became common knowledge, that the Earth was the circular motion, which is perfect because it a sphere, based on the arch of the shadow of a has no beginning and no end, and that this ac- lunar eclipse, and the appearance of new stars in tivity because of its perfection is the highest form the horizon as one walked north. of joy. Since the universe is finite, nothing ex- Unlike Eudoxus, however, Aristotle be- ists beyond the limits of the universe, and since lieved that these spheres actually physically ex- everything is an organism, this highest degree of isted. The heavens, he said, were divided into life in the cosmos must reside in the sphere of two distinct parts. Everything below the Moon, the aether. in the subluminary sphere, contained the four In the 13th century, the medieval theologian elements of earth, air, fire, and water, and this Thomas Aquinas (1225–74) found translations was the part of the universe where all change of Aristotle’s teaching notes on astronomy, and occurred, accounting for the existence of convinced the church to use this work as the growth, maturity, corruption, death, and decay. basis for explaining Christianity. When the Everything above the Moon, however, ex- church adopted these philosophies as the foun- isted in a pure, unchanging, eternal quintes- dation for the structure of the universe to ex- sence, or fifth element, which he called aether. plain heaven and God, it became the word of In these spheres, the heavens were in constant God, and questioning Aristotle was tanta- spherical movement, and they never stopped or mount to questioning God. This is what got changed because change did not exist. This GALILEO GALILEI in trouble, and is, in part, caused two problems. First, additional spheres what kept Aristotle’s work unchallenged for had to be added to make the whole system work, 2,000 years. and second, there was an issue with the logic of Most of Aristotle’s writings published dur- motion. ing his lifetime are lost. Only quoted fragments Aristotle changed the spherical layout remain in the work of others. The writings that Eudoxus had devised by adding 22 more spheres do exist from Aristotle consist of his lecture to explain how the motion of some of the spheres notes from courses at the Lyceum, more than worked in a way that would not interfere with 2,000 pages, although it is generally believed the motion of others. With the Earth at the cen- that at least some of this material has been added Arrhenius, Svante August 27 to by other teachers, students, and translators over the centuries. In 323 Alexander the Great died, and politics again caused Aristotle to leave Athens. He moved to his mother’s family estate in Chalcis, and died the following year, 322, at the age of 62. Aristotle is now a crater on the Moon.

ᨳ Arrhenius, Svante August (1859–1927) Swedish Chemist, Exobiologist

Years ahead of his time, Svante August Arrhenius was the pioneering physical chemist who won the 1903 Nobel Prize in chemistry for a brilliant idea that his conservative doctoral dissertation committee barely approved in 1884. His wide- ranging talents anticipated such Space Age scientific disciplines as planetary science and exobiology. In 1895 Arrhenius became the first scientist to formally associate the presence of “heat trapping” gases, such as carbon dioxide, in In 1908 the Nobel laureate Svante August Arrhenius a planet’s atmosphere with the greenhouse ef- introduced the panspermia hypothesis when he published his book Worlds in the Making. His fect. Then, early in the 20th century, he caused hypothesis was a bold speculation that life could another scientific commotion when he boldly spread through outer space from planet to planet by speculated about how life might spread from the diffusion of spores, bacteria, or other planet to planet and might even be abundant microorganisms. He was also one of the first scientists to anticipate global warming issues, when he throughout the universe. presented a paper at the end of the 19th century that Arrhenius was born on February 19, 1859, discussed the role of carbon dioxide as a heat- in the town of Vik, Sweden, on the University trapping gas in Earth’s atmosphere. (Elliot V. Fry, of Uppsala’s estates, to Carolina Christina courtesy AIP Emilio Segrè Visual Archives) Thunberg and Svante Gustaf Arrhenius, a land surveyor responsible for managing the estates. His uncle, Johan Arrhenius, was a well-respected interest in mathematics and physics. Upon grad- professor of botany and rector of the Agricul- uation in 1876, he entered the University of tural High School near Uppsala who also served Uppsala, where he studied mathematics, chem- as the secretary of the Swedish Academy of istry, and physics. He earned his bachelor’s Agriculture. degree from the university in 1878, and con- In 1860 Arrhenius’s family moved to tinued his studies there for an additional three Uppsala. While a student at the Cathedral years as a graduate student. However, Arrhenius School, he demonstrated his aptitude for arith- encountered professors at the University of metical calculations and developed a great Uppsala who dwelled in what he felt was too 28 Arrhenius, Svante August conservative a technical environment and who theory quite differently than did his doctoral would not support his innovative doctoral re- committee. It awarded Arrhenius the 1903 search topic involving the electrical conduc- Nobel Prize in chemistry “in recognition of the tivity of solutions. So in 1881 he went to extraordinary services he has rendered to the ad- Stockholm to perform his dissertation research vancement of chemistry by his electrolytic the- in absentia under Professor Eric Edlund at the ory of dissociation.” At the awards ceremony in Physical Institute of the Swedish Academy of Stockholm, he met another free-spirited genius, Sciences. Marie Curie (1867–1934), who shared the 1903 In this more favorable research environment, Nobel Prize in physics with her husband, Pierre Arrhenius pursued his scientific quest to answer Curie (1859–1906), and A. Henri Becquerel the mystery in chemistry of why a solution of salt- (1852–1908) for the codiscovery of radioactiv- water conducts electricity when neither salt nor ity. Certainly, 1903 was an interesting and chal- water do by themselves. His brilliant hunch was lenging year for the members of the Nobel Prize “ions”—that is, electrolytes that when dissolved selection committee. Arrhenius’s great discovery in water split or dissociate into electrically oppo- shattered conventional wisdom in both physics site positive and negative ions. In 1884 he pre- and chemistry, while Marie Curie’s pioneering sented this scientific breakthrough in his thesis, radiochemistry discoveries forced the committee “Recherches sur la conductibilité galvanique des élec- to include her as a recipient, making her the first trolytes” (“Investigations on the galvanic conduc- woman to receive the prestigious award. tivity of electrolytes”). But, the revolutionary In 1905 Arrhenius retired from his profes- nature of Arrhenius’s ionic theory simply over- sorship in physics and accepted a position as the whelmed the orthodox thinkers on the doctoral director of the newly created Nobel Institute of committee at the University of Uppsala. They Physical Chemistry in Stockholm—a position just barely passed him, giving his thesis the expressly tailored by the Swedish Academy of equivalent of a blackball fourth-class rank and Sciences to accommodate his wide-ranging declaring only that his work was “not without technical interests. That same year, he married merit.” his second wife, Maria Johansson, who bore him Undeterred, Arrhenius accepted his doc- two daughters and a son. toral degree, continued to promote his new ionic Soon a large number of collaborators came theory, visited other innovative minds through- to the Nobel Institute of Physical Chemistry out Europe, and explored new areas of science from all over Sweden and numerous other coun- that intrigued him. For example, in 1887 he tries. The institute’s creative environment al- worked with LUDWIG BOLTZMANN in Graz, lowed Arrhenius to spread his many ideas far and Austria. In 1891 Arrhenius accepted a position wide. Throughout his life, he took a very lively as a lecturer in physics at the Stockholms interest in various branches of physics and chem- Högskola, Stockholm’s Technical University. In istry and published many influential books, in- Stockholm in 1894, he married his first wife, cluding Textbook of Theoretical Electrochemistry Sofia Rudeck, his student and assistant. The fol- (1900), Textbook of Cosmic Physics (1903), lowing year, he received a promotion to profes- Theories of Chemistry (1906), and Theories of sor in physics and the newly married couple had Solutions (1912). a son, Olev Wilhelm. But his first marriage was In 1895 Arrhenius boldly ventured into the a brief one, ending in divorce in 1896. fields of climatology, geophysics, and even plan- The Nobel Prize committee viewed the etary science, when he presented an interesting quality of Arrhenius’s pioneering work in ionic paper to the Stockholm Physical Society.Titled Aryabhata 29 “On the Influence of Carbonic Acid in the Air Faraday Medal. He remained intellectually ac- upon the Temperature of the Ground,” the pa- tive as the director of the Nobel Institute of per anticipated by decades contemporary con- Physical Chemistry until his death in Stockholm cerns about the greenhouse effect and the rising on October 2, 1927. carbon dioxide (carbonic acid) content in Earth’s atmosphere. In the article, Arrhenius argued that variations in trace atmospheric constituents, es- ᨳ Aryabhata (Aryabhata I, pecially carbon dioxide, could greatly influence Aryabhata the Elder) Earth’s overall heat (energy) budget. (476–550) During the next 10 years, Arrhenius con- Indian tinued his pioneering work on the effects of car- Mathematician, Astronomer bon dioxide on climate, including his concern about rising levels of anthropogenic (human- Born in India in 476, Aryabhata is considered caused) carbon dioxide emissions. He summa- to be one of the most brilliant original rized his major thoughts on the issue in his 1903 thinkers in mathematics and astronomy, mak- book Lehrbuch der kosmichen Physik (Textbook of ing computations and explaining the nature of cosmic physics)—an interesting work for plane- our solar system some 1,000 years before tary science and Earth system science, scientific NICOLAS COPERNICUS suggested the heliocen- disciplines that did not yet exist. tric system. A few years later, in 1908, Arrhenius pub- The exact years of Aryabhata’s birth and lished the first of several of his popular techni- death are fixed from 476 to 550, but the loca- cal books, Worlds in the Making. In this book, he tion of his birthplace has never been determined describes the “hot-house theory” (now called the with any consensus. Drawing conclusions from greenhouse effect) of the atmosphere. He was texts others have written about him, many ex- especially interested in explaining how high- perts believe he was born in Kerala or one of a latitude temperature changes could promote the number of other cities in southern India. Some onset of the ice ages and interglacial periods. believe he was born in Bengal in the northeast, In Worlds in the Making, he also introduced while others suspect that it was Pataliputra in his “panspermia” hypothesis—a bold speculation the north, or the more common assumption of that life could be spread through outer space Kusumapura, which is thought to be current-day from planet to planet or even from star system Patna, but even the exact location of this an- to star system, by the diffusion of spores, bacte- cient city is unclear. ria, or other microorganisms. It is agreed, however, that Aryabhata did In 1901 he was elected to the Swedish most, if not all, of his work in Kusumapura, one Academy of Sciences despite lingering academic of the mathematical capitals of India, and that opposition in Sweden to his internationally rec- around the year 499 he wrote the Aryabhatiya, ognized achievements in physical chemistry. The the only surviving text of several he is believed Royal Society of London awarded him the Davy to have written concerning astronomy. The Medal in 1902, and in 1911 elected him as a for- Aryabhatiya is written in 121 verses, or couplets, eign member. That same year, during a visit to on mathematics and astronomy. The first sec- the United States, he received the first Willard tion is an introduction to some of the mathe- Gibbs Medal from the American Chemical matics in the document. The next collection of Society. Finally, in 1914 the British Chemical 33 verses covers algebra, trigonometry, frac- Society presented him with its prestigious tions, and equations, and includes the accurate 30 Aryabhata estimate of the value of pi, which he concluded Moon, he explains solar and lunar eclipses. He was 62732/20000, or 3.1416. The remainder of also determined that the Moon revolves around the text focuses on the heavens. the Earth. All of Aryabhata’s work was done be- Aryabhata’s astronomy is one of many firsts. fore the invention of the telescope. He is the first to describe the Earth as a sphere, There is an ancient Sanskrit saying that and as a planet that rotates about its axis. It is there are suns in all directions. Another suggests this rotation, he explains, that makes the night that when our Sun “sinks below the horizon, a sky appear to move above us. thousand suns take its place.” It is likely that His work also looks at the relationships be- Aryabhata’s original work led to this very early tween the Sun, the Earth, and the Moon. He is understanding by Indian astronomers that our the first to compute the ratio between lunar Sun is in fact a star. orbits and rotations of the Earth, and also to Aryabhata’s work was originally written in calculate the length of the solar orbit. In meas- Sanskrit, and Aryabhatiya was finally translated uring time, Aryabhata determined that the into Latin toward the end of the 13th century, length of a year is 365 days, six hours, 12 min- making its way to Europe, where its biggest im- utes, 30 seconds, an extremely close calcula- pact was on mathematicians. By this time, as- tion to the modern standard of 365 days, six tronomers were already familiar with the work hours. of Copernicus, so Aryabhata’s text was not con- Much of his work concerns the Moon. sidered groundbreaking. Aryabhata explains the phases of the Moon, In honor of his magnificent original work in which he says result from the shadows of the the field of astronomy, the first Indian satellite Earth, and using this same concept of shadows was named after him, and a crater on the Moon and the proximity of the Earth, the Sun, and the carries the name of Aryabhata.

Soon after beginning work at Hamburg, ᨳ Baade, Wilhelm Heinrich Walter Baade made his first major discovery, that of an (1893–1960) unusual asteroid he named Hidalgo, which has American the largest known orbit of any asteroid. He had Astronomer already started to get attention from the astro- German-born American astronomer Walter Baade nomical community, and was invited to the made a name for himself many times over for Mount Wilson Observatory in California for a his significant contributions to the understand- one-year visit through a Rockefeller fellowship. ing of the universe. He collaborated with Swiss Upon his return to Germany, he urged that stud- astronomer FRITZ ZWICKY on supernovae and ies should be done in the Southern Hemisphere neutron stars, and with Rudolf Leo Bernhard rather than competing with the United States Minkowski on radio sources as they pertained to in Northern Hemisphere astronomy. He was par- Cygnus A and others. But it was taking advan- ticularly interested in studying variable stars. tage of wartime blackouts and peering into When Bernhard V. Schmidt (1879–1935), Andromeda that led to his greatest discoveries, an accomplished optical specialist who made tel- in which he determined through new classifi- escopic mirrors, joined the staff at Hamburg in cations of stars that the galaxy was twice as big 1926, Baade made another contribution to the and twice as old as scientists had previously field. Schmidt joined him in a 1929 expedition imagined. to the Philippines, and Baade suggested that the Baade was born in Schröttinghausen, astronomical community really needed a good Germany, on March 24, 1893. He began his aberration-free wide-field camera. The cameras higher education at the University of Münster, used at the time were not precise enough for and obtained his Ph.D. in astrophysics from astronomers to make any accurate estimates, in the University of Göttingen in 1919. Through Baade’s opinion. Schmidt set upon the task im- the 1920s and into the early 1930s, he worked mediately after returning to Hamburg, and on staff at the Hamburg Observatory where, de- created the Schmidt camera in 1930, which spite the less-than-ideal instruments he had to ultimately replaced all of the old-technology work with, he began studying comets, star portrait lenses previously used in astronomy, clusters and variable stars, minor planets, and providing astronomers with clear, sharp images galaxies. for study.

31 32 Baade, Wilhelm Heinrich Walter By 1931 Baade made his next big move. He himself prohibited from getting involved in mil- left Hamburg to immigrate to the United States, itary research. During World War II, blackouts securing a position at Mount Wilson Observatory. were frequent enough in Los Angeles that Baade This was the first Carnegie observatory built, was able to use the 100-inch Hooker telescope and it housed the historic 60-inch reflecting to focus on the center of the Andromeda Galaxy. telescope, which was completed in 1909, plus Classified as M31, Andromeda was first recorded the world’s largest telescope, the 100-inch, by the Persian astronomer Abd-al-Rahman al- which was completed in 1918. EDWIN POWELL Sufi (903–986) who called it “little cloud,” but HUBBLE had used this telescope to make his dis- its discovery was credited to Simon Marius covery of the expanding universe. It was here (1573–1624) in 1612 by the French astronomer that Baade peered into the night sky to study CHARLES MESSIER, who was the first astronomer spiral galaxies, especially the Andromeda to view the galaxy through a telescope, and cat- Galaxy (M31). alogued it as the 31st nonstar object in 1774. Baade’s collaborators over the next several Baade became the first astronomer of record to years included Swiss astronomer Fritz Zwicky. In study the galaxy. 1934 the two collaborated on their theories and During his observations, Baade focused his announced that neutron stars and cosmic rays attention on variable stars, both eruptive vari- were the result of supernovae. ables, and a special kind of pulsating variable— Baade’s interest in finding the center of the the Cepheid variables. First discovered in Milky Way Galaxy began in earnest in 1937. He 1784 by a 19-year-old English astronomer, John expanded his work to include observations of Goodricke (1764–86), Cepheid variable stars are the Sculptor and Fornax dwarf galaxies with yellow supergiants that expand and contract in Hubble in 1939, and searched for the central star a pulsating fashion. The pulsating is not only an of the Crab Nebula, which he ultimately identi- expansion and contraction of the physical size fied as having resulted from the supernova of 1054. of the star, but also of the star’s brightness or lu- By the 1940s Baade discovered a window of minosity. The time it takes to go through a puls- opportunity to gather data on our galaxy. The ing cycle depends on the star’s density—longer Milky Way had proved difficult to penetrate for a giant star with low density, and shorter for because it was so obscured by cosmic dust. But a smaller star with high density. The North Baade made a discovery near the center of the Star, Polaris, is a Cepheid variable that takes a Galaxy, finding an area, which he called a win- little less than four days to go through a pulsing dow, that contained relatively little opaque dust, cycle. allowing observers to peer inside. This region In 1912 an astronomer at Harvard, HENRIETTA contains millions of visible stars, and is viewed SWAN LEAVITT, was examining 25 Cepheid vari- through what is now called Baade’s Window to ables that she discovered in the Small Mag- study the composition and design of the Milky ellanic Cloud, and found that there is a rela- Way. Baade’s interest in spiral galaxies turned to- tionship between the stars’ luminosity and its ward the Andromeda Galaxy. period of pulsation—stars that appear to be In 1941 the United States went to war. brighter have longer periods of light variation. Many of Baade’s colleagues were helping with During the same time that Leavitt made her dis- the war effort, but Baade, a German-born im- coveries, HARLOW SHAPLEY had concluded that migrant who had intended to file for U.S. citi- Cepheid variables could be used to calculate dis- zenship but with his busy schedule and his distance. Based on his conclusions, Shapley was like of bureaucracy let his papers expire, found involved in a famous debate in 1920 with HEBER Baade, Wilhelm Heinrich Walter 33

DOUST CURTIS over the size of the galaxy, which Another of Baade’s major discoveries in- at that time was synonymous with the size of volved another type of variable star—the erup- the universe. The score on this issue was finally tive variable. This kind of star has an unpre- settled some years later by Hubble. dictable outburst—or, more rarely, a decrease—in Baade’s work in 1941 allowed him to make its luminosity. A nova is an eruptive variable. a remarkable discovery about the variable stars Nova, which means “new,” describes a star that is he saw and expand the ever-evolving ideas about very hot and very small. Because of its size, a nova the state of the universe. He realized that there has such a low luminosity that it cannot be seen were two kinds of Cepheid variable stars in by the naked eye. It suddenly flares up to thou- Andromeda. The younger, whitish-blue stars sands of times its luminosity, often resulting in ex- found in the spiral arms he called Population I ploding fragments of itself hurtling through space. stars. The older, reddish stars, found in the core When the star flares up to this kind of brightness, of the galaxy, became known as Population II it appears to suddenly burst into the night sky. stars. During the next decade, Baade was able to The ancient Chinese astronomers, called them identify more than 300 Cepheid variables, and “guest stars” because they suddenly just show up. he categorized these stars into two types. This A nova can take years or decades to return information was significant. to its original luminosity, and its course can be The Cepheid variables in the arms of the charted as a light curve. Another eruptive Andromeda Galaxy were found to be four times star is the supernova, and it is a far more rare brighter than their counterparts. Hubble had phenomenon than the nova. The most famous previously used only the older stars to estimate are the Supernova of 1054, and Tycho’s Star in the age of the universe based on the equipment 1572, viewed in the constellation Cassiopeia by he had at the time for observation, and he de- the Renaissance astronomer TYCHO BRAHE, who termined that Andromeda was 800,000 light- named it Stella Nova. Baade took a look at an- years away, and the universe was approximately other star that had appeared to have undergone 1 billion light-years in size. But with Baade’s a nova reaction in 1604 in Serpens, which discovery of two kinds of Cepheid variables, JOHANNES KEPLER and GALILEO GALILEI had with differing factors of brightness, using both witnessed. Studying the star’s light curve, and Population I and Population II stars for compu- using the photographic capability of the 100- tations allowed the astronomer to determine inch telescope, Baade set out searching for evi- that Andromeda was actually 2 million light- dence and he soon found it in fragments of the years away. It followed that other galaxies were star’s explosion. The discovery made this the also farther away, twice as far as had been orig- third famous supernova in recorded history. inally calculated. Suddenly, the size of the uni- The next big event came in 1944, again verse had increased by a magnitude of two. using the 100-inch reflector. Baade found the And so, too, the age of the galaxy doubled, to center of the Andromeda Nebula, and its two approximately 10 billion years old. companion galaxies M32 and NGC205, two of This had an impact back home in the the four small cluster galaxies in the spiral Milky Way. Baade suggested that data about Andromeda Galaxy. This was a feat that many Andromeda’s spiral nature could be applied to were anticipating with the upcoming completion our own galaxy. And he suggested a search for of the 200-inch telescope, still under construc- new cluster variables in the Magellanic Clouds, tion at Palomar, and one that had been consid- which he urged to be studied from the new ered impossible with the current equipment. It 1.5-meter reflector telescope in Argentina. was a major victory for Baade. 34 Barnard, Edward Emerson Baade’s career came full circle with the dis- little in writing, “he ‘publishes’ his data by con- covery of another asteroid in 1949. As unique versations in his office with the world’s as- as his first, this new asteroid was both an Earth- tronomers,” adding that Baade “is one of the grazer, because of its close proximity of a mere most prolific of our staff.” 4,000,000 miles in its orbit from Earth, and an After his retirement, Baade went to Australia Apollo-object, because it passes the Sun by a dis- for six months and studied the center of the tance of just 17,700,000 miles during its 1.12 Milky Way on a 74-inch telescope at the Mount year orbit. Baade named this asteroid after the Stromlo Observatory in Canberra. The follow- Greek mythic character Icarus, whose wax wings ing year, he returned to Göttingen to accept a melted and cost him his life when he flew too position as Gauss professor, bringing his astro- close to the Sun. nomical career full circle. Plagued with hip trou- Prior to 1952, astronomers had argued that ble for many years, Baade underwent surgery to radio sources were coming from distant galaxies. take care of the problem, and died of respira- In fact, they were right, but it took Baade, in tory failure, a complication from the surgery, on collaboration with Minkowski, to prove them so. June 25, 1960. His work, finally in preparation Centaurus A was discovered on August 4, 1826, for publication, is now in the hands of the by James Dunlop (1793–1848) and described in Mount Wilson, Palomar, and Leiden observato- detail in 1849 by SIR JOHN FREDERICK WILLIAM ries. In honor of his contributions to astronomy, HERSCHEL, but basically ignored by the astro- lunar crater Baade was named for him, and the nomical community until 1949 when an 80- Magellan I telescope has been renamed the Walter foot radio antenna erected in Dover Heights, Baade Telescope. Australia, was used by astronomers John Bolton, G. Stanley, and Bruce Slee, who became the first to identify it as a radio galaxy. By 1954 Baade ᨳ Barnard, Edward Emerson and Minkowski had begun a new project of (1857–1923) systematically surveying the positions of radio American sources with the new 200-inch telescope at the Astronomer Palomar Observatory. They needed optical identification, and they got it. The two visually con- A Nashville, Tennessee, native son born into firmed that Centaurus A was truly a galaxy. In extreme poverty, Edward Emerson Barnard ex- addition to making visual identifications of the celled in astronomy against all odds through his radio source from this galaxy, they identified oth- intelligence, perseverance, and dedication to the ers as well, including Cassiopeia A, Cygnus A, field, and became recognized as one of the great- Perseus A, and Virgo A. est astronomers of the late 19th and early 20th Baade was awarded the Royal Astronomical centuries. Gifted with uncanny eyesight, great Society Gold Medal in 1954, and the prestigious photographic skills, and exceptional powers of Bruce Medal in 1955. He continued his work at observation, Barnard discovered 16 comets, a Mount Wilson until 1958, and said later that he moon, a couple hundred nebulae, some binary “greatly regretted” his retirement. Baade’s publi- stars, and a namesake star, and was a pioneer in cations were few, considering the enormous con- astrophotography, using wide-angle photography tributions he made to science, and this fact was to record stars, comets, nebulae, and the Milky noted, and yet accepted, by his colleagues, one Way. For his extraordinary work and contribu- of whom, a former executive at Carnegie Institute, tions, he gained both fortune and international explained that while Baade had published very fame during his lifetime. Barnard, Edward Emerson 35 Barnard was born in Nashville, Tennessee, to make astronomy a profession, and advised when the Union army had control of the city that he should just stick with it as a hobby. Many during the Civil War. His father died before he years later, Barnard confessed that he left the was born, leaving Barnard’s mother destitute. meeting with Newcomb, found a secluded spot Unable to afford schooling for her son, she ed- behind the state capitol building, and cried. ucated him herself until he was nine years old, Fortunately, he did not heed Newcomb’s and was finally able to scrimp together enough advice. He continued to peer into space, and money to send him to school. But after just two began to record his thoughts about planetary months, the depth of their poverty hit home, observation in 1880 in a little book he wrote, and with no child labor laws in place, Barnard but never published, about Mars. Then came was forced to quit school and get a job to help news about a lucrative, although unconven- support them. He found work at a photography tional, way to generate income in astronomy. gallery manning a solar enlarger, a device that H. H. Warner, a wealthy astronomy patron from tracks the sun to make photographic prints. His Rochester, New York, announced that he would job was to manually position the enlarger to keep give $200 to anyone who discovered a new it pointed directly at the Sun on sunny days. comet. Barnard jumped at the opportunity, and In 1876 the book The Practical Astronomer made his first new comet discovery through his was given to him by a friend as a gift for a favor five-inch telescope in 1881. As a newlywed, he had done, and Barnard was suddenly intro- Barnard used the money from the discovery of duced to the field that would become his life’s comet 1881 VI, as it was named, as a down pay- work. Aided by a coworker, James W. Braid, ment to build a house for his bride, Rhoda Barnard built his first telescope out of a card- Calvert. board tube and a broken glass lens they found Later that year he was offered a job at the on the street. He later recalled in his writings Mount Hamilton Lick Observatory, near San that looking through this homemade telescope Jose, California, taking inventory of the prop- “filled my soul with enthusiasm when I detected erty. He worked during the day and anticipated the larger lunar mountains and craters, and the opportunity to make important observations caught a glimpse of one of the moons of Jupiter.” with the big 36-inch telescope at night, for He was inspired enough that he decided to in- which he traveled west. But Edward Holden vest $380 the following year to buy a five-inch (1846–1914), the observatory’s director, had refracting telescope. This amounted to two- grand ideas of his own, assigning himself two thirds of his entire salary for the year. nights a week on the apparatus while giving two Armed with his new investment, Barnard other astronomers, S. W. Burnham and James was presented with another exciting opportunity Keeler, two nights each, leaving one night open in 1877, when the American Association for the for the public and leaving Barnard out of the Advancement of Science (AAAS) held its an- loop. If Barnard wanted to do any observations, nual meeting in Nashville. Buoyed by his love it would have to be on the 12-inch refractor in for the field, an excited Barnard sought out the the observatory’s other dome, which he had to AAAS president, SIMON NEWCOMB, hoping to share with the other astronomers, or on his own get some solid advice on how to become a pro- telescope. fessional astronomer. When Newcomb heard Holden’s newfound desire for personal fame that Barnard had no formal education and led him to decide to produce a pictorial atlas of no mathematical background, he allegedly told the Moon, and he wanted Barnard to help Barnard that there was no opportunity for him develop his pictures. Upon discovering that 36 Barnard, Edward Emerson Holden’s pictures were for the most part out of Barnard’s interest in Mars was never far from focus and of very poor quality, Barnard instead his mind, and in 1892 he had the opportunity rigged up a camera on the observatory’s inex- to observe it at opposition. But the timing was pensive six-inch telescope and started tracking cursed with poor viewing conditions that meant comets. His pictures were extremely well fo- he could only use magnifications of 350x or less cused. In 1892 he made the first photographic on the 36-inch telescope, making it nearly im- discovery of a new comet. With such clear pic- possible to record any visual observations. tures, he began photographically recording the Undaunted, he waited for the next opportunity Milky Way and, as with his early days at the in 1894, and he began making observations three photography gallery using the solar enlarger, it months before opposition, in July. By September, demanded that he keep the telescope pointed he was using magnifications of 1000x, observing exactly at its target for hours at a time while it from sunset to sunrise, and recording in his notes tracked the night sky. that he “failed to see any of Schiaparelli’s canals Barnard did get some use out of the 12-inch as straight narrow lines,” adding that even “un- telescope at Lick, and began to observe Jupiter der the best conditions,” they “could never be that same year, noting that the moon Io ap- taken for the so-called canals.” He was certain peared to him darker at the poles and lighter at there was nothing artificial on the Martian the equator. This took amazing eyesight and landscape. focused observation to see with such limited By 1895, despite his growing public acclaim, equipment, and it was not until bigger telescopes Barnard was getting nowhere with Holden. The were developed in the 1900s that his observations president refused to publish any of Barnard’s about Io were confirmed. stunning Milky Way photographs, and when the From 1888 to 1892, Barnard did not get to disillusioned Barnard was presented with an- use the 36-inch telescope. But that was about to other opportunity to further his contributions to change. Holden was alienating the staff, and his field, he took it. The University of Chicago Burnham decided to leave the observatory. was surpassing the Lick Observatory by building Barnard jumped at the opening on the telescope, a 40-inch refracting telescope at the new Yerkes asking the regents to let him have the time pre- Observatory, and they wanted Barnard to join viously allocated to Burnham. Within three them as a professor of practical astronomy. short months, in September 1892 Barnard made True to form, Barnard and his wife moved a discovery that propelled him into instant to Chicago nearly a year before the Yerkes ob- fame. While looking at Jupiter’s four moons, dis- servatory was finished, and he began working at covered by GALILEO GALILEI in 1610, he found the Kenwood Observatory for GEORGE ELLERY that the planet actually had five moons. His dis- HALE, who was designated to become the direc- covery of Jupiter’s fifth moon, Amalthea, on the tor at Yerkes. This time, Barnard also had his 36-inch telescope, made him an instant portfolio of photographs to work on from the celebrity. Today, Jupiter is known to have 60 Lick Observatory, which he was preparing to moons and is predicted to have 100 or so, the publish as an atlas, as well as his continued ob- most recent 43 of which were discovered at the servations of the Milky Way, comets, and nebu- University of Hawaii by physics professor David lae, while he waited for construction of Yerkes C. Jewitt and graduate student Scott S. Sheppard, to be completed. using the 3.6-meter (approximately 140-inch) In 1897 Barnard and his wife moved to Canada-France-Hawaii telescope atop Mauna Yerkes in Williams Bay, Wisconsin, and he was Kea—a far cry from Barnard’s 36-inch variety. joined on staff by his old colleague Burnham Barnard, Edward Emerson 37 from the Lick Observatory, where the two research he was overseeing at the Mount Wilson worked with Hale to compare observations Observatory in California, so the telescope, and between the Yerkes 40-inch refractor and the Barnard, were shipped to California for several 36-inch from Lick. During their tests, Barnard’s months to gather visual data that was not pos- observational skills, coupled with the great sible at the altitudes at Yerkes. Here, Barnard power of the new telescope, led to his discovery continued his photographic discovery of the that Vega was actually a double star. Milky Way for about seven months before In May Barnard and Hale’s assistant returning to Wisconsin. Ferdinand Ellerman were scheduled to observe In May 1916, while looking at a new pho- nebulae one evening using the 40-inch refrac- tographic plate he had taken, Barnard discovered tor. At around 12:45 A.M., the men heard a noise a star that he could not find when he compared when they raised the elevated floor, but they it to another plate he took in August of 1894. could not figure out the source of the sound. However, there was a star at a different location After two and a half hours of observation, on the 1894 plate that was not on the 1916 plate. Barnard uncharacteristically cut short his typi- He compared the two to a third plate taken in cal all-night observation. Soon after the two 1904, and found that neither star was on the 1 men left the building, the 37 ⁄2-ton floor’s sup- 1904 plate, but there was another star that was porting cable broke, and the floor crashed to the located about half the distance between the two. ground, exploding into a heap of rubble. Barnard had discovered a new star.A red dwarf, Burning with a passion to collect the best Barnard’s Star has the largest proper motion of photographic data of the galaxy, Barnard so- any known star, at 10.3 arcsecond per year as licited a $7,000 grant in 1897 from another New compared to the typical rate of about 1 arcsec- York astronomy patron, Catherine W. Bruce ond, and is the fourth closest star to our system, (1816–1900). With Bruce’s gift, Barnard over- after the three Alpha Centauri stars, at 1.821 saw the creation of a new five-inch telescope parsecs. on which he had mounted two photographic Barnard spent a total of 28 years at Yerkes, 1 doublets of a 6 ⁄4-inch and 10-inch aperture. lecturing, researching, photographing, and writ- Barnard’s unbending determination in getting ing. In 1897 the Royal Astronomical Society of the widest photographic field and the shortest Great Britain awarded him the gold medal for relative focus caused multiple delays in the com- his photographic work with the six-inch tele- pletion of the telescope, which took until 1904. scope at Lick. In 1917 he was awarded the Bruce In the meantime, he continued observations Medal. He is the only faculty member at throughout the night at Yerkes, sometimes to his Vanderbilt University to have a building named own detriment in the cold Wisconsin winters. after him, and after his death in 1923, the Barnard was known for getting completely lost Barnard Astronomical Society was founded in in his work, so it was not too surprising when his honor in Chattanooga, Tennessee. His home one particularly cold Wisconsin night he did at Yerkes was deeded to the university upon his not realize that his nose had frozen stuck to the wife’s death, and it remains today as the resi- eyepiece of the telescope. dence of the director of the observatory. By the time the new Bruce five-inch pho- Barnard discovered nearly 200 nebulae in tographic telescope was finally completed in his lifetime, published more than 900 articles, 1904, a small wooden observatory with a 15-foot and created more than 4,000 photographic dome was built for it near Barnard’s home. Soon, plates of the Milky Way. He was the first to Hale wanted to put the telescope to use on solar discover a comet with photography, and the 38 al-Battani last to discover a moon visually. His life’s work, Al-Battani was born in about 858, in the Photographic Atlas of Selected Regions of the Milky ancient town of Harran, located in northern Way, was published after his death by the Mesopotamia some 44 kilometers southeast of University of Chicago Press. His belief that the modern Turkish city of Anliufra. His full sleep was a complete waste of time, along with Arab name is Abu Abdullah Mohammad ibn his dedication to observation, earned him the Jabir ibn Sinan al-Raqqi al-Harrani al-Sabi title as the man who never sleeps, and he was al-Battani, which later European medieval universally recognized as one of the greatest and scholars who wrote exclusively in Latin changed most prolific observers ever to work in the field to Albategnius. His father, Jabir ibn Sinan al- of astronomy. Harrani, was an astronomical instrument maker and a member of the Sabian sect, a religious group of star worshippers in Harran. So al- ᨳ al-Battani (Abu Abdullah Mohammad Battani’s lifelong interest in astronomy probably ibn Jabir ibn Sinan al-Raqqi al-Harrani started at his father’s knee in early childhood. al-Sabi al-Battani, Albategnius) Al-Battani’s contributions to astronomy are best (ca. 858–929) appreciated within the context of history. At this Arab time, Islamic armies were spreading through Astronomer, Mathematician Egypt and Syria and westward along the shores of the Mediterranean Sea. Muslim conquests in Al-Battani (Latinized name: Albategnius) is the eastern Mediterranean resulted in the cap- regarded as the best and most famous astronomer ture of ancient libraries, such as the famous one of medieval Islam. As a skilled naked-eye ob- in Alexandria, Egypt. Ruling caliphs began to server he refined the sets of solar, lunar, and plan- recognize the value of many of these ancient etary motion data found in PTOLEMY’s great work, manuscripts and so they ordered Arab scribes to The Almagest, with more accurate measurements. translate any ancient document that came into Centuries after his death, these improved obser- their possession. vations, as contained in his compendium, Kitab By fortunate circumstance, while the Roman al-Zij, worked their way into the Renaissance Empire was starting to collapse in western and exerted influence on many western European Europe, Nestorian Christians busied themselves astronomers and astrologers alike. Al-Battani preserving and archiving Syrian-language trans- and his fellow Muslim stargazers preserved and lations of many early Greek books. Caliph refined the geocentric cosmology of the early Harun al-Rashid ordered his scribes to purchase Greeks. all available translations of these Greek manu- Though al-Battani was a devout follower of scripts. His son and successor, Caliph al- Ptolemy’s geocentric cosmology, his precise ob- Ma’mun, who ruled between 813 and 833, went servational data encouraged NICOLAS COPERNICUS a step beyond. As part of his peace treaty with to pursue heliocentric cosmology—the stimulus the Byzantine emperor, Caliph al-Ma’mun was for the great scientific revolution of the 16th and to receive a number of early Greek manuscripts 17th centuries. Al-Battani was also an innova- annually. tive mathematician who introduced the use of One of these tribute books turned out to trigonometry in observational astronomy. In be Ptolemy’s great synthesis of ancient Greek 880 he produced a major star catalog (the Kitab astronomical learning. When translated, it be- al-Zij) and refined the length of the year to came widely known by its Arabic name, The approximately 365.24 days. Almagest (or “the greatness”). So the legacy of al-Battani 39 geocentric cosmology from ancient Greece explain the physics behind this discrepancy. They narrowly survived the collapse of the Roman would first need to use heliocentric cosmology Empire and the ensuing Dark Ages in western to appreciate why the Sun’s apparent (measured) Europe by taking refuge in the great astronomi- diameter kept changing throughout the year as cal observatories of medieval Islam as found in Earth traveled along its slightly eccentric orbit Baghdad, Damascus, and elsewhere. around the Sun. Second, the Sun’s annual ap- But Arab astronomers, like al-Battani, did parent journey through the signs of the zodiac not just accept the astronomical data presented corresponded to positions noted by the early by Ptolemy. They busied themselves checking Greek astronomers. But because of the phe- these earlier observations and often made im- nomenon of precession (the subtle wobbling of portant refinements using improved instruments, Earth’s spin axis), this correspondence no longer including the astrolabe, and more sophisticated took place in al-Battani’s time—nor does it to- mathematics. History indicates that al-Battani day. As al-Battani looked out from Earth, he was a far better observer than any of his con- noticed that when the Sun’s apparent diameter temporaries. Yet, collectively these Arab astro- was smallest, it did not occur where the great nomers participated in a golden era of naked-eye star master Ptolemy said it was supposed to. But astronomy enhanced by the influx of ancient without the benefit of a wobbling Earth model Greek knowledge, mathematical concepts from (to explain precession) and heliocentric cos- India, and religious needs. For example, Arab as- mology (to explain the variation in the Sun’s tronomers refined solar methods of timekeeping apparent diameter) it was clearly impossible for so Islamic clergymen would know precisely when him, or any other follower of Ptolemy, to appre- to call the faithful to daily prayer. ciate the true scientific significance of what he Al-Battani worked mainly in ar-Raqqah, discovered. and also in Antioch (both now located in mod- Al-Battani’s precise observations also al- ern Syria). Ar-Raqqah was an ancient Roman lowed him to improve Ptolemy’s measurement city along the Euphrates River, just west of where of the obliquity of the ecliptic—that is, the an- it joins the Balikh River at Harran. Like other gle between Earth’s equator and the plane de- Arab astronomers, he essentially followed the fined by the apparent annual path of the Sun writings of Ptolemy and devoted himself to re- against fixed star background. He also made fining and improving the data contained in The careful measurements of when the vernal and Almagest. While following this approach, he autumnal equinoxes took place. These observa- made a very important discovery concerning the tions allowed him to determine the length of a motion of the aphelion point—that is, the point year to be about 365.24 days. The accuracy of at which Earth is farthest from the Sun in its an- al-Battani’s work helped the German Jesuit nual orbit. He noticed that the position at which mathematician Christopher Clavius (1537–1612) the apparent diameter of the Sun appeared reform the Julian calendar and allowed Pope smallest was no longer located where Ptolemy Gregory XIII (1502–85) to replace it in 1582 said it should be with respect to the fixed stars with the new Gregorian calendar that now of the ancient Greek zodiac. Al-Battani’s data serves much of the world as the international were precise, so he definitely encountered a sig- civil calendar. nificant discrepancy with the observations of While al-Battani was making his astronom- Ptolemy and early Greek astronomers. But nei- ical observations between the years 878 and ther al-Battani nor any other astronomer who 918, he became interested in some of the new adhered to Ptolemy’s geocentric cosmology could mathematical concepts other Arab scholars 40 Bayer, Johannes were discovering in India. Perhaps al-Battani’s eventually became a lawyer and the city’s legal greatest contribution to Arab astronomy was his adviser. As analytical as his chosen profession introduction of the use of trigonometry, espe- was, his interest in astronomy allowed him to cially spherical trigonometric functions, to re- integrate both his analytical mind and his aes- place Ptolemy’s geometrical methods of calcu- thetic talents, as evidenced by his artistic and lating celestial positions. This contribution meticulously accurate book. allowed Muslim astronomers to use some of the Printed in 1603 by the 31-year-old Bayer, most complicated mathematics known in the Uranometria was considered the first modern at- world up to that time. las of the constellations. Devised to give as- Al-Battani died in 929 in Qar al-Jiss (now tronomers a precise guide to the stars, his atlas in modern Iraq) on a homeward journey from was a combination of beautiful plates of the con- Baghdad. His contributions to astronomy constellations plus technical data regarding their po- tinued for many centuries after his death. For sitions and brightness. example, medieval astronomers became quite The atlas included many firsts. Instead of familiar with Albategnius, primarily through a using PTOLEMY’s original 48 constellations, Bayer 12th-century Latin translation of his Kitab used the star calculations compiled by TYCHO al-Zij, renamed De motu stellarum (On stellar BRAHE and JOHANNES KEPLER, which they had motion). The invention of the printing press published only one year prior to Bayer’s book, in 1436 by Johann Gutenberg soon made it and which included more than 700 stars. practical to publish and widely circulate the Uranometria was also the first book to include Latin translation. This occurred in 1537 in the 12 new Southern Hemisphere constellations Nuremberg, Germany—just in time for the of Apus, Chamaeleon, Dorado, Grus, Hydrus, centuries-old precise observations of al-Battani Indus, Musca (also called Apis), Pavo, Phoenix, to spark interest in some of the puzzling astro- Triangulum Australe, Tucana, and Volans, orig- nomical questions that spawned the scientific inally discovered and catalogued by the 16th- revolution. century Dutch navigator Pietr Dirksz Keyser. The book took a new artistic path as well. Rather than using woodcuts, the star maps were done ᨳ Bayer, Johannes (Johann) as large, detailed engravings. And despite the (1572–1625) fact that they were presented as beautiful art, German Bayer never lost sight of the fact that the plates Lawyer, Astronomer (Amateur) and the accompanying tables were first and foremost meant to be accurate maps. For a man whose work in astronomy was con- The most important feature of Bayer’s atlas ducted purely as a hobby while he made his liv- was the system he created to name and classify ing as a lawyer, the Bavarian-born Johann Bayer the stars, using lowercase Greek letters followed made one of the most important contributions by the plural Latin name of the constellation. to the field of astronomy when he published his He designated the brightest star of a constella- star atlas, Uranometria. tion with the first letter in the Greek alphabet, Little is known about Bayer’s early life. His making it the alpha star. The remaining letters formal education began with an interest in of the Greek alphabet were used in decreasing philosophy at the university in Ingolstadt, order to indicate each star’s brightness within a Germany, but he switched schools and changed constellation, making the brightest star alpha, his focus to study law at Augsburg, where he the second brightest beta, and so on. Under this Beg, Muhammed Taragai Ulugh 41 system, the brightest star in the constellation and trading capital. When Beg was 16, his father Centaurus became Alpha Centauri. This nomen- turned over leadership of the Mawaraunnahr clature was printed in tables, along with de- region to him, giving him control of, among scriptions and positions of the stars, used in other cities, Samarkand. conjunction with the engraved charts. The learned Beg was a gifted poet and Bayer’s classifications were modified some- historian, and a Hafiz, one who could recite the what in 1725, when the British astronomer John Qur’an by heart. But despite the legacy left by Flamsteed created a numbering system that indi- his grandfather, Beg was not afflicted with a cated a star’s position from west to east. In 1774 desire to conquer. Instead, his intentions were CHARLES MESSIER expanded on and devised his to further the study of science, particularly own system when he began cataloging nebulae mathematics and astronomy. and galaxies. And in 1843 FRIEDRICH WILHELM Beg’s interest in astronomy reportedly came AUGUST ARGELANDER released Uranometria Nova, about from a visit to the ruins of the Maragheh a new, updated version of the atlas, in homage observatory, the workplace of the famous as- to the work done by Bayer nearly two and half tronomer Nas ir al-Din Tusi (1201–74), who centuries earlier. authored nearly 150 books and translated the The International Astronomical Union, great works of the ancients, including Archimedes, founded in 1919, picked up where Bayer and his Euclid, and PTOLEMY. In 1271 al-Tusi wrote the successors left off, regulating star classifications Zij-i Ilkhani, also known as the famous Ilkhan as more and more stars become visible with the Tablets, a compilation of tables of planetary aid of modern technology. For his contribution orbits. through Uranometria, Bayer’s work became the In pursuit of his desire to turn Samarkand foundation of today’s star classifications, and the into a leading educational center, Beg ordered standard to which star atlases have been held for the building of a madrasah, an institution for more than 400 years. higher learning, in 1417. When construction was completed in 1420, the facilities opened with approximately 70 of the leading scientists ᨳ Beg, Muhammed Taragai Ulugh of the day participating in the most advanced (ca. 1393–1449) research, observations, discussions, and lectures. Persian Surrounded by great minds, and an accom- Mathematician, Astronomer plished astronomer in his own right, Beg’s vision for furthering scientific study grew into a plan The mathematician and astronomer Ulugh Beg to build a massive observatory. In 1428 con- was by birthright a Persian prince, son of Shah struction began on a great circular building that Rukh, and grandson of the Mongol conqueror was three stories high and more than 50 meters Timur, who amassed a great empire, including in diameter. The combination of the huge ob- parts of modern-day Iran, Iraq, Turkey, Syria, and servatory and the brilliant minds working at India. Married around age 10, Beg tended to his the madrasah on important observations made princely duties under his father’s rule, and be- Samarkand the world capital for major astro- came even more active in his role after his grand- nomical study at the time. father’s death in battle in 1405. In 1409 Shah Beg was the first in recorded history to Rukh moved the seat of his empire to present- develop the concept of permanently mounting day western Afghanistan, and set out to make astronomical instruments in a building. His ob- the chosen city of Herat a cultural, educational, servatory included an armillary sphere, a device 42 Bell Burnell, Susan Jocelyn that consisted of spherical rings used to model After Beg’s death the city of Samarkand the shapes and positions of celestial spheres eventually lost its status as a leading educational and to help identify the position of the stars; a center. The observatory fell to ruins and was left marble sextant, known as the Fakhri sextant, for virtually untouched until excavated by Russian observing stars and planets and measuring their archaeologists in 1908. Beg’s fully-clothed body declinations; and a quadrant that measured stel- was discovered in 1941 in a mausoleum in lar and planetary altitudes. The quadrant was so Samarkand, buried at the foot of his grandfather’s massive that the ground had to be excavated to tomb. The importance of the clothing indicates bring the piece of equipment into the building that Beg’s people considered him a martyr. for installation. Today, the observatory at Samarkand is an Inspired, perhaps, by the writings of al-Tusi, archaeological site consisting of the building’s Beg is also credited with the creation of his own foundation and part of the sextant, plus a small zij, which is an astronomical compilation con- museum in honor of Beg. Using the Latin spelling taining tables for calculating current positions of his name, the lunar crater Ulugh Beigh has and predicting the future positions of celestial been named in his honor. bodies. Beg’s Zij-i Sultani (Catalog of the stars), was published in 1437, and included the names and positions of approximately 1,000 stars (the ᨳ Bell Burnell, Susan Jocelyn reported number varies from 992 to 1,018 to (1943– ) 1,022), plus calendar information, an explana- Irish tion of the methods and uses of astronomical ob- Radio Astronomer, Astrophysicist servations, a description of the movements of the Sun, the Moon, and the planets, a treatise Born and raised in Belfast, Northern Ireland, on astrology, and trigonometry tables of sines near the Armagh Observatory, Jocelyn Bell took and tangents that are accurate to eight decimal an interest in astronomy during her early teenage places. Beg calculated the length of a year as 365 years. As an accomplished astronomer, Bell is days, five hours, 49 minutes, 15 seconds—less known for her discovery of “little green men” than one minute off today’s measurement. (or LGM, as she nicknamed them), more com- Beg’s Zij was the first major star compila- monly known as pulsars. tion since Ptolemy’s work around the year 170. Bell’s family strongly encouraged her as a And despite the fact that it preceded TYCHO young girl to study her field of choice, and she BRAHE’s work, and the invention of the tele- had access to the observatory in part because of scope, by approximately 200 years, it remained her proximity to it, and in part because her fa- unknown in Europe until some 50 years after ther, an architect, had designed it. She lived in Brahe’s publications, which were so accurate a very literate household, and was serious about that they made the discovery of Beg’s writings education, although she did not pass entrance ex- inconsequential. ams to get into the British university she wanted Leadership of the family’s empire defaulted to attend, and ended up attending a boarding to Beg in 1447 when his father died. In such a school before starting her university education. political position, the scholarly Beg soon became Encouraged by radio astronomer Professor victim to another family member who had aspi- Bernard Lovell, Bell took up physics and became rations of conquest. Beg’s son, ‘Abd al-Latif, the only woman in her class of 50 at the secured the services of an assassin and had his University of Glasgow, from which she graduated father murdered by beheading in 1449. with a physics degree in 1965. She immediately Bell Burnell, Susan Jocelyn 43 went to Cambridge University to start working and the theory about extraterrestrial life fizzled on her Ph.D., and she immersed herself in build- based on the probability of the science. Odds ing an 81.5-megahertz radio telescope designed were decidedly against multiple civilizations to track quasi-stellar radio sources, or quasars. sending the same signal at the same frequency The intent of the project was to significantly im- at the same time to the same planet. Plus, when prove research in the field of radio astronomy, Bell recognized that the source changed at a rate which originally began as a field of study in the very similar to the rate of the movement of the 1950s. To that end, this new radio telescope was stars, it became clear that these signals were not massive, using more than four and a half acres artificially manufactured; in fact, they had to be of cabling and wires to connect thousands of naturally occurring phenomena. nine-foot poles. Further research proved that the radio waves With the telescope’s construction com- emulated from a special kind of rapidly spinning pleted in July 1967, Bell’s task turned toward neutron star, the dense result of an exploding star. that of a research student, operating the tele- The stars, named pulsars, for “pulsating radio scope and analyzing the data at the university’s stars,” emit signals much like beams of light from Mullard Radio Astronomy Laboratory. The ra- a lighthouse beacon sweeping across the night dio waves, which turned into signals once they sky. Only in this case, they are electromagnetic hit the telescope, were recorded on chart paper radiation combined with radio waves pulsing every four hours, spewing out 121.8 meters’ through space in regular bursts as they are thrown worth of paper, nearly 400 feet, every four days, off the rapidly spinning stars. The original pul- all of which had to be carefully studied and an- sar, dubbed LGM, was officially named CP alyzed by hand. Within a few months, the (Cambridge Pulsar) 1919. Due to naming stan- November analysis showed something different. dards, the opportunity to designate this newly Bell noticed some glitches in a length of data discovered star as Bell’s Star, as had been the that took up just 2.5 centimeters, or just under precedent in previous centuries, was completely an inch. Uncertain about what she was seeing, out of the question. Additional pulsars were soon she thought the unusual signal might be “scruff,” discovered by Bell, but the first one was, of as she called it, some sort of cosmic interference. course, the most important discovery in this She made notes and waited. newly expanded field of radio astronomy. The signals occurred again a few weeks later, For Bell’s work, her thesis adviser at and it soon became clear that she was seeing Cambridge University, ANTONY HEWISH, re- some very regular patterns: a series of fast pulses ceived the Nobel Prize in physics in 1974, the occurring exactly every 1.337 seconds, originat- first time the award was given for a discovery in ing from outside of our solar system. Excitement the field of astronomy. Controversy was on the over the discovery fueled the imagination of the heels of the Nobel announcement, since the dis- entire research group, and soon speculation was covery had clearly been made by the hard work rampant throughout the astronomical commu- and dedication of Jocelyn Bell. But research nity that the signal might be from beacons students typically do not get Nobel prizes— developed by extraterrestrials, instantly giving their professors do. Bell graciously accepted her teeth to the theory of intelligent life elsewhere fate, stating that giving it to a student could in the universe. Bell named the signal Little “demean” the prize. Green Men (LGM) and waited some more. Bell received her Ph.D. from Cambridge in As the weeks went on, more signals oc- 1968, married Martin Burnell that same year, curred, this time from other areas in the galaxy, and moved to the University of Southampton 44 Bessel, Friedrich Wilhelm to begin work on gamma-ray research, where Bessel, the credit clearly goes to physician she stayed until 1973. During her time at HEINRICH WILHELM MATTHÄUS OLBERS, an am- Southampton, she was elected to the Royal ateur astronomer who encouraged the young Astronomical Society in 1969, and eventually Bessel to develop a career devoted to astronomy. served as vice president of the organization. In The resulting good fortune for the field of as- 1973 she moved to the Mullard Space Science tronomy was the introduction of Bessel func- Laboratory at University College in London to tions, the discovery of the proper motion and work on X-ray astronomy. Nearly a decade later, location of more than 50,000 stars, and the first in 1982, she took a position to focus on infrared accurate measurement of the distance to the and optical astronomy, heading the James Clerk stars. Maxwell Telescope project in Hawaii for the Bessel began his life in Minden, Westphalia Royal Observatory in Edinburgh. (now part of Germany), living a modest life as Despite the Nobel Prize incident in 1974, one of nine children of Carl Friedrich Bessel, a Bell Burnell received many awards for her ac- government employee, and Friederike Ernestine complishments in later years. She was awarded Schrader, a pastor’s daughter. His childhood ed- the Beatrice M. Tinsley Prize in 1987 by the ucation was a brief one at the Gymnasium in American Astronomical Society and the Herschel Minden, where after four years, at the age of 14, Medal from the Royal Astronomical Society in the uninspired student quit school to work as an 1989. She redirected her career in 1991 to be- unpaid accounting apprentice for an import-ex- come a physics professor and department head at port business in the town of Bremen. This first Open University in Milton Keynes, England. She job proved to be valuable for Bessel because it won the Edinburgh Medal in 1999, and took a introduced him to the world at large, and as his leave from Open University to work as a distin- interest in other countries grew, so did his mo- guished visiting professor at Princeton University tivation to learn about them. Within a few short in 1999 and 2000. In October 2001 she accepted years, Bessel taught himself geography, English, the position of dean of science at the University Latin, Spanish, and mathematics, and he began of Bath, England. In addition to her other kudos, to study astronomy as a by-product of his inter- Bell Burnell is the recipient of the Oppenheimer est in navigation. At some point during his stud- Prize, the Michelson Medal, the Tinsley Prize, and ies, Bessel ran across calculations on Halley’s the Megallanic Premium Award. She has received Comet made by the British mathematician and honorary doctorates from universities all over the astronomer Thomas Harriot (1560–1621), who world, and dedicates a portion of her time to fur- observed the comet on September 17, 1607— thering women’s study of physics. just seven days after JOHANNES KEPLER made his observation. Using Harriot’s data, Bessel recal- culated the comet’s orbit and sent his informa- ᨳ Bessel, Friedrich Wilhelm tion to Olbers, who was considered something (Wilhelm Bessel) of an expert on comets despite his amateur sta- (1784–1846) tus in the field. German Olbers responded with praise and encour- Astronomer agement, asking Bessel to do more—make observations, do more detailed calculations—gently It is often difficult to know the exact event that pushing the 20-year-old to create a high-quality causes someone to head his life in a certain di- paper worthy of publishing. He also put Bessel rection. But in the case of Friedrich Wilhelm in communication with the noted mathematician Bessel, Friedrich Wilhelm 45 Johann Gauss (1777–1855), and the two devel- servatories, but he chose to stay at Lilenthal oped a relationship that lasted throughout until an offer came around that he could not Bessel’s life. When Bessel finally sent Olbers his refuse. completed work, Olbers recognized that the im- In 1809 Prussia’s King Frederick William pressive paper would have earned Bessel a III (1770–1840) ordered the building of a new Ph.D. if he were in a formal university setting, observatory in Königsberg (now Kaliningrad, and he advised Bessel to pursue astronomy as a Russia), and the position of director was offered profession. to the 26-year-old Bessel, along with the role The opportunity arose for Bessel to do just of teaching astronomy at Albertus University. that in 1806, when a job was offered to him as However, the uneducated Bessel needed a doc- assistant director at the private Lilenthal torate to teach at the university level, so his fa- Observatory near Bremen, owned by German mous friend and colleague Gauss offered his astronomer Johann Schroter (1745–1816). But whole-hearted recommendation, and Bessel seven years with the import-export firm had was granted a Ph.D. on the basis of his previ- given him a sense of security, not to mention a ous work from the university at Göttingen. decent salary, and Bessel had to weigh giving up With the observatory still under construction, his well-paying job for one that paid next to Bessel moved to Königsberg in May 1810 and nothing, yet was in the field he loved. Whether his career in his new home was officially it was his youth or his passion that swayed his launched when he began teaching classes that decision is unknown, but Bessel left the import- summer. Bessel stayed in Königsberg for the rest export business and never looked back. of his life. Bessel’s first order of business in his new The year 1812 marked two milestones in career was to learn the art of observation, which Bessel’s life—he married Johanna Hangen, with he did through an expertly crafted seven-foot whom he would have four children, and he was telescope built by SIR WILLIAM HERSCHEL. He elected to the Berlin Academy of Sciences. His was given the task, and the opportunity, to fo- monumental task of working on Bradley’s obser- cus his observations on the planet, rings, and vations took a great deal of time, but the fol- satellites of Saturn, and he continued observing lowing year he would become internationally comets, which always fascinated him. While ad- renowned for undertaking such an extraordinary vancing his observational skills, he devoted venture. time to furthering his knowledge of celestial In 1813 the observatory was finally ready, mechanics, a field derived from SIR ISAAC and Bessel began his job as director. His timing NEWTON’s laws of motion. to leave the Lilenthal Observatory proved to be In 1807 Bessell began delving into the very fortunate. King Frederick William III’s de- work of the third Astronomer Royal, Reverend cision in 1806 to start a war with France, in- JAMES BRADLEY, whose more than 60,000 ob- voking the wrath of the emperor Napoleon servations of heavenly bodies, made between Bonaparte (1769–1821), resulted in an attack 1748 and 1762, were published in two volumes that divided his country. In the fray, the French in 1798 and 1805, over a quarter of a century marched into Schroter’s observatory and com- after his death. Star by star, Bessell worked on pletely destroyed it and everything inside. identifying the precise locations of more than Stricken by the loss, Schroter died of apparent 3,000 stars as they appeared in 1755. As word agony two years later, in 1815—the same year got out about his work, he was offered posi- Bessel was honored for his work by the Berlin tions at both the Greifswald and Leipzig ob- Academy. 46 Bessel, Friedrich Wilhelm In 1817 Bessel started working on the prob- The first official star catalog, credited to lem of planetary perturbations—changes in PTOLEMY in the second century, consisted of their orbits—and devised a new class of math- more than 1,000 stars and was used until the ematical functions called cylindrical functions, 17th century. Bessel’s undertaking was somewhat more commonly known as Bessel functions. larger than Ptolemy’s, creating a star catalog that This type of analysis ultimately had a wider would have the proper motions and positions of application than working on planetary pertur- more than 50,000 stars. The resulting catalog of bations, and is now used in hydrodynamics and 75,011 stars would be completed by Bessel’s stu- wave theory, as well as in applied mathematics dent FRIEDRICH WILHELM AUGUST ARGELANDER, and engineering. and named Bonner Durchmusterung. The overwhelming task of defining Bradley’s While working on this extraordinary task of work was finally realized in 1818, when Bessel cataloging, Bessel focused his attention on 61 published Fundamentae Astronomiae pro Anno Cygni. Since this star had the greatest proper MDCCLV deducta ex Observationibus viri incom- motion of any star he knew, Bessel (correctly) parabilis James Bradley (Foundations of astron- thought it might mean that the star was rela- omy for the year 1755, deduced from the ob- tively close to the planet. He wanted to know servations of the incomparable man James exactly how close. Bradley). Written in Latin, the work was a thor- Accurately measuring the distance to a star ough compilation of the positions of 3,222 stars, was something that had never been accom- including proper motion and spherical astron- plished, and was in fact a task that seemed to omy theory. baffle the scientific community. In order to Bessel seemed to enjoy delving into the measure the distance, the star needed to be ob- work of the royal astronomers. Perhaps it was served from two different locations, and a trian- his induction into the Royal Society in 1825 gle formed between the two points of measure- that sparked an interest in the work of the ment and the star. The problem had been that Astronomer Royal Nevil Maskelyne (1732–1811), there were no two places on Earth that were far and his “fundamental stars.” In 1830 Bessel pub- enough apart to set up a usable triangulation to lished his work on 38 stars, of which 36 were the star. Bessel came up with the brilliant idea fundamental stars and the remaining two were of observing the star from one place on Earth polar stars, giving their mean and apparent po- when the Earth was in two different locations— sitions as they appeared between 1750 and along its path as it rotated around the Sun— 1850. While Bessel worked on this production, taking calculations of the stars position every six he became particularly interested in two of months, which he did for three years. Maskelyne’s stars, Sirius and Procyon. He would This measurement of looking at an object return to these two stars in another 14 years and from two different views, and creating a trian- achieve another milestone in his field. gle connecting the points of view and the ob- But first, he returned to one of his favorite ject, is called parallax. In 1838 Bessel an- subjects—comets. After all, it was now 1835, nounced that he had determined the distance and Halley’s Comet, which was responsible for to 61 Cygni using parallax, becoming the first getting him started in astronomy in the first astronomer to measure the parallax of a star, to place, was swinging back around in its 76-year see the motion of a star due to its parallax, and orbit, and Bessel would have the good fortune to calculate the distance to a star. The star 61 of being able to observe it. In 1836 he published Cygni, located in the constellation Cygnus the his observations in Physical Theory of Comets. Swan, was declared to be 10.3 light-years away— Bethe, Hans Albrecht 47 remarkably close to current calculations of 11.2 Bessel made numerous contributions to light-years, or 219,072,000,000 miles, from astronomy and science, and was deservedly awar- Earth. In 1841 his accomplishment was offi- ded memberships in a variety of prestigious or- cially recognized, and SIR JOHN FREDERICK ganizations, including the Royal Astronomical WILLIAM HERSCHEL congratulated him on “the Society, the Royal Meteorological Society, the greatest and most glorious triumph which prac- Berlin Academy, Palermo Academy, Stockholm tical astronomy has ever witnessed.” Bessel was Academy, and others. A star atlas, Akademische consequently awarded the Gold Medal by the Sternkarten (Academic star maps), inspired by Royal Society. Bessel, was completed 13 years after his death, Now it was time to return his attention to in 1859, through the collaboration of a number Sirius. Bessel noticed that there were inequali- of observatories. In 1935 a lunar crater was ties in the orbits of the two Dog Stars, Sirius named Bessel in his honor, and in 1938 an and Procyon. After studying them at great asteroid was given his name. length, he felt he had figured out the reason why. In 1844 he announced that their proper motions were off because they each revolved ᨳ Bethe, Hans Albrecht around another object that could not be seen (1906– ) but which had a mass similar to that of the Sun. American This hypothesis became known as “astronomy Astrophysicist of the invisible,” and was an important break from traditional astronomy, which relied upon The scientist who answered the question “Where visible observations. Bessel was proved correct do stars get their energy?” is Hans Albrecht in his theory when companion stars were dis- Bethe, born on July 2, 1906, in Strassburg, covered for Sirius in 1682 by ALVAN GRAHAM Germany (now Strasbourg, Alsace-Lorraine, CLARK while he tested an 18-inch refractor tel- France). The son of a psychologist, Bethe started escope, and for Procyon in 1896, by John school at the age of nine, attending the Schaeberle (1853–1924) using the 36-inch Lick Gymnasium in Frankfurt until 1924, then into refractor. This gave Bessel the distinction of be- higher education at the University of Frankfurt, ing the first astronomer to predict the existence where he started his studies in physics. After of “dark stars,” which in this case turned out to two years, Bethe transferred to Munich, and be white dwarf stars. in July 1928 earned his Ph.D. in theoretical Bessel was dedicated to the Königsberg ob- physics under the expert tutelage of Arnold servatory from its inception through the end Sommerfeld, a good friend of ALBERT EINSTEIN. of his life, forsaking all offers from competitive Bethe immediately began teaching after observatories, including the University of Munich—first at the University of Frankfurt, Berlin. He left on a scientific trip in 1842 to where he taught for one term, then on to the attend the Congress of the British Association University of Stuttgart, also for just one term in England, where he at long last met many until he obtained a teaching position in fall of the most famous scientists of his time. The 1929 at the University of Munich. By the trip inspired him to do more publishing, and following May, Bethe was promoted to a he published Astronomische Untersuchungen Privatdozent (lecturer), and given a fellowship (Astronomical observations) that same year. to travel by the International Education Board. After six years of declining health, Bessel died He wasted no time in setting out for Cambridge of cancer in 1846. in the fall term, and completed his fellowship 48 Bethe, Hans Albrecht travels with spring terms in Rome the follow- and British physicist Robert d’Escourt Atkinson ing two years. (1893–1981) published a paper using the newly Bethe advanced his teaching career in accepted theory of relativity and quantum me- 1932, when he became a faculty member at chanics explaining that fusion occurs in a star’s the highly regarded Tübingen University in center. Along came Bethe. In 1938, at a summit Germany, founded in 1477 and modeled after in Washington, D.C., leading physicists and as- the Renaissance methods of learning in Italy. tronomers were introduced to Bethe’s work on But his assistant professorship came to a sudden nuclear reactions. end when Adolf Hitler (1889–1945) came into Stars with a mass the size of the Sun or power and summarily fired all of the Jews in ac- smaller generate heat up to 16 million kelvins, ademic positions. Bethe, who had a Jewish burning hydrogen via the process known as the mother but did not consider himself Jewish, proton-proton chain—the fusion of hydrogen found out about his dismissal from a student who into helium. This happens in several steps. First, saw it printed in the local newspaper. Neither two hydrogen protons combine—one proton Sommerfeld nor his student Bethe could find an- turns into a neutron and in the process releases other position in Munich, so Bethe went back a positron (an electron with a positive charge), to England, this time to lecture at the University and a neutrino (which has no charge), creating of Manchester for a year, then accepting a fel- a hydrogen isotope called deuterium. The neu- lowship for the 1934 fall term at the University trino escapes, and the positron collides with an of Bristol. While he was at Bristol, Cornell electron, creating gamma rays. Next, a third hy- University, located in Ithaca, New York, con- drogen proton combines with the deuterium and tacted Bethe and offered him a position that be- produces a lightweight isotope of helium—the came the career move of a lifetime. Bethe packed helium nucleus now contains two protons and his bags and moved to the United States to one neutron, and more high-radiation gamma become an assistant professor at Cornell. The rays are released. Finally, two helium nuclei com- following year, 1935, Bethe started the project bine to produce an ordinary nucleus of helium, that would earn him a permanent place in the and releases two protons—hydrogen. The end history of astronomy. result is that six hydrogens combined to form About 20 years earlier, the British astro- one helium and two hydrogens. The mass that physicist SIR ARTHUR STANLEY EDDINGTON is lost becomes energy, which is proved by ALBERT 2 devoted a great deal of his efforts to uncover EINSTEIN’s equation E ϭ mc . the internal structure of stars. At the time, the For stars more massive than the Sun with theoretical physicist HENRY NORRIS RUSSELL temperatures exceeding 16 million kelvins, an- held the leading theory that a star’s energy was other process occurs. In this case, carbon serves generated through gravitational contraction. as a catalyst for burning hydrogen. The fusion But Eddington thought it had something to do begins with a hydrogen and carbon nucleus with radiation pressure, espousing the theory forming nitrogen. After a much more compli- that the actual energy source was from a “trans- cated combination, the carbon is converted into mutation of elements,” in other words, some sort nitrogen and oxygen, and in the end releases one of conversion of hydrogen into helium that re- helium and one carbon nucleus. Since there is sulted in an energy release. But no definitive an- the same amount of carbon in the end of the swer was found. process as the beginning, the cycle stars again. Around 1930, the collaborating team of This is known as the CNO (carbon-nitrogen- Austrian physicist Fritz Houtermans (1903–66) oxygen) cycle. Bethe, Hans Albrecht 49 Bethe’s work on nuclear reactions from 1935 and, after some consideration, he decided to join through 1938 became his most famous work, the team. Between 1943 and 1946 Bethe was and is considered one of the greatest accom- the director of the theoretical physics division plishments in science in the 20th century, with at the Los Alamos National Laboratory in Los far-reaching effects for other scientists. FRITZ Alamos, New Mexico. After the war, Bethe re- ZWICKY ran experiments that confirmed Bethe’s turned to Cornell and resumed his teaching and theories. SUBRAHMANYAN CHANDRASEKHAR cre- research. ated the Chandra limit and opened the doors to In 1947 Bethe explained an occurrence in exploring the collapse of stars, which was subse- a hydrogen atom called the Lamb shift, which quently picked up by Roger Penrose (1931– ) helped create the new field of quantum elec- and SIR STEPHEN WILLIAM HAWKING.RALPH trodynamics. He also did work involving the ASHER ALPHER, working under his doctoral ad- production via electromagnetic radiation of viser GEORGE GAMOW, created the Big Bang the- particles known as pi mesons—the lightest par- ory, determining when the universe was created ticles consisting of a quark and an antiquark. and the elements that were present in the be- The following year found Bethe as an unwill- ginning—hydrogen, helium, and lithium. Fred ing participant in the science news event of the Hoyle (born 1915), WILLIAM ALFRED FOWLER, century—the announcement of the big bang and Geoffrey and ELEANOR MARGARET PEACHEY theory. Gamow, who wanted to create the play BURBIDGE showed how the nuclear fusion in stars on words of “alpha, beta, gamma,” added Bethe’s could create the heavier elements, and how they name to Alpher’s paper on the big bang, saying are dispersed throughout the galaxy through it was authored by Alpher, Bethe, and Gamow. such events as supernovae. In 1967 Bethe re- Bethe refused to take credit for work that was ceived the acknowledgment of a lifetime when not his own. he won the Nobel Prize in physics for his work Bethe’s old friend and colleague Edward on solar and stellar energy. Teller (1908–2003) from the Manhattan Project, While Bethe was creating his amazing work, contacted Bethe in 1949, hoping to persuade he was promoted to full professor of physics at him to return to Los Alamos and work on the Cornell, and he settled in to continue on his next big project—the hydrogen bomb. Bethe path of research and discovery. Then came declined on the basis that a war fought with a World War II. hydrogen bomb would result in humankind los- Bethe was eager to contribute to the war ing “the things we were fighting for.” He did effort to help defeat Hitler. He left Cornell consult with the Los Alamos staff for about six and traveled to the Massachusetts Institute of months in 1952, and has ever since been a vocal Technology (MIT), in Cambridge, Massachusetts, opponent to the H-bomb, working throughout where he joined fellow scientists at the radiation his life for disarmament. laboratory working on microwave radar. But in In the mid-1950s Bethe began to look once summer 1942 he was invited to take part in a again at the physics of atoms and collision the- project that he initially wanted nothing to do ory, a subject he had worked on in the earlier with because he felt it was entirely too implau- days of his career. He became the president of sible. Robert Oppenheimer (1904–67) was as- the President’s Science Advisory Committee sembling the most brilliant scientific minds in from 1956 to 1959, working on the failed nego- the United States to take part in the Manhattan tiations with the Soviet Union to ban nuclear Project—an effort to design and build the first testing. In 1995 the 88-year-old professor was atomic bomb. Bethe’s participation was requested still working for the good of the planet when he 50 Bode, Johann Elert wrote an open letter calling on all of the scien- creation of several publications that were unlike tists of the world to “cease and desist from work any ever done in the field, and 43 years of serv- creating, developing, improving, and manufac- ice at Berlin’s Academy of Science. turing further nuclear weapons . . .” adding that, Bode’s scientific career began in 1768 when, as one of the few original Manhattan Project sci- at age 21, he published the first of many editions entists still alive, he viewed with “horror that to come of his textbook Anleitung zur Kenntnis tens of thousands of such weapons have been des gestirnten Himmels (Instruction for the built since that time, one hundred times more knowledge of starry heavens). In 1772 Bode be- than any of us at Los Alamos could ever have came an astronomer at Berlin’s Academy of imagined.” Science, where he stayed throughout his entire In the 1990s Bethe worked on calculating career. the maximum mass of neutron stars, and in 1994 Viewing the heavens and publishing about he was the guest of honor at a Cornell physics them were the themes for Bode’s working life. symposium entitled “Celebrating 60 Years at In 1774 he teamed up with mathematician and Cornell with Hans Bethe,” where he was de- publisher Johann Lambert (1728–77), famous scribed as the “father of nuclear physics,” and for proving that pi is immeasurable, and perhaps the “social conscience of physics.” Bethe’s career more important to Bode, the editor of an early has continued into the 21st century. He won astronomy-based almanac. The pair created one the prestigious Bruce Gold Medal from the of the first European publications dedicated Astronomical Society of the Pacific in 2001, and specifically to scientific research, an ephemeris— he remains, at the age of 98, a professor at a publication that lists data on the locations of Cornell University in New York. Between 1928 stars and other heavenly bodies for each day of and 1996 Bethe published 290 papers, and he the year. Originally named the Astronomisches continues to publish. He is the author of the Jahrbuch oder Ephemeriden (Astronomical year- book The Road from Los Alamos (1991), and the book and ephemeris), it was soon shortened to 1997 book Intermediate Quantum Mechanics, the Astronomisches Jahrbuch, and finally to Berliner cowritten with R. W. Jackiw. With the excep- Astronomisches Jahrbuch. It became an annual tion of his time at Los Alamos and a few sab- publication that was widely used by astronomers baticals to Columbia University, University of and navigators as an accurate assessment of the Cambridge, and Copenhagen, Bethe has never night skies. left his work at Cornell. With Bode’s publishing goals firmly established, he aimed his sights at the night skies and began searching for nebulae. In 1774 he made ᨳ Bode, Johann Elert his first two deep-sky discoveries, each of which (1747–1826) he referred to as a “nebulas patch” in the Ursa German Major constellation: the Spiral Galaxy M81, Astronomer which he described as “mostly round [with] a dense nucleus in the middle,” and the Irregular The self-taught German astronomer Johann Galaxy M82, also known as the Cigar Galaxy, Bode is best known for the unusual mathemati- which he considered to be “very pale” and “elon- cal formula that bears his name and explains the gated” in shape. Both are at a distance of 12 mil- relationship of planetary distances from the Sun. lion light-years (12,000 kly), and both were But his lifelong dedication to astronomy also in- found on December 31, 1774. Less than six cludes the discovery of five deep-sky objects, the weeks later, on February 3, 1775, he discovered Bode, Johann Elert 51 the Globular Cluster M53. At nearly 60 thou- of Wittenberg, Germany, became the German sand light-years (60 kly), it appeared to Bode in translator of Bonnet’s popular book. But when the “northern wing of Virgo,” looking “rather he got to the text explaining the relationship vivid and of round shape.” In 1776 Bode became between the distances of the planets, Titius the director of the Berlin Observatory. added his own formula to his translation. First, Publishing gave Bode his next big career a set of numbers is created starting with 0, then boost, when he popularized a mathematical phe- 3, then doubling each subsequent number, cre- nomenon that ultimately became known as ating the series of numbers 0, 3, 6, 12, 24, 48, Bode’s Law. The origin of the formula came from 96, 192, 384, and so on. The next step is to add David Gregory (1659–1708), a University of 4 to each number, creating the new series 4, 7, Edinburgh mathematics and astronomy profes- 10, 16, 28, 52, 100, 196, 388, and so on. The sor, who introduced the concept in his book final step is to divide this new group of num- Astronomiae physicae et geometricae elementa (The bers by 10, which results in .4, .7, 1.0, 1.6, 2.8, elements of astronomy). Printed first in Latin in 5.2, 10.0, 19.6, 38.8, etc. This last group of num- 1702, then in English in 1715, with a second bers gives the location of the known planets by printing in each language in 1726, Gregory’s their distances from the Sun in AU. Titius failed book suggested that the distances between the to note that this was his own work, and it was planets and the Sun could be assigned a simple not until his second translation of Bonnet’s mathematical value: “supposing the distance of book was printed two years later, in 1768, that the Earth from the Sun to be divided into ten he pointed this out in an added footnote, clear- equal parts, of these the distance of Mercury will ing things up. Not that it mattered. No one no- be about four, of Venus seven, of Mars fifteen, ticed the concept. of Jupiter fifty two, and that of Saturn ninety But that same year Bode’s Anleitung zur five[.]” Kenntniss des gestirnten Himmels was printed, and This is essentially the idea of the astro- it became a well-received and widely read as- nomical unit (AU), in which the distance from tronomy textbook—so much so that he revised the Earth to the Sun is 1 AU, and the distances it and reprinted it in 1772, and in this edition of the remaining planets are expressed as a he added Titius’s formula. As with his predeces- ratio. sors, Bode included the information in his own The idea resurfaced in 1724, when the book without mentioning the origin of the work. German mathematician, philosopher, and pro- But unlike the earlier authors, Bode was a much lific writer Christian Wolff (1679–1754) men- more public figure and a highly regarded as- tioned the relationships in his book Vernünfftige tronomer. So when the concept was published Gedanken von den Absichten der natürlichen Dinge. in his book, it was immediately accepted and be- It faded into obscurity for another 40 years, but came known as Bode’s Law. emerged again thanks to Swiss philosopher Since Bode’s Law gave the nearly perfect lo- Charles Bonnet (1720–93), who became famous cations of the then-known planets, Mercury at as the first to propose a scientific theory of .4 AU (actual distance is 0.39), Venus at .7 (ac- evolution. Bonnet wrote about the ratios in his tual 0.72), Earth at 1.0, Mars at 1.6 (actual 1.52), 1764 book, Contemplation de la Nature (The Jupiter at 5.2, and Saturn at 10.0 (actual 9.54), contemplation of nature), which was subse- speculation was high that there were more plan- quently translated into several languages. ets waiting to be discovered. The search was on, In 1766 Johann Titius (1729–96), astronomer, with a sense of certainty that Bode’s Law would mathematician, and professor at the University lead to new discoveries. 52 Bode, Johann Elert The next several years proved fruitful for Gottfried Koehler, who discovered the Elliptical Bode. His publishing goals were ambitious. In Galaxy M59 (60,000 kly) and the Spiral Galaxy 1777 he created a compilation of all of the known M60 (60,000 kly), Barnabas Oriani (1752–1832), nebulous stars and clusters and published it in who discovered the Spiral Galaxy M61 (60,000 Astronomisches Jahrbuch for the 1779 calendar kly) and Messier, who discovered the Globular year. Using data recorded by Johannes Hevelius Cluster M56 (nearly 33 kly) and the Spiral (1611–87), along with the catalog compiled in a Galaxy M58 (60,000 kly). All were discovered two-year journey to the Cape of Good Hope by while observing Bode’s comet. French astronomer Nicolas-Louis de Lacaille Finally, in 1781 the solar system’s seventh (1713–62), and CHARLES MESSIER’s 1771 deep- planet was found in the constellation Gemini, sky catalog, Bode created the Complete Catalogue by the amateur astronomer SIR WILLIAM of Hitherto Observed Nebulous Stars and Star HERSCHEL, located at 19.18 AU, near the 19.6 Clusters, consisting of 75 entries, many of which, AU location predicted by Bode’s Law. because of their creators’ mistakes, did not actu- In honor of Herschel’s discovery, Bode cre- ally exist. Not one to skimp on his own obser- ated a new constellation that he named vational tasks, Bode dutifully ended the year by Herschels Teleskop, depicting the instrument discovering the Globular Cluster M92 at ap- Herschel used in his momentous discovery, and proximately 26 kly, on December 27, 1777, in placed next to the constellation Auriga. the Hercules constellation. As astronomers around the world observed The Complete Catalogue of Hitherto Observed the new planet, Bode was more than happy to Nebulous Stars and Star Clusters grew by two ob- collect and print their data. During his research jects in its 1779 printing. Bode added his dis- Bode found evidence that it had actually been covery of M92, which he described as “. . . a seen at least twice before; first in 1690 by John mostly round figure with a pale glimmer of light,” Flamsteed (1646–1719), who designated it in his and his newest nebula, M64, which he found on catalog as star 34 Tauri, and again in 1756 by April 4, 1779. the German mathematician and astronomer But on March 23 the Welsh astronomer Tobias Mayer (1723–62). Edward Pigott (1753–1825) had also found the In 1782 Bode turned his attention to a new nebula, just 12 days before Bode’s discovery, al- publishing format, creating a star atlas he named though his discovery was not published until Die Gestirne. It was the third in a succession of 1781. Messier found it as well, on March 1, 1780, atlases that began in 1792, when Flamsteed and published his finding in the summer of that printed his famous Atlas coelestis in response to year. For more than two centuries, most forgot what he felt were problematic constellations in that Pigott had rightful title to the discovery, un- JOHANNES BAYER’s Uranometria. Next in line til April 2002, when it was uncovered by British came Atlas Céleste de Flamstéed, (Flamsteed’s astrophysicist Bryn Jones. Pigott and Bode are Celestial Atlas), printed in 1776, by the French now considered codiscoverers of the Spiral astronomer Jean Fortin (ca. 1750–1831) in hom- Galaxy M64. age to Flamsteed’s atlas. Bode’s was the last to Bode’s discovery of a comet in 1779— use Flamsteed’s data, although Bode did add a named C/1779 A1, 1779 Bode—led to a slew of nebulae he apparently discovered, named Bode new discoveries by other astronomers. Six new I, which today is believed to possibly be the open nebula were found, by astronomers Antoine cluster IC1434. Darquier de Pellepoix (1718–1802), who dis- With the discovery of Herschel’s planet in covered the Ring Nebula M57 (2.3 kly), Johann 1781, excitement about Bode’s Law was rekindled, Bok, Bartholomeus Jan 53 and astronomers became even more convinced Bode revised and reprinted Die Gestirne in that a planet had to exist in the gap between 1805, publishing it as Vorstellung der Gestirne Mars and Jupiter at 2.8 AU. A worldwide team (Introduction of the Luminaries). In addition to of astronomers cooperated to systematically di- the stars he added, Bode customarily revised the vide the night sky and search for the missing artwork of the constellations. This became known planet. In 1801 the Sicilian monk GIUSEPPE as the Bode-Flamsteed atlas, and includes 34 maps PIAZZI, astronomer and director of the Palermo featuring 26 constellations that Bode could see Observatory, found the next best thing to a from his observatory in Germany, plus plani- missing planet—the minor planet or asteroid spheres, hemispheres, star clusters, and nebulas. Ceres, which he named Cerere di Ferdinando A long and full career at the Berlin Observatory for the goddess of grain and the patron goddess ended after nearly 40 years when Bode retired of Sicily and for King Ferdinand, Piazzi’s pa- from his position as director in 1825. He con- tron. This was the first asteroid ever discov- tinued to publish Berliner Astronomisches Jahrbuch ered, and remains the largest known, with a di- until his death in November of 1826, just one ameter of 623 miles, compared with the year after his retirement. smallest planet, Pluto, which has a diameter of Bode’s Law was confirmed by the discovery 1,457 miles, Earth, which is 7,926 miles, and of Uranus in 1781 and the Ceres asteroid and the largest planet, Jupiter, which rolls in at subsequent asteroid belt in 1801. But when 88,700 miles. At 2.77 AU, it was nearly ex- Neptune was discovered in 1846 at 30.06 AU, actly where Bode’s Law predicted a planet where no planet should have been, the idea fell should be. from grace with the astronomical community. Never far from publishing, Bode returned Not until Pluto’s discovery in 1930, at 39.44 AU, again to the monumental task of creating a new near the predicted 38.8 distance of Bode’s Law, atlas, this time designing the biggest star atlas did it come back into favor. To this date, there ever made. Bode did not research the validity remains no explanation of why Bode’s Law works. of any information, and he did not edit any- The Spiral Galaxy M81, discovered in 1774 thing out, but rather made a compilation of all by the 25-year-old Bode, is known as Bode’s known star atlases and catalogs. The book con- Galaxy, and M82 and M81 are often referred sists of 20 double-page plates, including all of to as Bode’s Nebulae or Bode’s Galaxies. The the constellations that were ever suggested, with asteroid first discovered on August 6, 1923, Bode’s new constellations Apparatus Chemica, by Karl Wilhelm Reinmuth (1892–1979) in Custos Messium, Felis, Globus Aerostaticus, Heidelberg, Germany, was named Asteroid Honores Frederici, and Officina Typographica, Bodea, and in 1935, a crater on the Moon was none of which still exist, plus new figures for named in Bode’s honor. old constellations, more than 17,000 stars, and approximately 2,000 nebulae discovered by Herschel. The constellations were represented ᨳ Bok, Bartholomeus Jan (Bart Bok) by beautiful, stylistically new artwork, making (1906–1983) it unlike any atlas ever published. Bode’s Uran- Dutch/American ographia is considered the book that marked the Astronomer end of an era in star atlases, giving way to maps that simply connected the stars with lines, In the 1930s and 1940s this Dutch astronomer rather than depicting the constellations with conducted detailed investigations of the star- artistic figures. forming regions of the Milky Way Galaxy. He 54 Bok, Bartholomeus Jan school years he was an active amateur astronomer and became an admirer of HARLOW SHAPLEY. Upon completing high school with high honors, he entered the University of Leiden in 1924 and remained there until 1927. Leiden proved to be a stimulating environment for this young astronomer, where one of his classmates was GERARD PETER KUIPER and among his professors were ENJAR HERTZSPRUNG and JAN HENDRIK OORT. His studies at the University of Leiden provided Bok with a strong foundation in classical astronomy. In 1927 Bok went to the University of Groningen to pursue his doctoral degree. In summer 1928 Bok attended the Third General Assembly of the International Astro- nomical Union in Leiden, where two special things occurred that would greatly influence the rest of his life. First, he met Harlow Shapley, who was then director of the Harvard College Observatory. Shapley was impressed with the young Dutch astronomer and invited Bok to The Dutch-American astronomer Bart Bok at the University of Arizona’s Steward Observatory in Tucson, come the following year to do his research on the a major astronomical facility under his direction Milky Way at the Harvard College Observatory. between 1966 and 1970. Earlier in his career, he Second, Bok met and immediately fell in love discovered the small, cool (~10 kelvins) dark nebulas with the American astronomer Priscilla Fairfield now called “Bok globules” in his honor. (AIP Emilio Segrè Visual Archives, Physics Today Collection) (1896–1975). Despite the fact she was 10 years his senior, Bok decided to marry Fairfield, whom he called “the love of his life.” She eventually accepted his proposal of matrimony and they made careful studies of interstellar dust and gas were wed in Troy, New York, on September 9, and their relation with respect to star formation. 1929—just two days after Bok arrived in the In 1947 he discovered the small, near-spherical, United States to work at Harvard College dense dark nebulas, now called “Bok globules,” Observatory. that contain enough interstellar material to Bok’s marriage provided him with a founda- eventually condense into star clusters. tion upon which he could build his career as a Bartholomeus (Bart) Jan Bok was born on world-class astronomer. As an astronomer her- April 28, 1906, in Hoorn, the Netherlands, to self, Priscilla Fairfield Bok was an eager collab- Sergeant Major Jan Bok and Gesina Annetta van orator on her husband’s astronomical projects. der Lee Bok. The family moved to The Hague in As a devoted wife, she was always there to pro- 1918, where Bok attended high school. At age vide the gentle, introspective judgment needed 13 Bok knew he wanted to be an astronomer, to balance his often spontaneous and unre- having been strongly influenced in science by strained approach to new opportunities and one of his schoolteachers. Throughout his high ideas. Bok found the Harvard Observatory a Boltzmann, Ludwig 55 most exciting place to do research. The couple’s traveled to South Africa and set up a new tele- first child, a son, was born in August 1930. After scope at the Harvard Boyden Station. Bok es- conducting research at the Harvard College pecially enjoyed this opportunity to view regions Observatory, Bok successfully defended his doc- of the Milky Way and the Magellanic Clouds toral dissertation, “A Study of the Eta Carinae from Earth’s Southern Hemisphere. Region,” at the University of Groningen on July Several years after Shapley retired as direc- 6, 1932. He became an assistant professor at tor of the Harvard College Observatory, Bok re- Harvard in 1933. Later that year, the couple’s signed his professorship and departed the insti- second child, a daughter, arrived. tution he served for so many years. In January In the 1930s he performed detailed studies 1957 he and his wife went to Australia, where of the Milky Way and published an important he accepted a position as the director of the monograph, The Distribution of the Stars in Space, Mount Stromlo Observatory, near Canberra. He in 1937. The following year he became a natu- also became a professor of astronomy at the ralized citizen of the United States, and in 1939 Australian National University. Just before re- he earned a promotion to associate professor of turning to the United States in 1966, Bok helped astronomy at Harvard College Observatory. establish Australia’s Siding Spring Observatory. Starting in about 1937, Bok collaborated with When the couple returned to the United his wife to write a book called The Milky Way. States, Bok become director of the University of Five years later, the published book served as a Arizona’s Steward Observatory in Tucson and much-needed comprehensive treatment of kept that position until he retired in 1970. He galactic astronomy and became a very popular suffered a crushing blow when his wife died on work that went through five editions. As a re- November 19, 1975. He remained withdrawn for sult, this collaborative writing effort attracted several years, emerging from his self-imposed many bright young minds to the field of astron- solitude in 1977 to receive the prestigious Bruce omy. In 1946 Harlow Shapley appointed Bok as Medal of the Astronomical Society of the the associate director of the Harvard College Pacific. He resumed some of his astronomical ac- Observatory—a position he kept until Shapley tivities in the early 1980s, but died suddenly on retired in 1952. August 5, 1983, while making plans to attend Bart Bok became a full professor of astron- an upcoming astronomical conference. omy at the Harvard College Observatory in 1947. That same year he also made his most famous astronomical discovery—the small, dark, ᨳ Boltzmann, Ludwig cool (about 10 kelvins), almost circular, inter- (1844–1906) stellar clouds observable against the background Austrian of stars or luminous gas regions in the Milky Physicist Way. Because they contain enough interstellar material, these protostar regions, or “Bok glob- This brilliant, though troubled, Austrian physi- ules,” can be thought of as candidate stellar cist developed statistical mechanics and the nurseries for some of the Galaxy’s lower-mass kinetic theory of gases. His pioneering work stars. affected many areas of science, including ther- Starting in the late 1940s Bok became in- modynamics and astronomy. In the 1870s volved in the process of establishing new obser- and 1880s Boltzmann collaborated with JOSEF vatories in different parts of the world. For STEFAN in creating an important physical prin- example, in February 1950 he and his family ciple, now called the Stefan-Boltzmann Law, 56 Boltzmann, Ludwig mercurial personality that would swing him suddenly from intellectual contentment into a deep depression. His academic appointments included the University of Graz (1869–73; 1876 –79); the University of Vienna (1873–76; 1894–1900; 1902–06); the University of Munich (1889–93), and the University of Leipzig (1900 –02). On the positive side, his movement from institution to institution brought him into contact with many great 19th-century scientists, including ROBERT WILHELM BUNSEN, RUDOLF JULIUS EMMANUEL CLAUSIUS, and GUSTAF ROBERT KIRCHHOFF. Boltzmann was a popular lecturer and entertained diverse academic interests that encompassed physics, mathematics, chemistry, and philosophy. As a physicist, he is best remembered for his invention of statistical mechanics and its pioneering application in thermodynamics. His the- In the 1870s and 1880s Ludwig Boltzmann, the oretical work helped scientists connect the prop- brilliant Austrian physicist, collaborated with his mentor, Josef Stefan, to create the Stefan-Boltzmann erties and behavior of individual atoms and law—an important physical principle now used by molecules (viewed statistically on the micro- astronomers and astrophysicists to relate the total scopic level) to the bulk properties and physical radiant energy output (or luminosity) of a star to the behavior (such as temperature and pressure) that fourth power of its absolute temperature. (University of Vienna, courtesy of AIP Emilio Segrè Visual Archives) a substance displayed when examined on the familiar macroscopic level used in classical thermodynamics. One key to this development was Boltzmann’s equipartition of energy principle. It that relates the total radiant energy output (or stated that the total energy of an atom or mol- luminosity) of a star to the fourth power of its ecule is equally distributed, on an average basis, absolute temperature. over its various translational kinetic energy Ludwig Boltzmann was born on February 20, modes. Boltzmann postulated that each energy 1844, in Vienna, Austria. His father was a gov- mode had a corresponding degree of freedom. He ernment official involved in taxation. He further theorized that the average translational studied at the University of Vienna, earning a energy of a particle in an ideal gas was propor- doctoral degree in physics in 1866. His disserta- tional to the absolute temperature of the gas. tion was supervised by Stefan and involved the This principle provided an important connec- kinetic theory of gases. Following graduation, tion between the microscopic behavior of an in- Boltzmann joined his academic adviser as an credibly large number of atoms or molecules and assistant at the university. macroscopic physical behavior (such as temper- Starting in 1869 he held a series of profes- ature) that physicists could easily measure. The sorships in mathematics or physics at a number constant of proportionality in this relationship of European universities. Boltzmann’s physical is now called Boltzmann’s constant, for which restlessness mirrored the hidden torment of his the symbol “k” is usually assigned. Boltzmann, Ludwig 57 Boltzmann developed his kinetic theory of The Sun and other stars closely approxi- gases independent of the work of the great mate the thermal radiation behavior of black- Scottish physicist James Clerk Maxwell (1831 bodies, so astronomers often use the Stefan- –79). Their complementary activities resulted Boltzmann law to approximate the radiant in the Maxwell-Boltzmann distribution—a energy output (or luminosity) of a stellar object. mathematical description of the most probable A visible star’s apparent temperature is also re- velocity of a gas molecule or atom as a function lated to its color. The coolest red stars (called of the absolute temperature of the gas. The stellar spectral class “M” stars), such as Betelgeuse, greater the absolute temperature of the gas, the have a typical surface temperature of less than greater will be the average velocity (or kinetic 3,500 K. However, very large hot blue stars energy) of individual atoms or molecules. (called spectral class “B” stars), like Rigel, have

Considering a container filled with oxygen (O2) surface temperatures ranging from 11,000 to gas at a temperature of 300 kelvins (K), for ex- 28,000 K. ample, the Maxwell-Boltzmann distribution In the mid-1890s Boltzmann related the predicts that the most probable velocity of an classical thermodynamic concept of entropy oxygen molecule in that container is 395 meters (symbol S), recently introduced by Rudolf per second. Clausius (1822–88), to a probabilistic meas- In the late 1870s and early 1880s Boltzmann urement of disorder. In its simplest form, S ϭ k collaborated with Stefan in developing the very ln ⍀. Here, Boltzmann boldly defined entropy important physical principle that describes the (S) as a natural logarithmic function of the amount of thermal energy radiated per unit time probability of a particular energy state (⍀). The by a blackbody. In physics, a blackbody is de- symbol k again represents Boltzmann’s constant. fined as a perfect emitter and perfect absorber of This important equation is even engraved on electromagnetic radiation. All objects emit ther- his tombstone. mal radiation by virtue of their temperature. The Toward the end of his life, Boltzmann en- hotter the body, the more radiant energy it emits. countered very strong academic and personal By 1884 Boltzmann had finished his theoretical opposition to his atomistic views. Many eminent work in support of Stefan’s observations of the European scientists of this period could not grasp thermal radiation emitted by blackbody radia- the true significance of the statistical nature of tors at various temperatures. The result of their his reasoning. One of his most bitter professional collaboration was the famous Stefan-Boltzmann and personal opponents was the Austrian physi- law of thermal radiation. A physical principle of cist Ernest Mach (1838–1916), who as chair of great importance to both physicists and as- history and philosophy of science at the tronomers, this law states that the luminosity of University of Vienna essentially forced the bril- a blackbody is proportional to the fourth power liant but depressed Boltzmann to leave that in- of the body’s absolute temperature. The constant stitution and move to the University of Leipzig of proportionality for this relationship is called in 1900. the Stefan-Boltzmann constant, and scientists Boltzmann continued to defend his statisti- usually assign this constant the symbol “␴”—a cal approach to thermodynamics and his belief lowercase sigma in the Greek alphabet. The in the atomic structure of matter, but he could Stefan-Boltzmann law tells scientists that if the not handle having to continually defend his absolute temperature of a blackbody doubles, for theories against mounting opposition in certain example, its luminosity will increase by a fac- academic circles. So, while on holiday with his tor of 16. wife and daughter at the Bay of Duino, near 58 Bradley, James Trieste, Austria (now part of Italy), Boltzmann England’s second Astronomer Royal, and he en- hanged himself in his hotel room on October 5, couraged the young man to pursue astronomy as 1906, as his wife and child enjoyed a swim. Was a career. Halley also recommended that Bradley the tragic suicide of this brilliant physicist the be elected as a fellow of the Royal Society in result of a lack of professional acceptance of his London. work or the self-destructive climax of his life- As a result of this encouragement, Bradley long battle with bipolar disorder? No one can abandoned any thoughts of an ecclesiastical ca- say for sure. Sadly, at the time of his death, other reer. In 1721 he accepted an appointment to the great physicists were performing key experiments Savilian Chair of Astronomy at the University that would soon prove Boltzmann’s atomistic of Oxford. Throughout his career as an as- philosophy and life’s work correct. tronomer, Bradley concentrated his efforts on making improvements in the precise observation of stellar positions. For example, in 1725 he ᨳ Bradley, James started on his personal quest to be the first as- (1693–1762) tronomer to measure stellar parallax—the very British small apparent change in the position of a star Astronomer when viewed by an observer on Earth as the planet reaches opposing extremes of its ellipti- James Bradley was the 18th-century English cal orbit around the Sun. However, the difficult minister turned astronomer who made two im- measurement of stellar parallax managed to baf- portant astronomical discoveries. His first was fle and elude all astronomers, including Bradley, the aberration of starlight, announced in 1728. until FRIEDRICH WILHELM BESSEL accomplished It represented the first observational proof the task in 1838. Nevertheless, while searching that Earth moves in space, confirming the for stellar parallax, Bradley accidentally discov- Copernican hypothesis. His second discovery ered another very important physical phenome- was that of nutation—a small wobbling varia- non that he called the aberration of starlight. tion in procession of Earth’s rotational axis, The aberration of starlight is the tiny ap- reported in 1748, after 19 years of careful obser- parent displacement of the position of a star from vation. Upon the death of the legendary SIR its true position due to a combination of the fi- EDMUND HALLEY in 1742, Bradley was appointed nite velocity of light and the motion of an ob- as the third Astronomer Royal of England. server across the path of the incident starlight. He was born sometime in March 1693 (the For example, an observer on Earth would have precise date is not recorded) in Sherborne, Earth’s orbital velocity around the Sun, approx- England. As a young child, Bradley was being imately 30 kilometers per second. As a result of prepared for a life in the ministry when he suf- this orbital motion effect, during the course of a fered an attack of smallpox. His uncle, the year the light from a “fixed” star appears to move Reverend James Pound, introduced Bradley to as- in a small ellipse around its mean position on tronomy while nursing him back to health. The the celestial sphere. Reverend Pound was an avid amateur astronomer By a stroke of good fortune, on December 3, and friend of Halley. Before long, Bradley began 1725, Bradley began observing the star Gamma to demonstrate his great observational skills as Draconis, which was within the field of view of he practiced amateur astronomy while studying his large telescope pointed at zenith. He was to become a vicar in the Church of England. By forced to look at the stars overhead because his 1718 Bradley’s talents sufficiently impressed refractor telescope was assembled in a long Brahe, Tycho 59 chimney, with its telescopic lens above rooftop around the Sun. So it happened that early in and its objective (viewing lens) below, in the his career as an astronomer, Bradley made a unused fireplace. Bradley was actually attempt- major discovery—the aberration of starlight. ing to become the first astronomer to experi- This discovery was the first observational proof mentally detect stellar parallax, and he used this that Earth moved in space, confirming the relatively immobile telescope pointed at zenith Copernican hypothesis. to minimize atmospheric refraction. He viewed Bradley soon constructed a new telescope, Gamma Draconis again on December 17 and was one not placed in a chimney, so he could make quite surprised to find that the position of the precise observations of other stars. Starting in star had shifted a tiny bit. But the apparent shift 1728 and continuing for many years, Bradley pre- was not by the amount or in the direction ex- cisely recorded many stellar positions. His efforts pected, if he was observing the phenomenon of greatly improved upon the earlier work of many parallax. He continued these careful observa- notable astronomers, including England’s first tions over the course of an entire year and found Astronomer Royal, John Flamsteed (1646–1719). that the position of Gamma Draconis actually His ability to make precise measurements led traced out a very small ellipse. him to a second important astronomical discov- Bradley puzzled over the Gamma Draconis ery. He found that Earth’s axis experienced small problem for about three years, but still could not periodic shifts that he called “nutation” after satisfactorily explain the cause of the displace- the Latin word nutare, “to nod.” The new phe- ment. Then, in 1728, while he was sailing on nomenon, characterized as an irregular wob- the Thames River, inspiration suddenly struck as bling superimposed upon the overall precession he watched a small wind-direction flag on a mast of Earth’s rotational axis, is primarily caused by change directions. Curious, Bradley asked a the gravitational influence of the Moon, as it sailor whether the wind had changed directions. travels along its somewhat irregular orbit around The sailor informed him that the direction of Earth. Bradley waited almost two decades, until wind had not changed. So Bradley realized that 1748, to publish this discovery, because he wanted the changing position of the small flag was due to carefully study and confirm the very subtle to the combined motion of the boat and of the shifts in stellar positions before announcing his wind. This connection helped him solve the findings. Gamma Draconis displacement mystery. When Halley died in 1742, Bradley was Based on the previous attempts by the appointed as England’s third Astronomer Royal. Danish astronomer Olaus Roemer (1644–1710) He most competently served in that distin- to measure the velocity of light, Bradley hy- guished post until his death on July 13, 1762, in pothesized correctly that light must travel at a Chalford, England. very rapid, finite velocity. He also further speculated that a ray of starlight traveling from the top of his tall telescope to the bottom would ᨳ Brahe, Tycho (Tÿge Brahe) have its image displaced in the objective ever (1546–1601) so slightly by Earth’s orbital motion. Bradley Danish finally recognized that the mysterious annual Astronomer, Mathematician, shift of the apparent position of Gamma Cartographer Draconis, first in one direction and then in another, was due to the combined motion of History has recorded that if any of the great sci- starlight and Earth’s annual orbital motion entists had a nose for astronomy, it was Tycho 60 Brahe, Tycho Brahe. Born December 14, 1546, to an aristo- which he named Stella Nova. In truth, this was cratic family in Knudstrup, Denmark, Tÿge a supernova, one of three famous supernova Brage spent the better part of his 54 years be- events in the history of astronomy—one occur- coming both a master of science and a master- ring in 1054; and another in 1604 observed by ful entrepreneur. (He adopted the Latin form of GALILEO GALILEI and JOHANNES KEPLER as a Tÿge, Tycho, when he was about 15.) nova, then finally determined to be a supernova Brahe had the opportunity to study the sci- some 350 years later by WILHELM HEINRICH ences thanks in large part to his father’s wealth WALTER BAADE. and power. Otte Brahe was a member of By mid-1573 Brahe met Kirsten Jörgensdatter, Denmark’s elite ruling oligarchy, Rigsraad, and a priest’s daughter, and the two married and was the first in an impressive line of patrons for eventually had a family of eight children. By the studious young Brahe. On April 19, 1559, at 1574 it was clear that Brahe was ready to make age 12, Tycho began his lessons in earnest at the himself, and his science, known to the world. He University of Copenhagen. It was here, on August presented his first lecture, on mathematics, at 21, 1560, that he experienced a solar eclipse that, the University of Copenhagen. By 1577, at age according to philosopher Pierre Gassendi, turned 30, he was offered what many would have con- Brahe’s interest toward astronomy. sidered the enviable position of rector at the After three years in Copenhagen, Brahe left university. to attend the University of Leipzig, where for the But six months earlier Brahe had received a next three years he focused on humanities and notice from a new patron, King Frederick II, of- astronomy. With his father’s funds available to fering him an island, Hven, on which Tycho pay for travel and continued studies, Brahe ex- could build an observatory and leave his legacy. plored several universities over the following The castle Uranienborg was meant to be Brahe’s two years, including Wittenberg, which he left astronomical haven. All expenses would be pro- because of an outbreak of the plague, Rostock, vided by the king to build, maintain, and pros- and finally Basel. per, for the rest of Brahe’s life. The foundation It was while at Rostock that the hotheaded was started with a helping hand from the French young Brahe took on fellow noble scholar, ambassador, Charles Dançay, who placed the Manderup Parsbjerg, in a heated debate over first stone in the castle’s wall. which of the two was the better mathematician. Over the next few years, Tycho participated This led to a duel with swords, and on December in more than stargazing. He continued amassing 29, 1566, by the time their score was settled the assets and significant revenue in an effort to se- 20-year-old Tycho had forever lost the end of cure his status as nobility in his own right. He his nose. was granted farms, a fiefdom, and the position Otte Brahe’s death in 1571 left Tycho a sub- of canon in Roskilde cathedral in 1579, which stantial estate, consisting of assets including more he held for nearly 20 years. than 200 farms. Even after dividing the assets with But in 1597 Brahe’s time at Hven came to an his brother, the 25-year-old Brahe had enough end, and on April 22, after losing royal support funds to live comfortably for the rest of his life. for his work, the astronomer left his haven of 21 Truly a scholar of science, Brahe’s breadth of years, writing, “boring weather on a boring day.” expertise included astronomy, astrology, meteorol- After a trip to Wandsbech, near Hamburg, Brahe ogy, iatrochemistry, cartography, instrumentation, settled in Prague. The following year, Brahe pharmacology, and mathematics. His first major wrote Mechanica, in which he described many of astronomical discovery occurred in 1572, when he the extraordinary instruments he had designed found a new star in the constellation Cassiopeia, over the past 20 years. In an attempt to elicit Braun, Wernher Magnus von 61 support for his work, Brahe dedicated the piece and later a family of powerful space launch ve- to the Holy Roman Emperor Rudolf II. And it hicles for the National Aeronautics and Space worked. The emperor spent an estimated 10,000 Administration (NASA). One of his giant guldens on a house for Brahe in Prague, and in Saturn V rockets successfully sent the first hu- 1599 appointed him imperial mathematician. man explorers to the Moon’s surface in July It was during the following year that Brahe, 1969, as part of NASA’s Apollo Project. who was a patron himself, employed Kepler. Braun was born on March 23, 1912, in Brahe’s system of explaining the Earth and its Wirsitz, Germany (now Wyrzsk, Poland). He was place in the universe was flawed, but it gave the second of three sons of Baron Magnus von Kepler an extraordinary opportunity that ulti- Braun and Baroness Emmy von Quistorp. As a mately concluded in proving the correct nature of our solar system. Ever concerned with his status, Brahe applied for the rank of nobility in February 1601. Several months later, while having dinner with Baron Peter Vok Rosenberg in Prague, Brahe became quite ill. Over the next few days, his condition worsened with fever, and on October 24, 1601, the noted scientist and mathematician uttered his last words to Kepler: “Don’t let me seem to have lived in vain.” On November 11, 1601, Brahe was buried in Prague as nobility. Kepler’s work ensured that Brahe got his final wish. While Kepler fundamentally supported, and helped prove, the Copernican theory of a heliocentric universe, disproving Brahe’s system of the planets revolving around the Sun and all revolving around the Earth, it was Brahe’s extremely accurate observations of Mars that led to Kepler’s conclusions and the creation of the laws of planetary motion.

ᨳ Braun, Wernher Magnus von (1912–1977) The brilliant rocket engineer Wernher von Braun poses with a Saturn IB launch vehicle perched on its pad at German/American the Kennedy Space Center in 1968. Von Braun Rocket Engineer devoted his professional life to creating ever more powerful liquid-propellant rockets. In 1958 he quickly The brilliant rocket engineer Wernher von Braun adapted a U.S. Army rocket to carry the first U.S. turned the impossible dream of interplanetary satellite (Explorer 1) into orbit around Earth. Then in the 1960s, he developed the family of powerful Saturn space travel into a reality. He started by devel- rockets for NASA. Starting in July 1969, his giant oping the first modern ballistic missile, the liq- Saturn V rockets rumbled skyward, successfully uid-fueled V-2 rocket, for the German army. He sending teams of human explorers to the Moon’s then assisted the United States by developing a surface in timely fulfillment of President John F. Kennedy’s bold lunar exploration commitment. family of ballistic missiles for the U.S. Army (Courtesy of NASA/Marshall Space Flight Center) 62 Braun, Wernher Magnus von young man, he enjoyed the science fiction nov- the German military and a larger, more remote els of Jules Verne and H. G. Wells, which kin- test facility near the small coastal village of dled his lifelong interest in space exploration. Peenemünde, on the Baltic Sea. HERMANN JULIUS OBERTH’s book The Rocket into The Kummersdorf team moved to Peenemünde Interplanetary Space (1923) introduced him to in April 1937. Soon after relocation, von Braun’s rockets. In 1929 Braun received additional inspi- team began test firing the A-3 rocket, which ration from Oberth’s realistic “cinematic” rocket was plagued with many problems. As World that appeared in Fritz Lang’s (1890–1976) motion War II approached, the German military directed picture Die Frau im Mond (The woman in the Braun to develop long-range military rockets and moon). That same year, he became a founding he accelerated design efforts for the much larger member of Verein für Raumschiffahrt, or VFR, the A-4. At the same time, an extensive redesign of German Society for Space Travel. Through the the troublesome A-3 rocket resulted in the A-5 VFR, he came into contact with Oberth and rocket. other German rocket enthusiasts. He also used When World War II started in 1939 Braun’s the VFR to carry out liquid propellant rocket ex- team began launching the A-5. The results of periments near Berlin in the early 1930s. these tests gave Braun the technical confidence He enrolled at the Berlin Institute of Tech- he needed to pursue final development of the nology in 1930. Two years later, at age 20, he A-4 rocket—the world’s first long-range, liquid- received his bachelor’s degree in mechanical fueled military ballistic missile. engineering. In 1932 he entered the University The A-4’s state-of-the-art liquid-propellant of Berlin, where as a graduate student he received engine burned alcohol and liquid oxygen, and a modest rocket research grant from a German was approximately 14 meters long and 1.66 me- army officer, Artillery Captain Walter Dorn- ters in diameter. These dimensions were inten- berger (1895–1980). This effort ended in disap- tionally selected to produce the largest possible pointment when Braun’s new rocket failed to mobile military rocket capable of passing through function before an audience of military officials the railway tunnels in Europe. Built within these in 1932. But the young graduate so impressed design constraints, the A-4 rocket had an oper- Dornberger that he hired him as a civilian engi- ational range of up to 275 kilometers. neer to lead the German army’s new rocket Braun’s first attempt to launch the A-4 artillery unit. In 1934 Braun received his Ph.D. rocket at Peenemünde occurred in September degree in physics from the University of Berlin. 1942 and ended in disaster. As its engine came A portion of his doctoral research involved test- to life, the test vehicle slowly rose from the ing small liquid-propellant rockets. launch pad for about one second. Then the en- By 1934 Braun and Dornberger had assem- gine’s thrust suddenly tapered off, causing the bled a rocket development team totaling 80 en- rocket to slip back to Earth. As its guidance fins gineers at Kummersdorf, a test facility located crumpled, the doomed rocket toppled over and some 100 kilometers south of Berlin. That year, destroyed itself in a spectacular explosion. But the Kummersdorf team successfully launched success finally occurred on October 3, 1942. In two new rockets, nicknamed Max and Moritz its third flight test, the experimental A-4 vehi- after German fairy tale characters. Max was a cle roared off the launch pad and reached an al- modest liquid-fueled rocket, and Moritz flew to titude of 85 kilometers while traveling a total altitudes of about two kilometers and carried a distance of 190 kilometers downrange from gyroscopic guidance system. These successes Peenemünde. The successful flight marks the earned the group additional research work from birth of the modern military ballistic missile. Braun, Wernher Magnus von 63 Impressed, senior German military officials Proving Ground in southern New Mexico. immediately ordered the still-imperfect A-4 During this period, Braun also married Maria von rocket into mass production. By 1943 the war was Quistorp on March 1, 1947. Relocated German going badly for Nazi Germany, so Adolf Hitler engineers and captured V-2 rockets provided a decided to use the A-4 military rocket as a common technical heritage for the major military vengeance weapon against Allied population missiles initially developed by both the United centers. He named this long-range rocket the States and the Soviet Union during the cold war. Vergeltungwaffe-Zwei (Vengeance Weapon Two), In 1950 the U.S. Army moved Braun and his or V-2. In September 1944 the German army team to the Redstone Arsenal near Huntsville, started launching V-2 rockets armed with high- Alabama. At the Redstone Arsenal, Braun su- explosive warheads (about one metric ton) pervised development of early ballistic missiles, against London and southern England. Another such as the Redstone and the Jupiter, for the U.S. key target was the Belgian city of Antwerp, Army. These missiles descended directly from the which served as a major supply port for the ad- technology of the V-2 rocket. As the cold war vancing Allied forces. More than 1,500 V-2 rock- arms race heated up, the U.S. Army made Braun ets hit England, killing about 2,500 people and chief of its ballistic weapons program. causing extensive property damage. Another Starting in fall 1952, Braun also provided 1,600 V-2 rockets attacked Antwerp and other technical support for the production of a beau- continental targets. Although modest in size and tifully illustrated series of visionary space travel payload capacity when compared to modern mil- articles that appeared in Collier magazine. The itary rockets, Braun’s V-2 significantly advanced series caught the eye of the American enter- the state of rocketry and was a formidable, un- tainment genius Walt Disney (1901–66). By the stoppable weapon that struck without warning. mid-1950s Braun became a nationally recog- Fortunately, the V-2 rocket arrived too late to nized space travel advocate through his frequent change the outcome of World War II in Europe. appearances on television. Along with Walt In May 1945 Braun, along with some 500 of Disney, Braun served as a host for an inspiring his colleagues, fled westward from Peenemünde three-part television series on human space to escape the rapidly approaching Russian forces. flight and space exploration. Thanks to Braun’s Bringing along numerous plans, test vehicles, influence, when the Disneyland theme park and important documents, he surrendered to opened in southern California in 1955 (the year U.S. forces at Reutte, Germany. Over the next Braun became a U.S. citizen), its “Tomorrowland” few months, U.S. intelligence teams, under section featured a “Space Station X-1” exhibit Operation Paperclip, interrogated many German and a simulated rocket ride to the Moon. A gi- rocket personnel and sorted through boxes of ant, 25-meter tall, needle-nosed rocket ship captured documents. (personally designed by Willy Ley [1906–69] Selected German engineers and scientists and Braun) also greeted visitors to the Moon accompanied Braun and resettled in the United ride. During the mid-1950s, the Disney–Braun States to continue their rocketry work. At the relationship introduced millions of Americans end of the war, American troops also captured to the possibility of the Space Age, which was hundreds of intact V-2 rockets. After Germany’s actually less than two years away. defeat, Braun and his colleagues arrived at Fort On October 4, 1957, the Space Age arrived Bliss, Texas, to help the U.S. Army (under when the former Soviet Union launched Sputnik Project Hermes) reassemble and launch captured 1, Earth’s first artificial satellite. Following the German V-2 rockets from the White Sands successful Soviet launches of the Sputnik 1 and 64 Bruno, Giordano Sputnik 2 satellites and the disastrous failure of him to a Washington, D.C., headquarters “staff the first American Vanguard satellite mission in position” in which he could “perform strategic late 1957, Braun’s rocket team at Huntsville was planning” for the agency. Braun, now an inter- given less than 90 days to develop and launch nationally popular rocket scientist, had openly the first U.S. satellite. On January 31, 1958, a expressed desires to press on beyond the Moon modified U.S. Army Jupiter C missile, called the mission and send human explorers to Mars. This Juno 1 launch vehicle, rumbled into orbit from made him a large political liability in a civilian Cape Canaveral Air Force Station. Under space agency that was now faced with shrink- Braun’s direction, this hastily converted military ing budgets. In less than two years at NASA rocket successfully propelled Explorer 1 into headquarters, Braun decided to resign from the Earth orbit. The Explorer 1 satellite was a highly civilian space agency. By 1972 the rapidly de- accelerated joint project of the Army Ballistic clining U.S. government interest in human Missile Agency (AMBA) and the Jet Propulsion space exploration clearly disappointed him. He Laboratory (JPL) in Pasadena, California. The then worked as a vice president of Fairchild spacecraft carried an instrument package pro- Industries in Germantown, Maryland, until ill- vided by JAMES ALFRED VAN ALLEN, who dis- ness forced him to retire on December 31, 1976. covered Earth’s trapped radiation belts. He died of a progressive cancer in Alexandria, In 1960 the U.S. government transferred ad- Virginia, on June 16, 1977. ministration of Braun’s rocket development cen- Braun’s aerospace engineering skills, leader- ter at Huntsville from the U.S. Army to a newly ship abilities, and technical vision formed a created civilian space agency called the National unique bridge between the dreams of the Aeronautics and Space Administration (NASA). founding fathers of astronautics: KONSTANTIN Within a year, President John F. Kennedy made EDVARDOVICH TSIOLKOVSKY,ROBERT HUTCHINGS a bold decision to put U.S. astronauts on the GODDARD, and Oberth and the first golden Moon within a decade. The president’s decision age of space exploration, which took place from gave Braun the high-level mandate he needed to approximately 1960 to 1989. In this unique build giant new rockets. On July 20, 1969, two period, human explorers walked on the Moon Apollo astronauts, Neil Armstrong (born 1930) and robot spacecraft visited all the planets in and Edwin (Buzz) Aldrin (born 1930), became the solar system (except tiny Pluto) for the first the first human beings to walk on the Moon. They time. Much of this was accomplished through had gotten to the lunar surface because of Braun’s Braun’s rocket engineering genius, which helped flawlessly performing Saturn V launch vehicle. turn theory into powerful, well-engineered As director of NASA’s Marshall Space Flight rocket vehicles that shook the ground as they Center in Huntsville, Alabama, Braun supervised broke the bonds of Earth on their journey to development of the Saturn family of large, pow- other worlds. erful rocket vehicles. The Saturn I, Saturn IB, and Saturn V vehicles were well-engineered expend- able rockets that successfully carried teams of ᨳ Bruno, Giordano (Filippo Bruno) U.S. explorers to the Moon between 1968 and (1548–1600) 1972 and performed other important human Italian space flight missions through 1975. Philosopher But just after the first human landings on the Moon in 1969, NASA’s leadership decided While many would argue that Giordano Bruno to move Braun from Huntsville and assigned was one of the great philosophical influences of Bruno, Giordano 65 all time, it cannot be overlooked that his beliefs turing position. Bruno also began publishing about the universe and our place within it were books, in which he wove his philosophy through in great part responsible for his execution at the dialogue and questioned the then-known reali- hands of the Roman Inquisition. ties of the church, God, and the universe. In 1548, just five years after the death of Of particular importance is his book The Ash NICOLAS COPERNICUS, Filippo Bruno was born in Wednesday Supper (1584), which is typically cited Nola, Italy, just outside Naples. Very little is as Bruno’s most significant perspective on as- known about his early childhood. His father was tronomy. Following Copernicus’s lead, Bruno de- a soldier in Naples and the family was presum- fied the church’s teachings, based purely on ably poor, yet Bruno managed to begin his edu- ARISTOTLE, and supported the theory that the cation in logic in Naples at about age 11. But it Earth is not the center of the universe. Bruno went was his studies in theology and philosophy, which even further to argue that the universe is infinite, he started at age 15, that began his life of piety, and imagined that within this infinite universe and eventually led to discord with the church. there exists an infinite number of suns and From 1563 to 1576 Bruno was a member of earths. He believed that our Sun and Earth, the St. Dominico monastery in Naples. While when looked at from other vantage points, there, he changed his name to Giordano and be- would look like any other stars. Using logic, Bruno gan studying both ancient and current philoso- threatened current knowledge. Unfortunately, this phy. It was also during this time that he learned was tantamount to challenging the foundation of of the works of Copernicus. Outspoken and per- the church, thus defying God. haps dangerously frank, Bruno had the innate Bruno’s grace with the French aristocracy ability to easily offend those around him. There helped him in his subsequent travels from 1583 is little doubt that he started exhibiting these to 1592. His audience with royalty, including characteristics while in the monastery. Queen Elizabeth, and his nearly 20 books and By the time he was 28, he had angered the plays contributed significantly to the acceptance church on more than one occasion. His first of- of debating his philosophical viewpoints in in- fense involved giving away images of saints. tellectual circles. In March 1592 he agreed to Charges were brought against him, most likely return to Venice by invitation of another aris- as a disciplinary tactic to keep him in line (they tocrat, Zuane Mocenigo, who proclaimed inter- were dropped almost immediately), but in 1576 est in learning about mnemonics. they were brought back up in conjunction with Apparently, Mocenigo was hoping mnemon- a new charge of heresy for reading philosophi- ics would also involve black magic. When cal texts that were out of favor with the church. Bruno was both unwilling and unable to deliver Threatened with the possibility of proceedings the secrets of the occult, Mocenigo turned him against him in Rome as a heretic, Bruno fled to over to the Venetian Inquisition for blasphemy avoid persecution, giving up all affiliation with and heresy, on May 23, 1592. The Roman the Dominicans. Inquisition took custody of Bruno the following Over the next 16 years, Bruno led the life January 27, and carried out its mandate to de- of a Renaissance man, wandering through liver truth through interrogation and torture for Europe, espousing his philosophy, and gaining the next seven years. Unwilling to recant his be- favor with royalty for his unique ways of think- liefs, Bruno was accused of heresy on January 20, ing. France’s King Henri III was so intrigued with 1600, by the Holy Inquisition. All of his books Bruno’s teachings in mnemonics that he helped and writings were proclaimed “heretical and the young philosopher obtain a university lec- erroneous” and placed on the church’s Index of 66 Bunsen, Robert Wilhelm Forbidden Books, and Bruno was sentenced to death. Upon receiving his verdict, it is said that he replied, “Perhaps your fear in passing judgment on me is greater than mine in receiving it.” Giordano Bruno is known as a wanderer, an independent thinker, a rationalist, and a martyr. For the crime of freethinking, on February 17, 1600, he was led from his dungeon in Rome to a stake in the Campo de’ Fiori square. His mouth was bound with an iron gag made with spikes to pierce his tongue and palette, and he was burned alive, becoming the first martyr of modern science.

ᨳ Bunsen, Robert Wilhelm (1811–1899) German Chemist, Spectroscopist

This innovative German chemist collaborated The German chemist Robert Bunsen’s collaboration with GUSTAV ROBERT KIRCHHOFF in 1859 to with Gustav Kirchhoff in 1859 revolutionized develop spectroscopy. Their innovative efforts astronomy by allowing scientists to determine the entirely revolutionized astronomy by offering sci- chemical composition of distant luminous celestial bodies through spectroscopy. Despite his very entists a new and unique way to determine the important role in the development of spectroscopy as chemical composition of distant celestial bodies. a means of identifying individual chemical elements, An accomplished experimentalist, Bunsen also most science students usually remember him as the made numerous contributions to the science of person who developed the popular gas burner that bears his name. (AIP Emilio Segrè Visual Archives, chemistry, including improvement of the popu- E. Scott Barr Collection) lar laboratory gas burner that carries his name. Robert Bunsen was born in Göttingen, Germany, on March 31, 1811, the youngest child out Germany and other countries in Europe, en- in a family of four sons. The fact that his father gaging in scientific discussions and visiting many was an academician and served as a professor of laboratories. He remained in Vienna from 1830 linguistics at the University of Göttingen al- to 1833. During these travels, Bunsen estab- lowed Bunsen to experience the academic envi- lished a network of professional contacts that ronment at an early age and to select a similar would prove very valuable during his long and professional path. He attended preparatory illustrious career. school in Holzminden and, upon graduation, Upon his return to Germany, Bunsen ac- enrolled at the University of Göttingen as a cepted a position as a lecturer in chemistry at chemistry major. An excellent student, Bunsen the University of Göttingen. It was here that graduated in 1830 with his doctoral degree in he also began an interesting set of experiments chemistry at age 19. After graduation, the young investigating the insolubility of metal salts of scholar traveled for an extensive period through- arsenious acid. As part of this pioneering chem- Bunsen, Robert Wilhelm 67 ical research at Göttingen, the young chemist association that changed the world of chemical discovered what is still the best antidote against analysis and astronomy. While JOSEPH vON arsenic poisoning. FRAUNHOFER’s earlier work laid the foundations In 1836 Bunsen accepted a position at the for the science of spectroscopy, Bunsen and University of Kassel, but departed within two Kirchhoff provided the key discovery that un- years to work at the University of Marsburg. leashed the great power of spectroscopy. Their While continuing his arsenic chemistry research, classic 1860 paper, “Chemical Analysis through he experienced a near fatal laboratory explosion Observation of the Spectrum,” revealed the im- in 1836 that cost him an eye. After that acci- portant fact that each element has its own char- dent, his chemistry research still remained quite acteristic spectrum—much as fingerprints can hazardous, because twice he nearly died from ar- help identify an individual human being. In a senic poisoning. An intrepid and intelligent ex- landmark experiment, they sent a beam of sun- perimenter, Bunsen was elected as a member of light through a sodium flame. With the help of the Chemical Society of London in 1842. their primitive spectroscope (a prism, a cigar He accepted a position at the University of box, and optical components scavenged from Heidelberg in 1852 and he remained with this two abandoned telescopes) they observed two university until he retired in 1889. Bunsen was dark lines on a brightly colored background just an outstanding teacher who never married and where the sodium D-lines of the Sun’s spectrum instead focused all his time and energy on his occurred. Bunsen and Kirchhoff immediately laboratory and his students. He eagerly taught concluded that gases in the sodium flame were the introductory chemistry courses normally absorbing the D-line radiation from the Sun, shunned by his academic colleagues. His lectures creating an absorption spectrum. The sodium emphasized experimentation and the value of in- D-line appears in emission as a bright, closely dependent inquiry.A superb mentor, Bunsen spaced double yellow line, and in absorption as taught many famous chemists, including the a dark double line against the yellow portion of Russian Dmitri Mendeleev (1834–1907), who the visible spectrum. The wavelengths of these developed the periodic table. double bright emission lines and dark absorption Bunsen’s continuing contributions to chem- lines are identical and occur at 5889.96 angstroms istry were recognized by his induction to the and 5895.93 angstroms, respectively. Académie des Sciences in 1853 and by his elec- After some additional experimentation, tion as a foreign fellow of the Royal Society of they realized that the Fraunhofer lines were ac- London. Despite his numerous achievements in tually absorption lines—that is, gases present in the field of chemistry, he is often best remem- the Sun’s outer atmosphere were absorbing some bered for his improvement of a simple labora- of the visible radiation coming from the solar in- tory burner. Although the “Bunsen burner” was terior. By comparing the solar lines with the actually invented by a technician, Peter Desaga, spectra of known chemical elements, Bunsen at the University of Heidelberg, Bunsen greatly and Kirchhoff detected a number of elements improved the original device through his concept present in the Sun, the most abundant of which of premixing the gas and air prior to combustion was hydrogen. Their pioneering discovery paved in order to provide a burner that yielded a high- the way for other astronomers to examine the temperature, nonluminous flame. elemental composition of the Sun and other In 1859 Bunsen began his historic collab- stars and made spectroscopy one of modern as- oration with the German physicist Gustav tronomy’s most important tools. Just a few years Kirchhoff (1824–87)—a productive technical later, in 1868, the British astronomer SIR JOSEPH 68 Burbidge, Eleanor Margaret Peachey

NORMAN LOCKYER attributed an unusual bright After excelling in mathematics at private line that he detected in the solar spectrum to an primary and secondary schools, Peachey was ex- entirely new element then unknown on Earth. cited to discover that the University of London He named the new element “helium,” after offered a degree in astronomy, unlike most col- helios, the ancient Greek word for the Sun. leges at the time. She eventually earned her B.S. Bunsen and Kirchhoff then applied their degree, the only woman in her class majoring in spectroscope to resolving elemental mysteries astronomy, and thanks to the frequent blackouts right here on Earth. In 1861, for example, they during German air raids was able to observe discovered the fourth and fifth alkali metals, through the observatory’s one functional tele- which they named cesium (from the Latin scope without the visual pollution of city lights. caesium, “sky blue”) and rubidium (from the (A second telescope was rendered useless by a Latin rubidus, “darkest red”). Today scientists use buzz bomb.) spectroscopy to identify individual chemical el- She remained at the university’s observatory ements from the light each emits or absorbs after the war, where she observed for several years when heated to incandescence. Modern spectral until she received her Ph.D. in astronomy, even- analyses trace their heritage directly back to the tually becoming assistant director in the astron- pioneering work of Bunsen and Kirchhoff. omy department. While in that position she The scientific community bestowed many applied for a Carnegie Fellowship at the Mount awards on Bunsen. In 1860 he received the Wilson Observatory, in the San Gabriel Moun- Royal Society’s Copley Medal; he shared the first tains above Pasadena, California; she received Davy Medal with Kirchhoff in 1877; and re- her first taste of gender discrimination when told ceived the Albert Medal in 1898. After a life- in their response letter that women were not time of technical accomplishment, Bunsen died accepted. The excuse was that the observatory peacefully in his sleep at his home in Heidelberg had only one toilet! on August 16, 1899. Two lifetime milestones in one year do not occur very often, but after receiving her Ph.D. in 1948, she also married her lifetime partner ᨳ Burbidge, Eleanor Margaret and co-researcher Geoffrey Burbidge, a theo- Peachey retical physicist and her former physics (1919– ) teacher. American Burbidge’s first significant appointment in Astronomer, Astrophysicist the United States was as a research fellow at the University of Chicago’s Yerkes Observatory, With a lot of science genes going for her, where she worked from 1951 to 1953. Geoffrey Margaret Burbidge was born Eleanor Margaret also did research at the university and, indeed, Peachey on August 12, 1919, in Davenport, throughout Burbidge’s career her husband would Cheshire, England, to parents who both stud- accompany her in associated academic positions. ied chemistry at the Manchester School of She then returned to England to do research at Technology. She recalled in a biography that her the Cavendish Laboratory, which is in the interest in astronomy was kindled during a boat Department of Physics at Cambridge University. crossing from England to France when she was It was here that the couple met the renowned four years old and, having become seasick and British astronomer Sir Fred Hoyle (born 1915) confined to her bunk, spent many hours gazing and the American nuclear physicist WILLIAM at the brilliant stars through her porthole. ALFRED FOWLER. Burbidge, Eleanor Margaret Peachey 69

The English astrophysicist Eleanor Margaret Burbidge reviews images of quasars and various spiral galaxies in 1980. Collaborating with her husband and other physicists in 1957, she published an important scientific paper that described how nucleosynthesis creates elements of higher mass in the interior of stars. She also coauthored a fundamental book on quasars in 1967 and became the first female director of the Royal Greenwich Observatory, serving in that post from 1972 to 1973. (AIP Emilio Segrè Visual Archives, Physics Today Collection)

Burbidge returned to the United States in Wilson telescope, she soon discovered that she 1955 when her husband was awarded the not only was barred from the dormitory at the Carnegie Fellowship for astronomical research at observatory, but also that women were not the Mount Wilson Observatory, the position for allowed to use any of the telescopes. However, which Burbidge had previously been turned she convinced administrators that she was down ostensibly because of the solitary toilet. Geoffrey’s “assistant.” The pair, along with other When she won a fellowship from California coworkers, protested the discrimination, but it Institute of Technology (Caltech), which also would be 10 years before the “no women” policy was affiliated with the then-famous Mount was overturned. 70 Burbidge, Eleanor Margaret Peachey In 1957 Burbidge returned to Chicago when spectra of more than 50 spiral galaxies, deter- Geoffrey received a position as assistant profes- mining their rotations, masses, and chemical sor of astronomy at the Yerkes Observatory in compositions. Wisconsin. To avoid charges of nepotism, which Burbidge took a leave from UCSD and re- she stated “are always used against the wife,” she turned to England in 1972 to take the position had to settle for a position as an associate pro- as director of the Royal Greenwich Observatory, fessor of astronomy at the university. the oldest scientific institution in Great Britain. It was during this tenure that she coformu- However, Geoffrey could not find a similar po- lated what is known as the “B2FH Theory,” sition, so he stayed at UCSD. After a year had named for the principal authors: she, her hus- passed, she both missed her husband and grew band, Fowler, and Hoyle. Based on the concept frustrated with bureaucratic stumbling blocks. that there is no simple way by which the ele- She resigned her position and returned to ments could have formed, since space matter is UCSD, where she eventually became the direc- subjected to different conditions, the theory pre- tor of the university’s Center for Astrophysics sented the then-revolutionary explanation that and Space Sciences. In what must have been an the elements were formed by nuclear reactions emotionally satisfying event after so many years inside stars. In 1959 the American Astronomical of gender discrimination and nepotism rules, in Society awarded the Burbidge husband-and-wife 1976 she was named the first female president team the Helen B. Warner Prize for Astronomy, of the American Astronomical Society. One of recognizing the importance of their theory to the her first accomplishments was to get the organ- new field of nuclear astrophysics. ization to refuse to hold meetings in states that Yet another nepotism issue arose in 1962, had not ratified the Equal Rights Amendment. when Geoffrey was given a position as professor Soon after that, in 1978, she was elected to the in the Department of Physics at the University National Academy of Sciences. of California at San Diego (UCSD). Since For years an idea had been rolling around UCSD did not have a separate astronomy de- the back of Burbidge’s mind: Why not try to sta- partment at the time, and the husband and wife tion a large telescope in space? When the con- were prohibited from working together, Burbidge cept of the Hubble Space Telescope was put forth had to accept a position in the chemistry de- by NASA, Burbidge helped design the faint ob- partment. Two years later, the university abol- ject spectrograph (FOS), a high-resolution in- ished its nepotism rule and she joined Geoffrey strument aboard the Hubble Space Telescope that as a full professor of physics. records the spectra of galaxies. Beginning in During these years Burbidge had been pio- 1990, she was the coprincipal investigator of neering investigations into the nature of quasars, data emanating from the FOS for the next six or quasi-stellar radio sources, which, in simple years. terms, are galaxies billions of light-years away One of the great pioneers in the field of that can be detected only with radio telescopes. astronomy in the 20th century, Burbidge at age In 1967 she and Geoffrey published the book 82 was still professor emeritus of astronomy Quasi-Stellar Objects, which even today remains a and research professor at UCSD. She has won classic in the field of quasar research and radioas- dozens of professional honors, prizes, and hon- tronomy. She also delved into the nature of orary degrees, and is noted as having turned galaxies and, using the telescope at the MacDonald down the Annie J. Cannon Award in Astronomy Observatory operated by the University of Texas from the American Association of University at Austin, she pioneered work in measuring the Women, a prestigious prize offered only to Burbidge, Eleanor Margaret Peachey 71 women astronomers, on the ground that special omy, for “a lifetime of distinguished service and honors and discrimination for women should be achievement.” In 1985 President Reagan pre- abolished. sented her with the National Medal of Science, In 1982 she became the first woman in the and in 1988 she won the Albert Einstein World 84-year history of the Astronomy Society of the Award of Science Medal. The minor planet 5490 Pacific to win the Catherine Wolfe Bruce Medal, has been named Burbidge in her honor. one of the highest honors in the field of astron-

years in Colorado, Campbell returned to the ᨳ Campbell, William Wallace University of Michigan in 1888 and taught as- (1862–1938) tronomy there until 1891. While teaching in American Colorado, he also met the student who became Astronomer his wife. Betsey (Bess) Campbell proved to be a Early in the 20th century, the American as- very important humanizing influence on her tronomer William Campbell made pioneering husband, who was known for being domineering spectroscopic measurements of stellar motions and inflexible, personal traits that made him ex- that helped astronomers better understand the tremely difficult to work with or for. motion of our solar system within the Milky Way In 1890 he traveled west from Michigan to Galaxy and the overall phenomenon of galactic become a summer volunteer at the Lick Obser- rotation. He perfected the technique of photo- vatory of the University of California, located graphically measuring radial velocities of stars, on Mount Hamilton near San Jose. His hard and discovered numerous spectroscopic binaries. work and observing skills earned him a perma- Campbell also provided a more accurate confir- nent position as astronomer on the staff of the mation of ALBERT EINSTEIN’s theory of general observatory the following year. On January 1, relativity when he carefully measured the subtle 1901, he became director of the Lick Observa- deflection of a beam of starlight during his solar tory and ruled that facility in such an autocratic eclipse expedition to Australia in 1922. manner that his subordinates often privately Campbell was born on April 11, 1862, in called him the czar of Mount Hamilton. In 1923 Hancock County, Ohio. He experienced a child- he accepted an appointment as the president of hood of poverty and hardship on his family’s the University of California (in Berkeley), but farm. He originally enrolled in the civil engi- he also retained his former position as the direc- neering program at the University of Michigan. tor of the Lick Observatory. However, his encounter with SIMON NEWCOMB’s Wallace Campbell’s permanent move from work Popular Astronomy (1878) convinced him the University of Michigan to California in 1891 to become an astronomer. After graduating from proved to be a major turning point in his career the University of Michigan in 1886, he accepted as an astronomer. Until then, he had devoted a position in the mathematics department at the his observational efforts to the motion of comets. University of Colorado. After working for two At the Lick Observatory, he brought about a

72 Campbell, William Wallace 73

American astronomer William Wallace Campbell in 1893, standing beside the 36-inch refractor telescope with its specially designed spectrograph at the Lick Observatory, on Mount Hamilton near San Jose, California. Campbell used this equipment to make pioneering measurements of the radial (line of sight) velocities of stars by measuring the Doppler shift of their spectral lines. (AIP Emilio Segrè Visual Archives) 74 Cannon, Annie Jump revolution in astronomical spectroscopy when SIR ARTHUR STANLEY EDDINGTON during the he attached a specially designed spectrograph to 1919 solar eclipse. the Lick Observatory’s 36-inch refractor tele- Campbell retired as the president of the scope—then the world’s largest. He used this University of California (Berkeley) and as the powerful instrument to measure stellar radial director of the Lick Observatory in 1930. He and (that is, line of sight) velocities, by carefully ex- his wife then moved to Washington, D.C., where amining the telltale Doppler shifts of stellar he served as the president of the National spectral lines. He noted that when a star’s Academy of Sciences from 1931 to 1935. spectrum was “blueshifted,” it was approaching Returning to California, he spent the last three Earth; when “redshifted,” it was receding. He years of his life in San Francisco. On June 14, perfected his spectroscopic techniques and in 1938, he died by his own hand—driven to sui- 1913 published Stellar Motions, his classic text- cide by declining health and approaching total book on the subject. In that same year, Campbell blindness. William Campbell’s contributions to also prepared a major catalog, listing the radial astronomy were acknowledged through several velocities of more than 900 stars. He later ex- prestigious awards. The French Academy pre- panded the catalog in 1928 to include 3,000 sented him with its Lalande Medal in 1903 and stars. His precise work greatly improved knowl- its Janssen Medal in 1910, the British Royal edge of the Sun’s motion in the Milky Way and Astronomical Society awarded him its Gold the rotation of the Galaxy. Medal in 1906, and the National Academy of Campbell also used his spectroscopic skills Sciences of the United States gave him the to show that the Martian atmosphere contained Henry Draper Medal in 1906. Finally, in 1915, very little water vapor—a finding that put him the Astronomical Society of the Pacific awarded in direct conflict with other well-known as- Campbell its Bruce Gold Medal. tronomers at the end of the 19th century. Using the huge telescope and clear-sky advantages of the Lick Observatory, Campbell, who was never ᨳ Cannon, Annie Jump diplomatic, quickly disputed the plentiful water (1863–1941) vapor position of SIR WILLIAM HUGGINS,SIR American JOSEPH NORMAN LOCKYER, and other famous Astronomer European astronomers. While Campbell was indeed correct, the abrupt and argumentative way At the turn of the 20th century, the director of he presented his data won him few personal the Harvard College Observatory hired several friends within the international astronomical women as data analysts, not paying them very community. much but nevertheless remunerating them for He enjoyed participating in international reducing and filing complex data accumulated solar eclipse expeditions. His wife joined him on from stellar observations. Many of these women these trips, and she was often put in charge of became respected members of the astronomical the expeditions provisions. During a 1922 solar community. The most famous among them was eclipse expedition in Australia, Campbell meas- Annie Jump Cannon, who became the most ured the subtle deflection of a beam of starlight prolific and studious star spectrum classifier in just as it grazed the Sun’s surface. His precise history, and eventually the world’s foremost measurements helped confirm Albert Einstein’s authority on classifying stars. theory of general relativity and reinforced the Born in Dover, Delaware, Cannon was only previous, but less precise, measurements made by 16 years old when she became one of the first Cannon, Annie Jump 75 College, where she learned how to make spectroscopic measurements. After graduating in 1884, and taking up the newly developed science of photography as an avocation, she traveled extensively with her camera. During her travels she contracted scarlet fever and was struck deaf, having to use a hearing aid for the rest of her life. However, this af- fliction is said to have honed her great powers of concentration, responsible for propelling her into the highest ranks of astronomers of her time. After the death of her mother in 1894, Cannon returned to Wellesley to teach physics, and did further studies in astronomy at Radcliffe. In 1896 she became one of “Pickering’s women,” taking part in some of the first X-ray experiments, and on May 14 she made her first observation of a star’s spectrum. At the time, the accumulation of the massive stellar data was funded by Anna Draper, widow of the wealthy physician and amateur astronomer HENRY DRAPER. Pickering set up the Henry Draper American astronomers Annie Jump Cannon (left) and Memorial as a long-term project to gather the Henrietta Swan Leavitt (right) outside the main optical spectra of as many stars as possible. entrance to the Harvard College Observatory, where This had begun in 1886 and was carried on by they worked under the supervision of Edward Charles Pickering to publish the Henry Draper Catalogue—a several women, each using her own system of nine-volume document that contained the spectral classification. classifications of more than 225,000 stars. Cannon Eventually the work fell to Cannon, who was the driving force behind the development of a threw herself into the project with an intensity refined system for classifying stellar spectra that became known as the Harvard Classification System. and devotion unparalleled in the history of as- (Courtesy AIP Emilio Segrè Visual Archives, Shapley tronomy. The speed with which she worked was Collection) almost superhuman. It is said that Cannon classified 5,000 stars a month between 1911 and 1915, and one report has it that before she was women from that state to be admitted to college. through she had classified the spectra of more Her father was Wilson Cannon, a shipbuilder than 400,000 stars. and state senator, and her mother, Wilson’s sec- She began by developing a classification sys- ond wife, Mary Jump, taught her the constella- tem that utilized the best parts of those systems tions from the family’s “star book.” As a child, developed before her, and assigned a division of Cannon was fascinated by how crystal pendants stars into O, B, A, F, G, K, M categories, lead- on the candelabra separated sunlight into col- ing to the famous “Oh, Be a Fine Girl, Kiss Me” orful rainbow patterns. These two interests led mnemonic memorized by every astronomy student her to study physics and astronomy at Wellesley since. The classification catalog she ultimately 76 Cassini, Giovanni Domenico developed, called the HD Catalog, is still in use Cassini reportedly studied for two years at today as the cornerstone of modern spectro- Vallebone before becoming a student, first at the scopic astronomy. She also published several Jesuit college in Genoa and then at the abbey catalogs of variable stars, 300 of which she dis- of San Fructuoso, where he became very inter- covered herself. ested in astrology. But after casually perusing a Cannon went on to win practically every book on astronomy, which by this time was a award and honor the scientific community could separate discipline, he decided to drop astrol- bestow. In 1911 she became curator of the ob- ogy and focus on learning astronomy instead. servatory; in 1923 she was reportedly declared to However, his technical background served him be one of the “12 greatest living American well when he was consulted about the flood- women.” In 1925 she was the first woman to ing of the river Po, and he worked for Pope receive an honorary doctorate degree from Alexander VII to negotiate arrangements for the Oxford University, and in 1931 she received the navigation of the rivers Po and Remo. Later he coveted Draper Gold Medal from the National was named superintendent of the fortifications Academy of Sciences, again the first woman so of Fort Urban and the fortress of Perugia, and honored. The American Association of University was appointed to solve problems surrounding the Women named its annual award to the foremost course of the river Chiana, as well as supervis- woman of science the Annie J. Cannon Award. ing effluent control of the rivers Tiber and Arno, In all, she received a total of six honorary doctoral which was causing friction between the pope and degrees. the grand duke of Tuscany. Annie Jump Cannon died on April 13, The extensive knowledge he had of both 1941, after 42 years of dedication at Harvard. astronomy and astrology, with the necessary She is one of only 20 women who have a lunar mathematical ability to work in both fields, crater named in her honor. gave Cassini the foundation he needed for a new position offered to him in 1644, when he was invited by a powerful political figure in ᨳ Cassini, Giovanni Domenico Bologna, the marquis Cornelio Malvasia, to (Gian Domenico Cassini, Jean- come to the university and work in the new Dominique Cassini, Cassini I) observatory. It was an opportunity Cassini (1625–1712) could not, and did not, pass up, and it was the Italian (naturalized French) beginning of a 20-year relationship with the Astronomer, Mathematician university. By 1648 the new Panzano Observatory was Born in what is now Italy, but eventually be- finally built, and Cassini was able to start his ob- coming a naturalized French citizen, Cassini is servations, which were initially aimed at the known as the “Father of French Astronomy.” He Sun. Within two years he was also a professor of was born on June 8, 1625, to Julia Crovesi and astronomy and mathematics. By 1653 he was oc- Jacopo Cassini in the city of Perinaldo, which cupied with a task that seemed nearly impossi- was either in the French county of Nice or the ble to carry out—he wanted to build a gnomon Republic of Genoa, depending on the source, similar to the one he had seen at a church in and is now a part of Italy. One of the great as- San Petrino, which had been built between the tronomers of his time, Cassini was also an ex- mid-15th and early 16th centuries. The gnomon pert in hydraulics and engineering, specializing would be used to calculate the altitude of the in river management and flood control. Sun as the Sun cast a shadow over the sundial- Cassini, Giovanni Domenico 77 like apparatus, but the one in San Petrino had Colbert, with inviting Cassini to come to France been obstructed and was worthless, and Cassini and join France’s Académie Royale des Sciences, wanted to build a much bigger device. giving him an opportunity to work at the new Cassini designed the new instrument and observatory then being built. However, this re- oversaw its completion. His calculations had to quired the permission of Cassini’s new boss, Pope be precise for it to work, and when it was finally Clement IX, who generously gave his approval. installed, it was perfect. This accomplishment If Italy wanted to keep Cassini for itself, this gave Cassini instant success and, more impor- proved a costly mistake, for when Cassini left, tant, allowed him to start making observations he only returned to Italy to visit relatives or with this new tool. He published his work in a make observations. book entitled Specimen observationum bononien- Cassini reached Paris in 1669, and went to sium in 1656 and dedicated it to the exiled live at the new observatory, where he was pro- Queen Christina of Sweden. vided with a sizable salary, a travel allowance, The period between 1656 and 1659 made and free accommodations. In 1673 he requested Cassini’s name in the world of astronomical French nationality, changed his name from the science. In these few years he calculated a new Italian Giovanni Domenico to the French Jean- value of the inclination of the ecliptic as Dominique, married Genevieve de Laistre, 230Њ29Ј15Љ, the most precise of his era; he drew daughter of a high-ranking military officer, and up a table of the atmospheric refractions, which moved into the castle of Thury, near Beauvais, were the most accurate for a century after his as a family residence—which, coincidentally, was death; and he proved that the orbital velocity of crossed by the Paris meridian. the Earth was not constant. At the new observatory, Cassini started a se- In 1661, even while doing his hydraulic ries of observations of the lunar surface, which work on the flooding rivers, he worked out a way resulted in his writing a lunar atlas, a large map, to determine longitudes by observing solar and to propose a theory of the oscillation of the eclipses, but the Inquisitor of Modena refused to Moon. He also used his tables of refractions to allow publication of his paper. It would be pub- calculate the Mars parallax and that of the Sun. lished 10 years later in France. This information greatly increased the scale of Cassini obtained one of the first long fo- the solar system at the time. cal lenses made by the lensmaker Giuseppe Of all the objects in the heavens, it is the Campani, and began to study the planets. With planet Saturn that is most closely associated with these lenses he observed the shadows of Jupiter’s Cassini’s name. While SIR WILLIAM HUYGENS moons on the surface of the planet and calcu- had discovered Titan, Saturn’s first satellite in lated their rotational period, and he observed 1655, Cassini, working at the Paris Observatory, Jupiter’s Great Red Spot, which in turn allowed discovered four others: Iapetus in 1671, Rhea in him to calculate Jupiter’s rotational period. At 1672, and Dione and Thetys in 1684. In 1675 this time he also evaluated Mars’s rotational Cassini discovered that Saturn’s famous ring was period. actually two rings separated by a dark space, now All of this innovational astronomy gave called Cassini’s Division. He also recorded the Cassini a reputation that went beyond the flatness of the ring, and observed a cloudy strip boundaries of Italy. In France Louis XIV was de- parallel to Saturn’s equator. Eventually he ciding that France should become as prominent suggested that the ring was not solid, but com- in the arts and sciences as it was in warfare and posed of tiny “satellites” that could not be re- weaponry, and charged one of his ministers, solved with currently available lenses, a thesis 78 Cavendish, Henry borne out only recently by today’s observational of hydrogen, determining the composition of air, technology. and calculating the mean density of the Earth. Cassini also made important measurements But he was considered as eccentric as he was bril- of the Earth, and undertook an important geo- liant, and led a life in which he almost never graphical work. He extended the meridian line spoke, not even to his household staff. established from Paris to Amiens by Jean Picard Cavendish was born to English nobility on (1620–82) and made great determinations of October 10, 1731, in Nice, France, where his longitudes. As young Jesuit priests studied under family lived temporarily because of his mother’s him at the Paris Observatory and then went on health. He was the oldest son of Lord Charles their missionary assignments, Cassini began to Cavendish and Lady Anne Gray. The duke of receive results of their observations from China, Devonshire was his paternal grandfather and Africa, and America. He marked these on a large the duke of Kent was his maternal grandfather. planisphere, 7.8 meters in diameter, and made a While little is known about his early education, pen-and-ink sketch on the ground at the obser- it is safe to say that his family’s status and vatory. In this manner, the longitudes of distant wealth probably afforded him private tutors in countries could be corrected more accurately his early childhood. When he turned 11 years old, than ever before. Cavendish was sent to study at Dr. Newcome’s Cassini carried on his research until 1711, School in Hackney, England. At 18 he was off when the strain of a lifetime of squinting to Cambridge, where he enrolled in St. Peter’s through lenses, often at the Sun, rendered him College. totally blind. He was always described as a After dropping out of Cambridge during his man of kind and gentle demeanor, with a fourth year and taking a traditional tour of pleasant nature and deeply religious, which al- Europe with his brother, he inherited a fortune lowed him to bear his blindness with good that made him one of the wealthiest men in cheer and stoicism. He died in the Paris England. However, instead of behaving as one Observatory on September 14, 1712. A space- might expect after such good luck, Cavendish craft launched in 1997 was sent on a seven- became a virtual recluse for the rest of his life, year voyage that successfully reached the Saturn living frugally in London and immersing himself system in July 2004, where it would gather data in scientific studies. and pictures never before available to as- As strange and solitary as Cavendish was, tronomers. It is named Mission Cassini. he was an extraordinary scientist. One of his first accomplishments occurred in 1766 with the discovery of hydrogen. Known as “flammable air” ᨳ Cavendish, Henry and studied by others for a century before him, (1731–1810) this gas was often also called “phlogiston,” an British ancient term for a nonexistent element that, Chemist, Physicist prior to the discovery of oxygen, was thought to be released as a product of combustion. But The reclusive Henry Cavendish was perhaps one Cavendish was the first to measure its specific of the oddest, and yet one of the most impor- gravity and posited that hydrogen was a differ- tant, scientists of the 18th century. He was ent gaseous substance from ordinary air, whose known as an expert at scientific experimenta- components he subsequently analyzed as com- tion, and dedicated his life completely to posed of nitrogen and oxygen in an approximate the study of science, resulting in the discovery 4:1 ratio. Cavendish, Henry 79 The discovery of water, or rather its com- resulted in accurately measuring the mass and position, is also due to Cavendish’s experiments. density of the earth as 5.48 times that of water, In 1781 he discovered that water was composed stunningly close to the 5.5268 calculated by of hydrogen, his “flammable air” discovery, and modern techniques. This constant of propor- oxygen, which he determined by burning the tionality used in Newton’s Law of Universal two chemicals together, in the proper ratio now Gravitation, or G, was found to be 6.67 ϫ 10–11 known as H2O. He was the first person to hear newtons between two objects with a mass of one the famous “POP!” that high school chemistry kilogram each at a distance from each other of students experience when they hold a Bunsen one meter. Cavendish calculated this constant burner to the mouth of the bottle of collected measuring the gravitational force between two hydrogen. metal spheres. Knowing G permitted the deter- Cavendish wrote, “. . . on applying the lighted mination of the Earth’s mass, and subsequently paper to the mouth of the bottle . . . with 3 parts the mass of the Sun and planets. of flammable air to 7 of common air, there was Cavendish also dabbled in electrical meas- a very loud noise.” Then, when he combined the urements, sometimes measuring the strength of hydrogen with the oxygen, he produced water, an electrical current by shocking himself and leading him to reverse the process and prove once then comparing the levels of pain he experi- and for all that water was composed of “flamma- enced. Some of his experiments investigated the ble air” and oxygen. As Cavendish described it, phenomenon of capacitance, and he came very “By the experiments . . . it appeared that when close to formulating what was to become Ohm’s flammable and common air are exploded in a Law. Cavendish’s work in electricity was redis- proper proportion, almost all of the flammable covered and published after his death by James air and near one-fifth of the common air lose Clerk Maxwell (1831–79), the scientist known their elasticity and are condensed into dew.” for discovering electromagnetism. While he was at it, Cavendish also noted Although he himself admitted to having “a that the water’s weight was equal to the weight singular love of solitariness,” Cavendish did have of the gases. French chemist Antoine-Laurent one social function in his life, albeit a scientific de Lavoisier (1743–94) named the new gas hy- social function, that he religiously attended—he drogen—Greek for “water-former.” Cavendish was a member of the Royal Society and is re- eventually calculated the composition of air to ported to have rarely missed the weekly dinner be 79.167 percent “phlogisticated air” (now meetings. But while his scientific discoveries known as nitrogen) and 20.833 percent “de- were highly regarded by his contemporaries, phlogisticated air” (oxygen), but also estab- even they considered him an extremely odd 1 lished that ⁄120 was a mysterious third gas, man. It could have been due to the way he which 100 years later was discovered to be ar- dressed. Although a man of amazing wealth, gon in 1894 by the Scotsman Sir William Ramsey Cavendish wore the same clothes nearly every (1852–1916) at University College, London. day—an outfit that consisted of “a crumpled vi- Such chemistry discoveries ultimately sup- olet suit” that was in style during the previous ported his work in astronomy. Cavendish was the century, with ruffled cuffs and a high ruffled col- first to determine SIR ISAAC NEWTON’s “gravita- lar, topped off by his equally-out-of-style trade- tional constant,” which he published in 1798 mark three-cornered hat. Or perhaps it was the as “Experiments to Determine the Density of way he talked, or more accurately did not talk, the Earth,” one of his few published papers in that put off his contemporaries. When he his lifetime. His work over a two-year period spoke, which was rare even at the Royal Society 80 Chandrasekhar, Subrahmanyan meetings, his voice was described as shrill and He was born in Lahore, southern India, then part high, and he was so shy that he stammered and of British colonial India, to an educated family. communicated with great difficulty. Completely His uncle was a Nobel laureate and his father inept in dealing with women, Cavendish com- was an executive for the Indian railway system municated with his household staff strictly using who moved the family to Madras when Chandra handwritten notes, and the women who worked was six. for him were ordered to stay completely out of Chandra was an exceptionally brilliant stu- his sight under threat of being fired. dent from the start. At the tender age of 15, he Social skills aside, his brilliance was still able was admitted to the most prestigious college in to shine despite his lack of verbal and written Madras, the Presidency College, where he en- communication with his colleagues. Cavendish rolled in the school’s physics honors program, published fewer than 20 papers in his 50-year graduating with a bachelor’s degree in theoreti- career, but his first, titled “Factitious Airs” and cal physics at the top of his class. During this published in 1766, earned him the Royal program he read Ralph H. Fowler’s (1889–1944) Society’s Copley Medal. He was a member of the early work at Cambridge University’s Trinity Royal Society from 1760 until his death. Never College on “white dwarfs,” stars that have married, Cavendish’s sole social contact was din- burned off their internal supply of hydrogen and ing with other Royal Society members. Lord have collapsed into themselves as intensely hot, Henry Broughman (1778–1868), a fellow mem- highly massive, but very small, remnant stars. ber who eventually became Lord Chancellor This subject fascinated him, and at 18 years old of England, once commented that Cavendish Chandra wrote his first scientific paper and “probably uttered fewer words in the course of sent it to Fowler, who liked it so much he sent his life than any man who ever lived to fourscore it to the Royal Society. It was published as years, not at all excepting the monks of La “Compton Scattering and the New Statistics” Trappe.” Cavendish was a scientist to the end. in the Proceedings of the Royal Society. It was be- According to Broughman, Cavendish wanted to cause of this paper that upon graduation be left alone on his deathbed, because he did not Chandra was accepted as a research student at want any interruptions while he observed and Cambridge after winning an Indian government recorded the progress of the disease that was run- scholarship. ning through his body. Cavendish died alone at When Chandra left Bombay on the voyage home, except for his staff-in-hiding, on March to England, he became seasick and, confined to 10, 1810. The famous Cavendish Laboratory at his stateroom, worked out new calculations Cambridge University is named in his honor, as based on Fowler’s work and his own training in is a crater on the Moon. relativity theory. By the time the ship docked two weeks later, Chandra had worked out his first suspicion that there was an upper limit to ᨳ Chandrasekhar, Subrahmanyan the mass of a white dwarf, a concept that went (Chandra) completely against the prevailing theory at the (1910–1995) time. When he put forth his new theory at Indian, Naturalized American Cambridge, the country’s two leading astro- Astrophysicist physicists, SIR ARTHUR STANLEY EDDINGTON and Edward A. Milne (1896–1950), dismissed his Subrahmanyan Chandrasekhar was known for proposition as impossible, and Eddington in par- most of his scientific life simply as “Chandra.” ticular publicly rejected Chandra’s conclusions. Chandrasekhar, Subrahmanyan 81 Chandra’s theory was essentially this: During political unrest in his native India made re- its evolution, a star goes through a stage known turning home imprudent. Thus, he accepted an as a “red giant,” in which its radius may be hun- offer from Otto Struve (1897–1963) to join the dreds of times its original size; after this the star faculty at the Yerkes Observatory of the University gradually implodes, even if it were once a 7- or of Chicago in 1937. Before reporting, however, 10-solar mass, into a mass lower than Chandra’s he journeyed back to India to marry Lalitha 1.4 solar mass limit. At this stage no more nu- Doraiswamy, a former schoolmate in the physics clear energy can be gained, and when the new program at Presidency College in Madras. Lalitha dwarf star’s iron core grows to the 1.4 solar mass was then working in the Bangalore laboratory of number, it collapses by gravitation again. Chandra’s uncle, the physics Nobel laureate Chandra continued to work on his theory Chandrasekhara Venkata Raman (1888–1970). and, after receiving his Ph.D., was elected a Chandra would remain at the University of Fellow of Trinity College. After undertaking Chicago for the rest of his life, becoming more complete calculations, he confirmed his Morton D. Hall Distinguished Service Professor earlier result and concluded that the mass of a in Astronomy and Astrophysics in 1952. While white dwarf had an upper limit of 1.4 solar mass. at Chicago, he delved into theoretical work on At age 25, he was then invited to present his stellar interiors, and became keenly interested in results in a lecture in 1935 at the Royal the gravitational frictional drag on a star pass- Astronomical Society. When he did, Eddington ing through a tenuous cloud of stars, using such again publicly rejected Chandra’s results, and “drag” to determine the ages of globular clusters. one report quotes him as saying, “I think there He also developed equations for interacting should be a law of nature to prevent a star from gravitational waves, and is responsible for de- behaving in this absurd way.” Scientific ob- veloping the post-Newtonian approximation servers of the day realized that Eddington’s life’s that has become the standard formal approach work had been to prove that every star, regard- to calculating the gravitational waves from dy- less of its mass, had a stable configuration and namic systems of massive particles. Chandra’s contention, if valid, would destroy Chandra was a great supporter of Mohandas that proof. Gandhi, but when World War II broke out he Nevertheless Chandra was devastated. He felt that helping the cause of victory over finally appealed to some respected physicists he Hitler’s Nazi Germany was his most important knew—Léon Rosenfeld (1904–74), Niels Bohr duty. His contribution to the war effort was (1885–1962), and Wolfgang Pauli (1900–58)— working half time at the Aberdeen Proving who unanimously made it known to the scien- Ground on shock waves, and only lengthy clear- tific community that they heartily agreed with ance problems prevented him from accepting an Chandra’s conclusions. His upper limit of 1.4 so- invitation to join the Manhattan Project at Los lar masses is known today as “Chandrasekhar’s Alamos. He became an American citizen in Limit.” However, it is generally agreed in sci- 1953. entific circles that the monkey wrench thrown While at Chicago, Chandra published six into the discussion by Eddington and Milne books and numerous scientific papers, each of was responsible for Chandra having to wait 50 which is considered definitive in its field: An years before winning the Nobel Prize in physics Introduction to the Study of Stellar Structure in 1983. It apparently made it difficult for (1939); Principles of Stellar Dynamics (1943); Chandra to acquire any kind of prestigious Radiative Transfer (1950); Hydrodynamic and position in England, and the beginnings of Hydromagnetic Stability (1961); Ellipsoidal Figures 82 Charlier, Carl Vilhelm Ludvig of Equilibrium (1968); and The Mathematical local high school and in 1881 entered the pres- Theory of Black Holes (1983). tigious University of Uppsala, the oldest uni- He and Eddington eventually patched up versity in the Nordic countries, founded in their differences, and Eddington was instrumen- 1477. There, he came under the influence of tal in Chandra’s 1944 election to the Royal Professor Herman Shultz, then director of the Society. Eddington died that year, and in an Uppsala Observatory, becoming an assistant in obituary speech, Chandra ranked Eddington his third year, and he studied theoretical math- next to KARL SCHWARZSCHILD as the greatest as- ematics and astronomy using the observatory’s tronomer of his time. In 1962 Chandra received 9-inch refractor. the Royal Society’s coveted Royal Medal. In Charlier received his Ph.D. in 1887 with a 1966 he received the National Medal of Science. dissertation on Jupiter’s effect on the orbit of mi- He was also editor of the Astrophysical Journal nor planet 17 Thetis. A year later he became an from 1952 to 1971, taking it from a relatively assistant at nearby Stockholm Observatory, un- small and unnoticed university journal to the in- der the direction of Johan A. H. Gylden, a ternationally respected journal of the American leader in celestial mechanics research. However, Astronomical Society. Charlier brought his mathematical expertise to Chandra also developed an intense interest more practical problems, such as the new appli- in literature and music, and was considered by cation of photography to astronomical observa- many authorities to be a master of the English tions. His initial task was to develop a practical language. His 1987 book, Truth and Beauty, is a method for photographic photometry. At Uppsala collection of essays exploring the similarities in he had gained some experience in the use of motivation and aesthetic rewards of artists and a visual photometer, and at the Stockholm scientists. Observatory he used a small photographic tele- At his death in 1995, he was praised by stu- scope to observe the Pleiades group of stars. dents, associates, and world scientific leaders as Using a micrometer, he measured the diameters possibly the greatest astrophysicist of the 20th of the various star disks on his plates and estab- century. NASA renamed its Advanced X-ray lished a formula relating the image diameters to Astrophysics Facility (AXAF) the Chandra X- the photometric magnitudes of the brighter ray Observatory in honor of him, and launched Pleiades stars. This formula enabled him to be- it in the space shuttle Columbia in 1999 to study come the first observer to determine the magni- faint sources in X-rays in crowded fields from an tudes of the fainter Pleiades stars. At the time, elliptical high-earth orbit. his paper describing his Pleiades work was considered a groundbreaking contribution and was selected by the Astronomische Gesellschaft for ᨳ Charlier, Carl Vilhelm Ludvig dedication of the Pulkowa Observatory on its (1862–1934) 50th anniversary. Swedish After two years at Stockholm Observatory, Astronomer, Mathematician Charlier went back to Uppsala, where from 1890 to 1897 he was chief assistant. During this time Carl Vilhelm Ludvig Charlier was born April 1, a new photographic refractor was installed and 1862, in Ostersund, the capital of Jamtland, a Charlier became interested in the theory of province in northern Sweden. He was the son astronomical and photographic lens combina- of Emanuel Charlier, a government official, and tions. He published many papers on the de- Aurora Kristina Hollstein. He attended the velopment of an achromatic objective lens Clark, Alvan Graham 83 comprised of two lenses of the same glass mate- Charlier became a member of the Astro- rial instead of the current standard of flint and nomische Gesellschaft in 1887, and in 1904 was crown glass. elected to the board of directors, on which he In 1897, at age 35, Charlier received the served for 13 years. He was awarded the Watson highest position in Swedish astronomy: profes- Gold Medal of the National Academy of sor of astronomy and director of the observatory Sciences in 1924; the Memorial Medal of the at the University of Lund, a position he held for Royal Physiographic Society at Lund, also in 30 years. One of his accomplishments during this 1924; an honorary membership in the American tenure was to establish two series of observa- Astronomical Society in 1921; and in 1933 was tory publications, published under the name awarded the prestigious Bruce Gold Medal of the Meddelanden. More than 150 issues were printed Astronomical Society of the Pacific. In his re- under his direction, comprising 10 volumes. He tirement he translated SIR ISAAC NEWTON’s continued his work in celestial mechanics at Principia Mathematica Philosophiae Naturalis into Lund. It is noteworthy that, while Charlier’s Swedish, and he wrote a French textbook on early works were published in Swedish, he even- the applications of statistics to astronomy. tually also wrote his technical papers and books Charlier was one of the most influential in German, French, and English. Writing scien- teachers of astronomers and statisticians, and el- tific papers in four different languages is quite evated the University of Lund to a prominent possibly a feat achieved by no other astronomer position in the world astronomical community. in history. Among his students were Gustav Stromberg The contributions Charlier made to theo- (1882–1962), who did important spectroscopic retical astronomy and statistical theory are research at the Lick Observatory on Mount many. Chief among them are a study on the ef- Wilson, and Karl Malmquist (1893–1982), who fect on asteroid orbits of secular perturbations, described analysis pitfalls of brighter object bias that is, the slow progressive changes in plane- in astronomical surveys. tary orbits, and a study of the rotation of plan- Charlier was stricken by an apoplectic event ets around their axes. Also while at Lund, in 1932, and he died at Lund on November 5, Charlier brought his knowledge of mathemati- 1934, leaving his widow Siri Dorotea Leissner cal statistics to the field of astronomy. Charlier and five daughters. demonstrated that all distribution laws in nature can be represented by one of two classes of error functions. He was called upon to test this ap- ᨳ Clark, Alvan Graham plication in other fields as well, such as biology, (1832–1897) medicine, and population statistics. The courses American he taught at the University of Lund led to the Astronomer, Lensmaker establishment of a separate chair for mathematical statistics. Alvan Graham Clark made several of the finest Charlier also made extensive statistical stud- telescope lenses ever produced. Clark was born ies of the distributions and motions of stars near in Fall River, Massachusetts, in 1832. His father, the Sun, and showed that hotter stars and galax- Alvan Clark, made instruments for a living. ies form a flattened system. His hierarchical Alvan Senior had very definite plans about his model of the universe proposed that it is made business life, and in 1846 he opened a com- up of a successive series of higher and higher pany, Alvan Clark & Sons, that specialized in systems. making lenses for telescopes. Alvan Junior 84 Clark, Alvan Graham wanted to be an artist, specifically a portrait In 1861 SIMON NEWCOMB was appointed to painter, but at the age of 20 he joined his the Naval Observatory, which had been founded father’s firm in Cambridgeport and learned the in 1830 as the Depot of Charts and Instruments, lens-grinding art, eventually becoming the firm’s in Washington, D.C. He supervised Clark in chief optician. building a new 26-inch refractor for the obser- It was while Clark was testing one of his cre- vatory, the largest refractor ever made. In 1877 ations, a new 18-inch lens in a telescope he had ASAPH HALL used this telescope to discover built for the Dearborn Observatory in Chicago Deimos and Phobos, the two moons of Mars. (now Northwestern University’s observatory), The telescope is still in use today to monitor that he made his first astronomical discovery. He double stars, and the observatory reports that its turned the instrument toward Sirius, the Dog optics are “phenomenally good.” Star, and observed for the first time a compan- In 1878 a new 30-inch refractor was built ion star. This star had been predicted 18 years for Polkovo Observatory near Leningrad, earlier by astronomer FRIEDRICH WILHELM BESSEL, Russia, which was used some years later by the who had observed Sirius for more than 10 years Russian astrophysicist Gavriil Adrianovich Tikhov and concluded that it had an unseen compan- (1875–1960), the founder of astrobiology, to ion, but now Clark confirmed its existence. study the Martian terrain. The telescope was Sirius B is a white dwarf star—an extremely hot destroyed during World War II. but very small star—the first white dwarf to ever The 36-inch refractor built for the Lick be discovered. For his achievement, Clark was Observatory in Mount Hamilton, California, honored with the Lalande Prize of the French cost approximately $180,000 when it was in- Academy of Science. As a companion star to stalled in 1888 in the large dome at the obser- the Dog Star, Sirius B is nicknamed “the Pup.” vatory, considered the most advanced at the But Clark’s most significant contributions to time. This was the first time an observatory had astronomy were the famous and coveted lenses been built for its favorable location to observe he built for the major observatories and as- rather than its proximity to a university. EDWARD tronomers of the time. He built five significant EMERSON BARNARD made many of his famous lenses in his lifetime, and each of these impor- observations on this telescope, including his distant lenses, bigger than the previous, became covery of the fifth moon of Jupiter. The tele- the largest refractor available, setting new world scope is still in operation today. records when they were installed. The 40-inch refracting telescope at the In 1896 Clark built the 24-inch lens for the University of Chicago’s Yerkes Observatory in Lowell Observatory in Flagstaff, Arizona. This Williams Bay, Wisconsin, remains the largest telescope is still on display in the “wedding refractor ever made. The lens was installed into cake” dome at the observatory. PERCIVAL LOWELL the 63-foot (19.2 m) telescope on May 20, (1855–1916), who was convinced that there was 1897, and operated in a small but significant a planet beyond Neptune, funded three projects ceremony the next evening by GEORGE ELLERY for the search. During the third project, on HALE, who pointed the telescope at Jupiter February 18, 1930, a young astronomer named and showed guests what the planet looks like CLYDE WILLIAM TOMBAUGH discovered the at 400x the magnification of the naked eye. planet on his photographic plates. He is the only Some of the most famous astronomers have American to discover a planet. His plates of used the 40-inch Yerkes telescope to make Pluto are on display at the observatory near the their observations and discoveries, including telescope. Barnard, Hale, GERARD PETER KUIPER, and Clausius, Rudolf Julius Emmanuel 85

SUBRAHMANYAN CHANDRASEKHAR. This was the last lens made by Clark, just before his death. Because there is an optical limit to using lenses larger than 40 inches, scientists in that era began using mirrors in reflecting telescopes to achieve greater magnifications, which is why the Yerkes lens is still, more than a century later, the largest refracting telescope in the world. Clark discovered 16 more double stars before he died in 1897, and most of his discoveries came by testing lenses he had made for other people or institutions. Eventually, refracting telescopes incorporating lenses made by Clark would make some of the major astronomical discoveries of the late 19th and 20th centuries.

ᨳ Clausius, Rudolf Julius Emmanuel Through his work on the second law of thermo- (1822–1888) dynamics and his development of the concept of entropy, the German theoretical physicist Rudolf German Clausius had a major impact on 19th-century Physicist cosmology. He concluded that the entropy of the universe was striving to achieve a maximum value By introducing the concept of entropy in 1865, under the laws of thermodynamics. The end condition Rudolf Clausius completed his development of would be what he called “the heat death” of the universe—a state of complete temperature equilibrium the first comprehensive understanding of the with no energy available to perform any useful work. second law of thermodynamics—a scientific feat (AIP Emilio Segrè Visual Archives) that allowed 19th-century cosmologists to postulate a future condition (end state) they called “heat death of the universe.” doctorate in mathematical physics from the A German theoretical physicist, Clausius University of Halle. In 1850 he accepted a po- was born on January 2, 1822, in Köslin, Prussia sition as a professor at the Royal Artillery and (now Koszalin, Poland). His father, the Reverend Engineering School in Berlin. C. E. G. Clausius, served as a member of the In 1850 Clausius also published his first and Royal Government School Board and taught what is now regarded as his most important pa- at a small private school where Clausius at- per discussing the mechanical theory of heat. tended primary school. In 1840 he entered the The famous paper, entitled “Uber die bewegende University of Berlin as a history major, but Kraft der Wärmer” (“On the Motive Force of emerged in 1844 with his degree in mathemat- Heat”), provided the first unambiguous state- ics and physics. After graduation Clausius taught ment of the Second Law of Thermodynamics. In mathematics and physics at the Frederic-Werder this paper, read at the Berlin Academy on Gymnasium (secondary school), while pursuing February 18, 1850, and then published in its his graduate degree. In 1848 he received his Annalen der Physik (Annals of physics) later that 86 Clausius, Rudolf Julius Emmanuel year, Clausius built upon the heat engine theory (first law principle); the entropy of the universe of the French engineer and physicist, Sadi strives to reach a maximum value (second law Carnot (1796–1832), and introduced his version principle).” of second law of thermodynamics in a simple, By introducing the concept of entropy in yet important statement: “Heat does not spon- 1865, Clausius provided scientists with a con- taneously flow from a colder body to a warmer venient mathematical way to understand and body.” While there is one basic statement of the express the second law of thermodynamics. In First Law of Thermodynamics, namely, the addition to its tremendous impact on classical conservation-of-energy principle, there are quite thermodynamics, his pioneering work also had literally several hundred different, yet equally an enormous impact on 19th-century cosmology. appropriate, statements of the second law. Clau- As previously stated, Clausius assumed that the sius’s perceptive statements and insights, as ex- total energy of the universe (taken as a closed pressed in 1850, lead the long and interesting system) was constant, so the entropy of the uni- parade of second law statements. This particular verse must then strive to achieve a maximum paper is often regarded as the foundation of value in accordance with the laws of thermody- classical thermodynamics. namics. According to this model, the end state However, in the 19th century many physi- of the universe is one of complete temperature cists, including the famous British natural equilibrium, with no energy available to perform philosopher William Thomson Kelvin, first any useful work. Cosmologists call this condi- baron of Largs (1824–1907), were also grappling tion the heat death of the universe. with the nature of heat and developing basic In 1855 Clausius accepted a position at the mathematical relationships to describe and pre- University of Zurich and in 1859 married his first dict how thermal energy flows through the uni- wife, Adelheid Rimpam. She bore him six chil- verse and is transformed into mechanical work. dren, but died in 1875 giving birth to the cou- Clausius is generally given credit as the person ple’s last child. While he enjoyed teaching in who most clearly described the nature, role, and Zurich, he longed for Germany and returned to importance of the second law—although others, his homeland in 1867 to accept a professorship like Lord Kelvin, were simultaneously involved at the University of Würzburg. He moved on to in the overall quest for understanding the me- become a professor of physics at the University chanics of thermophysics. of Bonn in 1869, where he taught for the rest of Between 1850 and 1865 Clausius published his life. At almost 50 years of age, he organized a number of other papers dealing with mathe- some of his students into a volunteer ambulance matical statements of the second law of ther- corps for duty in the Franco-Prussian War modynamics. This effort climaxed in 1865, when (1870–71). Clausius was wounded in action and he introduced the concept of entropy as a ther- received the Iron Cross in 1871 for his services modynamic property to describe the availability to the German army. He remarried in 1886, and of thermal energy (heat) for performing me- his second wife, Sophie Stack, bore him a son. chanical work. In his paper of 1865, Clausius He continued to teach until his death on August considered the universe to be a closed system 24, 1888, in Bonn, Germany. (that is, a system that has neither energy nor Despite a certain amount of nationalistically mass flowing across its boundary) and then suc- inspired international controversy over who de- cinctly tied together the first and second laws of served credit for developing the second law of thermodynamics with the following elegant thermodynamics, Clausius left a great legacy in statement: “The energy of the universe is constant theoretical physics and earned the recognition Compton, Arthur Holly 87 of his fellow scientists from throughout Europe. He was elected as a foreign fellow of the Royal Society of London in 1868 and received that society’s prestigious Copley Medal in 1879. He also was awarded the Huygens Medal in 1870 by the Holland Academy of Sciences and the Poncelet Prize in 1883 by the French Academy of Sciences. The University of Würzburg bestowed an honorary doctorate upon him in 1882.

ᨳ Compton, Arthur Holly (1892–1962) American Physicist

Arthur Holly Compton was one of the pioneers of high-energy physics. In 1927 he shared the Nobel Prize in physics for his investigation of the scattering of high-energy photons by electrons— The Nobel laureate physicist Arthur Holly Compton an important phenomenon called the “Compton identified a special high-energy photon scattering effect.” His research efforts in 1923 provided the phenomenon. This phenomenon, now called Compton first experimental evidence that electromag- scattering, has become the foundational principle netic radiation possessed both particle-like and behind many of the gamma ray detection techniques used in modern high-energy astrophysics. Compton wavelike properties. Compton’s important dis- shared the Nobel Prize in physics in 1927 for his covery made quantum physics credible. In the discovery. To further honor his achievements, in 1991 1990s the National Aeronautics and Space NASA named its large astrophysics laboratory the Administration (NASA) named its advanced Compton Gamma Ray Observatory (CGRO). (Photograph by Moffett Studio, AIP Emilio Segrè high-energy astrophysics spacecraft the Compton Visual Archives) Gamma Ray Observatory (CGRO) after him. A. Compton was born on September 10, 1892, into a distinguished intellectual family in Wooster, Ohio. Elias Compton, his father, was a him that, because of his talent and intellect, he professor at Wooster College, and his older could be of far greater service to the human brother, Karl, studied physics and went on to race as an outstanding scientist. His older become the president of the Massachusetts brother also helped persuade him to study sci- Institute of Technology. As a youth, Compton ence, and in the process changed the course of experienced two very strong influences from his modern physics by introducing him to the study family environment: a deep sense of religious of X-rays. service and the noble nature of intellectual work. Compton carefully weighed his career op- While he was an undergraduate at Wooster tions and then followed his family’s advice by College, he seriously considered becoming a selecting a career of service in physics. He Christian missionary. But his father convinced completed his undergraduate degree at Wooster 88 Compton, Arthur Holly College in 1913 and joined his older brother at It was Wilson’s cloud chamber that helped Princeton. He received his master of arts degree verify the behavior of Compton’s X-ray scattered in 1914 and his Ph.D. degree in 1916 from recoiling electrons. Telltale cloud tracks of re- Princeton University. For his doctoral research, coiling electrons provided corroborating evidence Compton studied the angular distribution of of the particle-like behavior of electromagnetic X-rays reflected from crystals. Upon graduation, radiation. Compton’s precise experiments de- he married Betty McCloskey, an undergraduate picted the increase in wavelength of X-rays due classmate from Wooster College. The couple had to the scattering of the incident radiation by free two sons: Arthur Allen and John Joseph. electrons. Since his results implied that the scat- After spending a year as a physics instructor tered X-ray photons had less energy than the at the University of Minnesota, Compton worked original X-ray photons, Compton became the for two years in Pittsburgh, Pennsylvania, as an first scientist to experimentally demonstrate engineering physicist with the Westinghouse the particle-like “quantum” nature of electro- Lamp Company. Then, in 1919, he received magnetic waves. His book Secondary Radiations one of the first National Research Council fel- Produced by X-Rays (1922) described much of lowships awarded by the U.S. government. this important research and his experimental Compton used his fellowship to study gamma procedures. The discovery of the Compton effect ray scattering phenomena at Baron Ernest served as the technical catalyst for the accept- Rutherford’s (1871–1937) Cavendish Laboratory ance and rapid development of quantum me- in England. While working with Rutherford, he chanics in the 1920s and 1930s. verified the puzzling results obtained by other The Compton effect is the physical principle physicists—namely, that gamma rays experi- behind many of the advanced X-ray and gamma enced a variation in wavelength as a function ray detection techniques used in contemporary of scattering angle. high-energy astrophysics. In recognition of his The following year, Compton returned to uniquely important contributions to modern as- the United States to accept a position as head tronomy, NASA named a large orbiting high- of the department of physics at Washington energy astrophysics observatory, the Compton University in Saint Louis, Missouri. There, Gamma Ray Observatory (CGRO), in his honor. working with X-rays, he resumed his investiga- NASA’s space shuttle placed this important sci- tion of the puzzling mystery of photon scatter- entific spacecraft into orbit around Earth in April ing and wavelength change. By 1922 his exper- 1991. Its suite of gamma ray instruments operated iments revealed that there definitely was a successfully until June 2000 and provided scien- measurable shift of X-ray (photon) wavelength tists with unique astrophysical data in the gamma with scattering angle—a phenomenon now ray portion of the electromagnetic spectrum—an called the “Compton effect.” He applied special important spectral region not observable by relativity and quantum mechanics to explain the instruments located on Earth’s surface. results, presented in his famous paper “A In 1923 Compton became a physics profes- Quantum Theory of the Scattering of X-rays by sor at the University of Chicago. Once settled Light Elements,” which appeared in the May in at the new campus, he resumed his world- 1923 issue of The Physical Review. In 1927 changing research with X-rays. An excellent Compton shared the Nobel Prize in physics with teacher and experimenter, he wrote the 1926 Charles Wilson (1869–1959), for his pioneering textbook X-Rays and Electrons to summarize and work on the scattering of high-energy photons propagate his pioneering research experiences. by electrons. From 1930 to 1940 Compton led a worldwide Copernicus, Nicolas 89 scientific study to measure the intensity of cos- until failing health forced him to retire in 1961. mic rays and to determine any geographic varia- He died in Berkeley, California, on March 15, tion in their intensity. His precise measurements 1962. showed that cosmic ray intensity actually corre- Compton received numerous awards through- lated with geomagnetic latitude rather than ge- out his illustrious scientific career. In addition to ographic latitude. Compton’s results implied the Nobel Prize in physics, he also received the that cosmic rays were very energetic charged American Academy of Arts and Sciences particles interacting with Earth’s magnetic field. Rumford Gold Medal in 1927. The Radiological His pre–space age efforts became a major con- Society of North America presented him with tribution to space physics and stimulated a great its Gold Medal in 1928. The Royal Society in deal of scientific interest in understanding the London bestowed its Hughes Medal on him in Earth’s magnetosphere—an interest that gave 1940. That same year, he also received the rise to many of the early satellite payloads, in- Franklin Medal from the Benjamin Franklin cluding JAMES ALFRED VAN ALLEN’s instruments Institute in Philadelphia, Pennsylvania. Compton on the Explorer I satellite. served as the president of the American Physical During World War II Compton played a Society (1934) and the president of the American major role in the development and use of the Association for the Advancement of Science atomic bomb. He served as a senior scientific (1942). adviser and was also the director of the Manhattan Project’s Metallurgical Laboratory at the University of Chicago. Under Compton’s ᨳ Copernicus, Nicolas (Mikolaj leadership in the “Met Lab” program, the bril- Kopernik, Niklas Koppernigk, Nicolaus liant Italian-American physicist Enrico Fermi Copernicus, Nicholas Copernicus) (1901–54) was able to construct and operate the (1473–1543) world’s first nuclear reactor on December 2, Polish 1942. This successful uranium-graphite reactor, Astronomer called Chicago Pile One, became the technical ancestor for the large plutonium-production Revolutionary ideas gave Nicolas Copernicus his reactors built at Hanford, Washington. The permanent place of prestige in the field of as- Hanford reactors produced the plutonium used tronomy. His proposal that the Sun, rather than in the world’s first atomic explosion, the Trinity the Earth, was the center of our universe forever device detonated in southern New Mexico changed how we view ourselves in the cosmos. on July 16, 1945, and also in the Fat Man But Copernicus was neither a revolutionary nor atomic weapon dropped on Nagasaki, Japan, on an astronomer by trade. And his ideas of the August 9, 1945. Compton described his wartime structure of our solar system, called a heliocen- role and experiences in the 1956 book Atomic tric system, were ones he discovered as a student Quest—A Personal Narrative. in his late 20s at the University of Cracow, study- Following World War II, he put aside physics ing astronomy and ancient philosophy, among research and followed his family’s tradition of other subjects. Christian service to education by accepting the Yet it was his interpretation of what to do position of chancellor at Washington University with these radical theories, and his original in St. Louis, Missouri. He served the university thoughts surrounding his discoveries, that lead as its chancellor until 1953 and then contin- to revolutionary ideas supported by the likes ued there as a professor of natural philosophy, of GIORDANO BRUNO,JOHANNES KEPLER, and 90 Copernicus, Nicolas Copernicus’s university studies began at the University of Cracow, in the capital of Poland, where art, mathematics, astrology, and astronomy were part of his course of study. In 1496 he went to Italy, taking up studies in Bologna, Padua, and Ferrara, mostly in canon law and medicine. In 1501, when he began his studies in medicine at the University of Padua, Copernicus took courses in Greek and Latin. In addition to learning new languages, he was for the first time exposed to the writings of ancient philosophers. As with any medical student of the time, he also undertook more courses in astronomy and astrology. The exposure to philosophy and astronomy would ultimately have the biggest impact on his contribution to science. He returned to Poland in 1503, rejoining his uncle, who had risen through the ranks of the Catholic Church to the position of bishop of Ermeland. Copernicus, now 30 years old, accepted a position in the Chapter of Frauenberg, The 16th-century Polish astronomer and church and in addition to his duties as canon became official Nicolas Copernicus launched the scientific revolution with the deathbed publication of his book, his uncle’s personal physician. His life was to be On the Revolution of Heavenly Spheres in 1543. By one of dedication to the church, even to the advocating heliocentric cosmology, Copernicus point of ending a relationship with his house- helped overthrow the Ptolemaic system and nearly keeper when the church told him to do so. two millennia of mistaken adherence to the Earth- centered cosmology of the ancient Greek Astronomy was something he worked on in his philosophers. (AIP Emilio Segrè Visual Archives, spare time. T.J.J. See Collection) It was sometime around 1512 that Copernicus wrote his Commentariolus, a “short comment” GALILEO GALILEI, all of whom suffered at the outlining his thoughts on the order of the uni- hands of the Roman Catholic Church for sup- verse. This new world system was based on porting Copernicus’s published work, which was PTOLEMY’s geocentric system, with a twist— ironically dedicated to, and gratefully received instead of the Earth being the center of the by, the pope. universe, Copernicus theorized that everything Born in Thorn, Poland, in 1473, the revolved around the Sun. He also believed that younger of two brothers, Copernicus was taken the Earth rotated on its own axis, and he used into the care of his uncle at age 10 after his the rotation of the Earth and its revolution father’s death. This man, Lucas Waczenrode, around the Sun to explain the idea of planets with whom Copernicus would ultimately spend spinning in retrograde. most of his life, was dedicated to two things: Seventeen centuries earlier, according to serving the Catholic Church and providing his the work of Archimedes (287–212 B.C.E.), the young nephews with an education. Pythagorean ARISTARCHUS OF SAMOS had first Copernicus, Nicolas 91 proposed that the Earth rotated on its axis and bade the sun and not the earth to stand still,” as revolved around the Sun. His contemporaries proof that Copernicus was doing the devil’s thought his ideas were absurd, if not blasphemous, work, and emphatically stating that he believed based on simple observation of everything that the “fool” Copernicus would “reverse the entire was “natural.” Ptolemy’s geocentric model was up- Ars Astronomiae,” the science of all known held as the one true system that “worked,” even astronomy, if he continued putting forth such though it was extremely complicated and very ludicrous ideas. flawed. Common practice throughout the cen- But the persistent Rheticus would not let turies was to construct excuses to prove that Copernicus hide his work any longer, and he Ptolemy’s model was right. This was a normal part convinced Copernicus to let him get the work of science that became referred to as “saving the printed in Nuremberg. In 1542 Rheticus took appearances” that the geocentric system ruled. Copernicus’s manuscript to Nuremberg, where it When Copernicus worked out the same soon found its way into the publisher’s house ideas proposed by Aristarchus, he was the last to and the hands of a Lutheran priest, Andreas think that he was contradicting Ptolemy. He felt Oslander. Not wanting to stir things up with his that his theories were an extension of Ptolemy’s fellow Lutherans, Oslander took it upon himself work, offering some simplicity and clarity. He to write an anonymous preface, making it look worked on this process of clarification, making as though Copernicus had written it himself, stat- computations and creating new tables, for a few ing that the hypotheses contained in the book decades. He mostly kept his Commentariolus to were not necessarily true, “nor even probable.” himself, sharing it only with a few good friends, While many of Copernicus’s ideas were who also happened to be members of the church. flawed—for example, his belief, like Ptolemy’s, Surprisingly, the Catholics he entrusted with that all orbits were perfectly circular—they pro- his work applauded it, and repeatedly urged vided the foundation for a major shift in think- him to publish his ideas, which he declined to ing about the order of the universe. But not in do for several years. But word of his findings Copernicus’s lifetime. His book, De revolution- traveled, eventually making its way to a young ibus orbium coelestium (On the revolutions of the mathematician in Wittenberg named Rheticus heavenly spheres) was finally published and a (1514–74), who in 1539 traveled to meet the printed copy delivered, reportedly on May 24, man who had done what had never been done 1543, to him in Frauenberg. A victim of stroke, before—combine a simpler theory with personal he died that same day. observation, and computation with new tables, Oslander’s disclaimer served to lead many to to explain a new solar system. Copernicus gave believe that Copernicus’s theories were incon- Rheticus permission to tell others about this sequential to the author himself, although the theory, and the mathematician wrote about newly calculated tables were considered use- Copernicus’s work in his own publication Narratio ful. As for the Lutherans, the publication an- prima (First Communication), crediting the orig- gered them even more. Seven years later, the inator as “The Reverend Father Dr. Nicholas of Lutheran leader Melanchthon (1497–1560) was Torun, Canon of Ermland.” The Catholics em- still staunchly denouncing Copernicus, quoting braced the work of the good Reverend Father. the Bible, and decreeing that with “these divine The Lutherans, however, were another matter. testimonies we will cling to the truth.” Overall The Protestant leader Martin Luther (1483– acceptance of Copernicus’s theories did not hap- 1546) blasted Copernicus for his radical and pen. In addition to the religious flak the book heretical ideas, quoting the scripture “Joshua was taking, the scholars of the time dismissed 92 Curtis, Heber Doust the heliocentric system completely. His book freely take place, as the books of Galileo, Kepler, was not printed again until 1566, and then not and the man who started it all, Copernicus, were again until 1617. But the work caught the spirit removed from the church’s list of forbidden and minds of a few important figures who not books. only perpetuated the theories but also gave them new legs to stand on. Giordano Bruno was one brave soul who ᨳ Curtis, Heber Doust believed in Copernicus’s heliocentric system. (1872–1942) But by the time he started to spread the word American about his beliefs, the Catholic Church had de- Astronomer creed that the act of declaring the Sun as the center of the universe was heresy, and Bruno Heber Curtis gained national attention in 1920 was burned alive at the stake for speaking his when he engaged in the “Great Debate” over the truths. size of the universe with fellow American as- The biggest shift leading to the acceptance tronomer HARLOW SHAPLEY. Curtis supported to Copernicus’s new order happened when the daring hypothesis that spiral nebulas were Johannes Kepler learned about the heliocentric actually “island universes”—that is, other galax- system as a student at the university in Tubingen. ies, existing far beyond the Milky Way Galaxy. Kepler communicated with Galileo Galilei, who This radical position meant that the observable confessed that for “many years,” he had agreed universe was much larger than anyone dared with Copernicus. He told Kepler that he had imagine. By 1924 EDWIN POWELL HUBBLE was even written arguments for and against the ideas, able to support Curtis’s hypothesis, when he but had not told anyone about this “until now demonstrated that the great spiral Andromeda .. . deterred by the fate of Copernicus himself, “nebula” was actually a large galaxy similar to, our master, who although having won immortal but well beyond, the Milky Way. fame with some few, to countless others appears Heber Curtis was born in Muskegon, .. . as an object of derision and contumely.” He Michigan, on June 27, 1872. As a child, he told Kepler that “Truly, I would venture to pub- went to school in Detroit. He then studied lish my views if more like you existed; since this the classic languages (Latin and Greek) at the is not so, I will abstain.” University of Michigan for five years, receiving Kepler’s passionate reply called upon Galileo his bachelor of arts degree in 1892 and his mas- to show his proofs to the world: “Be confident ter of arts degree in 1894. Following gradua- Galilei and proceed!” It was 1597. An undeni- tion, Curtis moved to California to accept a able change must have been written in the stars. position at Napa College in Latin and Greek Galileo surely saw it when he made his first tel- studies. However, while teaching the classics, he escope in 1609. Unfortunately, the Catholic became interested in astronomy and volun- Church changed its once-favorable stance on teered as an amateur observer at the nearby Lick Copernicus, and the writings of all three men Observatory. In 1896 he became a professor of were declared heresy. mathematics and astronomy at the College of Centuries later, in 1835, after Galileo’s im- the Pacific, following a merger of that institu- portant work had finally been back in circula- tion with Napa College. tion for nearly 100 years, the church and the In 1900 Curtis served as a volunteer mem- scientific community were finally beginning to ber of the Lick Observatory expedition that coexist. Acceptance of heliocentric thinking could traveled to Thomaston, Georgia, to observe a Curtis, Heber Doust 93 eclipse expedition, he entered the University of Virginia on a fellowship and graduated in 1902 with his doctorate in astronomy. After graduation he joined the staff of the Lick Observatory as an astronomer. From 1902 to 1909 he made precise radial velocity measurements of the brighter stars in support of WILLIAM WALLACE CAMPBELL’s observation program. Starting in 1910, Curtis became interested in photographing and analyzing spiral nebulas. He was soon convinced that these interesting celestial objects were actually isolated independent systems of stars, or “island universes,” as IMMANUEL KANT had called them in the 18th century. Many astronomers, including Harlow Shapley, opposed Curtis’s hypothesis about the extragalactic nature of spiral nebulas. On April 26, 1920, Curtis and Shapley engaged in their famous “Great Debate” on the scale of the universe and the nature of the Milky Way Galaxy at the National Academy of Sciences, in Washington, D.C. At the time, the vast majority of astronomers considered the extent of the Milky Way Galaxy synonymous with the size of the universe—that is, they thought the universe was just one big galaxy. However, neither astronomer involved in this highly publicized debate was completely correct. Curtis argued that The American astronomer Heber Curtis stands on a ladder at the eyepiece of the 24-inch Crossley spiral nebulas were other galaxies similar to the reflector telescope at the Lick Observatory. Curtis Milky Way—a bold hypothesis later proven to gained national attention in 1920 when he engaged in be correct. But he also suggested that the Milky the “Great Debate” over the size of the universe with Way was small and that the Sun was near its fellow American astronomer Harlow Shapley. Curtis supported the then-daring hypothesis that spiral center—both of these ideas were subsequently nebulas were actually “island universes”—that is, proven incorrect. Shapley, on the other hand, other galaxies far beyond the boundaries of the Milky incorrectly opposed the hypothesis that spiral Way Galaxy. (Courtesy AIP Emilio Segrè Visual nebulas were other galaxies. He argued that the Archives, Shapley Collection) Milky Way Galaxy was very large (much larger than it actually is) and that the Sun was far from the galactic center. solar eclipse. His enjoyment of and outstanding In the mid–1920s the great American as- performance during the eclipse expedition con- tronomer EDWIN POWELL HUBBLE helped to re- verted Curtis’s amateur interests in astronomy solve one of the main points of controversy into a lifelong profession. After his first solar when he used the behavior of Cepheid variable 94 Curtis, Heber Doust stars to estimate the distance to the Andromeda In 1920 Curtis became the director of the Galaxy. Hubble showed that this distance was Allegheny Observatory of the University of much greater than the size of the Milky Way Pittsburgh. During the next decade he improved Galaxy proposed by Shapley. So, as Curtis had instrumentation at the observatory and partici- suggested, the great spiral nebula in Andromeda pated in four astronomical expeditions to ob- and other spiral nebulas could not be part of the serve solar eclipses. In 1930 he returned to the Milky Way and must be separate galaxies. In the University of Michigan as a professor of as- 1930s astronomers proved that Shapley’s com- tronomy and the director of the university’s ments were more accurate concerning the actual astronomical observatories. He served in those size of the Milky Way and the Sun’s relative lo- positions until his death in Ann Arbor, cation within it. Therefore, when viewed from Michigan, on January 9, 1942. His wife, Mary the perspective of science history, both eminent D. Rapier Curtis, his daughter, and three sons astronomers had argued their positions using survived him. He was president of the partially faulty and fragmentary data. The Curtis- Astronomical Society of the Pacific (1912), a Shapley debate triggered a new wave of astro- fellow of the American Association for the nomical inquiry in the 1920s that allowed Advancement of Science (1924), vice president astronomers like Hubble to determine the true of the American Astronomical Society (1926), size of the Milky Way and to recognize that it is a member of the American National Academy but one of many other galaxies in an incredibly of Sciences, and foreign associate of the Royal vast, expanding universe. Astronomical Society in London.

off to military service, allowing the younger ᨳ Dirac, Paul Adrien Maurice students better and more frequent access to the (1902–1984) science laboratories and other facilities. British He graduated at the top of his class, and in Physicist, Mathematician 1918, he went to the University of Bristol to Speaking at a dedication of a memorial plaque study electrical engineering before applying being unveiled at London’s Westminster Abbey, for and receiving a scholarship to Cambridge the famous physicist SIR STEPHEN WILLIAM University in 1921. But the scholarship required HAWKING said, “Paul Dirac has done more than additional money for full support, which he was anyone this century, with the exception of unable to obtain, so he enrolled in Bristol ALBERT EINSTEIN, to advance physics and change University. There, he continued to excel, and our picture of the universe.” graduated with a B.S. degree in mathematics Born in Bishopston, Bristol, United Kingdom, with honors in 1923. At this time he earned a to a Geneva-born Swiss-French father Charles research grant at St. John’s College at Cambridge. Dirac, and a Cornwall-bred mother Florence During this period, classical physicists Hannah Holton, Dirac, his older brother Reginald, (Newtonian scholars) were having trouble rec- and their younger sister Beatrice endured a harsh onciling SIR ISAAC NEWTON’s physics with the childhood under their father’s strict discipline behavior of electrons and atoms, and were la- and generally spent their time in an unhappy boring to develop a new theory to explain it. At household. Both boys would become alien- Cambridge, Dirac studied under Ralph Fowler ated from their father by the time they left for (1889–1944), the leading theoretician versed in college. the new theory of quantum physics, and became Dirac found solace in his studies, and by the enamored of the algebraic commutators put time he graduated from Bishop Primary School forth by Werner Heisenberg (1901–76). his exceptional talent for mathematics had be- Dirac soon developed his own theory, a com- come apparent. In 1914, at age 12, he entered bination of quantum mechanics and special rel- the secondary school at Merchant Venturers ativity, which included wave mechanics and ma- Technical College, where his father taught trix mechanics. By the time Dirac’s doctoral French. Dirac would later comment that as thesis, “Quantum Mechanics,” earned him his World War I broke out, the older students went Ph.D. in 1926, he already had 11 papers in

95 96 Dirac, Paul Adrien Maurice print. The thesis was widely acclaimed and he (1887–1961). A shy and retiring fellow who was elected a Fellow of St. John’s College in abhorred the limelight, Dirac at first wanted to 1927. refuse the Nobel Prize because of the publicity After receiving his degree, Dirac went to it would generate, but changed his mind when Copenhagen to work with Niels Bohr (1885– he was told that refusing it would bring only 1962), then went to Göttingen where he worked more publicity than ever upon him. with Robert Oppenheimer (1904–67), Max The years 1934 and 1935 were equally dra- Born (1892–1970), James Franck (1882–1964), matic, for both professional and personal rea- and the Russian Nobel laureate Igor Tamm sons. Dirac accepted an invitation to visit (1895–1971). He made it a point to visit the Princeton University to meet the famous Soviet Union several times, first in 1928 and Hungarian physicist and future Nobel laureate then almost once a year throughout the 1930s. (1963) Eugene Wigner (1902–95). While Dirac In 1928 Dirac published his famous “spin- was there, Wigner’s sister, Margit, came from 1/2 Dirac Equation,” which is still widely used Budapest to visit her brother, and Dirac fell in today, and which explained the mysterious mag- love. Married in London, the two eventually had netic and “spin” properties of the electron. He two daughters. Margit had two sons by a previ- used this equation to predict the existence of a ous marriage, and they took Dirac’s name; one particle with the same mass as an electron, but of them, Gabriel Andrew Dirac, became a fa- with an opposite charge (that is, a positively mous pure mathematician and was a professor of charged “antimatter” electron). This antimatter pure mathematics at the University of Aarhus was subsequently discovered and called a in Denmark. positron in 1932 by CARL DAVID ANDERSON. During World War II Dirac worked on ura- Today positrons are used every day in medicine, nium separation and nuclear weapons with a in PET (positron emission tomography) scan- Birmingham group investigating atomic energy, ners that pinpoint places in the brain, such as an assignment that led the British government where drugs are chemically active, which works to ban him from visiting the Soviet Union un- by detecting the radiation as the positrons emit- til 1957. ted from radioactive nuclei annihilate ordinary Dirac shunned all honorary degrees, of electrons nearby. which dozens were showered on him, but he In 1930 Dirac published his epic The readily accepted honorary admission to re- Principles of Quantum Mechanics, which is still in spected academies and scientific societies. Of print, and in 1932 he was appointed Lucasian these there are also dozens, but primary among Professor of Mathematics at Cambridge, a post them were the USSR Academy of Sciences in he held for 37 years, which was formerly held by 1931; Indian Academy of Science in 1939; Newton and since 1980 by Hawking. Also in Chinese Physical Society in 1943; the Royal 1930, he was made a Fellow of the Royal Society, Irish Academy in 1944; the Royal Society of and would be awarded that society’s Royal Medal Edinburgh in 1946; Institut de France in 1946; in 1939 and the prestigious Copley Medal in the National Institute of Sciences of India in 1952. 1947; the American Physical Society in 1948; The publication of his book took the physics the National Academy of Sciences in 1949; the community by storm, transformed the current National Academy of Arts and Sciences in 1950; image of the atomic universe, and resulted in his Accademia delle Scienze di Torino in 1951; sharing the 1933 Nobel Prize in physics at 31 Academia das Ciencias de Lisboa in 1953; years of age with Austrian Erwin Schrödinger Pontifical Academy of Sciences, Vatican City, Doppler, Christian Andreas 97 in 1958; Accademia Nazionale dei Lincei, enter the Vienna Polytechnic Institute. Doppler Rome, in 1960; the Royal Danish Academy in enrolled in 1822. 1962; and the Académie des Sciences de Paris Doppler finally began to excel and, indeed, in 1963. He was appointed to the Order of Merit mathematics turned out to be his forte. After in 1973. graduating in 1825, he returned to Salzburg and After a glorious career reshaping the way studied philosophy at the Lyceum, then returned physicists looked at the inner and outer uni- to Vienna, this time to study astronomy, me- verses, Dirac retired from Cambridge in 1969 chanics, and higher mathematics at the univer- and moved his family to Florida. He held visit- sity. In 1829 Doppler began a four-year tenure ing appointments at the University of Miami as an assistant to a professor of higher mathe- and at Florida State University (FSU). In 1971 matics and mechanics. He published his first he was appointed professor of physics at FSU, technical paper, “A Contribution to the Theory where he continued his research and continued of Parallels,” plus three others over the four-year to travel as well. In 1973 and 1975 he lectured at period. the Physical Engineering Institute in Leningrad. By the time Doppler was 30 years old, he “One of the most influential scientists of had grown weary of being someone’s assistant, the twentieth century,” as the editor of Physics and he began to think in terms of finding a per- World called him, this Bristol-born giant of the manent position in his own right. However, it world of quantum physics died in Tallahassee in was not easy at this time in Austria. Applicants 1984. for vacant professorships had to enter a public competition for the available jobs, in which the applicant had to take a day-long written exam ᨳ Doppler, Christian Andreas and then give a lecture to an appointed panel of (1803–1853) examiners. Politics played a key role in getting Austrian the final appointment. Mathematician Doppler applied for professorships at several schools in this manner, including the universi- Anyone who has ever gotten a speeding ticket ties in Gorizia, Linz, Ljubljana, Salzburg, the can thank Christian Doppler. It was he who de- Technical Secondary School in Prague, and veloped the famous “Doppler effect,” which is Vienna Polytechnic Institute. Meanwhile, to the principle used in speed guns and traffic radar. earn a living he took a job as a bookkeeper at a Doppler’s family had been stonemasons in cotton spinning factory. Through all these Salzburg, Austria, since 1674, and it was ex- stressful efforts, his health, which was not good pected that he, too, would enter the family busi- to begin with, began to deteriorate. ness. However, he was born to ill health and by The public competition for all those jobs the time he reached his teens he was too frail took almost two years to complete. At one point for the demanding work of stonemasonry. Doppler gave up and decided to move to After primary school in Salzburg, he at- America, but just when he was interviewing the tended secondary school in nearby Linz, but was American consul in Munich, he received the only an average student. When his parents con- happy news in 1835 that he had won the job at sulted a mathematics professor at the Salzburg the Technical Secondary School in Prague. Lyceum as to young Doppler’s potential, the pro- Once again, Doppler was unhappy with the fessor suggested that he might have a talent in situation. He considered teaching elementary mathematics, and recommended that Doppler mathematics in secondary school to be beneath 98 Doppler, Christian Andreas him, which indeed it was, and he cast around then prove Doppler’s work as it applies to light. for a better job. He failed again at getting a po- Doppler’s work placed him in the pantheon of sition at the Polytechnic Institute, but in 1836, astronomy because it was the first major contri- he got a part-time job teaching higher mathe- bution to the discovery that the universe is matics four hours a week, and kept this job for expanding. two years. Even with his new fame, he was having a In 1837 politics reared its ugly head again. hard time of it at work. When students com- The post of professor of geometry and mathe- plained that his examinations were too difficult, matics at the Polytechnic became vacant, and he was reprimanded by the authorities and the Doppler filled the post. However, even as he was stress further affected his health. At about this discharging his duties, the institute held a pub- time he was also under great duress to partici- lic competition for his job behind his back. pate in the examination of hundreds of students When he found out about it, he expressed his applying for competitive positions. For example, dismay in strong terms, and was told he did not one report states that in January and February have to take part in the competition. It remains 1843, he had to examine 256 students in 17 days, a mystery why it was even held at all, because including six hours of both oral and written Doppler was finally appointed formally to the exams in arithmetic and algebra. The same num- position of full professorship in 1841. ber of students sat for theoretical geometry ex- It was during this time that Doppler pre- ams in June and July, and in August Doppler had sented his magnum opus, a paper entitled “On to examine 145 students in eight days. The strain the Colored Light of the Double Stars and was too much for him, and in 1844 he finally re- Certain Other Stars of the Heavens,” which ex- quested a sick leave, which lasted two years be- plained Doppler’s idea that sound was composed fore he was well enough to return to work. of longitudinal waves that could be compressed In 1846 Doppler changed venues, accepting or expanded, and that the frequency of the wave a professorship of mathematics, physics, and me- varied according to its velocity in relation to an chanics at the Academy of Mines and Forests in observer. Banska Stiavnica, mostly to escape the political As a practical proof of his theory, Doppler unrest as the monarchy began to topple in arranged for a trumpeter to sound a series of the Prague. By now he was becoming famous because same notes over and over as he rode on a flat of his widely celebrated Doppler effect thesis, car pulled by a speeding railroad train. On the and was appointed professor again at the ground he stationed another musician with the Polytechnic Institute. In 1848 Doppler was ability to identify musical tones by ear. As the elected to the Imperial Academy of Sciences in train approached closer and then rushed past and Vienna and received an honorary doctorate from moved quickly away, the second musician the University of Prague. In 1850 he was ap- recorded that the notes from the trumpeter pointed the first director of the newly established sounded different when the train was ap- Institute of Physics at Vienna University. proaching than when it was moving away. Thus But his health took a serious turn for the was born the famous “Doppler effect,” which worse and by 1852 he decided to move to Venice everyone has experienced when riding a swiftly for the warmer climate. He could not recover, moving vehicle past a ringing bell. though, and he died there in March 1853. Doppler also tried to prove that his theory Although Doppler also published significant applied to light, but was unable to and it was left papers on electricity and magnetism, described for Armand Fizeau (1819–96) to generalize and the variation of magnetic declination with time, Douglass, Andrew Ellicott 99 and published papers on optics and astronomy, Harvard College Observatory. From 1891 to his definition of the Doppler effect was his 1893 Douglass served as the chief assistant on crowning glory. Today the Doppler effect is the the astronomical expedition that founded the principle behind technologies used across the Harvard Southern Hemisphere Observatory in spectrum of industry. In medicine, Doppler ul- Arequipa, Peru. trasound is used widely in imaging instrumenta- When Douglass returned from Peru, PERCIVAL tion and vascular studies. Doppler radar is both LOWELL hired him to help locate the most suit- an important military tool and useful in weather able site in the “Arizona Territory” (statehood forecasting. Oceanographers use Doppler sonar did not occur until 1912) for a new astronomi- to map ocean currents. Law enforcement uses cal observatory dedicated primarily to support speed guns and traffic radar. And in astronomy, Lowell’s obsession with Mars. Douglass recom- his principle is still useful for measuring the mended the city of Flagstaff and moved there af- speed of bodies and searching for new planets. ter the founding of the Lowell Observatory in 1894. He was a good astronomer and soon became Lowell’s chief assistant. Douglass had the ᨳ Douglass, Andrew Ellicott primary task of collecting data about Mars, but (1867–1962) the young astronomer from Vermont soon fell American into sharp disagreement with Lowell on how Astronomer, Environmental Scientist certain data were being selectively applied to support Lowell’s rather unscientific approach to Early in the 20th century, the American as- prove Mars was inhabited by intelligent beings. tronomer Andrew Douglass postulated that Lowell was actually a skilled observational as- there might be a measurable relationship be- tronomer, but his results were often blurred by tween sunspot activity and the terrestrial cli- the preconceived notion that GIOVANNI VIRGINIO mate. To explore this hypothesis, he started the SCHIAPARELLI’s canali (channels) were canals field of dendrochronology (tree-ring dating). built by a race of intelligent beings. After Despite his years of investigation, he could only numerous “scientific method” clashes, Lowell link tree ring data with local climate episodes, wanted no more internal dissidence, and he fired since this data could not provide an unambigu- Douglass in 1901. ous link between past global climate conditions Unperturbed, Douglass remained in the and sunspot activity. However, his pioneering ef- Flagstaff area until 1906, when he joined the forts provided both archaeologists and climatol- University of Arizona in Tucson as its first pro- ogists with an important new research tool and fessor of astronomy. He also taught physics at also anticipated the efforts by modern scientists the university and became the first astronomer who employ sophisticated satellites in their con- to photograph the zodiacal light. In 1916 he temporary investigation of Sun-Earth environ- secured funding from the Steward family to con- mental relationships. struct an astronomical observatory at the uni- Douglass was born in Windsor, Vermont, on versity. Two years later Douglass began his long July 5, 1867. He came from a family with a long and productive tenure as the director of the new tradition of academic service; his father and Steward Observatory. Construction of the ob- grandfather were both college presidents. He servatory was completed in 1923 and the new graduated with honors from Trinity College in facility represented the first of several important Hartford, Connecticut, in 1889, and upon grad- milestones that would make the University of uation accepted a research assistantship at the Arizona an internationally recognized center of 100 Douglass, Andrew Ellicott astronomy. As the city of Tucson grew with 1936 he summarized his pioneering efforts in his statehood, Douglass found it necessary to move three-volume treatise entitled Climate Cycles and the observatory to Kitt Peak (south of the city) Tree Growth. While his tree-ring data from to avoid the problems of light pollution from the Arizona and New Mexico indicated past periods expanding urban environment. Douglass served of drought, to his disappointment these data as the director of the Steward Observatory un- generally did not correlate with similar climate til 1937, when he became the director of the episodes in other parts of the world. He and university’s Laboratory for Tree-Ring Research. other scientists could only conclude that the past Although a skilled astronomer, Douglass is now climate changes revealed by such tree-ring best remembered for his pioneering work in tree- “clocks” were most likely only local environ- ring dating. mental episodes, and not necessarily correlated While working in Flagstaff, Douglass had with sunspot activity and climate stress on a the great inspiration that led him to create the planetary scale. Contemporary Earth system sci- field of dendrochronology (tree-ring dating). At ence models, using sophisticated spacecraft and the time, he was searching for a measurable en- computers, now help scientists investigate link- vironmental relationship that would link the ages between the Sun’s long-term behavior and sunspot cycle and past climate episodes. He rea- terrestrial weather and climate trends. soned that vegetation changes, especially as por- While never able to personally prove his trayed by the growth of certain species of trees original hypothesis and link sunspot activity such as ponderosa pines, Douglas firs, and the with vegetation changes and terrestrial climate, great sequoias (giant redwoods), might provide Douglass established tree-ring dating as a valu- the solution. Douglass hypothesized that the mo- able tool for archaeologists who needed to action of the planets and the behavior of the Sun curately date ancient structures and for envi- were responsible for weather and climate ronmental scientists who were searching for changes. Working in Arizona and portions of definitive records of past climate episodes. As a New Mexico, Douglass was soon able to analyze historic note, the American chemist Willard the rings of local trees, primarily pines and Libby (1908–80) invented radiocarbon dating in Douglas firs, and relate the size of each ring to 1949. Libby’s carbon-14 radioisotope technique previous annual levels of rainfall. A tree pro- provided archaeologists a universal clock with duces a ring each year and, depending on cli- which to study the past. Nevertheless, den- mate conditions, certain species of trees produce drochronology still remains a useful tool in ar- wide rings during wet years and narrow rings dur- chaeology and environmental studies and often ing dry years. In effect, the cross-sections of these provides a useful calibration tool for the radio- trees recorded past rainfall and served as a nat- carbon technique. ural clock. After an additional two decades of service Recognizing that tree-ring data in Arizona to the University of Arizona, Douglass retired represented a record of past rainfall, Douglass from his position as director of the Laboratory further hypothesized that the tree-ring data of Tree-Ring Research in 1958. He died in might also represent a quantitative indication Tucson on March 20, 1962. The world-famous about the abundance of solar energy and the in- Steward Observatory and the field of den- fluence of the Sun on Earth’s past climate. By drochronology are two important legacies of this 1911 he began studying the rings of the great se- remarkable scientist. His accomplishments quoias, trees that are estimated to be between earned him an appointment as research associ- 1,800 and 2,700 years old. Between 1919 and ate to the Carnegie Institution of Washington Drake, Frank Donald 101 and a life membership to the National Geographic This turned out to be a perfect fit with his navy Society. experience. Now hooked on radio astronomy, Drake received his Ph.D. in astronomy from Harvard in ᨳ Drake, Frank Donald 1958. He then took a position at the newly (1930– ) founded National Radio Astronomy Observatory American (NRAO) in Green Bank, West Virginia, where Radio Astronomer he eventually became head of the Telescope Operations and Scientific Services Division. Frank Drake was born in 1930 to Richard and There Drake organized a formal search for ex- Winifred Drake and raised on Chicago’s South traterrestrial signals called Project Ozma, a two- Shore with his sister, Alma, and brother, Robert. month observation of the close stars Tau Ceti Like millions of others of his generation, he and Epsilon Eridani, using the 85-foot single spent hundreds of hours experimenting with channel antenna tuned to the 1420 megahertz motors, clocks, chemistry sets, radios, and gaz- frequency of hydrogen. No signals were detected. ing up at the stars on clear summer nights. Also In 1959 two physicists at Cornell, Giuseppi like millions of kids who became hooked on Cocconi and Philip Morrison, published a paper science fiction, young Drake began to wonder in which they described the possibility of using about the existence of life elsewhere in the a microwave radio for interstellar communica- universe. tion, a potential apparatus that Drake had also Drake won a Reserve Officers’ Training Corps been contemplating. (ROTC) scholarship to Cornell University, ma- In 1961 Drake and J. Peter Pearman, of the jored in electronics, became fascinated by as- Space Science Board of the National Academy tronomy, and in 1952 received a B.A. degree in of Sciences, organized the now famous Search engineering physics. However, in his junior year for Extra-Terrestrial Intelligence (SETI) con- he attended a lecture by the famous astrophysi- ference at the NRAO. It was a small meeting, cist Otto Struve (1897–1963), during which with a dozen or so scientists attending to share Struve presented accumulating evidence that their views and interest in searching for extra- many stars in the Milky Way Galaxy had plan- terrestrial life. In preparation for this meeting, etary systems around them. Further, Struve went Drake formulated what became known as the on to speculate that with such a vast number of Drake equation to estimate the number of pos- solar systems, the chances were good that one of sible technologically advanced civilizations them could sustain life. At last, Drake had found that could be sending radio signals in Earth’s someone else who agreed with his growing con- direction: tention that the odds were almost overwhelm- N N*f n f f f L ing that life did exist somewhere else. ϭ p e l i c Drake then spent three years in the U.S. in which Navy as an electronics officer on the U.S.S. Albany, accumulating experience in fixing and N* represents the number of stars in the Milky operating the most modern high-tech electronic Way Galaxy, about 200 billion; equipment then available. When he finally left fp is the fraction of stars that have planets around the navy, Drake decided to go to Harvard and them; thanks to the Hubble telescope new study optical astronomy, but as fate would have it planets are being discovered every month, but the only course available was in radio astronomy. Drake estimates this to be 20 percent; 102 Draper, Henry ne is the number of planets per star that are capa- Besides sharing in the discovery of the radi- ble of sustaining life; based on this solar system, ation belts of Jupiter, conducting the first SETI the quantity is given as 4—Earth, Venus, Mars, organized searches, and positing Drake’s equa- and possibly one of Jupiter’s moons; tion, Drake’s methods were used in sending ad- fl is the fraction of planets in ne where life ditional messages to outer space on the Pioneer evolves; current estimates range from 100 10 and Pioneer 11 (with plaques designed by percent to close to 1 percent, so 50 percent Drake, CARL SAGAN, and Linda Sagan), and on is used as a good arbitrary figure; board the Voyager spacecraft, conceived by fi is the fraction of fl where intelligent life Drake and compiled by several scientists. evolves; again, guesses range from 100 per- Drake has received numerous honorary decent to 1 percent, the logic being that intelli- grees and appointments, was chairman of the gence is such a survival advantage that it will National Research Council Board of Physics and certainly evolve; Astronomy, a member of three NAS/NRC fc is the fraction of fi that communicate; again Astronomy Survey committees, and president of impossible to guess, but experts give it 10 the Astronomical Society of the Pacific. The percent to 20 percent; Frank D. Drake Planetarium was dedicated in L is the length of time the communicating civ- Norwood, Ohio, in 1983. He has also written ilizations send detectable communications more than 150 articles, and the book Is Anyone into space. Out There? (1992), an autobiographical work coauthored with Dava Sobel. Using us as an example, the expected life- Readers who wish to play with Drake’s equa- time of the Sun and Earth as roughly 10 billion tion may enter their own variable values on the years, and thus far humans have been commu- Internet at http://www.planetarysystems.org/drake nicating with radio waves for less than 100 years. _equation.html. Drake’s own solution to his The figure for this variable depends solely on es- equation is N=10,000 communicative civiliza- timates of how long the Earth’s civilization will tions in the Milky Way Galaxy. survive. All of these variables multiplied together results in N, the number of communicating ᨳ Draper, Henry civilizations in the galaxy. (1837–1882) After a brief tour with the Jet Propulsion American Laboratory in Pasadena, California, in 1963, Astronomer, Photographer Drake joined the Center for Radiophysics and Space Research at Cornell, and in 1965 became Henry Draper took the first photograph of a dis- director of Cornell’s Arecibo Observatory in tant astronomical object, the Orion Nebula, giv- Puerto Rico. He returned to Cornell in 1968 as ing a push to celestial photography that opened chairman of the astronomy department, and was modern astronomy to a new vision of the uni- Goldwin Smith Professor of Astronomy until verse. All the men in the Draper family made 1984. He then joined the faculty of the University pioneering strides in science, especially in the of California at Santa Cruz (UCSC) as dean of fields of meteorology and astronomy in the 19th the natural sciences division, then professor of as- century. Draper’s father, John William Draper, tronomy and astrophysics. He continues his who was primarily a chemist, took the first pho- tenure at UCSC today and is still chairman of the tograph, a daguerreotype, of the Moon in 1839, Board of Trustees of the SETI Institute. one of the first human photographs in 1840, and Draper, Henry 103 the first photograph of the diffraction spec- upon rapidly after his death in England. Draper trum. Henry’s brother John was a noted physi- took the first stellar spectrum photograph of cian and chemist, and his brother Daniel was Vega in August 1872, and, with Tebbutt’s comet a meteorologist who established the New York in 1881, made the first wide-angle photograph Meteorological Observatory in Central Park in of a comet’s tail and the first spectrum of a 1868. comet’s head. Refining his father’s work to a sig- Draper was born in Virginia to John nificant degree, he produced a great number of William Draper and Antonia Coetana de Paiva photographs of the Moon and made a bench- Pereira Gardner Draper, whose father was the mark spectrum of the Sun in 1873. He also took personal physician to the emperor of Brazil. As spectra of the Orion Nebula, the Moon, Mars, a boy, Draper assisted his father in pursuing Venus, and several first magnitude stars. photographic techniques, and at age 13 helped From there Draper went on to invent the him take pictures of microscope slides for a slit spectrograph, advancing the state-of-the- textbook. When he graduated from medical art in telescope clock drives and instrument op- school in 1857, he used this experience to tics. He also wrote a chemistry textbook and write his thesis on the spleen using photo- published many papers on his astronomical graphs of microscope slides as illustrations. work and telescope design. He was one of the However, the law at the time dictated that he first to recommend building an observatory in could not receive his medical degree until he the Andes Mountains to avoid atmospheric was 21, so he took a year off and traveled pollution. through Europe. Before his sudden death on November 20, During his travels, Draper visited Lord 1882, of double pleurisy during a hunting trip to Rosse’s observatory in Ireland, which at the time the Rocky Mountains, he had received honorary utilized the world’s largest telescope, the 72-inch law degrees from New York University and the Leviathan reflector. The experience kindled University of Wisconsin, a congressional medal within him an urgent desire to investigate the for directing a U.S. expedition to photograph use of photography in astronomical observations the transit of Venus in 1874, and was elected when he returned home. To this goal, he built both to the National Academy of Sciences and his own observatory on his father’s estate at Germany’s Astronomische Gesellschaft. He was Hastings-on-Hudson, New York, while he was a member of the American Photographic beginning his medical career. Draper joined the Society, the American Philosophical Society, staff at Bellevue Hospital in New York City, and the American Academy of Arts and Sciences, later became first a professor and then dean of and the American Association for the Advance- the New York University School of Medicine. ment of Science. In 1867 Draper married Anna Mary Palmer, After his death, Draper’s wife established the a wealthy socialite who not only became an ami- Henry Draper Memorial Fund to support the able and capable hostess, frequently entertain- advancement of photography in astronomical ing the prominent scientists and celebrities of efforts. This fund supported a massive photo- the day, but who also became a proficient and graphic stellar spectrum survey performed by dedicated laboratory assistant to Draper. ANNIE JUMP CANNON and other women at Draper is best known for recording on pho- Pickering’s observatory at Harvard University, tographic plates the Great Nebula of Orion on which became the celebrated Henry Draper September 30, 1880. The images were not of the Catalogue, or the HD Catalogue, as it is still best quality, but the techniques were improved known and used today. 104 Dyson, Sir Frank Watson 19th-century observations to determine proper ᨳ Dyson, Sir Frank Watson motions. Dyson’s efforts helped extend the “star (1868–1939) streaming” work of JACOBUS CORNELIUS KAPTEYN British to fainter stars. In 1904 Kapteyn first noticed Astronomer that instead of an anticipated random distribu-

Sir Frank Watson Dyson participated with SIR tion, the proper motions of stars in the Sun’s ARTHUR STANLEY EDDINGTON during the May neighborhood actually seemed to favor two op- 1919 solar eclipse expedition that measured the posite directions, called star streams. This was deflection of a beam of starlight as it passed actually the earliest observational evidence that close to the Sun. This effort provided the first the galaxy was rotating, but astronomers did not experimental evidence in support of ALBERT immediately recognize the phenomenon. EINSTEIN’s theory of general relativity. A spe- Dyson enjoyed participating in solar eclipse cialist in solar eclipses and in stellar motion stud- expeditions. At the start of the 20th century, he ies, Dyson also served as Astronomer Royal of was a member of eclipse expeditions to Portugal Scotland from 1905 to 1910 and then as in 1900, to Sumatra in 1901, and to Tunisia, England’s Astronomer Royal from 1910 to 1933. North Africa, in 1905. These activities made him Dyson was born at Measham, near Ashby- a recognized expert on the Sun’s corona and chro- de-la-Zouch, Leicestershire, England, on January mosphere. In 1901 he was elected as a fellow of 8, 1868. He was the son of a minister and won the Royal Society, and he was knighted in 1915. scholarships for his secondary and college edu- Dyson is best remembered for organizing and cation. Dyson graduated from Trinity College at coordinating the two most significant solar Cambridge University in 1889 with a degree in eclipse expeditions in 1919, when he sent ex- mathematics. Following graduation, he became peditions to the island of Principe, in the Gulf a Fellow at Trinity College in 1891 and then of Guinea off the coast of West Africa, and to chief assistant to the Astronomer Royal at the Sobral in Brazil to carefully measure the posi- Royal Greenwich Observatory in 1894. His pri- tions of stars near the Sun’s rim during the mary astronomical studies involved the proper eclipse. Any deflection of starlight would promotions of stars and participating in solar eclipse vide evidence to support Einstein’s general the- expeditions on which he made special observa- ory of relativity. While Dyson led the British tions of the Sun’s outer regions. expedition to Sobral, Brazil, Eddington led the Dyson managed the Carte du Ciel project of British expedition to Principe. It was on Principe photographing the entire sky—a project that in- during the solar eclipse of May 29, 1919, that volved an investigation of the proper motion of Eddington successfully measured the tiny de- many stars and eventually led other astronomers flection of a beam of starlight as the star’s light to discover that the Milky Way Galaxy was ro- just grazed the rim of the Sun—a subtle, gravi- tating. In astronomy, the proper motion of a star tationally induced bending that provided scien- is its apparent annual angular motion on the ce- tists with their first experimental verification of lestial sphere—a tiny effect that after thousands general relativity. Dyson also participated on of years causes groups of stars with differences in solar eclipse expeditions to Australia (1922), the direction of their proper motions to change Sumatra (1926), and Malaya (1929). shape in some appreciable manner. In collabo- Except for his five years in Edinburgh as ration with William G. Thackeray, Dyson meas- Scotland’s Astronomer Royal from 1905 to 1910, ured the position of 4,000 circumpolar stars and Dyson spent his entire career as an astronomer then compared these measurements with early at the Royal Greenwich Observatory in southeast Dyson, Sir Frank Watson 105 London. In 1910 he was appointed as England’s His numerous contributions to astronomy ninth Astronomer Royal and served in this pres- were honored in many ways. Dyson received the tigious position until his retirement in 1933. He Bruce Gold Medal from the Astronomical made improvements in precision timekeeping at Society of the Pacific in 1922 and the Royal the observatory and was instrumental in the first Astronomical Society bestowed its Gold Medal radio (“wireless”) signal broadcast of time in on him in 1925. He became a Knight of the 1924. Upon retirement he and his wife, Lady British Empire (KBE) in 1926. Dyson published Dyson, focused their attention on the welfare of his important book, Eclipses of the Sun and their community. While on a voyage from Moon, in 1937 in collaboration with the British Australia to the United Kingdom Dyson died at astronomer Sir Richard van der Riet Woolley sea on May 25, 1939. (1906–86).

a space-time continuum, light is composed of ᨳ Eddington, Sir Arthur Stanley matter that will be affected by strong gravita- (1882–1944) tional forces. Eddington grasped the significance English of the theory, and when fellow astronomer SIR Astrophysicist FRANK WATSON DYSON pointed out that an up- Arthur Eddington was born in Kendall, England, coming total solar eclipse would be an ideal phe- to strict Quaker parents, but his father died when nomenon to test the theory, Eddington seized he was two years old and he was raised in the opportunity. In 1919 he led an expedition Somerset by his mother. When he was 16, to Brazil to observe a total eclipse of the Sun, Eddington was awarded a local scholarship and and confirmed with photographic evidence the attended Owens College (now the University of predictions of relativity that light rays are indeed Manchester) where he studied physics and bent when they pass stellar objects of great grav- mathematics. After graduating in 1902 he was itational fields. Eddington thus became the first awarded a scholarship to study at Cambridge, person to prove Einstein’s theory to be correct, from which he graduated in 1905, and then won and he confirmed it again on another solar another scholarship to study at Trinity College, eclipse expedition to Príncipe Island in West where his research work won him the coveted Africa. Smith Prize, an honor still awarded to graduate During this period at Cambridge he became research students devoted to mathematics, ap- recognized throughout the scientific community plied mathematics, and theoretical physics. From as the world’s foremost authority on the theory 1906 to 1913 he was chief assistant director of the of relativity aside from Einstein himself. In fact, Royal Observatory in Greenwich, and in 1914 he Einstein called Eddington’s Mathematical Theory was named Plumian Professor of Astronomy and of Relativity, published in 1923, “the finest pres- became director of the observatory. entation of the subject in any language.” As a Quaker, his conscientious objector Eddington went on to study the internal status kept him out of World War I and thereby composition of stars. Among his discoveries was allowed him to continue his studies at Cambridge that a star’s interior is under radiative equilib- from 1914 to 1918. ALBERT EINSTEIN had pub- rium, involving the three forces of gravity, gas lished his theory in 1915, which created a world- pressure, and radiation pressure. He demonstrated wide stir among astrophysicists, claiming that in that energy could be transported by radiation as

106 Ehricke, Krafft Arnold 107 well as convection, and that the temperature of was awarded the Bruce Medal in 1924, received the center of a star is in the millions of degrees. the Royal Society Royal Medal in 1928, was He also put forth the theory that the chief source knighted in 1930, and then was president of the of star energy was subatomic, supplied mostly by Physical Society from 1930 to 1932. Eddington hydrogen that was fused into helium. Most of died in Cambridge on November 22, 1944, and this research was published in his 1926 book, has been remembered as “the father of modern The Internal Constitution of Stars. astrophysics.” A crater on the Moon bears the In his later years Eddington came to believe name Eddington in his honor. that the basic constants of nature, such as the mass of the proton and the charge of the electron, were not coincidental but, as he put it, were ᨳ Ehricke, Krafft Arnold part of a “natural and complete specification for (1917–1984) constructing a Universe.” He did not live to German/American complete this thesis, but his book on the sub- Rocket Engineer ject, Fundamental Theory, was published after his death. This talented rocket engineer conceived ad- Eddington spent most of his life reviewing vanced propulsion systems for use in the U.S. and critiquing the works of his contemporaries, space program of the late 1950s and 1960s. One an endeavor that often leads to controversy and of Krafft Ehricke’s most important technical hurt feelings. Eddington’s most famous battle was achievements was the design and development with SUBRAHMANYAN CHANDRASEKHAR, the of the Centaur upper-stage rocket vehicle—the celebrated Indian American astrophysicist who first American rocket vehicle to use liquid was an expert on white dwarfs, stars that have hydrogen (LH2) as its propellant. His Centaur burned off their internal supply of hydrogen and vehicle made possible many important military have collapsed into themselves as intensely hot and civilian space missions. As an inspirational but very small stars. Chandra, as he was called, space visionary, Ehricke’s writings and lectures had postulated that there was an upper limit to eloquently expounded upon the positive conse- the mass of a white dwarf, a concept that quences of space technology. He anchored his Eddington dismissed as impossible. Because Ed- far-reaching concept of an “extraterrestrial imper- dington was the most respected astrophysicist of ative” with the concept of a permanent human his day, Chandra was crushed by the rejection, settlement of the Moon. appealing to several leading physicists of the Ehricke was born in Berlin, Germany, on time, and it was eventually accepted that March 24, 1917, at a turbulent time when im- Chandra was right and Eddington wrong. The perial Germany was locked in a devastating war upper limit of 1.4 solar masses for white dwarfs with much of Europe and the United States. He is today known as Chandrasekhar’s Limit. grew up in the political and economic chaos of This academic defeat notwithstanding, Germany’s postwar Weimar Republic. Yet, de- Eddington went on to establish himself as the spite the gloomy environment of a defeated most prominent and important astrophysicist of Germany, Ehricke developed his lifelong posi- the interwar years, making several valuable tive vision that space technology would serve as contributions to the field of physics. During his the key to improving the human condition. respected career, Eddington was elected a fellow Following World War I, his parents, both of the Royal Society in 1914, was president of the dentists, attempted to find schooling of sufficient Royal Astronomical Society from 1921 to 1923, quality to challenge him. Unfortunately, Ehricke’s 108 Ehricke, Krafft Arnold frequent intellectual sparring contests with rigid energy. Impressed, Ehricke would later recom- Prussian schoolmasters earned him widely vary- mend the use of nuclear power and propulsion ing grades. By chance, at age 12, Ehricke saw in many of the space development scenarios he Fritz Lang’s 1929 motion picture, Die Frau im presented in the 1960s and 1970s. Mond (The woman in the moon). The Austrian Wartime conditions played havoc with filmmaker had hired the German rocket experts Ehricke’s attempt to earn his degree. While en- HERMANN JULIUS OBERTH and Willy Ley (1906–69) rolled at the Technical University of Berlin, he as technical advisers during the production of was drafted for immediate service in the German this film. Oberth and Ley gave the film an ex- army and sent to the western front. Wounded, ceptionally prophetic two-stage rocket design he came back to Berlin to recover and resume that startled and delighted audiences with its im- his studies and in 1942 obtained a degree in aero- pressive blast-off. Advanced in mathematics and nautical engineering from the university. But physics for his age, he appreciated the great tech- while taking postgraduate courses in orbital me- nical detail that Oberth had provided to make chanics and nuclear physics, he was again the film realistic, and he viewed Lang’s film at drafted into the German army, promoted to the least a dozen times. This motion picture served rank of lieutenant, and ordered to serve with a as Ehricke’s introduction to the world of rockets Panzer (tank) division on the eastern (Russian) and space travel, and he knew immediately what front. But fortune played a hand, and in June he wanted to do for the rest of his life. He soon 1942 the young engineer received new orders, discovered KONSTANTIN EDUARDOVICH this time reassigning him to rocket development TSIOLKOVSKY’s theoretical concept of a very ef- work at Peenemünde. From 1942 to 1945 he ficient chemical rocket that used hydrogen and worked on the German army’s rocket program oxygen as its liquid propellants. Then, as a under the overall direction of WERNHER MAGNUS teenager, he attempted to tackle Oberth’s famous VON BRAUN. 1929 book Roads to Space Travel, but struggled As a young engineer, Ehricke found himself with some of the more advanced mathematics. surrounded by many other skilled engineers and In the early 1930s he was still too young to technicians whose goal was to produce the participate in the German Society for Space world’s first modern liquid-propellant ballistic Travel (Verein für Raumschiffahrt, or VFR), so missile, the A-4 rocket. This rocket is better he experimented in a self-constructed laboratory known as Hitler’s Vengeance Weapon Two, or at home. As Adolf Hitler (1889–1945) rose to simply the V-2. After World War II the German power in 1933, Ehricke, like thousands of other V-2 rocket became the ancestor to many of the young Germans, got swept up in the Nazi youth larger missiles developed by both the United movement. His free-spirited thinking, however, States and the Soviet Union during the cold soon earned him an unenviable position as a war, a period ranging roughly from 1946 to conscripted laborer for the Third Reich. Then, 1989. just before the outbreak of World War II, he was Near the end of World War II, Ehricke released from the labor draft so he could attend joined the majority of the German rocket sci- the Technical University of Berlin. There, he entists at Peenemünde and fled to Bavaria to majored in aeronautics, the closest academic escape the advancing Soviet army. Swept up in discipline to space technology. One of his pro- Operation Paperclip along with other key fessors was Hans Wilhelm Geiger (1882–1945), German rocket personnel, Ehricke delayed ac- the noted German nuclear physicist. Geiger’s lec- cepting a contract to work on rockets in the tures introduced Ehricke to the world of nuclear United States by almost a year. He did this in Ehricke, Krafft Arnold 109 order to locate his wife, Ingebord, who was then California. As the U.S. government wound somewhere in war-torn Berlin. After a long down Project Apollo in the early 1970s, Ehricke search that culminated in a happy reunion, continued to champion the use of the Moon and Ehricke, his wife, and their first child journeyed its resources. His extraterrestrial imperative was to the United States in December 1946 to begin based upon the creation of a selenospheric a new life. (Moon-centered) human civilization in space. For the next five years, Ehricke supported Until his death in late 1984, he spoke and wrote the growing U.S. Army rocket program at tirelessly about how space technology provides White Sands, New Mexico, and Huntsville, the human race with the ability to create an Alabama. In the early 1950s he left his position unbounded “open world civilization.” with the U.S. Army and joined the newly formed Ehricke was a dedicated space visionary who Astronautics Division of General Dynamics (for- not only designed advanced rocket systems (such merly called Convair). There he worked as a as the Atlas-Centaur configuration) that greatly rocket concept and design specialist and partic- supported the first “golden age” of space explo- ipated in the development of the first U.S. in- ration, but also addressed the important, but fre- tercontinental ballistic missile, the Atlas. He quently ignored, social and cultural impacts of became a U.S. citizen in 1955. space technology. He created original art to com- Ehricke strongly advocated the use of liquid municate many of his ideas. He coined the term hydrogen as a rocket propellant. While at General androsphere to describe the synthesis of the ter- Dynamics, he recommended the development of restrial and extraterrestrial environments. The a liquid hydrogen/liquid oxygen propellant up- androsphere relates to human integration of per-stage rocket vehicle. His recommendation Earth’s biosphere—the portion of Earth that became the versatile and powerful Centaur contains all the major terrestrial environmental upper-stage vehicle. In 1965 he completed his regimes, such as the atmosphere, the hydros- work at General Dynamics as the director of the phere, and the cryosphere—with the material Centaur program and joined the advanced and energy resources of the solar system. This is studies group at North American Aviation in space age philosophy on a very grand scale. Anaheim, California. From 1965 to 1968 this In spring 1980 Ehricke was the prime lecturer new position allowed him to explore pathways during an innovative short course on space in- of space technology development across a wide dustrialization held at California State University spectrum of military, scientific, and industrial in Northridge. Here, in a number of wonderful applications. The excitement of examining pos- two-hour sessions, he had the time to properly sible space technologies and their impact on the introduce many of the complex ideas that sup- human race remained with him for the rest of ported his grand vision of the extraterrestrial his life. imperative. He carefully pointed out to an en- From 1968 to 1973 Ehricke worked as a sen- thusiastic audience of college students, faculty, ior scientist in the North American Rockwell and aerospace professionals how space technol- Space Systems Division in Downey, California. ogy was providing a crucial open-world pathway In this capacity, he fully developed his far- for human development. Ehricke’s lectures in- ranging concepts concerning the use of space cluded such visionary concepts as “astropolis” technology for the benefit of humankind. After and the “androcell.” Astropolis is his concept for departing Rockwell, he continued his visionary a large urban extraterrestrial facility that orbits space advocacy efforts through his own consult- in Earth-Moon (cislunar) space and supports ing company, Space Global, located in La Jolla, the long-term use of the space environment for 110 Einstein, Albert basic and applied research, as well as for indus- Einstein was born on March 14, 1879, in trial development. Ehricke’s androcell concept Württemberg, Germany, to a nonobservant is bolder and involves a large human-made world Jewish family. He reportedly did not speak his in space, totally independent of the Earth-Moon first words until he was three years old, going in system. These extraterrestrial city-states, with an instant from complete silence to complete human populations of 100,000 or more, would sentences. He began school at the Humanistiche offer their inhabitants the excitement of multi- Gymnasium in Munich, around age six. He also gravity-level living at locations throughout began playing the violin around this time, tak- heliocentric space. Just weeks before his death ing lessons for the next seven years and devel- on December 11, 1984, Ehricke was a featured oping a skill and love for music that he kept speaker at the national symposium on lunar for a lifetime. Never athletic, he acknowledged bases and space activities for the 21st century as an adult that he had no use for physical ex- held that October in Washington, D.C. Despite ertion, having a fondness only for the sport of being terminally ill, Krafft traveled across the sailing. United States from his home in San Diego, As a child, the precocious Einstein was in- California, to give a moving presentation on the doctrinated with religion via the “traditional importance of the Moon in creating a polyglobal education-machine,” as he called it in his later civilization for the human race. biographical writings, but discovered science Ehricke authored many innovative techni- around age 12 and “soon reached the convic- cal papers on topics that ranged from hydrogen tion that much in the stories of the Bible could rocket propulsion systems to space industrial- not be true. The consequence was a positively ization and settlement. He received the first fanatic orgy of freethinking coupled with the Gunter Löser Medal from the International impression that youth is intentionally being Astronautical Federation in 1956. deceived by the state through lies.” This was, he said, “a crushing impression.” The result left Einstein suspicious of authority and skeptical ᨳ Einstein, Albert of the generally accepted truths and norms of (1879–1955) society—a skepticism that was according to his Swiss-American writings, “an attitude which has never again Physicist, Philosopher left me.” For the next four years, Einstein read vora- The most recognizable face in science belongs ciously. He was interested in mathematics, par- to the physicist Albert Einstein—a man who ticularly differential and integral calculus, and reportedly suffered greatly from being thrown stated that he had “the good fortune of hitting into the celebrity spotlight in the press over his on books which were not too particular in their scientific epiphanies because, according to a logical rigor but which made up for this by per- friend, the mathematician Arnold Sommerfeld mitting the main thoughts to stand out clearly (1868–1951), “every form of vanity was foreign and synoptically.” One mathematics book in to him.” Einstein credited philosophy as much particular that had an effect on the young as his scientific education with his ability to Einstein was a book on Euclidean plane geome- think in cosmically new ways, and he relied on try. But even more important to Einstein than physical relationships instead of mathematics to mathematics was the study of the natural sci- conceive the ideas that were considered truly ences. He devoured books on science, particu- genius. larly a multivolume work entitled People’s Books Einstein, Albert 111 on Natural Science, with, he confessed, “breath- daughter had scarlet fever, Mileva returned to less attention.” tend to the child. Leiserl’s fate is unclear— At age 17 Einstein entered the Polytechnic whether she succumbed to scarlet fever, or she Institute of Zurich, focusing on mathematics survived and was adopted, or taken in by one of and physics, where one of his professors was Mileva’s closest friends, remains a mystery. But Rudolf Minkowski (1895–1976). But Einstein it is known that Mileva returned to Bern alone. wrote that he “neglected mathematics,” because The following year, Einstein’s job was made per- he felt that any one discipline in the field could manent, and in 1904 his wife had their first son, “easily absorb the short lifetime granted to us,” Hans, who would remain their “only child” un- and besides, he was really more interested in til Eduard came along six years later. science. During this time, Einstein began to write. Einstein was critical, however, of an educa- His ideas on physics were haunting him. “By and tional system that he felt did more to discour- by I despaired of the possibility of discovering age freethinking than it did to promote it, even the true laws by means of constructive efforts though he felt that he was better off in Zurich based on known facts. How could such a uni- than in universities elsewhere. He referred to the versal principle be found?” he wrote. The known system’s practices as “coercion” to “cram all this facts he referred to were, of course, SIR ISAAC stuff into one’s mind” for the sole purpose of NEWTON’S theories on physics, which Einstein passing examinations. “This coercion had such felt were “the dogmatic rigidity [that] prevailed a deterring effect,” he wrote, that after passing in matters of principles: In the beginning (if his final exams he “found the consideration of there was such a thing) God created Newton’s any scientific problems distasteful to me for an laws of motion together with the necessary entire year.” Einstein believed that this type of masses and forces.” forced indoctrination “smothers every truly sci- The idea that this is all there is did not fit entific impulse,” and added that “It is, in fact, with his intuition, and yet he needed a sign that nothing short of a miracle that the modern there was another way. The answer came to him methods of instruction have not yet entirely in Maxwell’s theory of electromagnetism. The strangled the holy curiosity of inquiry.” Einstein electric industry was a new and exciting one, and graduated in 1900 with barely passing grades. Einstein credited James Maxwell (1831–79) as After that, Einstein wandered before set- freeing up the Newtonian “dogmatic faith,” call- tling into, and settling for, a “temporary” job at ing Maxwell’s work a profound influence on his the Swiss Patent Office in Bern in 1902. This ability to rethink the problems he strove to year marked two other big events in Einstein’s solve. life. One was his father’s death. The other was Within two years, Einstein began to publish the birth of his daughter. Einstein’s classmate in his work. His ideas were revolutionary—the dis- theoretical physics from the university, Mileva covery of light quantum, which validated the Maric, with whom he had a long and passionate field of quantum physics introduced by MAX relationship, became pregnant in her final year KARL PLANCK, and his explanations of Brownian in school and gave birth to their baby daughter, motion, explaining how particles submerged in a Leiserl, while staying in the care of her parents. liquid will “jitter” as a result of being bombarded When Mileva went to Bern to help Einstein get with molecules, which he based on statistical settled, she left the baby with her parents. thermodynamics. He earned a Ph.D. from the Within the year Einstein and Mileva were mar- University of Zurich for his paper “On a New ried, but when they received news that their Determination of Molecular Dimensions.” 112 Einstein, Albert In 1905 Einstein presented a theory that he course, mathematics. When Minkowski started entitled “On the Electrodynamics of Moving using the theory in his work on world geome- Bodies—The special theory of relativity.” This try, Einstein said, “Since the mathematicians idea resulted, he admitted, “from a paradox upon have invaded the theory of relativity, I do not which I had already hit at the age of 16: If I pur- understand it myself any more.” sue a beam of light with the velocity of light in Einstein’s published work succeeded in grab- a vacuum, I should observe such a beam of light bing the attention of the universities that had as a spatially oscillatory electromagnetic field at ignored him after his graduation. He left his job rest. However, there appears to be no such thing.” at the patent office and became an associate The special theory of relativity shows that professor at the University of Zurich, then a pro- two observers who are moving with respect to fessor of theoretical physics in Prague in 1911, one another will disagree on their observations then went back to Zurich in 1912 before ac- of length, time, velocity, and mass. “Space and cepting a research fellowship, in 1914, at the time cease to possess an absolute nature,” he University of Berlin. Here, the absent-minded wrote. “In space-time, each observer carves out Professor Einstein, who was notorious for losing in his own fashion his space and his time.” He his lecture notes, was free to give up lecturing went on to explain, “Each observer, as his time and focus entirely on research. passes, discovers, so to speak, new slices of space- Between 1905 and 1914, while Einstein was time, which appear to him as successive aspects trying his hand at teaching in various institu- of the material world, though in reality the en- tions, he continued pondering the ideas that led semble of events constituting space-time exist to the theory of special relativity. His memoirs prior to his knowledge of them.” reveal, “That the special theory of relativity is This theory was based on two postulates. only the first step of a necessary development First, that there is no absolute way to measure became completely clear to me only in my ef- absolute motions in space, but instead relative forts to represent gravitation in the framework motion can be obtained on an object as com- of this theory.” He found the special theory “too pared to another object; and second, that the narrow.” speed of light always travels at the same rate. Back in 1907, while working at the patent Experiments began to prove the theory, and be- office, Einstein had an image in his head of a fore long Einstein had the most famous equation person falling through space, and realized that of all time—one showing that mass and energy the person would not feel his own weight. He are equivalent: called this the “happiest thought of my life.” He needed to somehow explain this with the the- E mc2. ϭ ory of relativity, but he could not figure out how Einstein credited his ability to come up with to work in the gravity. this theory to two sources. “The special theory In Berlin Einstein finally had the creative of relativity owes its origin to Maxwell’s equa- freedom to pursue these thoughts that had tions of electromagnetic field,” he said. But, “the seemed so difficult to him during the past seven type of critical reasoning which was required for years because, as he put it, “It was not so easy to the discovery . . . was decisively furthered in my free oneself from the idea that coordinates must case . . . by the reading of David Hume’s and have an immediate metrical meaning.” But the Ernest Mach’s philosophical writings.” four-dimensional work that Minkowski pro- Einstein’s special theory of relativity affected duced based on the special theory of relativity many disciplines—physics, philosophy, and, of was now starting to make sense, and Einstein Einstein, Albert 113 credited it as indispensable in the theory that ARTHUR STANLEY EDDINGTON proved that would be the grandfather of them all: the general Einstein’s ideas about deflected light were cor- theory of relativity. rect. Able to compare positions of stars during a The generalization of the theory of relativ- blocked-out Sun to their positions when the Sun ity was presented in 1916, and it put forth new was in full view, scientists found that the light laws of motion and gravitation. The idea that had been diverted. On November 7, 1919, the space curves around a mass is explained today in Times of London proclaimed his accomplish- high school science classes as the “bowling ment with the headline “Revolution in science— ball on the water bed” experiment: If a bowl- New theory of the Universe—Newtonian ideas ing ball (a heavy mass) is dropped onto a water overthrown.” According to Sommerfeld, “We bed, the mattress of the water bed curves around owe the completion of his general theory of the bowling ball, and when an object of less relativity to his leisure while in Berlin.” mass, for example a marble, is dropped in the Einstein’s wife left him and returned to vicinity of the bowling ball, it falls toward the Switzerland with their two children shortly af- heavier mass. Thus, the object of smaller mass ter the family moved to Berlin. Einstein had is attracted to the object of greater mass because rekindled a romantic relationship with his first it is traveling along the curves of space. cousin, Elsa, and when he began placing de- Additionally, Einstein imagined a person mands on his wife that did not suit that edu- encapsulated in an elevator in space, noting that cated woman’s nature, nor their relationship, she the person would experience the sensation of left the country and refused a divorce. In 1919 weightlessness until the elevator accelerated up- the Einsteins finally made their dissolution legal, ward, at which point the person would hit the and Albert married Elsa within a few months. floor, experiencing the sensation of gravity; if the The war was inciting anti-Semitic meetings, and person dropped something during the accelera- Einstein considered leaving Berlin, but changed tion, the floor would come up to meet it, but it his mind when he attended a meeting at the would also appear that the object “fell” to the Nauheim Congress of Natural Scientists in 1920 floor. The person would feel no different in and Planck urged him to stay. the accelerating elevator in space than he or she In 1921 Einstein received the Barnard Medal would in the gravitational field on Earth. The and then the Nobel Prize in physics, but surpris- concept, then, is that gravity and acceleration ingly not for his theories on relativity—they were are the same. Einstein also proposed that light, still too controversial—but rather for his discov- when passing near the surface of the sun, is de- eries from 1905 on quantum light. He sent his flected, and that the wavelengths of light from ex-wife the money from the prize, which he had extremely dense stars, such as white dwarfs, are promised (assuming he would some day win a lengthened. Nobel Prize) as a condition of their divorce, go- Einstein was so certain about the simplicity ing to great lengths to hide the transaction. In of his theory that he felt no compunction to ex- 1925 he received the Royal Society’s Copley plain it to those who questioned its validity. He Medal, and in 1926, its Gold Medal. After ex- wrote to Sommerfeld in February 1916, “Of the tensive travel—to the United States, Japan, general theory of relativity you will be con- France, Palestine, and South America—the sci- vinced, once you have studied it. Therefore I am entist eventually collapsed from exhaustion, and not going to defend it with a single word.” he took the better part of 1928 to recuperate. A solar eclipse expedition in 1919 organized In 1933 Einstein returned to the United by SIR FRANK WATSON DYSON and led by SIR States. Sommerfeld writes that “Einstein was 114 Euler, Leonhard driven out of Berlin and robbed of his posses- which point they were willed to the Hebrew sions,” in 1933, and that “a number of countries University in Jerusalem. Included in his docu- vied for his immigration.” With an offer to teach ments were letters he had exchanged with at Princeton, Einstein, his wife, and his secre- Mileva, and the discovery that stunned the sci- tary (who ultimately worked for him for 50 entific world—it was clear that the two had years) stayed in the United States and never re- corresponded about scientific theories and prin- turned to Germany. He became a U.S. citizen ciples for years before they married, and Einstein in 1940, giving him dual citizenship in the himself wrote to her about “our theory,” and “our United States and Switzerland. work” on relativity. These letters have sparked In August 1948 Einstein’s first wife, Mileva, heated debates in the scientific community, with died after a series of strokes three months after a various interpretations about Mileva’s contribu- nervous breakdown brought on by repeated con- tions to Einstein’s great discoveries. It is well ac- frontations with their son Eduard, who suffered cepted that her background and education gave from violent attacks of schizophrenia. her the access and knowledge to be a collabora- But Einstein’s scientific brilliance at this tor, but whether she played a substantial role will point was behind him. His work at Princeton most likely remain a source of contention among was dedicated to finding one system that ex- the scientific community and historians for years plained the subatomic realm of the microcosm to come. with the macrocosmic universe. His ideas were The crater Einstein on the surface of the perceived as unachievable, and even he recog- Moon was named in his honor in 1964, and nized that he was digging himself into a deeper serves as a small reminder of one of the most and deeper hole, writing, “I have locked myself brilliant thinkers in the history of humankind. into quite hopeless scientific problems.” Einstein lived a personal life of campaigning for peace—his last effort was signing a manifesto ᨳ Euler, Leonhard that urged the elimination of all nuclear (1707–1783) weapons. His professional life was one of imag- Swiss ination—visualizing problems as they physically Mathematician, Physicist exist rather than thinking about them purely from a mathematical perspective, and giving One of the most brilliant and productive math- their solutions with unprecedented simplicity, ematicians of all time, Leonhard Euler developed allowing others to do the detailed work that de- advanced analytical techniques to treat the veloped their proof. In explaining his concepts complex orbital motion of the Moon and to ef- on thinking, he said, “All our thinking is of this ficiently determine the orbital paths of newly nature of a free play with concepts.” discovered comets. His improved methods in Einstein wrote his autobiographical notes at celestial mechanics advanced 18th-century ob- the age of 67, a task he likened to writing his servational astronomy and also supported im- own obituary. In his notes he gives a glimpse of portant improvements in maritime navigation his perception of his place in the world. “The by making possible the preparation of more essential in the being of a man of my type lies accurate lunar tables. precisely in what he thinks and how he thinks, Leonhard Euler was born on April 15, not in what he does or suffers.” 1707, in Basel, Switzerland. His father was the Einstein’s papers stayed in a basement file Reverend Paul Euler and his mother was at Princeton until his secretary passed away, at Margaretha Brucker, a minister’s daughter. While Euler, Leonhard 115 an undergraduate, Paul Euler became a classmate large family might prove distracting, but Euler and friend of the great Swiss mathematician proudly claimed that some of his greatest Johann Bernoulli (1667–1748). With a strong mathematical inspirations and discoveries came religious environment influencing his child- while he was holding a baby in his arms and had hood, Leonhard Euler entered the University of other children playing around his feet. In 1735 Basel at the age of 14 to undertake general he contracted a severe case of fever that almost studies in preparation for his own career in the proved fatal. Then he experienced eyesight ministry. But Bernoulli, then a professor at the problems in 1738 and by 1740 had completely university, quickly recognized that the boy was lost vision in his right eye. a mathematical genius. In 1723 Euler completed During his first St. Petersburg period, Euler’s his master’s degree in philosophy and then sought reputation as a mathematician grew. In 1736 he his father’s consent to abandon his ministerial wrote Mechanica (Mechanics)—an important study to pursue a new career in mathematics with treatise that completely transformed Newtonian the brilliant Bernoulli as his mentor. dynamics into a comprehensive and readily un- The fact that Paul Euler and Bernoulli were derstandable form of mathematical analysis. He undergraduates at the University of Basel helped wrote award-winning papers for which he shared secure paternal approval for Euler to make this the Grand Prize of the Paris Academy in both major career change. Euler completed his formal 1738 and 1740. studies in mathematics at the University of To escape the harsh winters and the growing Basel in 1726 and soon began writing the first political turmoil in Russia, Euler accepted an of his almost 900 scientific papers and books. invitation from the Prussian king Frederick the As a recent graduate, he won the second-place Great. Euler traveled to Berlin in 1741 on a mis- prize in mathematics at the Paris Academy in sion to revitalize the Prussian Academy of 1727 for his innovative paper that addressed Sciences. During the 25 years he spent in Berlin, the mathematical arrangement of masts on sail- Euler wrote numerous papers and important ing ships. Altogether, Euler would win 12 in- books on algebra, calculus, planetary orbits, and ternational academy prizes in mathematical on the motion of the Moon. In 1744 Euler pub- competition. lished Theorium motuum planetarium et cometarium Although reluctant to leave Switzerland, (Theory of the motion of planets and comets)— Euler departed Basel in April 1727 for St. an influential precursor to the more precise or- Petersburg, Russia, to accept a position in the bital mechanics work of COMTE JOSEPH LOUIS newly founded Academy of Sciences. The acad- LAGRANGE. In 1753 Euler wrote Theoria Motus emy in St. Petersburg provided Euler an enriched Lunaris (Theory of the lunar motion), his first working environment that encouraged him to attempt to analyze the exact motion of the explore all aspects of the mathematical sciences. Moon, a challenging problem that had baffled Like many great mathematical figures of the astronomers and mathematicians since the time 18th century, he applied his talents to theoret- of JOHANNES KEPLER. ical astronomy, especially the treatment of By 1759 Euler had assumed the virtual lead- planetary motions and the orbit of comets. ership of the Berlin Academy of Sciences and his In January 1734 he married Katharina Gsell, numerous contributions to theoretical and ap- the daughter of the Swiss painter George Gsell, plied mathematics were internationally recog- who was then working in St. Petersburg. The nized. However, because of disagreements with couple had 13 children, although only five sur- King Frederick, Euler was never offered the po- vived infancy. Normally the demands of such a sition of academy president. So in 1766 Euler 116 Euler, Leonhard returned to St. Petersburg, accepting an invita- treatment of the Moon’s motion enhanced tion from the Empress Catherine II (Catherine maritime navigation by providing detailed lu- the Great). Euler’s departure from Berlin greatly nar and planetary tables to assist in longitude angered the Prussian king, whose own bumbling determination. had encouraged the brilliant Swiss mathemati- What is especially amazing about Euler dur- cian to leave. ing the later part of his life is the level of pro- Back in St. Petersburg, Euler again experi- ductivity he maintained even after he became enced physical difficulties, but maintained an in- totally blind and his first wife, Katharina, died. credibly high level of productivity. In 1771 his In 1776 Euler married her half sister, Abigail home burned to the ground in the great St. Gsell. He continued to use his phenomenal Petersburg fire. Later that year, he went com- memory and some kindly assistance from two of pletely blind. Despite his blindness, he used his his sons to remain history’s most prolific math- phenomenal memory to continue to publish ematician until his death in St. Petersburg on papers and books at an enormous rate. In 1772 September 18, 1783. he published a second, more detailed book on But even death did not stop his contributions the Moon’s orbital behavior, Theoria Motuum to mathematics. He left behind a huge legacy of Lunae novo modo pertractata (Theory of lunar unpublished works that kept the printing presses motion, applying new rules)—a monumental in Russia busy for another three and a half analytical effort dealing with the difficult three- decades. Euler’s mathematical contributions to body problem in orbital mechanics. astronomy and orbital mechanics stretched well Because of Euler’s efforts, 18th-century as- into the next century. His analytical methods tronomers were able to more quickly and precisely prepared the way for the great achievements of estimate the orbital path of newly discovered 19th-century astronomy, when mathematicians comets, using just a few precise observations. working closely with telescopic astronomers the- These analytical procedures greatly improved oretically predicted the position of, and then the business of “comet chasing” by astronomers soon discovered previously unseen, solar system such as CHARLES MESSIER. Euler’s sophisticated objects such as Neptune and the minor planets.

became the first “computer,” as they were called, ᨳ Fleming, Williamina Paton Stevens at the Harvard Observatory, and the first woman (Mina Fleming) in a group of famous female astronomers that (1857–1911) would become known as “Pickering’s harem.” American Despite her lack of formal higher education, Astronomer Fleming soon proved adept at both mathematics Williamina Paton Stevens was born in Dundee, and astronomical science. Scotland, on May 15, 1857. Her father, a pic- Under Pickering’s guidance, Fleming de- ture framer and early hobbyist in photography, vised the first system of classifying stars accord- died when she was only seven. She was educated ing to their spectra, determined by holding a in local public schools, and at age 14 gave up prism up to the objective lens of a telescope. her education to take a job as a teacher, which Using this system, which was later named after she pursued until 1877, when at age 20 she her, Fleming cataloged more than 10,000 stars married James Orr Fleming. during the next nine years. In 1890 her work In 1878 the Flemings left Scotland for was published in a book entitled The Draper the United States, immigrating to Boston, Catalogue of Stellar Spectra. Massachusetts. A year later, James Fleming Fleming was eventually put in charge of abandoned Mina, as she was known, when she dozens of more women hired to do computations was pregnant with their first child. Mina at the observatory, among them ANNIE JUMP Fleming was then forced to take a job as a CANNON, who eventually succeeded Fleming. housemaid, an event that actually proved to be Fleming was also named editor of all publica- to her great benefit, because her employer was tions issued by the observatory, and in 1898 the none other than the famous professor EDWARD Harvard Corporation appointed her as the first CHARLES PICKERING, director of the Harvard woman curator of astronomical photographs. Observatory. Among Fleming’s other accomplishments were Pickering had been having problems with the discovery of 59 nebulae, 10 novae, and more his personnel and had long advocated using than 300 variable stars. The eminent British women in support positions. In 1881 he hired astronomer Herbert Hall Turner (1861–1930) Fleming to do clerical work in the observatory once said of Fleming, “Many astronomers are de- and to do mathematical calculations, and she servedly proud to have discovered one variable

117 118 Fowler, William Alfred star, but [her discoveries are] an achievement football, track, and tennis, earning his varsity bordering on the marvelous.” letter in football his senior year. His teachers en- In 1906 Fleming became the first American couraged his interest in engineering and science woman to be elected to the Royal Astronomical and, perhaps sensing a future for him in higher Society. In 1910 she discovered “white dwarfs,” education, insisted that he study Latin for four stars in the late stages of their existence that are years instead of the traditional French and hot, dense, and appear white or bluish in color. German. During this time, when the family In 1911 Fleming was named an honorary mem- spent their annual vacation back in Pittsburgh, ber of the Astronomical Society of Mexico and Fowler developed an interest in steam locomo- the Astronomical Society of France. That same tives, and would spend hours at the Pennsylvania year she also received the Guadalupa Almendaro Railroad switch yards in Pittsburgh and at local Medal and, noting her lack of a graduate degree, railroad yards in Lima. This interest became one Wellesley College named her honorary fellow on of his passionate avocations throughout his life, astronomy. along with baseball and music, and in 1973 Fleming was the most famous female as- he would embark on a 1,500-mile trek from tronomer of her time, and one of the first women Khabarovsk to Moscow on the steam-powered to have a lunar crater named after her. At the Trans-Siberian Railroad. time of her death from pneumonia in Boston, on In high school Fowler had written a May 21, 1911, she had discovered 10 of the 28 prizewinning essay on how Portland cement was known novae and 94 of the 107 known Wolf- produced, and when he enrolled in Ohio State Rayet stars—more than any single astronomer University he thought he would pursue ceram- in history. ics engineering as his major. However, in his lower-division physics and mathematics courses, Fowler became interested in physics. Upon learn- ᨳ Fowler, William Alfred ing that a new degree field was being offered he (1911–1995) switched his major to engineering physics. In his American junior year he was elected to the engineering Physicist honorary society, Tau Beta Pi, and in his senior year he was elected president of the Ohio “Willy” Fowler, as he was known internationally State chapter of that society. He received his by all his colleagues, friends, and associates, was B.S. degree in 1933 and was a classmate of the born August 9, 1911, in Pittsburgh, Pennsylvania, renowned theoretical physicist Leonard I. Schiff, the first child of John MacLeod Fowler and who became a lifelong friend. Jennie Summers Watson Fowler. His younger Fowler’s path from Ohio led him straight to brother, Arthur, came next and was soon fol- the California Institute of Technology (Caltech) lowed by a sister, Nelda. Fowler was the pater- in Pasadena, California, where he became a nal grandson of an immigrant coal miner from graduate student at the Kellogg Radiation Scotland and an immigrant grocer from Northern Laboratory under the renowned Charles C. Ireland. When he was two years old, Fowler’s Lauritsen (1892–1968). Throughout his career family moved to Lima, Ohio, where his father Fowler referred to Lauritsen as “the greatest in- had been transferred. fluence in my life,” beginning with Lauritsen’s su- Fowler attended Horace Mann Grade School pervision of Fowler’s doctoral thesis, “Radioactive and Lima Central High School, where he was a Elements of Low Atomic Number,” which ac- popular student and an active athlete in baseball, cording to a brief autobiographical piece, Fowler Fowler, William Alfred 119 described as a study “in which we discovered President Harry S. Truman in 1948; elected a mirror nuclei and showed that the nuclear forces member of the National Academy of Sciences are charged symmetric—the same between two in 1956; awarded the Barnard Medal for protons and between two neutrons when Meritorious Service to Science in 1965; desig- charged particle Coulomb forces are excluded.” nated Benjamin Franklin Fellow of the Royal He received his Ph.D. in 1936. Society of Arts in 1970; awarded the G. Unger Fowler then joined the Caltech faculty as Vetlesen Prize in 1973; awarded the National a research fellow and in 1939 was appointed Medal of Science by President Gerald Ford in assistant professor. Prior to World War II he 1974; designated Associate of the Royal married Ardiane Foy Olmsted, with whom he Astronomical Society in 1975; elected president had two daughters. During the war he spent time of the American Physical Society in 1976; in the South Pacific as a civilian with simulated awarded the Eddington Medal of the Royal military rank, doing research and development Astronomical Society in 1978; awarded the work on rocket ordnance and proximity fuses. Bruce Gold Medal of the Astronomical Society Back at Caltech, he was appointed as full proof the Pacific in 1979; awarded the Legion fessor in 1946 and named Institute Professor of d’Honneur from French president François Physics in 1970. Mitterrand in 1989, and received honorary de- During 1954–55, Fowler spent a sabbatical grees from a dozen prestigious universities world- year as a Fulbright scholar in Cambridge, wide. He reached the apogee of his career when England, where he worked closely with Fred he was awarded the Nobel Prize in physics in Hoyle (1915–2001), who in 1946 had estab- 1983 “for his theoretical and experimental stud- lished the concept of nucleosynthesis in stars. ies of the nuclear reactions of importance in the While there, he was joined by ELEANOR formation of the chemical elements in the uni- MARGARET PEACHEY BURBIDGE and her husband verse.” He also collected several awards for his Geoffrey, and in 1956 the Burbidges and Hoyle nonscientific interests in baseball, steam loco- all came to the Kellogg Laboratory at Caltech. motives, art, music, and outdoor activities. The following year, Fowler coauthored one of Fowler was one of the pioneers in the new the most famous papers in astrophysics history, field of astrophysics, and his work defining the “Synthesis of the Elements in the Stars,” which creation of new elements inside stars contributed showed conclusively that all of the elements significant new knowledge to astronomy and to from carbon to uranium could be produced by the increasingly popular Big Bang theory of the nuclear fission processes in stars, beginning with origin of the universe. A few years before his only the helium and hydrogen produced in the death he observed, “It is a remarkable fact that big bang, made famous by RALPH ASHER humans, on the basis of experiments and meas- ALPHER. This paper was cowritten by the urements carried out in the lab, are able to un- Burbidges and Hoyle and is commonly referred derstand the universe in the early stages of its to by the authors’ initials, B2FH. evolution, even during the first three minutes of During his 60-year career, Fowler carried out its existence.” both theoretical studies to calculate fusion rates Fowler’s wife Ardiane died in May 1988, in elements, and experimental studies with par- and he remarried in December 1989 to Mary ticle accelerators to corroborate his theories. Dutcher, a former schoolteacher. He wrote in his He was honored with an array of international Nobel autobiography that after retirement he awards for his lifetime achievements. He was spent his time attending weekly seminars at awarded the medal of merit, presented by Caltech and “in general try to stay out of trouble.” 120 Fraunhofer, Joseph von On March 14, 1995, Fowler died of natural clever way to measure the refractive indices of causes in his home in Pasadena, California. optical glass by using the bright yellow emission line of the chemical element sodium as his reference, or standard. To support his calibration ᨳ Fraunhofer, Joseph von efforts, in 1814 he created the modern spectro- (1787–1826) scope by placing a prism in front of the object German glass of a surveying instrument called a theodo- Optician, Physicist lite. Using this instrument, he discovered (or more correctly rediscovered) that the solar spec- Early in the 19th century, Joseph von Fraunhofer trum contained more than 500 dark lines, a pair pioneered the important field of astronomical of which corresponded to the closely spaced spectroscopy. A skilled optician, he developed bright double emission lines of sodium found in the prism spectrometer in about 1814. Then, the yellow portion of the visible spectrum. while using his new instrument, he discovered In 1802 the British scientist William H. more than 500 mysterious dark lines in the Sun’s Wollaston (1766–1828) first observed seven spectrum—lines that now carry his name. In dark lines in the solar spectrum. But he did not 1823 he observed similar (but different) lines in know what to make of them and speculated (in- the spectra of other stars, but left it for other sci- correctly) that the mysterious dark lines were entists, among them ROBERT WILHELM BUNSEN merely divisions between the colors manifested and GUSTAV ROBERT KIRCHHOFF to solve the by sunlight as it passed through a prism. Working mystery of the “Fraunhofer lines.” with a much better spectroscope 12 years later, Fraunhofer was born in Straubing, Bavaria, Fraunhofer identified 576 dark lines in the solar on March 6, 1787. His parents were involved in spectrum and labeled the position of the most the German optical trade, primarily making dec- prominent lines with the letters A to K—a orative glass. When they died, leaving him an nomenclature physicists still use today in dis- orphan at age 11, his guardians apprenticed him cussing the Fraunhofer lines. He also observed to an optician (mirror maker) in Munich. While that a dark pair of his so-called D-lines in the completing this apprenticeship, Fraunhofer solar spectrum corresponded to the position of a taught himself mathematics and physics. He brilliant pair of yellow lines in the sodium flame joined the Untzschneider Optical Institute, lo- he produced in his laboratory. However, the true cated near Munich, as an optician in 1806. He significance of this discovery escaped him and, learned quickly from the master glassmakers in busy making improved lenses, he did not pursue this company and then applied his own talents the intriguing correlation any further. He also to greatly improve the firm’s fortunes. His life- observed that the light from other stars when long contributions to the field of optics laid the passed through his spectroscope produced spec- foundation for German supremacy in the design tra with dark lines that were similar but not and manufacture of quality optical instruments identical to those found in sunlight. But once in the 19th century. again, Fraunhofer left the great discovery of Fraunhofer’s great contribution to the prac- astronomical spectroscopy for other scientists. tice of astronomy occurred quite by accident, Fraunhofer was content to note the dark line while he was pursuing the perfection of the phenomenon in the solar spectrum and then con- achromatic lens, a lens capable of greatly reduc- tinue in his quest to design an achromatic ob- ing the undesirable phenomenon of chromatic jective lens—a task he successfully accomplished aberration. As part of this quest, he devised a in 1817. He did such high-quality optical work Fraunhofer, Joseph von 121 that his basic design for this type of lens is still for a “technician”—no matter how skilled—to used by opticians. present a scientific paper to a gathering of In 1821 he built the first diffraction grating learned academicians. Yet 19th-century German and used the new device instead of a prism to astronomers, such as FRIEDRICH WILHELM BESSEL, form a spectrum and make more precise meas- used optical instruments made by Fraunhofer to urements of the wavelengths corresponding to make important discoveries. In 1823 Fraunhofer the Fraunhofer lines. But again, he did not in- was appointed as the director of the Physics terpret these telltale dark lines as solar absorp- Museum in Munich and given the honorary title tion lines. In 1859 Bunsen and Kirchhoff would of professor. He died of tuberculosis in Munich on finally put all the facts together and provide as- June 7, 1826. On his tombstone is inscribed the tronomers with the ability to assess the ele- following Latin epithet: “Approximavit sidera” (in mental composition of distant stars through contemporary English: “He reached for the stars.”) spectroscopy. In his honor, scientists now refer to the dark Because Fraunhofer did not have a formal (absorption) lines in the visible portion of the university education, the German academic Sun’s spectrum as Fraunhofer lines. These lines community generally ignored his pioneering are the phenomenological basis of astronomical work in optical physics and astronomical spec- spectroscopy and give scientists the ability to troscopy. At the time, it was considered improper learn what stars are really made of.

now known as the scientific method—an en- ᨳ Galilei, Galileo tirely new way of looking at the universe and (1564–1642) one of the greatest contributions of Western civ- Italian ilization to the human race. Astronomer, Mathematician, Physicist The Italian astronomer, mathematician, and As the incomparable “founding father of modern physicist Galileo Galilei was born in Pisa on science,” Galileo Galilei used his own version of February 15, 1564. Galileo is commonly known the newly invented telescope to make detailed by his first name only. His father, Vincenzo astronomical observations that ignited the sci- Galilei (ca. 1520–91) was a scholar and musi- entific revolution of the 17th century. In 1610 cian. When Galileo entered the University of he announced some of his early telescopic find- Pisa in 1581, his father encouraged him to study ings in the publication Sidereus Nuncius (The medicine. However, his inquisitive mind soon starry messenger)—including his discovery of became more interested in physics and mathe- the four major moons of Jupiter, now called the matics than medicine. While still a medical stu- Galilean satellites in his honor. Their orbital be- dent, he attended church services one Sunday havior, like a miniature solar system, stimulated and noticed a chandelier swinging in the breeze. his enthusiastic support for the heliocentric cos- He began to time its swinging motion using his mology of NICOLAS COPERNICUS. Unfortunately, own pulse as a crude clock. When he returned this scientific position led to a direct clash with home, he immediately set up an experiment that ecclesiastical authorities bent on retaining revealed the pendulum principle. After just two Ptolemaic cosmology for a number of political years of study, Galileo abandoned medicine and social reasons. By 1632 this conflict earned and focused on mathematics and science. This the fiery Galileo an Inquisition trial at which change in career pathways also changed the his- he was found guilty of heresy for advocating tory of modern science. Copernican cosmology. Because of his advanc- In 1585 Galileo left the university without ing age and blindness, he was confined to house receiving a degree to focus his activities on the arrest for the remainder of his life. This unjust physics of fluids and solid bodies. The following incarceration could not prevent his brilliant sci- year, he published a small booklet that described entific work in astronomy, physics, and mathe- the clever hydrostatic balance he invented to matics from creating the revolution in thinking determine relative densities. This was Galileo’s

122 Galilei, Galileo 123 liant lecturer and students came from all over Europe to attend his classrooms. Galileo often used his tenacity, sharp wit, and biting sarcasm to win philosophical arguments against his university colleagues. His fiery, unyielding personality earned him the nickname “the Wrangler.” While his personal characteristics drove Galileo to many great discoveries, they also left a trail of bitter opponents who waited patiently for him to stumble so they could exact their revenge. By 1592 he had sufficiently offended his academic colleagues at the University of Pisa so that university officials chose not to renew his teaching contract. In the late 16th century, European professors usually taught physics (then called “natural philosophy”) as an extension of Aristotelian philosophy and not as a science, based on observation and experimentation, as it is practiced today. Through his skillful use of mathematics and innovative experiments, Galileo singlehandedly changed that approach. The motion of falling A 1640 portrait of the incomparable “Founding objects and projectiles intrigued him, and his sci- Father of Modern Science,” Galileo Galilei. This fiery entific experiments constantly challenged the Italian astronomer, physicist, and mathematician 2,000-year tradition of ancient Greek learning. used his own version of the newly invented ARISTOTLE stated that heavy objects would telescope to make detailed astronomical observations that flamed the scientific revolution in fall faster than lighter objects. Galileo disagreed the 17th century. In 1610 his Sidereus Nuncius (The and declared that, except for air resistance, the starry messenger), proclaimed the discovery of the two objects would fall at the same rate regard- four major moons of Jupiter—now called the less of their mass. It is not certain whether he Galilean satellites in his honor. Because they behaved like a miniature solar system, Galileo threw actually performed the legendary musket ball– his enthusiastic support behind the controversial cannonball drop experiment from the Leaning heliocentric cosmology of Nicolas Copernicus. Tower of Pisa to prove this point. However, he Unfortunately, this scientific position ultimately did conduct a sufficient number of experiments earned him a conviction for heresy in 1632 and confinement to house arrest for the remainder of his with objects on inclined planes to upset life. (Courtesy of the National Aeronautics and Aristotelian physics and establish the science of Space Administration [NASA]) mechanics. Throughout his life, Galileo was limited in his motion experiments by an inability to accurately measure small increments of time. Despite first splash into science and it brought him at- this impediment, he conducted many important tention from the academic world. experiments that produced remarkable insights In 1589 Galileo became a mathematics pro- into the physics of free fall and projectile mo- fessor at the University of Pisa. He was a bril- tion. A century later, SIR ISAAC NEWTON would 124 Galilei, Galileo build upon Galileo’s pioneering work to create daughter, Livia Galilei, was born in Padua in his universal law of gravitation and three laws 1601, and his son, Vincenzio Galilei, was also of motion. born in Padua in 1604. Galileo did not marry As previously mentioned, by 1592 Galileo’s his children’s mother because in 17th-century anti-Aristotelian research and abrasive behavior Italy, the relationship was considered inappro- had sufficiently offended his colleagues at the priate—Gamba was much younger than Galileo University of Pisa to the point that university and from a socially inferior family. Yet Galileo officials not so politely invited him to teach else- always remained financially responsible to her where. So Galileo moved to the University of and his children—although he did so always un- Padua—the main institution of higher learning der extreme financial stress. When his father for the powerful Republic of Venice. This uni- died at a young age in 1591, Galileo followed versity had a more lenient policy of academic contemporary social custom and assumed fa- freedom, encouraged in part by the progressive milial financial responsibility by providing a Venetian government. Galileo eagerly accepted substantial dowry for his sister, Virginia Galilei. an appointment as a professor of mathematics. This constant drain on his meager salary as a He even wrote a special treatise on mechanics mathematics professor made him resort to tu- to accompany his lectures. In Padua he taught toring and casting horoscopes to make financial courses on Euclidian geometry and on astron- ends meet. omy. The late 16th-century astronomy courses Between 1604 and 1605, Galileo performed at Padua were primarily intended for medical his first public work involving astronomy. He students who needed to learn enough Ptolemaic observed the supernova of 1604 in the constel- astronomy to practice medical astrology. Italian lation Ophiuchus and used the phenomenon to physicians of the High Renaissance were ex- refute the cherished Aristotelian belief that the pected to “consult with the stars” as part of treat- heavens were immutable (that is, unchange- ing patients. Such academic duties gave Galileo able). He boldly delivered this challenge on his first formal contact with astronomy, and the Aristotle’s doctrine in a series of public lectures. practice of science would never be the same. Unfortunately, these well-attended lectures In 1597 the German astronomer JOHANNES brought him into direct conflict with the uni- KEPLER, gave Galileo a copy of Copernicus’s versity’s pro-Aristotelian philosophy professors. book—even though the book was then officially In 1609, Galileo learned that a new optical banned in Italy. Up to this point in his life instrument (called a magnifying tube) had just Galileo had not been seriously interested in been invented in Holland. Within six months, astronomy, but in this “forbidden” book he dis- he devised his own version of the instrument, covered heliocentric cosmology and immedi- then in 1610 he turned this improved telescope ately embraced it. Galileo and Kepler continued to the heavens and started the age of telescopic to correspond until about 1610. astronomy. With his crude instrument, he made Almost coinciding with his interest in a series of astounding discoveries, including the Copernican theory, Galileo experienced several existance of mountains on the Moon, many new important changes in his personal life while liv- stars, and four moons orbiting Jupiter. His pub- ing in Padua. The first of his three out-of-wed- lished discoveries in The starry messenger stim- lock children by Marina Gamba of Venice was ulated both enthusiasm and anger. The moons born in Padua on August 21, 1600. She was orbiting Jupiter proved that not all heavenly named Virginia Galilei and would later assume bodies revolve around Earth; direct observa- the name Sister Maria Celeste. His second tional evidence for the Copernican model. Galilei, Galileo 125 Personally unable to continue teaching the support for Copernican theory. He even dedi- Aristotelian doctrine at the university because cated the book to his lifelong friend, the new of the overwhelming evidence against it, Galileo pope, Urban VIII (1623–44). left Padua in 1610 and went to Florence where However, in 1632 Galileo pushed his friend- he accepted an appointment as chief mathe- ship with the pope to the limit by publishing Dia- matician and philosopher to the grand duke of logue on the Two Chief World Systems. In this Tuscany, Cosimo II. By now Galileo’s fame had masterful satirical work, Galileo uses two main spread throughout Italy and the rest of Europe. characters to present scientific arguments, con- His telescopes were in demand and he obligingly cerning the Ptolemaic and Copernican world- provided them to selected astronomers through- views, to an intelligent third person. Galileo’s out Europe, including Kepler. In 1611 he proudly fictional Copernican, Salviati, cleverly wins took his telescope to Rome and let church offi- these lengthy arguments. In contrast, Galileo cials personally observe some of his discoveries. presents Aristotelian thinking and the Ptolemaic While in Rome, he also became a member of system through an ineffective character he calls the prestigious Accademia dei Lincei (Lyncean Simplicio. The pope regarded Galileo’s fictional Academy), the first true scientific society, founded Simplicio as an insulting personal caricature, and in 1603. within months the Inquisition summoned In 1613 Galileo published his “Letters on Galileo to Rome. Under threat of execution, the Sunspots” through the academy. He used the ex- aging Italian scientist publicly retracted his sup- istence and motion of sunspots to demonstrate port for the Copernican model on June 22, 1633. that the Sun itself changes, again attacking Tradition suggests that a feeble, but defiant, Aristotle’s doctrine of the immutability of the Galileo whispered these words as he rose from his heavens. In so doing, he also openly endorsed knees after renouncing Copernican cosmology: the Copernican model. This started Galileo’s “Eppur si muove.” (“And yet it moves.”) long and bitter fight with church authorities. Instead of torture and death, the Inquisition Above all, Galileo believed in the freedom sentenced him to life in prison—a more lenient of scientific inquiry. Late in 1615 Galileo term that he was allowed to serve under house went to Rome and publicly argued for the arrest at his villa in Arceti near Florence. The Copernican model. Angered by Galileo’s open ecclesiastical authorities also banned his book defiance, Pope Paul V (1605–21) formed a spe- Dialogue. However, Galileo’s loyal supporters cial commission to review the theory of Earth’s smuggled copies out of Italy, and soon its motion. Dutifully, the unscientific commission pro-Copernican message was spreading across concluded that the Copernican theory was Europe. contrary to biblical teachings and possibly While under house arrest, Galileo spent even represented a form of heresy. In late his final years working on less controversial February 1616 Cardinal Robert Bellarmine of- physics. In 1638 he published Discourses and ficially warned Galileo to abandon his support Mathematical Demonstrations Relating to Two New of the Copernican hypothesis or face harsh Sciences. Fearing for his life, he carefully avoided punishment. astronomy in this seminal work and concen- The cardinal’s stern message toned down trated his creative energies on summarizing the Galileo’s behavior—at least for a few years. In science of mechanics, including uniform accel- 1623 Galileo published Il saggiatore (The as- eration, free fall, and projectile motion. sayer), a book in which he discussed the princi- Through Galileo’s pioneering work and ples for scientific research, but carefully avoided personal sacrifice, the Scientific Revolution 126 Galle, Johann Gottfried ultimately prevailed over misguided adherence Galle was born in Pabsthaus, Germany, on to centuries of Aristotelian philosophy. He June 9, 1812. He received his early education never really opposed the church nor its reli- at the Wittenberg Gymnasium (secondary gious teachings. He did, however, come out school) and then studied mathematics and strongly in favor of the freedom of scientific physics at the Berlin University. After graduat- inquiry and he would not tolerate supposedly ing from the university in 1833, Galle taught learned academicians or ecclesiastics who mathematics in the gymnasiums at Guben and remained mentally blind to demonstrable Berlin. Then, in 1835, his former professor scientific facts. Physical blindness struck the Johann Franz Encke (1791–1865) invited Galle brilliant scientist in 1638, and he died at home to become his assistant at the newly founded on December 25, 1642, the same day Newton Berlin Observatory. was born. Galle proved to be a skilled telescopic as- Some three and a half centuries later, on tronomer. In 1838 he discovered the C or October 31, 1992, Pope John Paul II formally re- “crêpe” ring of Saturn. He was also an avid comet tracted the sentence of heresy passed on Galileo hunter, and during winter 1839–40 Galle dis- by the Inquisition. As the pope was announcing covered three new comets. In 1846 good fortune this official retraction, a NASA spacecraft smiled on Galle and allowed him to play a named Galileo was speeding through interplan- major role in one of the most important mo- etary space on course for its successful ren- ments in the history of planetary astronomy. dezvous mission with Jupiter and the giant Independent of the British astronomer JOHN planet’s family of interesting moons, including COUCH ADAMS, the French astronomer and the Galilean moons that helped establish the mathematician Urbain-Jean-Joseph Leverrier, Scientific Revolution. studied the perturbations in the orbit of Uranus and made his own mathematical predictions concerning the location of another planet be- ᨳ Galle, Johann Gottfried yond Uranus. Leverrier corresponded with Galle (1812–1910) on September 18, 1846, and asked the German German astronomer to investigate a section of the night Astronomer sky to confirm his mathematical prediction that there was a planet beyond Uranus. By good fortune and some careful telescopic Upon receipt of Leverrier’s letter, Galle viewing, Johann Gottfried Galle became the and his assistant, Heinrich Ludwig d’Arrest first person to observe and properly identify the (1822–75), immediately began searching the planet Neptune. Acting upon a recommenda- portion of the sky recommended by the French tion from URBAIN-JEAN-JOSEPH LEVERRIER, mathematical astronomer. D’Arrest also sug- Galle began a special telescopic observation at gested to Galle that they use Encke’s most recent the Berlin Observatory on September 23, star chart to assist in the search for the elusive 1846. His search quickly revealed the new trans-Uranian planet. In less than an hour Galle planet precisely in the region of the night sky detected a “star” that was not on Encke’s latest predicted by Leverrier’s calculations. Improved chart. A good scientist, Galle waited 24 hours to mathematical techniques helped Galle and confirm that this celestial object was indeed Leverrier convert subtle perturbations in the the planet Neptune. On the following night orbit of Uranus into one of the major discov- (September 24), Galle again observed the object eries of 19th-century astronomy. and carefully compared its motion relative to that Gamow, George 127 of the so-called fixed stars. There was no longer 1873. Astronomers SIR DAVID GILL and SIR any question: The change in its position clearly HAROLD SPENCER JONES greatly improved meas- indicated that this “wandering light” was another urement of the Earth-Sun distance using Galle’s planet. suggestion. Galle discovered Neptune pretty much in Of the three codiscoverers of Neptune, only the position predicted by Leverrier’s calculations. Galle survived until 1896 to receive congratula- He immediately wrote to Leverrier, informing tions from the international astronomical com- him of the discovery and thanking him for the munity as it celebrated the 50th anniversary of suggestion on where to search. The telescopic their great achievement. He died on July 10, discovery of Neptune by Johann Galle on 1910, in Potsdam, Germany. September 23, 1846, is perhaps the greatest example of the marriage of mathematics and astronomy in the 19th century. Subtle perturbations ᨳ Gamow, George (Georgi Antonovich) in the calculated orbit of Uranus suggested to (1904–1968) mathematicians and astronomers that one or Ukrainian/American more planets could lie beyond. Yet this discovery Physicist, Cosmologist became one of the biggest controversies in the scientific community. Today, credit for the com- A successful nuclear physicist, cosmologist, and bined predictive and observational discovery of astrophysicist, George Gamow was a pioneering Neptune is awarded jointly to Adams, Galle, and proponent of the big bang theory, which boldly Leverrier. speculated that the universe began with a huge In 1851 Galle accepted a position as the di- ancient explosion. As part of this hypothesis, he rector of the Breslau Observatory and remained also participated in the prediction of the exis- there until his retirement in 1897. He made ad- tence of a telltale cosmic microwave back- ditional contributions to astronomy by focusing ground, observational evidence for which was his attention on determining the mean distance discovered by ARNO ALLEN PENZIAS and ROBERT from Earth to the Sun—an important reference WOODROW WILSON in the early 1960s. distance called the astronomical unit (AU). George Gamow was born on March 4, 1904, Astronomers relied on the transits of Venus in the city of Odessa in the Ukraine. His grand- across the face of the Sun to make an estimate father was a general in the Russian army and his of the astronomical unit. At the time, this was a father was a teacher. On his 13th birthday, rather difficult measurement, since astronomers Gamow received a telescope—a life-changing had to determine precisely the moment of first gift that introduced him to astronomy and contact. helped him decide on a career in physics. Having However, in 1872 Galle suggested a more survived the Russian Revolution, he entered accurate and reliable way of measuring the Novorossysky University in 1922 at 18 years of scale of the solar system. He recommended that age. He soon transferred to the University astronomers use the asteroids whose orbits come of Leningrad (now called the University of very close to Earth to measure solar parallax. St. Petersburg), where he studied physics, math- Galle reasoned that the minor planets offered ematics, and cosmology. Gamow completed his more precise, pointlike images and their large Ph.D. in 1928, the same year he proposed that number provided frequent favorable opposi- alpha decay could be explained by the phenom- tions. In an effort to demonstrate and refine this enon of the quantum mechanical tunneling of technique, Galle observed the asteroid Flora in alpha particles through the nuclear potential 128 Gamow, George Cavendish Laboratory in Cambridge, England. In 1931 he was summoned back to the Soviet Union to serve as a professor of physics at Leningrad University. However, after living in western Europe for several years, he found life in Stalinist Russia not to his liking. A highly creative individual, he obtained permission to attend the 1933 International Solvay Congress in Brussels, Belgium, and then never returned to Stalin’s Russia. He emigrated from Europe to the United States in 1934, accepting a faculty position at George Washington University, in Washington, D.C., and becoming a U.S. citizen. In 1936 he collaborated with the Hungarian- American physicist Edward Teller (1908–2003) in developing a theory to explain beta decay, the process whereby the nucleus emits an electron. At this point in his career, Gamow began exploring relationships between cosmology and nuclear processes. He used his knowledge of nuclear physics to interpret the processes taking A successful nuclear physicist, cosmologist, and place in various types of stars. In 1942, again in astrophysicist, George Gamow pioneered the big bang collaboration with Teller, Gamow developed a hypothesis in the late 1940s. Building up the theory about the thermonuclear reactions and preliminary concepts of others, he boldly concluded internal structures within red giant stars. These that the universe began with a huge explosion— sarcastically called the “big bang” by his detractors. efforts also led Gamow to conclude that the Gamow further suggested that the modern remnants of Sun’s energy results from thermonuclear reac- this ancient explosion would be a curtainlike tions. He was also an ardent supporter of EDWIN microwave (“cold light”) signal at the very edge of the POWELL HUBBLE’S expanding universe theory, an observable universe. Almost two decades before the event, Gamow had brilliantly anticipated the detection astrophysical hypothesis that made him an early of this telltale cosmic microwave background by the and strong advocate of the Big Bang theory. Nobel Prize–winning radio astronomers Arno Penzias RALPH ASHER ALPHER, a student under and Robert W. Wilson in 1964. (AIP Emilio Segrè Gamow, introduced the Big Bang cosmology Visual Archives) which Gamow had published in the 1948 paper “The Origin of the Chemical Elements.” barrier in the atomic nucleus. This innovative He based some of this work on cosmology con- work represented the first successful extension cepts previously suggested by ABBE-GEORGES- of quantum mechanics to the atomic nucleus. ÉDOUARD LEMAÎTRE. Starting with the explosion As a bright young nuclear physicist, Gamow of Lemaître’s “cosmic egg,” Gamow proposed a performed postdoctoral research throughout method of thermonuclear reactions by which the Europe, visiting the University of Göttingen in various elements could emerge from a primor- Germany, working with Niels Bohr (1885–1962) dial mixture of nuclear particles that he called in Copenhagen, Denmark, and studying be- the ylem. Although later nucleosynthesis mod- side Ernest Rutherford (1871–1937) at the els introduced by WILLIAM ALFRED FOWLER and Giacconi, Riccardo 129 other astrophysicists would supersede this work, efforts that popularized modern science around the Gamow’s pioneering investigations provided an world. He died in Boulder on August 19, 1968. important starting point. Perhaps the most significant postulation to emerge from these efforts was the prediction that the Big Bang would pro- ᨳ Giacconi, Riccardo duce a uniform cosmic microwave background— (1931– ) a lingering remnant at the edge of the observ- Italian/American able universe. The discovery of this cosmic Astrophysicist microwave background in 1964 by Penzias and Wilson renewed interest in the Big Bang cos- Using special instruments carried into space mology and provided scientific evidence that on sounding rockets and satellites, Riccardo strongly supported an ancient explosion hy- Giacconi helped establish the exciting new field pothesis. In his 1952 book, Creation of the of X-ray astronomy. This great astrophysical ad- Universe, Gamow presented a detailed discussion venture began quite by accident in June 1962, of these concepts in cosmology. when Giacconi’s team of scientists placed a spe- Just after James Watson (born 1928) and cially designed instrument package on a sound- Francis Crick (1916–2004) proposed their DNA ing rocket. As the rocket climbed above Earth’s model in 1953, Gamow turned his scientific in- sensible atmosphere over White Sands, New terests from the physics taking place at start of Mexico, the instruments unexpectedly detected the universe to the biophysical nature of life. He the first cosmic X-ray source—that is, a source published several papers on the storage and trans- of X-rays from beyond the solar system. Sub- fer of information in living cells. While his pre- sequently named Scorpius X-1, this “X-ray star” cise details were not terribly accurate by today’s is the brightest of all nontransient X-ray sources level of understanding in the field of genetics, he ever discovered. He shared the 2002 Nobel Prize did introduce the important concept of “genetic in physics for his pioneering contributions to as- code”—a fundamental idea confirmed by subse- trophysics. quent experimental investigations. Riccardo Giacconi was born in Milan, Italy, In 1956 Gamow became a faculty member on October 6, 1931. He earned his Ph.D. degree at the University of Colorado in Boulder and re- in cosmic ray physics at the University of Milan mained at that institution for the rest of his life. in 1956 and then immigrated to the United He was a prolific writer who produced highly States to accept a position as a research associ- technical books, such as the Structure of Atomic ate at Indiana University in Bloomington. In Nuclei and Nuclear Transformations (1937), and 1959 he moved to the Boston area to join also very popular books about science for gen- American Science and Engineering, a small sci- eral audiences. Several of his most popular books entific research firm established by scientists were Mr. Tompkins in Wonderland (1936), One, from the Massachusetts Institute of Technology, Two, and Three . . . Infinity (1947), and A Star where he began his pioneering activities in X- Called the Sun (1964). ray astronomy. George Gamow was elected to the Royal Collaborating with Professor BRUNO BENE- Danish Academy of Sciences in 1950 and the U.S. DETTO ROSSI at the Massachusetts Institute of National Academy of Sciences in 1953. The Technology and other researchers in the early United Nations Educational, Scientific, and 1960s, Giacconi designed novel X-ray detection Cultural Organization (UNESCO) bestowed its instruments for use on sounding rockets and Kalinga Prize on Gamow in 1956 for his literary eventually spacecraft. His June 1962 experiment 130 Giacconi, Riccardo first source of X-rays known to exist beyond the solar system. This fortuitous discovery is often regarded as the beginning of X-ray astronomy, an important field within high-energy astrophysics. Because Earth’s atmosphere absorbs X-rays, instruments to detect and observe X-rays produced by astronomical phenomena must be placed in space high above the sensible atmosphere. Sounding rockets provide a brief (typically just a few minutes) way of searching for cosmic X-ray sources, while specially instru- mented orbiting observatories provide scientists with a much longer period of time to conduct all-sky surveys and detailed investigations of interesting X-ray sources. Astrophysicists investigate X-ray emissions because they provide a unique insight into some of the most violent and energetic processes taking place in the universe. In the mid-1960s, as an executive vice president and senior scientist at American Science and Engineering, Giacconi headed the scientific team that constructed the first imaging X-ray telescope. In this novel instrument, incoming X- The Italian-American astrophysicist Riccardo Giacconi rays graze or ricochet off precisely designed and as he appeared in the mid-1960s, during that exciting shaped surfaces and then collect at a specific research period when he helped establish the foundations for modern X-ray astronomy. His first place called the focal point. The first such de- major achievement occurred in 1962 when he vice flew into space on a sounding rocket in 1965 collaborated with Bruno Rossi and placed a new type and made captured images of X-ray hot spots in of X-ray detection instrument on a sounding rocket that the upper atmosphere of the Sun. The National fortuitously discovered the first cosmic X-ray source called Scorpius X-1. In the 1970s he supervised the Aeronautics and Space Administration (NASA) development of several X-ray astronomy spacecraft for used greatly improved versions of this type of in- NASA. For these pioneering contributions to strument on the Chandra X-ray Observatory. astrophysics and to X-ray astronomy, he shared the The following analogy illustrates the signif- 2002 Nobel Prize in physics. (AIP Emilio Segrè Visual Archives, Physics Today Collection) icance of Giacconi’s efforts in X-ray astronomy and also serves as a graphic testament to the rapid rate of progress in astronomy brought on by the proved especially significant when his team, in space age. By historic coincidence, Giacconi’s search of possible solar-induced X-ray emissions first, relatively crude X-ray telescope was ap- from the lunar surface, accidentally detected the proximately the same length and diameter as the first known X-ray source outside the solar system astronomical telescope used by GALILEO GALILEI from Scorpius X-1. Previous rocket-borne experi- in 1610. Over a period of about four centuries, ments by personnel from the U.S. Naval Research optical telescopes improved in sensitivity by 100 Laboratory that started in 1949 had detected X- million times, as their technology matured from rays from the Sun, but the new X-ray star was the Galileo’s first telescope to the capability of Giacconi, Riccardo 131 NASA’s Hubble Space Telescope. About 40 years X-Ray Observatory. It was the first orbiting ob- after Giacconi tested the first X-ray telescope on servatory to use the grazing incidence X-ray tel- a sounding rocket, NASA’s magnificent Chandra escope (a concept initially proposed by Giacconi X-ray Observatory provided scientists with a leap in 1960) to produce detailed images of cosmic in measurement sensitivity of about 100 million. X-ray sources. The Einstein X-Ray Observatory Much as Galileo’s optical telescope revolution- operated until April 1981 and produced more ized observational astronomy in the 17th century, than 7,000 images of various extended X-ray Giacconi’s X-ray telescope triggered a modern sources, such as clusters of galaxies and super- revolution in high-energy astrophysics. nova remnants. Giacconi functioned well both as a skilled Giacconi’s display of superior scientific man- astrophysicist and as a successful scientific management skills during the Uhuru and Einstein ager capable of overseeing the execution of large, observatory projects secured his 1981 appoint- complex scientific projects. He envisioned and ment as the first director of the Space Telescope then supervised development of two important Science Institute—the astronomical research orbiting X-ray observatories: the Uhuru satellite center on the Homewood campus of Johns and the Einstein X-Ray Observatory. Hopkins University, in Maryland, responsible for In the late 1960s his group at American operating NASA’s Hubble Space Telescope. From Science and Engineering supported NASA in 1993 to 1999 Giacconi served as the director the design, construction, and operation of the general of the European Southern Observatory Uhuru satellite—the first orbiting observatory (ESO) in Garching, Germany. This was his first dedicated to making surveys of the X-ray sky. scientific leadership role involving ground-based Uhuru, also known as Small Astronomical Satellite astronomical facilities. Prior to leaving this 1, was launched from the San Marco platform European intergovernmental organization, he off the coast of Kenya on December 12, 1970. successfully saw the “first light” for ESO’s new By coincidence, that date marked the seventh Very Large Telescope in the Southern Hemisphere anniversary of Kenyan independence, so NASA on Cerro Paranal in Chile. called this satellite Uhuru, which is the Swahili In July 1999 Giacconi returned to the word for “freedom.” The well-designed space- United States to become president and chief craft operated for more than three years and de- executive officer of Associated Universities, tected 339 X-ray sources, many of which turned Inc.—the Washington, D.C.–headquartered not- out to be due to matter from companion stars for-profit scientific management corporation being pulled at extremely high velocity into sus- that operates the National Radio Astronomy pected black holes or superdense neutron stars. Observatory in cooperation with the National With this successful spacecraft, Giacconi’s team Science Foundation. In October 2002 the Nobel firmly established X-ray astronomy as an excit- Committee awarded Giacconi one-half of that ing new astronomical field. year’s Nobel Prize in physics for his pioneering In 1973 Giacconi moved his X-ray astron- contributions to astrophysics. omy team to the Harvard-Smithsonian Center A renowned scientist and manager, Giacconi for Astrophysics, headquartered in Cambridge, has received numerous awards, including the Massachusetts. There, he supervised the devel- Bruce Gold Medal from the Astronomical opment of a new satellite for NASA called High Society of the Pacific (1981) and the Gold Energy Astronomical Observatory 2 (HEAO-2). Medal of the Royal Astronomical Society in Following a successful launch in November 1978, London (1982). He is the author of more than NASA renamed the spacecraft the Einstein 200 scientific publications that deal with the 132 Gill, Sir David X-ray universe, ranging from black hole candi- curate time. He also purchased a 12-inch re- dates to distant clusters of galaxies. flecting telescope and modified the device to take photographs. Gill’s excellent photograph of the Moon taken on May 18, 1869, soon caught ᨳ Gill, Sir David the attention of the young Lord Lindsay, who (1843–1914) was persuading his father, the earl of Crawford, British to build him a private astronomical observa- Astronomer tory. After brief negotiations, Gill abandoned the family watchmaking business in 1872 to be- Sir David Gill was the Scottish watchmaker come the director of Lindsay’s observatory near turned astronomer who passionately pursued the Aberdeen. As a competent instrument maker measurement of solar parallax. His careful ob- and self-educated observational astronomer, Gill servations, often involving travel with his wife, set about the task of designing, equipping, and Lady Isabel Gill, to remote regions of Earth, es- operating Lord Lindsay’s observatory at Dun tablished a value of the astronomical unit that Echt, Scotland. served as the international reference until 1968. His years as a privately employed astronomer For example, in 1877 the couple lived for six at Dun Echt brought Gill in contact with the most months on tiny Ascension Island, in the middle prominent astronomers in Europe. The work also of the South Atlantic, just so Gill could estimate prepared him well for the next step in his career a value for solar parallax by observing Mars dur- as a professional astronomer, especially his expe- ing its closest approach. The couple also resided rience with precision measurements using the he- in South Africa for 28 years so he could serve as liometer. In the 19th century astronomers used the British royal astronomer in charge of the this (now obsolete) instrument to measure the Cape of Good Hope Observatory. parallax of stars and the angular diameter of plan- Gill was born in Aberdeen, Scotland, on ets. David Gill became a world-recognized expert June 12, 1843. From 1858 to 1860 he studied at in the use of the heliometer—an instrument he the Marischal College of the University of applied relentlessly in pursuit of his lifelong quest Aberdeen, but left without a degree because of to precisely measure solar parallax. family circumstances: As the eldest surviving Astronomers define solar parallax as the an- son, he abandoned college and trained to be a gle subtended by Earth’s equatorial radius when watchmaker, so he could take over his aging fa- Earth is observed from the center of the Sun— ther’s business. However, while at Marischal that is, at a distance of one astronomical unit. College, Gill had the brilliant Scottish physicist The astronomical unit (149,600,000 kilometers) James Clerk Maxwell (1831–79) as his professor is the basic reference distance in solar system as- of natural philosophy. Maxwell’s lectures greatly tronomy. By international agreement, the solar inspired Gill, and the young watchmaker would parallax is approximately 8.794 arc seconds. ultimately pursue a career in science. Sponsored by Lord Lindsay, Gill participated By good fortune, his activities in precision in an astronomical expedition to Mauritius in timekeeping led him directly into a career in as- 1874 to observe the transit of Venus. He took 50 tronomy. While operating his watch- and clock- precision chronometers on a long sea voyage making business, Gill developed a great facility around the southern tip of Africa to Mauritius, with precision instruments. As a hobby, he re- a small island in the Indian Ocean east of stored an old, abandoned transit telescope in Madagascar. Gill focused on providing precise order to provide the city of Aberdeen with ac- timing for the other astronomers. Gill, Sir David 133 A planetary transit takes place when one ce- onds obtained by radar observations of solar sys- lestial object moves across the face of another tem distances. Then, between 1930 and 1931, celestial object of larger diameter—such as SIR HAROLD SPENCER JONES followed Gill’s work Mercury or Venus moving across the face of the and used observations of the asteroid Eros to Sun as viewed by an observer from Earth. The make refined estimates of solar parallax. After a 1874 transit of Venus provided Gill with an op- decade of careful calculation, Jones obtained a portunity to contribute to the elusive value of value of 8.790 arc seconds. the astronomical unit. However, he soon dis- The astronomical expeditions of 1874 and covered firsthand the difficulty of using the tran- 1877 brought Gill recognition within the British sit of Venus to determine solar parallax. Upon astronomical community, and in 1879 he was ap- magnification, the image of the planetary disk be- pointed as Her Majesty’s Royal Astronomer at came insufficiently sharp, so it was very difficult the Cape of Good Hope Observatory in South for astronomers to measure the precise moment Africa. He served with great distinction as royal of first contact, even with Gill’s precision astronomer at this facility until his retirement in chronometers. In 1876 Gill departed on friendly 1907. Early in this appointment, he accidentally terms from his position as director of Lord became a proponent for astrophotography, Lindsay’s observatory. when he successfully photographed the great Along with his wife, Gill then conducted his comet of 1882 and then noticed the clarity of own privately organized expedition to Ascension the stars in the background of his comet pho- Island in 1877 to measure solar parallax. The tographs. He upgraded and improved the couple made their arduous journey to this tiny observatory so it could play a major role in pho- island in the middle of the South Atlantic tographing the Southern Hemisphere sky in Ocean just to precisely measure Mars during its support of such major international efforts as closest approach to Earth. Gill used the distance the Carte du Ciel project. He collaborated with from the Royal Greenwich Observatory to JACOBUS CORNELIUS KAPTEYN in the creation Ascension Island as a baseline. After six months of the Cape Durchmusterung—an enormous cat- on Ascension, he was able to obtain reasonable alog published in 1904 that contained more than results, but he was still not satisfied. He also rec- 400,000 Southern Hemisphere stars whose posi- ognized and began to follow JOHANN GOTTFRIED tions and magnitudes were determined from GALLE’S suggestion to use asteroids with their photographs taken at the Cape of Good Hope pointlike masses in making measurements of so- Observatory. Gill was knighted in 1900. lar parallax. He knew this was the right approach, The Gills returned to Great Britain from because he had already made a preliminary (but South Africa in 1907 and retired in London. not successful) effort, by observing the asteroid There, he busied himself by completing a book, Juno during the Mauritius expedition. History and Description of the Cape Observatory, In 1889 Gill organized an international ef- published in 1913. He died in London on January fort that successfully made precise measurements 24, 1914. He was internationally recognized as of the solar parallax by observing the motion of one of the great observational astronomers of the three asteroids (Iris, Victoria, and Sappho). period. He was elected as a fellow of the Royal From the observations, Gill calculated a value Astronomical Society in 1867 and served as the of the astronomical unit that remained the in- society’s president from 1909 to 1911. He received ternational standard for almost a century. His the society’s Gold Medal twice: in 1882 and again value of 8.80 arc seconds for solar parallax was in 1908. His numerous other awards included the replaced in 1968 with a value of 8.794 arc sec- 1900 Bruce Gold Medal from the Astronomical 134 Goddard, Robert Hutchings Society of the Pacific and the 1899 Watson Medal serial feature in a Boston newspaper. Many years from the U.S. National Academy of Sciences. later, Robert Goddard sent a personal letter to H. G. Wells, explaining what a career stimulus and source of inspiration that particular story ᨳ Goddard, Robert Hutchings was to him in his youth. The English author (1882–1945) penned a letter back to Goddard, acknowledg- American ing the kind remarks. Physicist, Rocket Engineer Starting in childhood, Goddard began to keep a diary in which he meticulously recorded Robert Goddard was the brilliant, but reclusive, his thoughts and his experiences—the successes American physicist who promoted rocket sci- as well as the failures. For example, one day ence and cofounded the field of astronautics in during his early teens, an explosive mixture of the early part of the 20th century—independent hydrogen and oxygen shattered the windows of of KONSTANTIN EDUARDOVICH TSIOLKOVSKY his improvised home laboratory. Without much and HERMANN JULIUS OBERTH. However, un- emotion he dutifully noted in his diary: “. . . like Tsiolkovsky and Oberth, who were pri- such a mixture must be handled with great care.” marily theorists, Goddard performed many Later on, his wife would help him carefully doc- hands-on pioneering rocket experiments. Included ument the results of his rocket experiments. in his long list of accomplishments is the suc- Goddard’s youthful diary describes a very cessful launch of the world’s first liquid pro- special event in his life that happened shortly pellant rocket on March 16, 1926. Goddard’s after his 17th birthday. On October 19, 1899, he lifelong efforts resulted in more than 214 U.S. climbed an old cherry tree in his backyard with patents, almost all rocket-related. Today, Goddard the initial intention of pruning it. But because is widely recognized as the father of modern it was such a pleasant autumn day, he remained rocketry. up in the tree for hours, thinking about his fu- Goddard was born in Worcester, Massa- ture and whether he wanted to devote his life to chusetts, on October 5, 1882, to Nahum Danford rocketry. His thoughts even wandered to devel- Goddard and Fannie Louise Hoyt Goddard. oping a device that could reach Mars. October When Robert was very young, the family moved 19 thus became Goddard’s personal holiday or to Boston, but returned to Worcester in 1898. special “Anniversary Day”—the day on which His father was a machine shop superintendent, he committed his life to rocketry and space and visits to his father’s shop helped nurture his flight. Of that life-changing day, Goddard later fascination with gears, levers, and all types of wrote: “I was a different boy when I descended mechanical gadgets. As a child he was very sickly the tree from when I ascended, for existence at and suffered from pulmonary tuberculosis. last seemed very purposive.” Forced to avoid strenuous youthful games and Because of his frequent absence from school sports, Goddard retreated to more cerebral pur- due to illness, he did not graduate from high suits like reading, daydreaming, and keeping a school until 1904, when he was in his early 20s. detailed personal diary. At high school graduation, he concluded his In the 1890s he became very interested in oration with the following words: “It is difficult space travel. He was especially influenced by to say what is impossible, for the dream of yes- Jules Verne’s classic science fiction novel From terday, is the hope of today, and the reality of the Earth to the Moon, and by H. G. Wells’s, The tomorrow.” This is Goddard’s most frequently War of the Worlds, which appeared as a daily remembered quotation. Goddard, Robert Hutchings 135

Robert H. Goddard and the world’s first liquid propellant rocket in its launch frame. On March 16, 1926, Goddard successfully flight-tested this historic liquid oxygen-gasoline rocket in a field at Auburn, Massachusetts. From 1930 to 1941 he made substantial progress in the development of larger liquid-propellant rockets. With his pioneering experiments he developed and demonstrated the fundamental principles of modern rocket technology. Along with visionary theoreticians Konstantin Tsiolkovsky and Hermann Oberth, Goddard is regarded as one of the founding fathers of astronautics. (Courtesy of NASA) 136 Goddard, Robert Hutchings When he became an undergraduate student, a long relationship with the institution, first as most people, including many supposed scientific a student and later as a faculty member. In 1910 experts who should have known better, mistak- he earned his master’s degree and followed it the enly believed that a rocket could not operate in next year with his Ph.D. in physics. After re- the vacuum of space because “it needed an at- ceiving his doctorate, he accepted a research mosphere to push on.” Goddard knew better. He fellowship at Princeton University from 1912 understood the theory of reaction engines, and to 1913. However, he suffered a near-fatal re- would later use novel experimental techniques lapse of pulmonary tuberculosis in 1913 that in- to demonstrate the fallacy of this common and capacitated him for many months. Recovered, very incorrect hypothesis about a rocket’s in- Goddard joined the faculty at Clark University ability to function in outer space. By the time the following year as an instructor of physics. By he died, the large liquid-propellant rocket was 1920 he was a full professor of physics and also not only a technical reality, but also was scien- the director of the physical laboratories at Clark. tifically recognized as the technical means for He retained these positions until he retired in achieving another 20th-century “impossible” August 1943. dream—interplanetary travel. Clark University provided Goddard with Goddard enrolled at Worcester Polytechnic the small laboratory, supportive environment, Institute in 1904. In his freshman year, he wrote and occasional, very modest amount of institu- a very interesting essay in response to one pro- tional funding necessary to begin serious exper- fessor’s assignment about transportation systems imentation with rockets. Following his return to people might use far in the future—the profes- Clark University, Goddard met his future wife, sor’s target year was 1950. Goddard’s paper de- Esther Christine Kisk. Beginning in 1918, she scribed a high-speed vacuum tube railway system started helping him carefully compile the notes that would take a specially designed commuter and reports of his many experiments. Over time train from New York to Boston in only 10 minutes! their professional relationship turned personal His proposed train used electromagnetic levita- and they were married on June 21, 1924. They tion and accelerated continuously for the first had no children. half of the trip and then decelerated continu- Esther Kisk Goddard created a home envi- ously at the same rate during the second half of ronment that provided her husband with a con- the trip. tinuous flow of encouragement and support. She In 1907 he achieved his first public notori- cheered with him when an experiment worked; ety as a “rocket man” when he ignited a black she was also there to cushion the blow of exper- powder (gunpowder) rocket in the basement of imental failure or to buffer him from the harsh the physics building. As clouds of gray smoke remarks of uninformed detractors. She was the filled the building, school officials became im- publicly transparent, but essential, partner in mediately “interested” in Goddard’s work. Much “Goddard, Inc.”—the chronically underfunded, to their credit, the tolerant academic officials at federally ignored, but nevertheless incredibly Worcester Polytechnic Institute did not expel productive husband-wife rocket research team him for the incident. Instead, he went on to that achieved many marvelous engineering mile- graduate with his bachelor of science degree in stones in liquid propulsion technology in the 1908 and then remained at the school as an in- 1920s and 1930s. structor of physics. As a professor at Clark University, Goddard He began graduate studies in physics at responded to his childhood fascination with Clark University in 1908. His enrollment began rockets in a methodical, scientifically rigorous Goddard, Robert Hutchings 137 way. Goddard recognized the rocket as the en- a tangible reason for supporting Goddard’s pro- abling technology for space travel and then, posed rocket work. unlike Tsiolkovsky and Oberth, he went well be- On January 5, 1917, the Smithsonian Institut- yond a theoretical investigation of these inter- ion informed Goddard that he would receive a esting reaction devices. He enthusiastically $5,000 grant from the institution’s Hodgkins designed new rockets, invented special equip- Fund for atmospheric research. Not only did the ment to analyze their performance, and then Smithsonian provide additional funding to flight-tested his experimental vehicles to trans- Goddard over the years, but equally important, form theory into real world action. In 1914 it published Goddard’s two classic monographs Goddard obtained the first two of his numerous on rocket propulsion: the first in 1919 and the rocketry-related U.S. patents. One was for a second in 1936. rocket that used liquid fuel; the other for a two- In 1919 Goddard summarized his early rocket stage, solid fuel rocket. theory work in the classic report “A Method of In 1915 Goddard performed a series of clev- Reaching Extreme Altitudes.” It appeared in erly designed experiments in his laboratory at volume 71, number two of the Smithsonian Clark University that clearly demonstrated a Miscellaneous Collections in late 1919 and then as rocket engine generates thrust in a vacuum. “Smithsonian Monograph Report Number 2540” Goddard’s work provided indisputable experi- in January 1920. This was the first American mental evidence showing that space travel was scientific work that carefully discussed all the indeed possible. Yet his innovative research was fundamental principles of rocket propulsion. simply too far ahead of its time. His academic Goddard described the results of his experiments colleagues generally did not understand or ap- with solid-propellant rockets and even included preciate the significance of the rocket experi- a final chapter on how the rocket might be used ments, and Goddard continued to encounter to get a modest payload to the Moon. He sug- great difficulty in gathering any financial support gested carrying a payload of explosive powder that to continue. Since no one else thought rocket would flash upon impact and signal observers on physics was promising, he became disheartened Earth. Unfortunately, nontechnical newspaper re- and even thought very seriously about aban- porters missed the true significance of this great doning his lifelong quest. treatise on rocket propulsion and decided instead But somehow Goddard persevered and in to sensationalize his suggestion about reaching September 1916 sent a description of his exper- the Moon with a rocket. The press gave him such iments along with a modest request for funding unflattering nicknames as “Moony” and the to the Smithsonian Institution. Upon reviewing “Moon man.” The headline of the January 12, Goddard’s proposal, officials at the Smithsonian 1920, edition of the New York Times boldly profound his rocket experiments to be “sound and claimed “Believes Rocket Can Reach Moon,” and ingenious.” One key point in Goddard’s favor the accompanying article proceeded to soundly was his well-expressed desire to develop the criticize Goddard for not realizing that a rocket liquid-propellant rocket as a means of taking in- cannot operate in a vacuum. Goddard became a struments into the high-altitude regions of newspaper sensation, but his newfound fame was Earth’s atmosphere—regions that were well be- all derogatory. yond the reach of weather balloons. This early Offended by such uninformed adverse pub- marriage between rocketry and meteorology licity, Goddard chose to work in seclusion for the proved very important, because this relationship rest of his life. He avoided further controversy by provided officials in private funding institutions publishing as little as possible and refusing to 138 Goddard, Robert Hutchings grant interviews to the press. These actions ing. During this test, Goddard’s rocket generated caused much of his brilliant work in rocketry to enough thrust to lift its own weight. Encouraged go unrecognized during his lifetime. The German by the static test, Goddard proceeded to construct rocket scientists from Peenemünde, who emi- and flight-test the world’s first liquid-fueled grated to the United States after World War II, rocket. expressed amazement at the extent of Goddard’s On March 26, 1926, Goddard made space inventions, many of which they had painfully du- technology history by successfully launching the plicated. They also wondered aloud why the U.S. world’s first liquid-propellant rocket. Even government had chosen to totally ignore this though this rocket was quite primitive, it is brilliant man. nonetheless the technical ancestor of all mod- Independent of Tsiolkovsky and Oberth, ern liquid-propellant rockets. The rocket engine Goddard recognized that the liquid-propellant itself was just 1.2 meters tall and 15.2 centime- rocket was the key to interplanetary travel. He ters in diameter. Gasoline and liquid oxygen then devoted his professional life to inventing served as its propellants. Only four people wit- and improving liquid-propellant rocket technol- nessed this great historic event. The publicity- ogy. Some of his most important contributions shy physicist took just his wife and two loyal staff to rocket science are briefly summarized below. members from Clark University (P. M. Roope In 1912 Goddard first explored on a theo- and Henry Sachs) to a snow-covered field at retical and mathematical basis the practicality Effie Ward’s farm in Auburn, Massachusetts. of using the rocket to reach high altitudes and “Auntie Effie,” as he referred to her in his diary, even attain a sufficiently high velocity (called was a distant relative. the escape velocity) to leave Earth and get to Goddard assembled a metal frame structure the Moon. He obtained patents in 1914 for the that resembled a child’s jungle gym to support liquid-propellant rocket and for the concept of the rocket prior to launch. His wife served as the a two-stage rocket. team’s official photographer. The launch proce- In 1915 he used a clever static test experi- dure was quite simple, since there was no count- ment in a vacuum chamber to show that the down: Goddard carefully opened the fuel valves, rocket would indeed function in outer space. As then, with the aid of a long pole, Sachs applied World War I drew to a close, Goddard demon- a blowtorch to ignite the engine. With a great strated several rockets to U.S. military officials, roar, the tiny rocket vehicle jumped from the including the prototype for the famous bazooka metal support structure, flew in an arc, and then rocket used in World War II. However, with landed unceremoniously some 56 meters away in World War I almost over, the U.S. government a frozen cabbage patch. In all, this historic rocket simply chose to ignore Goddard and the value rose to a height of about 12 meters and its en- of his rocket research. gine burned for only two and one-half seconds. Undiscouraged by a lack of government in- Despite its great technical significance, the terest, he turned his creative energy on the de- world would not learn about Goddard’s great velopment of the liquid-propellant rocket and achievement for some time. performed a series of important experiments at With modest funding from the Smithsonian, Clark University between 1921 and 1926. One Goddard continued his work. In July 1929 he test is particularly noteworthy. On December 6, launched a larger and louder rocket near 1925, Goddard performed a successful captive Worcester that successfully carried an instru- (that is, a static, or nonflying) test of a liquid- ment payload (a barometer and a camera)—the fueled rocket in the annex of the physics build- first rocket to do so. However, it also created a Goddard, Robert Hutchings 139 major disturbance. As a consequence the local in a liquid-propellant rocket, and developed the authorities ordered him to cease his rocket flight first liquid-propellant rocket cluster. experiments in Massachusetts. In his lifetime he registered 214 patents on Fortunately, the aviation pioneer Charles various rockets and their components. Unfortu- Lindbergh (1902–74) became interested in nately, since his pioneering rocket work went Goddard’s work and helped him secure addi- essentially ignored, he finally closed his rocket tional funding from the philanthropist Daniel facility near Roswell and moved to Annapolis, Guggenheim. A timely grant of $50,000 allowed Maryland. There he worked with the U.S. Navy Goddard to set up a rocket test station in a re- to provide his rocket technology expertise in the mote part of the New Mexico desert, near use of solid-propellant rockets to assist seaplane Roswell. There, undisturbed and well out of the takeoff. As a lifelong solitary researcher, Goddard public view, Goddard conducted a series of im- found the social demands of team-developing portant liquid-propellant rocket experiments in jet-assisted takeoff (JATO) for the government the 1930s. These experiments led to Goddard’s not particularly to his liking. second important Smithsonian monograph, Just before his death, he was able to inspect “Liquid-Propellant Rocket Development,” which the twisted remains of a German V-2 rocket that was published in 1936. On March 26, 1937, had fallen into U.S. hands and been taken back Goddard launched a liquid-propellant rocket to the United States for analysis. As he per- nicknamed “Nell” that flew for 22.3 seconds and formed a technical autopsy on the rocket, a mil- reached a maximum altitude of about 2.7 kilo- itary intelligence analyst inquired: “Dr. Goddard, meters. This was the highest altitude ever ob- isn’t this just like your rockets?” Without show- tained by one of Goddard’s rockets. ing any emotion, Goddard calmly replied: “Seems Goddard retained only a small technical staff to be.” to assist him in New Mexico and avoided con- America’s visionary “rocket man” died of tact with the rest of the scientific community. throat cancer on August 10, 1945, in Annapolis, Yet, his secretive, reclusive nature did not impair Maryland, and did not see the dawn of the space the innovative quality of his work. In 1932 he age. In 1951 Mrs. Esther Goddard and the pioneered the use of vanes in the rocket engine’s Guggenheim Foundation, which helped fund exhaust with a gyroscopic control device to help much of Goddard’s rocket research, filed a joint guide a rocket during flight. In 1935, he became lawsuit against the U.S. government for in- the first person to launch a liquid-propellant fringement on his patents. In 1960 the gov- rocket that attained a velocity greater than the ernment settled this lawsuit and in the process speed of sound. Finally, in 1937, Goddard suc- officially acknowledged Goddard’s great contri- cessfully launched a liquid-propellant rocket that butions to modern rocketry. That June, the had its motor pivoted on gimbals so it could re- National Aeronautics and Space Administration spond to the guidance signals from its onboard (NASA) and the Department of Defense jointly gyroscopic control mechanism. He also pio- awarded his estate the sum of $1 million for the neered the use of the converging-diverging (de use of his patents. NASA’s Goddard Space Flight Laval) nozzle in rocketry, tested the first pulse jet Center in Greenbelt, Maryland, now honors his engine, constructed the first turbopumps for use memory by carrying his name.

it was small and the images unclear. When he ᨳ Hale, George Ellery learned of the availability of a four-inch Clark (1868–1938) refractor, his father bought it for him. Hale in- American stalled the telescope on the roof of the house, Astrophysicist and after he observed Saturn, Jupiter, and the George Ellery Hale was born on June 29, 1868, Moon for the first time, was inspired to pursue in Chicago, Illinois. Because his mother, Mary, research in the field of astronomy. Soon after, he had lost two previous children in infancy, he was attached a plateholder to the telescope and coddled as a child by ever-attentive nurses and observed a partial eclipse of the Sun, marking teachers, as were two subsequent Hale children, the beginning of a lifelong passion of observing Martha and William. Hale’s father, William E. sunspots. Hale, was a young struggling engineer-salesman With the continuing encouragement of his for a company in nearby Beloit, Wisconsin, who mother to pursue intellectual endeavors and sat- later amassed a fortune in the emerging elevator isfy his inquisitive nature, Hale became educated business, which thrived as the city was rebuilt in the arts, literature, and music. Perhaps more after the Great Chicago Fire of 1871. This fam- important, Hale had his father’s wholehearted ily fortune was to have a crucial influence on financial support, which allowed him to accu- the course of Hale’s scientific life. mulate gratings, lenses, telescopes, and other Early on, Hale became fascinated with the instrumentation as he built a sophisticated plan- microscope. As he examined everything around etarium in the family backyard. By the time he him in great detail, taking copious notes, his was 17, Hale had met prominent astronomers in father bought more and more powerful instru- the Chicago area and had made observations at ments. In his early teens he came upon a de- the Dearborn Observatory in nearby Douglas scription of the spectrum, as seen as a rainbow Park. of light through a prism, and became fascinated Such was Hale’s scientific precocity that by the notion of determining physical proper- when he ordered a small diffraction grating from ties of the known universe by corresponding the famous instrument maker J. A. Brashear, spectroscopic analysis. Brashear was astounded to find Hale was only Hale’s biographical notebooks indicate that 17 years old when he finally met him after cor- he built his first telescope at the age of 13, but responding from his manufacturing facility in

140 Hale, George Ellery 141 Pittsburgh. Brashear had surmised during their to air turbulence caused by warming of the lo- correspondence that Hale was a mature and ex- cal terrain. perienced astronomer. The Hales returned to Chicago, where Hale Hale’s college years were eventful indeed. continued to build his own observatory with a He entered Massachusetts Institute of Techno- 12-inch refractor his father bought him. He logy (MIT) in 1886 and pursued a degree in called it the Kenwood Physical Observatory, and physics. Since MIT at the time did not offer as he worked there the huge 36-inch Lick tele- courses in astronomy, Hale wrote to the noted scope was always on his mind. During this time, professor EDWARD CHARLES PICKERING, direc- when he was only 22, Hale was elected a Fellow tor of the Harvard College Observatory, offer- of the British Royal Astronomical Society. Soon ing his services as a volunteer assistant. after, he was offered a position at the prestigious Pickering, who was breaking new ground in as- University of Chicago, but when he discovered tronomical photography and stellar spectral that the president of the university really cov- classification, was so impressed with the young eted his Kenwood telescope and instruments— Hale’s knowledge of spectroscopy as it could be and possibly was interested in a generous en- applied to astronomy that he hired Hale and dowment by his father—Hale decided to travel kept him employed as an assistant for almost to Europe instead. three years. In Europe, Hale met virtually every famous While a junior in college, and initially astronomer and astrophysicist and visited all the against his family’s wishes, Hale became engaged scientific institutions and laboratories he could. to a Brooklyn girl, Evelina Conklin, whom he Back in the United States, Hale proposed and had met on a family summer vacation when he developed a scientific journal that would even- was 13. This event was followed by the publica- tually become the esteemed Astrophysical Journal. tion of his first article, an essay describing the In 1892 he again was offered a position in the evolution of the spectroscope and its applica- University of Chicago’s new physics department, tions to astronomy. Also while a junior, he in- which he accepted due to the fact that he could vented the spectroheliograph, a device that then work with the eminent professor ALBERT made it possible to observe the Sun’s promi- ABRAHAM MICHELSON (who would become the nences and sunspots in daylight. He tested the university’s first Nobel laureate in 1908). Hale instrument with Pickering at the Harvard was named associate professor of astrophysics, Observatory, and the invention made him world the first astronomer in the world to hold such a famous by the time he graduated from MIT in title. Now came the work that would define 1890 with his degree in physics. Hale’s position forever in the field of astronomy: On their honeymoon in 1890, the Hales vis- his successive role in the creation of the world’s ited the Lick Observatory on Mount Hamilton, three greatest observatories. near San Jose, California. There, Hale had a While at the University of Chicago, Hale chance to observe through Lick’s 36-inch re- became aware of the availability of two 42-inch fractor, then the largest in the world, and was glass discs and decided to devote his energies offered the opportunity to work on the large tel- into creating a world-class observatory at the escope with his spectroheliograph. But by now university. However, he needed even more Hale was receiving job offers from all over the money than his father had, so Hale persuaded world, and he declined the Lick position after a local millionaire, Charles Tyson Yerkes, to being warned by colleagues that daytime obser- help fund the effort. When all was said and vations on Mount Hamilton were difficult due done, Hale found himself director of the Yerkes 142 Hall, Asaph Observatory at Williams Bay, Wisconsin, boast- Hale died of cardiac failure due to arterial ing a 40-inch refractor telescope, the largest as- sclerosis on February 21, 1938, in Pasadena, a trophysical laboratory in the world. Hale was 24 few months short of his 70th birthday. years old. Political strife and ego-driven financial arguments between Yerkes Observatory direc- ᨳ Hall, Asaph tors and the benefactors convinced Hale to (1829–1907) move his family to California in 1904. There, American on Mount Wilson, near Pasadena, Hale set up a Astronomer small laboratory to continue his sunspot observations, and received a grant from the Carnegie In 1877, while he was a staff member at the U.S. Institution to form the Mount Wilson Solar Naval Observatory in Washington, D.C., Asaph Observatory, which would eventually house a Hall discovered the two small moons of Mars. 100-inch telescope, the largest in the world. He called the larger innermost moon Phobos The Mount Wilson Observatory under Hale’s (“fear”), and the smaller outermost moon direction transformed the field of astrophysics. Deimos (“terrified flight”)—after the attendants Here, galaxies were explained, EDWIN POWELL of Mars, the god of war in Roman mythology HUBBLE discovered the expanding universe, and (known as Ares in Greek mythology). the phenomena of sunspots and solar magnet- The American astronomer Hall was born in ism were analyzed. Also while at Mount Wilson, Goshen, Connecticut, on October 15, 1829. His Hale played a major role in transforming the father died when he was just 13 years old, so he Throop Polytechnic Institute into the world- had to leave school to support his family as a acclaimed California Institute of Technology carpenter’s apprentice. In the early 1850s, Hall (Caltech). and his wife, Angelina, were working as school- Although he never lived to see his final teachers in Ohio, when he decided to become a project realized, Hale also set in motion the ef- professional astronomer. Since the difficult days forts to persuade the Rockefeller Foundation to of his childhood, he had always entertained a fund a 200-inch telescope, the largest ever built, deep interest in astronomy and taught himself at Mount Palomar, affiliated with Caltech. the subject as best he could. So in 1857, with Completed in 1948, 10 years after his death, it only a little formal training (approximately one was named the Hale Telescope. year) at the University of Michigan and a good Hale wrote three books: Depths of the deal of encouragement from his wife, he ap- Universe (1924), Beyond the Milky Way (1026), proached William Bond (1789–1859), the di- and Signals from the Stars (1931). He received rector of the Harvard College Observatory, for a every major scientific medal and award and was position as an assistant astronomer. Recalling his an esteemed member of every major scientific own struggle to become an astronomer, Bond ad- society of his time. He coined the word astro- mired Hall’s spunk and hired him as an assistant physics, and his invention of the spectrohelio- researcher to support his son, George Phillips graph ushered in the age of solar prominence and Bond (1825–65), who also worked at the obser- sunspot observation. He created the three most vatory. Hall’s starting salary was just three dollars famous observatories of the 20th century, and he a week, but that did not deter him from pursu- left the scientific community with what is to this ing his dream. day the world’s leading research journal in the His experience at the Harvard College field of astrophysics. Observatory polished Hall’s skills as a professional Hall, Asaph 143 astronomer. By 1863 he had joined the U.S. the interesting object to an assistant and in- Naval Observatory in Washington, D.C., and he structed him to keep quiet about the discovery. eventually took charge of its new 26-inch Hall wanted to confirm his observations before refractor telescope. During this period, the ob- other astronomers could take credit for his find- servatory and its instruments were under the di- ing. On the evening of August 17, as Hall rection of SIMON NEWCOMB, who was actually waited for Deimos to reappear in the telescope, more interested in the mathematical aspects of he suddenly observed the larger, inner moon of astronomy than in performing personal observa- Mars, which he called Phobos. By August 18, tions of the heavens. Hall’s excitement and log notes had informally In December 1876 Hall was observing the leaked news of his discovery to the other as- moons of Saturn when he noticed a white spot tronomers at the Naval Observatory. That on the generally featureless, butterscotch-col- evening the observatory was packed with ea- ored globe of the ringed planet. He carefully ob- ger individuals, including Newcomb, each try- served this spot and used it to estimate the rate ing to snatch a piece of the “astronomical of Saturn’s rotation to considerable accuracy. glory” resulting from Hall’s great discovery. For Hall worked out the period of rotation to be example, Newcomb improperly implied in a about 10.23 hours—a value comparable to the subsequent newspaper story that his calcula- value reported by SIR WILLIAM HERSCHEL in tions helped Hall realize that the two new 1794. The contemporary value for the period of objects were satellites orbiting Mars. This at- rotation of Saturn’s equatorial region is approx- tempt at “sharing” Hall’s discovery caused a imately 10.66 hours. great deal of personal friction between the two In summer 1877 Mars was in opposition astronomers that lasted for decades. Imitating and approached within 56 million kilometers Hall’s work, astronomers at other observatories of Earth. Hall pondered whether the Red soon claimed they had discovered a third and Planet had any natural satellites. Other as- fourth moon of Mars—hasty “discoveries” that tronomers had previously searched for Martian not only proved incorrect but were based on moons and were unsuccessful. However, curi- proclaimed orbital motion data violating ously, the writer Jonathan Swift mentioned two Kepler’s laws. Martian satellites in his famous 1726 novel, When the dust settled, astronomers around Gulliver’s Travels. On the night of August 10, the world confirmed that Mars possessed just two 1877, Hall made his first attempt with the pow- tiny moons, and Hall received full and sole credit erful Naval Observatory telescope, but viewing for the discovery. The Royal Astronomical conditions along the Potomac River were hor- Society in London awarded him its prestigious rible and Mars produced a glare in the telescope Gold Medal in 1877. that made searching for any satellites very dif- Hall remained at the Naval Observatory ficult. He returned home very frustrated, but until his retirement in 1891. He focused his at- his wife encouraged him to keep trying. On the tentions on planetary astronomy, determining following evening, Hall detected a suspicious stellar parallax, and investigating the orbital me- object near the planet just before fog rolled in chanics of binary star systems, such as the visual from the Potomac River and enveloped the binary 61 Cygnus. Following retirement from the Naval Observatory. It was not until the evening Naval Observatory, Hall became a professor of of August 16 that Hall again observed a faint astronomy at Harvard from 1896 to 1901. He starlike object near Mars, which proved to be died in Annapolis, Maryland, on November 22, its tiny outermost moon, Deimos. He showed 1907. 144 Halley, Sir Edmund southern skies, and he convinced the powers ᨳ Halley, Sir Edmund who could make this happen that it would com- (ca. 1656–1742) plement the Greenwich Observatory’s work in English the northern skies. This venture was financially Astronomer, Mathematician, Physicist supported by his father and by influential Royal Edmund Halley was born in Haggerston, Society members. King Charles II also got in- England, around October 29, 1656, a date that volved, personally requesting the East India is approximate, although somewhat based on the Company to transport Halley and a colleague. year Halley claims he was born, due to a change During the trip, Halley redesigned a sextant in the calendar system around that time. His fa- and made notes of oceanic and atmospheric ther, also named Edmund Halley, was a wealthy phenomena. soap maker and landlord, which afforded his son Halley was on St. Helena for 18 months, and many privileges in his early youth. When Halley he made the first complete observation of a tran- was 10 years old, the Great London Fire of 1666 sit of Mercury, catalogued 341 Southern ravaged the family’s business, but not com- Hemisphere stars in his Catalogus stellarum aus- pletely. The shrewd businessman managed his fi- tralium, and discovered the star cluster in nances well enough to provide private tutoring Centaurus—all of which he published upon his for his son and then enroll him in the presti- return to the Royal Society in 1678. This work gious St. Paul’s School, where young Halley ex- made him a reputable astronomer, but Halley of- celled in mathematics, began his fascination ficially had no degree. Since he had left Oxford with instrumentation, and started on his lifelong without graduating, which was very common for path of studying the night sky. wealthy students, in 1678 he was granted an When Halley entered Queen’s College at honorary degree from Oxford by edict of King Oxford in 1673, at 17 years old, he was already Charles II. That same year he was made a mem- an accomplished astronomer. With an extensive ber of the Royal Society, at the age of 22 one of set of instruments given to him as a gift from his its youngest Fellows. father, and the knowledge to use them, Halley In 1680 Halley decided to travel through easily caught the attention of John Flamsteed Europe with a friend from school. En route, near (1646–1719), the Astronomer Royal, who was Calais, he observed a comet. With his interest working both at Oxford and at the Greenwich sparked, he continued his trip to Paris, where he Observatory. By 1675 Halley had become his as- met up with fellow astronomer GIOVANNI sistant. One of Halley’s observations at Oxford DOMENICO CASSINI and the two observed the was an occultation, the concealing of one heav- comet together. enly body by another, as for example of a star by In 1681 he married Mary Tooke. The fol- a planet. He noted the occultation of Mars by lowing year he decided to visit SIR ISAAC the Moon on August 21, 1676, and featured this NEWTON in Cambridge for some professional ca- in his first published article in the journal maraderie. Halley had been working on a proof Philosophical Transactions of the Royal Society. of planets having elliptical orbits, and much to The next significant event in Halley’s life his amazement, Newton had already proved seems to be his travel in 1676, when he left the thesis. Even more astonishing, he had no in- Oxford to go on a voyage to the island of St. tention of publishing his proof. Halley then Helena, off the African coast, the southernmost urged Newton to compose his epic Principia territory under British rule. His dream, literally, Mathematica, and even financed its publication, was to construct an observatory to chart the eventually earning back his investment when Halley, Sir Edmund 145 the work sold extremely well. Halley edited the diatribe, it turned out, was that Flamsteed con- work and volunteered to write an introduction, sidered Halley a bad Christian because Halley “Ode to Newton,” which heaped great praise allegedly did not believe solely in the biblical on Newton and his scientific brilliance. Famous rendition of creation. The common theme in discoveries resulted for both men out of this astronomy of science versus religion reared its venture. Newton discovered gravity, and Halley ugly head. Flamsteed told the university that he discovered Newton. thought Halley would “corrupt” the students, In 1684 Halley’s father, who had remarried and Halley did not get the job. in 1681 after being a widower for 10 years, dis- Unperturbed, Halley continued his research appeared. After a five-week absence, his body and work for the Royal Society. In 1693 he pub- was found, the victim of a murder. In addition to lished another first, this time a study of mortal- the great emotional loss, it was a sudden end to ity rates related to age that was researched from Halley’s lifelong funding from his father, who documents in Breslau, Germany. This ultimately was a dedicated patron of his son’s work at the became the basis for future actuarial tables used rate of a £300 annual allowance. By 1685 Halley by insurance companies, and made Halley a pi- was working for the Royal Society as, among oneer in yet another new field of science, social other things, editor of their publication Philo- statistics. sophical Transactions, a position he held until Newton had become warden of the Royal 1696. Mint in 1696, and quickly appointed Halley as Halley’s vast interest in a variety of fields led deputy controller of the mint in Chester, him to make contributions in other areas of sci- England. Halley left the position in 1698 when ence over the next few years. By 1686 he had King William III awarded him the command of completed a new map of the world, in which he a warship, the Paramore Pink, built specifically showed the prevailing winds over the oceans. for scientific expeditions. Halley had been This new work on trade winds and the tides was working on the determination of longitude us- a great contribution to science, and ultimately ing a specially designed compass, and the pur- earned him credit as the founder of geophysics. pose of the voyage of the Paramore Pink was to By 1691, however, Halley felt ready to get test his new method and discover “new lands” back into academia, and he decided to pursue south of the equator. appointment to an astronomy chair at Oxford. As a naval captain, Halley started the three- Halley could have reasonably expected some year stint a little shaky. His first voyage in 1698 support from his old friend and mentor was aborted when he reached Barbados, and he Flamsteed, from his days at Oxford and the returned to Portsmouth. A second voyage, in Greenwich Observatory. But Flamsteed disliked 1699, charted the North American coast of the Newton, who owed his great success to Halley, Atlantic, after which he published the first and while it is fair to say that many people per- charts of equal lines of declination. Several other sonally disliked Newton, it seemed not enough voyages along the coasts of England followed. In reason to abandon Halley in his quest for a job. 1702 he spent a year inspecting a naval base and So Flamsteed created other reasons. From a sci- other ports in the Austrian Empire at the request entific perspective, Flamsteed was upset for of Queen Anne. what he perceived as a slap at the observatory In 1704, waving goodbye forever to his by Newton, thinking that the Royal Observa- oceanic duties, Halley finally made his goal of tory should have received more credit regarding teaching at Oxford a reality. He was appointed Newton’s theories. But his most convincing to the chair of geometry at Oxford as Savilian 146 Hawking, Sir Stephen William professor, a seat he held for the rest of his life. culus: Newton “won,” although the dispute was Flamsteed was not happy about this new ap- never really settled during their lifetime. pointment, apparently feeling that Halley’s time Over the years Halley was also in and out at sea had turned him into an even more of disputes and controversies with his old men- wretched creature than ever, complaining that tor-turned-critic, Flamsteed. Halley had the last Halley now “talks, swears and drinks brandy like laugh when he was appointed Royal Astronomer a sea captain.” Halley gave an impressive inau- at Greenwich in 1720, succeeding Flamsteed gural speech, including “an account of the most after the latter’s death. He held this post for 21 celebrated of the ancient and modern geometri- years, until age 85, and during this time he in- cians.” And whether for the sake of his friend vented the use of a transit to make lunar obser- Newton, or just for the fun of irritating vations to determine longitude at sea and Flamsteed, Halley confidently “gave his greatest completed an 18-year observation of the Moon. encomiums [to] . . . Mr. Newton.” In 1729 Queen Caroline wanted to make It was about this time that Halley started to certain that England’s beloved scientist Halley focus his interest on comets. Newton had pro- was financially secure. She decreed that Halley posed that comets had parabolic orbits, but should be given an additional salary equal to Halley suspected they might in fact be elliptical. half-pay of a naval captain—an amount he con- Using his own theory, he calculated that the or- tinued to receive until his death. bit of the Comet of 1682 was in fact periodic, Halley’s scientific and astronomical bril- and was the same comet that had appeared in liance, as well as his aptitude for mathematical 1531 and 1607. In 1705 Halley predicted that logic, gave the world knowledge that has the comet would reappear in a pattern of 76 affected even today the important fields of nav- years. Halley would not live to see the comet re- igation, geophysics, meteorology, astronomy, turn in December 1758, but when it did it was cartography, ballistics, and the development of immediately dubbed “Halley’s comet” and, of measurement instruments such as the ther- course, reappeared in 1836, 1910, and 1986; mometer, the backstaff, and the diving bell. every 76 years since, precisely as predicted. This preeminent scientist was a member of In 1710 Halley proposed that stars had their the Royal Society from 1678 to 1743, and of the own motions and proved his theory by calculat- Académie des Sciences at Paris from 1729 until ing the motions of three specific stars. The the- his death. His contributions have earned him ory of proper stellar motion, although new to the both a lunar and a Martian crater named in his Western world thanks to Halley’s research and honor. Halley died in Cambridge on January 14, calculations, had been originally proposed by the 1742. Buddhist monk and astronomer Zhang Sui (683–727). Halley probably had no knowledge whatsoever of Sui’s theory. This same year, most ᨳ Hawking, Sir Stephen William likely for his work on this theory, Halley was (1942– ) again awarded an honorary degree, an M.A., English from Oxford. Cosmologist, Physicist Halley continued his work in astronomy in conjunction with his position in geometry at There are few disciplines in which the word ge- Oxford. He also served as an arbiter of several nius is used to describe several of its members— disputes. Most famously, he “resolved” Newton’s physics is one of them. The most renowned ge- dispute with Leibniz over who invented the cal- nius of the late 20th and early 21st centuries is Hawking, Sir Stephen William 147 the Lucasian Professor of Mathematics at most complex subjects of space accessible to the Cambridge, Stephen Hawking—the man who world at large. brought the mind-boggling principles of cos- As a young boy, Hawking knew by age 14 mology into the everyday realm of the average that mathematics was his life’s calling. He at- person, and who helped popularize and main- tended St. Albans School starting at age 11; stream such science-fiction ideas as black holes, then, at age 17, he went to University College worm holes, time travel, and life elsewhere in in Oxford, his father’s alma mater, where he took the universe. Hawking is known as the scientist up physics because mathematics was not offered. who explains to the masses the laws that govern He was notorious for missing classes and labs, a the universe. trait he shared with another great physicist, Born on January 8, 1942, in Oxford, ALBERT EINSTEIN, whose work would play an im- England, Hawking is fond of saying that his portant role in Hawking’s future career. But un- birth date was the 300th anniversary of GALILEO like Einstein, who barely passed his exams, GALILEI’s death. This takes a bit of explaining. Hawking graduated at the top of his class with- One of the legends in astronomy since the late out much effort. With his undergraduate degree 18th century has been that Galileo and SIR in natural science behind him, Hawking left ISAAC NEWTON shared a date in their life— Oxford and went to Cambridge for his Ph.D. in Newton was born the same day that Galileo cosmology—a new and relatively unexplored died, and that day happened to be Christmas field. Day, 1642. More than 100 years later, in 1752, But something was not quite right with the calendar system was changed in England, Hawking—minor clumsiness escalated into and the Gregorian calendar was adopted. Going falling over for no reason, and pretty soon he back in time, after the implementation of the was having trouble tying his shoes. When Gregorian calendar, and updating the dates of Hawking went home for Christmas vacation, his the events that happened previous to the in- father, a doctor, noticed the symptoms and took stallation of this new system has the effect of him to a specialist, where multiple sclerosis was changing the date that Newton was born and ruled out. But within a few weeks, Hawking was that Galileo died. The date, while they were diagnosed with amyotrophic lateral sclerosis alive, was December 25, 1642—although even (ALS—also called Lou Gehrig’s disease), a de- this is in question! Some historians site Galileo’s generative motor neuron disease that causes the death in December 1641, so the new date would body’s muscles to atrophy. Hawking admits that then be January 1642; and some say that Newton the shock of finding out he had an incurable dis- was born in December 1642, so the corrected ease was compounded by the fact that it was year would be January 1643. In any event, if the probably going to kill him before he finished his dates are changed to the Gregorian system and Ph.D., but when he witnessed the agonizing corrected for today’s time, December 25 becomes death of a boy with leukemia in the hospital bed January 8, as it relates to our calendar. So, in across from him, he gained new insight, realiz- essence, Hawking was born the same day Galileo ing that “Clearly, there were people who were died and the same day Newton was born. worse off than me.” Perhaps all of this confusion is simply forewarn- The young boy’s death, and the ensuing ing from the universe that if the time of his birth dreams Hawking had, helped change Hawking’s is confusing, it is nothing compared to the perspective, and he realized that he needed to philosophies and theories he proposes. Yet this do something good with the life he had left. He brilliant man has managed to make even the stated to enjoy “life in the present,” and he felt 148 Hawking, Sir Stephen William a surge of hope and purpose. Shortly after his di- computer speak for him. It is by this method of agnosis, he resumed his research at Cambridge, writing, 15 words a minute, that Hawking has earned a research fellowship at Caius College in created extensive papers on complicated theo- Cambridge, and married an undergraduate at ries, written two books that have sold in the Westfield College in London named Jane Wilde. mainstream market with international appeal, Hawking’s chosen field, theoretical physics, and lectured around the world. The only prob- proved to be a blessing as his disease continued lem, Hawking says, is that he now speaks with to take its toll on his body. He found that the an American accent. worse his condition became, the more he could The beginning of Hawking’s development of focus his time on research, rather than lectur- his popular theories started at Cambridge when ing. He continued to research and live a rela- he met the brilliant mathematician Roger tively normal life until 1974, when he lost the Penrose, whose work on what happens at the ability to feed himself or manage the usual ritu- end of a star’s life inspired Hawking to devote als associated with going to bed. By this time he himself to the subject of collapsed stars. By 1970 and his wife had three children, and it was clear the mathematician-and-cosmologist team in- that she could not continue to take care of him formed the world that they had discovered that alone, so they came up with the brilliant solu- the universe had a definite beginning of time, tion of giving a research student free board and about 15 billion years ago in the big bang— personal access to Hawking in exchange for confirming the idea originally proposed by help. This lasted for six years, until 1980, when RALPH ASHER ALPHER. they brought in professional help and Hawking The idea of a beginning of time was a con- eventually needed round-the-clock medical cept that had been argued on the basis of reli- assistance. gion or philosophy for centuries. Hawking wrote, In the early 1980s Hawking’s speech became “SIR ARTHUR EDDINGTON once said, ‘Don’t slurred, and his lectures required the assistance worry if your theory doesn’t agree with the ob- of a close friend who could still understand him servations, because they are probably wrong.’ to “translate” for the audience. Then, in 1985, But if your theory disagrees with the Second Law Hawking came down with pneumonia. After a of Thermodynamics (in which disorder increases tracheotomy to save his life, his speaking ca- with time), it is in bad trouble.” pacity was destroyed. The only way he could Hawking and Penrose proved that Einstein’s communicate was by “raising [his] eyebrows general theory of relativity supported their the- when someone pointed to the right letter on a ories—that when a star collapsed it became a spelling card,” which made it nearly impossible black hole, a place where “time came to an end,” to get the ideas out of his head and onto paper. and that “the expansion of the universe is like A California computer whiz named Walt the time reverse of the collapse of a star.” They Woltosz came to Hawking’s rescue with a pro- cited the uncertainty principle of quantum me- gram he wrote in which Hawking could chose chanics that states an object cannot have both words from a computer screen with a click of a a well-defined position and a well-defined speed, switch. Soon, Hawking had a computer on his and used the debunked steady state theory (as wheelchair, and a voice synthesizer. The hard- galaxies move apart, new galaxies are formed in ware and software combination suddenly gave between them from new matter that is con- him the freedom to write at a rate of up to 15 stantly being formed) for further proof. words a minute, save his compositions to the By combining the uncertainty principle computer and print them out, or even have the with the general theory of relativity, Hawking Hawking, Sir Stephen William 149 created a new theory, the quantum theory, in- lications. Einstein’s theory of general relativity troducing the concept of “imaginary time,” was the next theory to address gravity and its ef- which when combined with three-dimensional fect on light. Then, in 1928, SUBRAHMANYAN space forms “a Euclidean space-time,” where CHANDRASEKHAR worked out his theory of how space and time are “like the surface of the stars maintain themselves with their own grav- Earth”—with no boundaries. Using the laws of ity, and determined that once a star reaches a physics, the state of the universe can be calcu- certain level of density, known as the Chandra lated in imaginary time, and therefore can also limit, it can no longer support itself. Eddington be calculated in real time, and so the beginning rebuked this idea, but the idea of gravitational of time can be pinpointed. collapse was revived again in 1939 by Robert In 1992, when the satellite COBE (Cosmic Oppenheimer (1904–67), then dropped during Background Explorer) found “irregularities in the World War II, and rediscovered in the 1960s. microwave background radiation,” Hawking The resulting work was supported by gen- says, “we saw back to the origin of the universe.” eral relativity, and suggested that light emitted The work Hawking and Penrose started more from a dense enough star would turn back in on than two decades prior suddenly had some ob- itself. This light, and everything else within its servational teeth, although even Hawking proximity, would be pulled into the field. An admits that more data is required to make a American scientist named John Wheeler labeled definitive stance. Their “no boundary” theory this phenomenon a black hole in 1969, and the explains that the universe is finite, self- boundary surrounding the black hole is called its contained in space and imaginary time. It also event horizon. Hawking first proclaimed in his implies that what had a beginning must also research that by its nature, a black hole emits have an end. nothing—it only devours, it does not spit out. Famous for his great sense of humor, Hawk- But he later discovered, with the prodding of an ing recounts the story of giving a presentation on American student at Princeton and two Russian the “beginning of time” in Japan, where his scientists, that black holes actually emit parti- sponsors requested that he “not mention the cles and radiation, and in this emission of en- possible re-collapse of the universe, because it ergy, there is a loss of mass, meaning the black might affect the stock market.” Hawking’s reply hole will actually get smaller and smaller and was to reassure “anyone who is nervous about eventually just evaporate, in a period of about their investment that it is a bit early to sell,” 1067 years. because the eventual end will not happen for In addition to creating theories on the about 20 billion years. workings of the universe, Hawking gives pre- Hawking also made headlines for his work sentations on such topics as time travel, pre- on black holes, which are formed when stars be- dicting the future of the cosmos, and life else- come so dense that nothing can escape their where in the universe. Time travel involves the gravitational fields, including light. This idea of general theory of relativity, quantum theory, the black holes was originally proposed in 1783 by uncertainty principle, and discussion of cosmic the English scientist John Michell (1724–93) at strings, and wormholes, along with such prac- Cambridge, then independently shortly there- tical observations as the fact that we have not after by PIERRE-SIMON,MARQUIS DE LAPLACE in yet been flooded by time-traveling tourists from his publication The System of the World. Neither the future. He similarly discusses Einstein’s fa- of them, nor anyone else in the scientific com- mous quote “God does not play dice,” and gives munity, took the ideas beyond their initial pub- his theories on this postulate, based, of course, 150 Herschel, Caroline Lucretia on scientific principles, to determine whether ᨳ Herschel, Caroline Lucretia this is true and/or if it is possible to predict the (1750–1848) future of the universe. The second law of ther- German modynamics, a definition of life, and a princi- Astronomer ple called the anthropic principle, along with information on the Big Bang, the makeup of Caroline Lucretia Herschel has often been men- DNA, and some comments on evolution, stoke tioned only in reference to “assisting” her famous the fire of his discussion of the question of life astronomer brother, SIR WILLIAM HERSCHEL, yet outside our solar system. This proprietary in- it was her calculations, her energy, and her ded- formation can be found on his Web site, ication to astronomy that led to her important http://www.hawking.org.uk. contributions to the field, including the compi- Hawking’s famous book A Brief History of lation of two catalogs and the discovery of the Time was published in 1988, and became an in- first comet ever found by a woman, winning her ternational best seller, translated into more than the praise of kings. 40 languages, and selling more than 9 million Born in 1750 in Hanover, Germany, Herschel copies. He updated the book with a new version was brought up in the somewhat traditional way entitled The Illustrated A Brief History of Time, used in rearing female children at the time. Her in 1996, and also published in 2001 a book en- mother, Anna Ilse Moritzen Herschel, believed titled The Universe in a Nutshell. He has also pub- that girls should be raised to learn only house- lished numerous technical papers, all of which hold tasks, and was opposed to any education of require a professional foundation in physics in her daughter. Her father, Isaac Herschel, was not order to understand. The Theory of Everything: necessarily in agreement, but given his wife’s dis- The Origin and Fate of the Universe is a new composition and the large number of children to pilation of his work, much of which is in print which the family had to attend, reported as six in A Brief History of Time, and is a book in which to 10 depending on the source, he gave as much he emphatically states he did not authorize and attention to providing some knowledge to his does not endorse. daughter as time and his wife would allow. Most A father of three, Hawking left his wife in important, he introduced her to the stars, “to 1990 and remarried in 1995. When asked how make me acquainted with several of the beauti- he feels about his disease, his standard answer is ful constellations, after we had been gazing at a “Not a lot. I try to lead as normal a life as pos- comet,” she wrote in her diary. But her father sible and not think about my condition, or re- left the family’s home to fight the French when gret the things it prevents me from doing, which she was only seven years old, and returned three are not that many.” Remembering the early days years later much worse for the wear. The young of his diagnosis and the boy who shared his girl was obliged to take on the role her mother room, Hawking has a strong reminder of how prescribed, strictly relegated to household chores fortunate he is. “Whenever I feel inclined to be and tending to her ill father for the next 10 years, sorry for myself, I remember that boy.” until he died in 1767. Hawking continues to travel around the The Herschel family was steeped in music. world, giving public lectures and attending sci- Isaac had been in the Hanoverian Foot Guard, entific conferences and symposiums. He has first as oboist and then eventually as bandmas- been awarded 12 honorary degrees, and is a ter, and Herschel’s older brother William, who member of the Royal Society and the U.S. played a profound role in her life, became a National Academy of Sciences. member of the band as well before leaving Herschel, Caroline Lucretia 151 home and becoming a music teacher in Bath, telescopes, but studying the stars was their main England. venture. In 1772, at age 22, Caroline Herschel de- With William manning the eyepiece, the cided to leave behind a life of knitting, dress- family’s goal was to do a systematic survey of the making, and studies to become a nanny. Her sky. Herschel wrote down all of the measure- brother William invited her to come and live ments William called out or signaled to her, and with him in Bath. Over the next few years, in then did the daily calculations and logged all of exchange for her help running William’s house- their findings. Her daily duties still included run- hold, a task at which by this time she excelled, ning the household, and by now she had also the organist, composer, and music teacher gave become an accomplished singer, giving perform- his sister singing lessons, and began to indoctri- ances as often as five times a week with her nate her in the higher education that she was so brother. But the most important thing seemed suited to absorb, including English, algebra, to be taking care of their work with the stars. geometry, spherical trigonometry, and astron- Herschel noted that “every leisure moment was omy. So much for her mother’s ideas. eagerly snatched at for resuming some work It is said that William’s interest in astron- which was in progress.” omy was spurred shortly after his sister’s arrival, In March 1781 Herschel was recording data in 1773, when at age 35 he bought a book by from her brother as he observed a comet in the James Ferguson entitled Astronomy Explained night sky. But calculations proved that this was upon Sir Isaac Newton’s Principles, and Made not a comet at all. The pair had discovered a Easy to Those Who Have Not Studied Math- new planet, as far beyond Saturn as Saturn is ematics. This book was also the inspiration for from the Earth. “William’s” discovery of the Robert Baily Thomas to create the Old planet, eventually named Uranus the father of Farmer’s Almanack 20 years later, in 1793, Saturn, Saturn being the father of Jupiter, cata- which is still in publication today and has the pulted the Herschel duo from local amateur as- distinction of being the longest-running al- tronomers to national treasures. King George III manac in history. gave William an annual salary of £200, and as a Apparently it took William next to no time new member of the Royal Society William to get hooked on astronomy, because before the decided to leave the music business for good, go- year was over, he and his sister, along with their ing from professional musician to professional as- brother Alexander, who was also living with tronomer overnight. While Herschel loathed them at the time, began working on building giving up her singing career, she acquiesced, al- their own telescopes. Herschel claims that though she enjoyed singing privately through- “nearly every room in the house [was] turned out the rest of her life, and sometimes for very into a workshop,” for some aspect of production. noble guests. And while the reality of seeing the house in a The following year, Herschel’s brother shambles “was to my sorrow,” she managed to moved them into a bigger house in Windsor, and work around it and became quite good at grind- she became the owner of a new telescope of her ing telescope mirrors. The resulting telescopes, own, a gift from William so that she could start most notably a seven-foot model, turned a making her own observations. As she had brother’s interest in peering at the night sky as learned with her brother, the best approach was often as the British weather would permit into systematic, so she began to methodically track what would become a lifelong family affair. the night sky in search of comets. But her work Over the years, they continued to make and sell with her brother continued to occupy most of 152 Herschel, Caroline Lucretia her time. He became more immersed in his own Flamsteed’s Historia Coelestis Britannica star cat- observations, and she was always present, record- alog. In 1798 she presented her first publication, ing data during night-time observations and cal- Index to Flamsteed’s Observations of the Fixed culating the work during the day. For the next Stars, in which she updated his catalog with 560 several years, she spent most of her time record- stars that were not previously included. This ing and working on computations with her would be her sole publication for the next 25 brother as he did work that led to discoveries of years. new binary stars, new moons, and eventually the In 1822 William Herschel passed away, and doubling of the size of the known solar system. Caroline, now 72, left England to live the rest Her own discoveries occurred, however, af- of her years in Hanover. By 1828 her next pub- ter a move in April 1786 to another house, a lication was ready to be presented to the world. home they called Observatory House. Here, on A catalog that she put together in part to help August 1, 1786, Caroline Herschel discovered her nephew with his own astronomical contri- her first comet. She became instantly famous. butions, the work was a compilation of 2,500 Her comet was dubbed “the first lady’s comet,” nebulae. This was a great achievement that was because Herschel was in fact the first “lady” to recognized with a gold medal in 1828 from the ever discover a comet. Royal Astronomical Society. In 1832 William’s This began an entirely new life for Herschel. widow died, and their son John went to Hanover In 1787 the king gave her a £50 annual salary, to visit his aunt, now aged 83, marveling that and the Herschels became frequent guests at the the petite woman “runs about the town with me, castle. Princess Augusta would often peer into a and skips up her two flights of stairs,” sings, telescope at the castle, and would invite guests dances, and is full of life “quite fresh and funny to look and see “Miss Herschel’s comet.” at ten p.m.” That same year, Herschel’s brother married The effervescent Herschel remained alert and, understandably, it was time for Herschel to and active for many years to come. She was hon- leave her brother’s house and make a home of ored in 1835 when she and MARY FAIRFAX her own. She was reportedly furious and bitter SOMERVILLE jointly became the first two women with her brother’s wife for insisting that she elected to the Royal Society. Leading scientists leave, but she moved within walking distance continued to visit her throughout her life, and and came to their house every day to work on she remained a celebrity for her amazing work his observations. Eventually, she softened toward in astronomy. In 1838 the Royal Irish Academy her sister-in-law, and things smoothed out be- elected her a member, and her 96th birthday was tween them, especially after the birth of marked with a gift from the king of Prussia, a William’s son John in 1792. As her nephew grew, gold medal for her scientific achievements. Herschel was able to start teaching him mathe- At her 98th birthday celebration, the crown matics and astronomy—a task that resulted in prince and princess of Prussia visited Herschel the formation of another renowned scientist at her home, where she said, “Let’s sing a catch,” in the family, SIR JOHN FREDERICK WILLIAM and proceeded to perform a song written much HERSCHEL. earlier in her lifetime by her brother William. Herschel continued both her work with her She remained active and alert until her death at brother and her search for comets, discovering a home on January 9, 1848, where she drifted away total of eight comets during the next 11 years. peacefully. The first home that she shared with She also embarked on another huge project, her brother William in Bath, located at 19 King working on updating Royal Astronomer John Street, is now the site of the William Herschel Herschel, Sir John Frederick William 153 Museum. In addition to her many awards, a mi- mother pulled him out within a few months, nor planet was named Lucretia in 1889 in her turning to private tutoring for her son’s educa- honor, and a crater on the Moon bears her name. tion. At the age of 17, in 1809, Herschel went to St. John’s College at Cambridge. Mathematics was the field of choice for ᨳ Herschel, Sir John Frederick William Herschel at Cambridge, and he teamed up with (1792–1871) two other brilliant students to force changes in British the way mathematics was being taught in Mathematician, Astronomer England. In 1812 he and classmates Babbage and George Peacock (1791–1858) formed an organ- Sir John Herschel had such a wide range of in- ization they called the Analytical Society, hop- terests in his life that he could easily be consid- ing to create enough of a critical mass to con- ered a Renaissance man of the Victorian age. vert the British educational system over to He influenced many of the great minds of his modern mathematics, specifically the teachings time, including Charles Babbage (1791–1871), of Sylvestre Lacroix (1765–1843). Herschel Charles Darwin (1809–82), and Michael Faraday translated from French Lacroix’s treatise on cal- (1791–1867). But as diverse as his interests were, culus, and added his own examples to the work. many of them melded seamlessly together allow- The society was short-lived, but the translation ing him to make some of the greatest contribu- was successful, and the work was adopted as a tions in his life to astronomy—both inheriting textbook, giving Herschel his first of many im- and passing on his family’s legacy of extraordi- pressive successes. nary scientific achievement. While working on changing the educational John Frederick William Herschel was born system, the 20-year-old undergraduate student on March 7, 1792, to Mary Pitt Herschel and published his first paper—a mathematics piece the famous “King’s Astronomer” SIR WILLIAM entitled, “On a Remarkable Application of HERSCHEL. He was Mary’s second child, from her Cotes’s Theorem”—in the Transactions of the second marriage. Mary’s first husband and child Royal Society. The following year, after graduat- died, leaving her a young widow until she mar- ing from Cambridge in 1813, Herschel was ried William in 1788. William’s only child, the elected a Fellow of the Royal Society based on boy was raised in the home they called the merits of his paper. Observatory House, where William had built his After graduation, Herschel took a detour 40-foot telescope with a £4,000 grant from the from science and decided to become a lawyer. king. He studied for about a year and a half, then aban- Education began early in Herschel’s life. doned the law and returned to Cambridge. In CAROLINE LUCRETIA HERSCHEL, at that time one 1816 he graduated from Cambridge again, this of the most famous women in the world, doted time with an M.A. in mathematics, and went on her nephew and took every opportunity to back home to spend the summer with his 78- teach him science and mathematics during her year-old father. This visit was a turning point daily visits to Observatory House. Herschel’s of- in Herschel’s professional life. He wrote to ficial schooling started at Dr. Gretton’s School, Babbage, saying that he was going back to in the town of Hitcham, where he went until Cambridge just long enough to pack up and take the age of eight, when he changed to Eton care of his personal affairs, and then “I am go- College. But as the new boy in school, Herschel ing under my father’s directions . . . and con- soon found himself a target for bullies, and his tinuing his scrutiny of the heavens.” 154 Herschel, Sir John Frederick William But while Herschel was committed to fol- Lalande Prize the following year and the Astro- lowing in his father’s footsteps, he was not quite nomical Society’s gold medal. Then, in 1826, he ready to give up his other interests—and he had began to focus his work on binary stars, which many. One of them was photography. In 1819 had been a major component of his father’s Herschel began experimenting with “photogra- work. He took time out only to write, and to phy,” a term that he made up. Interested in marry a woman named Margaret Brodie Steward chemistry, Herschel had done many experi- in 1829. ments with chemicals as they related to pho- Herschel began to make many important tography. He published his experiments, and contributions to encyclopedias, writing about sci- they would prove to have a profound impact on entific subjects to help educate the masses. His the development of photography in about 20 first such piece was a 245-page work on light, writ- years. ten in 1828, for the Encyclopaedia Metropolitana. In 1820 Herschel began to make some seri- Next came similar articles on mathematics for the ous inroads in astronomy. He joined his father at 1830 edition of the Edinburgh Encyclopaedia. That the first meeting of the Astronomical Society of same year, Herschel published one of his most fa- London—the precursor of the Royal Astronom- mous works, Preliminary Discourse on the Study of ical Society—and his father became the first Natural Philosophy, a book that influenced Darwin president of the society, with Herschel elected as and prompted Faraday to write to Herschel telling vice president. That same year, he published a him that the book “made me, if I may be per- book coauthored with Babbage, A Collection of mitted to say so, a better philosopher.” The fol- Examples of the Applications of the Differential and lowing year, Herschel was knighted. Then, in Integral Calculus. In 1821 the Royal Society 1832, his mother died. awarded him his first Copley Medal for his pub- Herschel continued concentrating on the lications. work his father had started with binary stars, and But the collaborations with his famous fam- he devised a way to determine their orbits and ily came to a sudden halt when, in 1822, his fa- discovered that they orbited a common center ther died and his aunt Caroline moved back to of gravity. He was awarded the Royal Medal from Germany. Left to make his name in astronomy the Royal Society in 1833, for his paper “On on his own, Herschel published his first astro- the Investigation of the Orbits of Revolving nomical paper, in which he described a new way Double Stars.” He also published A Treatise on to calculate lunar eclipses. He also spent some Astronomy as an encyclopedia entry. time studying light at a time when physicists were Heavily engrossed in carrying on his father’s beginning to look at the spectra of nonsolar light. work, Herschel packed his family, consisting of His experiments dealt with the spectra of metal- his wife and four children, and the 20-foot re- lic salts, in which he could determine that there fractor telescope that he and his father had were small quantities of salt in flames. This work built, and sailed for the Cape of Good Hope in marked the beginning of a new branch of physics South Africa, where the Royal Observatory had called spectroscopy. built a new facility in 1828, with a mission of By 1824 Herschel was fully engaged in cataloging the heavenly objects that could not astronomy. He was elected secretary of the Royal be seen in the Northern Hemisphere. He arrived Society, a position he kept for three years. He in January 1834, and set up observations in published his first major book, a catalog of dou- Feldhausen, near Cape Town. ble stars in the Transactions of the Royal Society, The next few years were busy for Herschel. for which he received the Paris Academy’s In South Africa he was able to observe and chart Herschel, Sir John Frederick William 155 the kinds of “exotic objects” that his father and Other Substances, Both Metallic and Non- found so fascinating, nebulae and star clusters. Metallic, and on Some Photographic Processes,” An exceptional artist, he drew many of the ob- printed in the Philosophical Transactions, which, servations he saw in the Southern Hemisphere in 1840, earned him another Royal Society sky. He had the extreme good fortune of being Royal Medal. able to observe the return of Halley’s comet in In 1842 he left photography in the capable 1835, and he noticed that there seemed to be hands of Talbot and others and got back to the something other than gravity that affected its business of compiling his data from South orbit, deciding that it was somehow being re- Africa. During this time, he became head of the pelled by the Sun. In truth, the repulsion he Marischal College in Aberdeen, and then, observed was caused by solar wind, leading three years later, in 1845, president of the many to believe that Herschel was the first to British Association at Cambridge. In August discover this unseen but documented force. He 1846 he heard about a new planet that fellow also discovered that the comet was expelling astronomer JOHN COUCH ADAMS had deter- evaporated gases. mined existed beyond Uranus, which was the In 1836 Herschel worked on establishing planet Herschel’s father had discovered. the relative brightness of nearly 200 stars. He Herschel was elated by the news, and did every- used the Moon as a focal point and compared thing he could to help Adams get support in stars and their apparent brightness as they re- his search for the planet, including setting up lated to the distance of the Moon and its ap- a presentation for Adams at a meeting of the parent brightness. In 1833 a paper he published British Association, for which Adams arrived on nebulae and star clusters in the Philosophical the day after the meeting. When the London Transactions earned him another Royal Medal Times ran the headline “Le Verrier’s Planet from the Royal Society. During his last two years Found” on October 1, 1846, Herschel notified in South Africa, Herschel also worked on meas- the press that this new planet, ultimately uring solar energy, and in 1838, loaded with data named Neptune, was really Adams’s planet, from his years of Southern Hemisphere observa- which started an international incident. tions, he headed home to England. When he was not involved in the Adams The next several years were full of big ad- scandal, Herschel continued working on his ob- vancements in photography, and Herschel put servations, computations, and compilations, and himself right in the middle of it. A good friend in 1847, he published Results of Astronomical of his, William Henry Fox Talbot (1800–77), Observations Made during the Years 1834, 1835, who is credited as the inventor of this field, con- 1836, 1837, and 1838, at the Cape of Good Hope, sulted with Herschel many times, as the two dis- Being the Completion of a Telescopic Survey of the cussed the new inventions Talbot was making. Whole Surface of the Visible Heavens, Commenced Herschel is credited with discovering that hy- in 1825. This work resulted in his second Copley posulfite of soda could be used as a photographic Medal from the Royal Society. In 1847, he also fixative, and for devising the terms negative and improved a device called a calorimeter, used to positive for paper photos. Seeing the obvious ben- measure the heat from a chemical reaction, efits of the new realm of photography, Herschel which had been originally constructed in 1783 soon became a very vocal advocate for its use in by Antoine Lavoisier (1743–94) and PIERRE- astronomical observations. He wrote a paper in SIMON,MARQUIS DE LAPLACE. 1839, “On the Chemical Action of the Rays of In 1849 Herschel expanded his work into the Solar Spectrum on Preparations of Silver, the Outlines of Astronomy, originally written as 156 Herschel, Sir William an encyclopedia entry in an in-depth textbook, was involved in many organizations to help fur- and it was an instant success. The book had 12 ther the sciences. editions in England, was translated into many Craters on the Moon and on Mars are languages, and was used as a textbook around named for this extraordinary scientist, who died the world for decades to come. on May 11, 1871, in Kent, England, and was As strange as Herschel’s detour into law buried in Westminster Abbey. Herschel had 12 seemed in the beginning of his career, he made children. His son, Alexander, became a profes- perhaps an even more bizarre stray from his sci- sor of physics and carried on the Herschel tra- entific endeavors in 1850, when he decided to dition of working with the Astronomer Royal, take on the role of Master of the Mint. For the advocating with George Biddell Airy (1801–92) next 13 years, Herschel overworked himself in the use of photography in astronomy. this position, and turned to writing poetry, much of which was published in 1857; and some scientific work, published in 1861, on meteorology, ᨳ Herschel, Sir William (Friedrich geography, and telescopes. In 1863 he finally re- Wilhelm Herschel) tired from his duties at the mint. His biggest pub- (1738–1822) lication was still to come. German In 1864 Herschel published his General Astronomer Catalogue of Nebulae and Clusters, listing 5,097 star clusters and nebulae, of which 4,630 were Sir William Herschel is the epitome of an ama- discovered by Herschel and his father through- teur astronomer who turned a passion for his out their careers. This was revised in 1888 by L. hobby into his life’s work. Thanks to a book that E. Dreyer into the New General Catalogue (NGC) caught his interest at age 35, and the help of his with 7,840 nebulae and clusters. The NGC num- sister, Caroline, Herschel went from being a mu- bers are still used to identify nonstellar objects. sician and amateur astronomer to being the Herschel followed this work in 1866 with a gen- King’s Astronomer in just nine years. He also be- eral publication entitled Familiar Lectures on came the last person to discover a planet purely Scientific Subjects. on observation rather than on mathematical Herschel’s life was full of accomplishment, computation. fueled in part by the diversity of interests that Friedrich Wilhelm Herschel was born on kept his mind active, including astronomy, biol- November 15, 1738, in Hanover, Germany, to ogy, chemistry, education, language, mathemat- Anna Ilse Moritzen Herschel, the strict matri- ics, music, poetry, philanthropy, physics, and arch of her family, and Isaac Herschel, an oboist public service. As a respected scientist, he cor- who eventually became the bandleader of the responded with some of the most brilliant minds Hanoverian Foot Guard. In 1750, when of the time. Herschel was 12 years old, his sister Caroline was Nearly all of Herschel’s documents have sur- born, and in a little more than 20 years she vived, including a collection of 10,000 letters (of would begin to play a profound role in his suc- which 75 percent are from the world’s leading cess as an astronomer. scientific minds of the time), his astronomical The young Herschel was a dedicated musi- observations, diaries, books, laboratory notes, cian, and as a teenager joined the Hanoverian and a collection of his photographic work. He Guard to be in the band with his father. But mil- won multiple awards for his contributions to sci- itary bands are first and foremost military, and ence in both mathematics and astronomy, and when the Seven Years’ War broke out, Herschel Herschel, Sir William 157 and his father were called to duty in 1757 to and the size of the known universe. Astronomy fight at the battle of Hastenbeck. Explained upon Sir Isaac Newton’s Principles, and Fighting in a war took its toll on both fa- Made Easy to Those Who Have Not Studied ther and son. The elder Herschel did everything Mathematics, written by James Ferguson, put a he could to help his son get out of the war, and burning desire in Herschel to study the stars. But in 1759, Herschel left Germany for England, in order to study them, Herschel needed a tele- where he would spend the rest of his life. He scope, so he collected used parts and built one. It earned a living as a traveling musician, stopping was small. It was also inadequate. in Halifax in 1765 and working as an organist Encouraged, he enlisted the help of his sib- for a year, then settling in Bath, England, where lings to build a bigger telescope, and Herschel, he became the organist at the Octagon Chapel Caroline, and Alexander proceeded to turn their and eventually acquired a job as city public con- home into their own private telescope manu- certs director. facturing facility. Caroline became adept at Meanwhile, Isaac Herschel continued fight- grinding mirrors, while Alexander helped with ing, and when he finally returned home in 1760, the overall construction. The family became so he was in need of constant care. Caroline took good at their avocation that they started selling care of their father until 1767, when he passed their telescopes to other amateur astronomers away. and even to the Royal Observatory. Working successfully in Bath, Herschel be- By 1774 they had constructed a seven-foot came a music teacher, composer, and conductor. telescope, and Herschel started studying the By 1772 he was a well-respected member of his heavens. Meticulous and methodical, Herschel community. Back home in Germany, Herschel’s devised a plan to study a strip of sky at a time. sister Caroline, who had so diligently tended Standing on a ladder, peering into the telescope, their father, was now serving her overbearing he told his sister everything he saw, and she mother, taking care of the household chores, and recorded it all in great detail. For the next sev- studying to become a nanny. eral years, the brother-and-sister team observed Herschel needed help running his house- the night sky as often as they could, concerts and hold, so in 1772 he invited his 22-year-old sis- local weather permitting, and Caroline recorded ter to live with him in England. She jumped at by night and computed by day in addition to the chance, and moved to England to join managing the house. Herschel and one of their brothers, Alexander, This was an interesting time in the evolu- in Bath. Herschel was soon teaching his sister tion of astronomy—a time when the observa- music, and she began singing in concerts the two tions that had been made up to this point were would give throughout the week. being compiled into useable data for navigators But Herschel did more for Caroline than at sea. Certainly, Herschel’s work could eventu- teach her music. He soon introduced her to the ally be useful for navigators, but while that was kind of intellectual stimulation that she had the sole purpose of the work being done at the longed for as a child but was denied because their Royal Observatory, it was not the foremost mother did not believe that girls should be ed- thought on Herschel’s mind. He wanted to make ucated. To their mutual benefit, he taught his a systematic survey of the stars, and he set about sister algebra, geometry, trigonometry, and as- observing and documenting everything he saw, tronomy. with his sister’s diligent help. On May 10, 1773, Herschel purchased a book On the evening of March 13, 1781, that would forever change his life, his sister’s life, Herschel was peering though his seven-foot 158 Herschel, Sir William telescope, equipped with a 6.2-inch reflector, at But what’s in a name? It was the discovery the constellation Gemini, when he saw a disk- that counted. Saturn had been the farthest shaped light shining back at him. He observed known planet, at a distance of 886,200,000 the object as it moved slowly across the sky, and miles from the Sun. Uranus, a little less than was convinced that he had discovered his first half the size of Saturn, about four times as big comet. His sister wrote down the observations as the Earth, was 1,782,000,000 miles from the and performed the calculations as the object Sun. This discovery was worthy of some recog- continued to move in the night sky. nition, even if an amateur made it. Within a But the “comet” was beyond Saturn, and if few short months, on December 7, 1781, the it really were a comet, it would have been too Royal Society elected Herschel into its ranks as small to see. Herschel’s suspicions were not cor- a Fellow, and Herschel was appointed the rect. The Royal Observatory’s fifth Astronomer “King’s Astronomer,” and was given a lifetime Royal, Nevil Maskelyne, discovered that salary of £200 per year by King George. The fol- Herschel’s “comet” was, instead, a planet that lowing year, in May 1782, Herschel and his sis- was farther beyond Saturn than Saturn is from ter quit the music business forever, and in the Sun. And since the galaxy and the universe August they moved into a bigger house in the were considered to be the same at this point in town of Datchet, where they lived for nearly history, Herschel’s discovery doubled the known three years. size of the universe. Herschel commented, “It During their time in Datchet, Herschel fo- was this night its turn to be discovered.” cused his attention on new heavenly bodies. A Astronomers from around the world were friend named William Watson had given ready to pounce on the chance to name the new Herschel a copy of CHARLES MESSIER’s catalog of planet, and the English were afraid that the star clusters and nebulae as a congratulatory gift French would steal the opportunity if Herschel upon his election into the Royal Society. did not come up with something fast. So Herschel was now interested in observing these Herschel suggested the most politically correct “exotic objects,” as he called them. In 1782 he name he could think of: Georgium Sidas, the and Caroline began their work on surveying the Georgian Planet, to honor the reign of King sky for these nebulae, and as a gift he gave his George III. Unfortunately, King George was not sister a telescope of her own. For the next few as beloved outside of England, so the French years, the duo worked diligently on recording gave it their own name—Herschel. Other sug- and classifying their observations, being careful gested names included Minerva, for the Roman not to duplicate the work of Messier. goddess of wisdom, and Hypercronius, which In 1785 Herschel and Caroline moved means “above Saturn.” But the Germans, who again, this time to Windsor to be near the king. had nothing to do with the discovery, seemed to Herschel was working on his theories about the be very adept at naming things and JOHANN shape of our galaxy. The small telescopes he had ELERT BODE took the logical approach and used up to this time were adequate for the work named the planet Uranus, who in mythology was he had done, but his needs were now outgrow- the son of Gaia (the Earth), and the father of ing his technology. So the king offered Herschel Saturn. The various countries continued calling his patronage again, this time in the form of a the planet by the names they liked best until £2,000 grant to build a telescope that would be- 1850, when JOHN COUCH ADAMS, who discov- come the world’s largest—a 40-foot reflector. ered Neptune, proposed that it should have the In April 1786 the Herschel siblings moved official name of Uranus. for the last time together, into a home they Herschel, Sir William 159 called Observatory House in Slough. The move father in astronomical work. In 1864 SIR JOHN was a good one for both of them. Herschel FREDERICK WILLIAM HERSCHEL published The started the process of building his new impres- General Catalogue of Nebulae, a collection of sive telescope, and in August Caroline made her more than 5,000 nebulae, of which 4,630 were first discovery—a comet. She was the first discovered by John and his father. woman ever to make such a discovery. It was Over the years, Herschel continued his ob- dubbed “the first lady’s comet,” and she was servations of nebulae, star clusters, the Sun, and awarded her own salary of £50 per year from the binary stars. He found that the Sun was gaseous king. From this point on, the two were frequent in nature, observed sunspots, and discovered in- guests at the palace. frared light emanating from the Sun. He dis- Herschel’s next two big discoveries occurred covered nearly 1,000 binary stars, and proposed in 1787, when he found the first two satellites that these stars have a common center of grav- of his planet, Titania and Oberon. The next two, ity around which they rotate. His observations Ariel and Umbriel, were discovered in 1787 by of nebulae led him to believe that they were clus- another British astronomer, and these four ters of stars he called “island nebulae,” and he moons were eventually named by Herschel’s son. believed that these were “island universes,” The fifth moon, Miranda, was discovered in galaxies, outside the Milky Way. He was, in fact, 1948 by GERARD PETER KUIPER. To date, 22 the first person to accurately describe the Milky moons have been discovered in its orbit. Way Galaxy, a feat he accomplished using the The following year marked perhaps the statistics he had accumulated during his obser- biggest change of all for the brother and sister vations with Caroline. astronomers. Herschel married a young widow On January 12, 1820, Herschel attended a named Mary Pitt, and Caroline was forced to dinner at the Freemason’s Tavern in London, move out of their home at Mary’s insistence. where a group of 14 men talked about forming This was the first time that Caroline had ever a society with the simple goal of promoting as- lived on her own, and she was extremely upset. tronomy. On March 10 the Astronomical Eventually she reconciled with her sister-in-law Society of London, later the Royal Astronomical and regretted her anger. Caroline continued to Society, had its first official meeting, and work with her brother, and walked to his house Herschel became its first president. daily to record their observations. Herschel was known for his tremendous Three years and £4,000 after construction enthusiasm for astronomy and for his exacting, began, Herschel’s 40-foot telescope was com- methodical style of observation of the night plete. His first discoveries with this new master- sky. He was knighted in 1816 for his contri- piece were Mimas and Enceladus, the sixth and butions to the field of astronomy. On August seventh moons of Saturn. He was also now able 25, 1822, Herschel died in Slough, England, to make out some individual stars in some of the and was laid to rest at St. Laurence’s Church globular clusters he had observed with his older in Upton. His work was his life’s gift, and his equipment. contributions earned him the respect and ad- In 1792, at age 55, Herschel became a fa- miration of far more learned men than he. The ther. His son John was born at Observatory house Herschel shared with his sister in Bath, House, and grew up with the 40-foot telescope the site of the discovery of Herschel’s planet, as part of his daily life. The boy was influenced Uranus, was opened in 1981 as the William by the music and science around him, especially Herschel Museum. The remains of his 40-foot by his Aunt Caroline, and eventually joined his reflector telescope from Observation House are 160 Hertz, Heinrich Rudolf now on display at the Royal Observatory in Greenwich. In honor of his work, a crater on the Moon was named Herschel for this amateur astronomer, as was one for his sister and another for his son.

ᨳ Hertz, Heinrich Rudolf (1857–1894) German Physicist

In 1888 Heinrich Hertz produced and detected radio waves for the first time. He also demonstrated that this form of electromagnetic radiation, like light, propagates at the speed of light. His discoveries form the basis of both the global telecommunications industry (including communications satellites) and radio astronomy. The hertz (Hz) is the Système Internationale (SI) unit of frequency, named in his honor. Hertz was born on February 22, 1857, in Hamburg, Germany, into a prosperous and cul- In 1888 the German physicist Heinrich Rudolf Hertz tured family. Following a year of military service became the first person to produce and detect radio (1876–77), he entered the University of Munich waves. He also demonstrated that radio waves, like other forms of electromagnetic radiation, propagate at to study engineering. However, after just one the speed of light. His scientific discoveries laid the year, he found engineering not to his liking and foundation for communications satellites as part of the began to pursue a life of scientific investigation global telecommunications industry and for radio as a physicist in academia. Consequently, in astronomy. (Deutsches Museum, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection) 1878 he transferred to the University of Berlin and started studying physics, with the famous German scientist Herman von Helmholtz (1821–94), as his mentor. Hertz graduated to 1889, Hertz finally gained access to the equip- magna cum laude with his Ph.D. degree in ment he needed to perform the famous experi- physics in 1880. After graduation, he continued ments that demonstrated the existence of working at the University of Berlin as an assis- electromagnetic waves, and he verified Maxwell’s tant to Helmholtz for the next three years. equations. During this period, Hertz not only pro- He left Berlin in 1883 to work as a physicist duced electromagnetic (radio frequency) waves at the University of Kiel. There, following sug- in the laboratory but also measured their wave- gestions from his mentor, Hertz began investi- length and velocity. Of great importance to mod- gating the validity of the electromagnetic theory ern physics and the fields of telecommunications recently proposed by a Scottish physicist, James and radio astronomy, Hertz showed that his Clerk Maxwell (1831–79). As a professor of newly identified radio waves propagated at the physics at the Karlsruhe Polytechnic from 1885 speed of light, as predicted by Maxwell’s theory Hertzsprung, Ejnar 161 of electromagnetism. He also discovered that ra- identified the fundamental principles for wire- dio waves were simply another form of electro- less communications. magnetic radiation, similar to visible light and In 1889 Hertz accepted a professorship at infrared radiation, save for their longer wave- the University of Bonn. There, he used cathode- lengths and shorter frequencies. Hertz’s experi- ray tubes to investigate the physics of electric ments verified Maxwell’s electromagnetic theory discharges in rarefied gases, again just missing and set the stage for others, such as Guglielmo another important discovery—X-rays—accom- Marconi (1874–1937) to use the newly discov- plished by the German physicist Wilhelm ered radio waves to transform the world of com- Roentgen (1845–1923) at Würzburg in 1895. munications in the 20th century. Hertz was an excellent physicist whose pio- In 1887, while experimenting with ultravi- neering research with electromagnetic waves olet radiation, Hertz observed that incidental ul- gave physics a solid foundation upon which oth- traviolet radiation was releasing electrons from ers could build. His major publications included the surface of a metal. Unfortunately, he did not Electric Waves (1890) and Principles of Mechanics recognize the significance of this phenomenon, (1894). He suffered from lingering ill health due nor did he pursue further investigation of the to blood poisoning and died as a young man, in photoelectric effect. In 1905 ALBERT EINSTEIN his late 30s on January 1, 1894, in Bonn. In his wrote a famous paper describing this effect, link- honor, the international scientific community ing it to MAX KARL PLANCK’s idea of photons as named the basic unit of frequency the hertz quantum packets of electromagnetic energy. (symbol Hz). One hertz corresponds to a fre- Einstein earned the 1921 Nobel Prize in physics quency of one cycle per second. for his work on the photoelectric effect. Hertz performed his most famous experiment in 1888, with an electric circuit in which ᨳ Hertzsprung, Ejnar he oscillated the flow of current between two (1873–1967) metal balls separated by an air gap. He observed Danish that each time the electric potential reached a Astronomer peak in one direction or the other, a spark would jump across the gap. Hertz applied Maxwell’s At the start of the 20th century, Ejnar Hertzs- electromagnetic theory to the situation and prung made one of the most important contribu- determined that the oscillating spark should tions to modern astronomy, when he showed in generate a very long electromagnetic wave that 1905 how the luminosity of a star is related to its traveled at the speed of light. He also used a sim- color, or spectrum. His work, independent of ple loop of wire, with a small air gap at one end, HENRY NORRIS RUSSELL, contributed to one of the to detect the presence of electromagnetic waves great observational syntheses in astrophysics— produced by his oscillating spark circuit. With the famous Hertzsprung-Russell (HR) diagram, an this pioneering experiment, Hertz produced essential tool for anyone seeking to understand and detected “Hertzian waves”—later called stellar evolution. radiotelegraphy waves by Marconi and then, The Danish astronomer Hertzsprung was simply, radio waves. By establishing that born on October 8, 1873, in Frederiksberg, near Hertzian waves were electromagnetic in nature, Copenhagen. His father, Severin Hertzsprung, the young German physicist extended human had graduated with a master of science degree knowledge about the electromagnetic spectrum, in astronomy, but for financial reasons worked validated Maxwell’s electromagnetic theory, and as a civil servant in the Department of Finances 162 Hertzsprung, Ejnar Denmark in 1902, Hertzsprung revived his lifelong interest in astronomy by becoming a private astronomer at the Urania and University Observatories in Copenhagen. During this period, he taught himself a great deal about astronomy and used the telescopes available at the two small observatories to make detailed photographic observations of the light from the stars. Hertzsprung’s earliest and perhaps most important contribution to astronomy started with the publication of two papers, both entitled “Zur Strahlung der Sterne” (On the radiation of the stars) in a relatively obscure German scientific American astronomer Harlow Shapley (left) appears in this photograph talking with the Danish astronomer photography journal. These papers appeared in Ejnar Hertzsprung (right), during the 1958 Moscow 1905 and 1907, respectively, and their existence meeting of the International Astronomical Union. was unknown to the American astronomer Henry Working independently of the American astronomer Norris Russell, who would soon publish similar Henry Norris Russell, Hertzsprung developed the famous Hertzsprung-Russell diagram—a useful graph observations in 1913. Publication of these two that depicts the stars arranged according to their seminal papers marks the beginning of the inde- luminosity and spectral classification. (D. Y. Martynov, pendent development of the Hertzsprung-Russell courtesy AIP Emilio Segrè Visual Archives, Shapley (HR) diagram—the famous tool in modern as- Collection) tronomy and astrophysics that graphically por- trays the evolutionary processes of visible stars. Its within the Danish government. Consequently, creation is equally credited to both astronomers. he encouraged his son to enjoy astronomy as an Hertzsprung’s two papers presented his insightful amateur, believing the field presented very few interpretation of the stellar photography data that opportunities for financial security. Hertzsprung revealed the existence of a relationship between responded to his father’s well-intended advice the color of a star and its respective brightness. and studied chemical engineering at Copenhagen He stated that his photographic data also sug- Polytechnic Institute. Upon graduating in 1898, gested the existence of both giant and dwarf stars. he accepted employment as a chemical engineer Hertzsprung then developed these and many in St. Petersburg, Russia, and remained there for other new ideas over the course of his long career two years. He then journeyed to the University as a professional astronomer. of Leipzig, where he studied photochemistry Between 1905 and 1913 Hertzsprung and for several months under the German physi- Russell independently observed and reported cal chemist Wilhelm Ostwald (1853–1932). that any large sample of stars, when analyzed sta- The thorough understanding of photochemical tistically using a two-dimensional plot of magni- processes he acquired from Ostwald allowed tude (or luminosity) versus spectral type (color Hertzsprung to make his most important contri- or temperature), form well-defined groups or bution to modern astronomy. bands. Most stars in the sample will lie along an He became one of the great observational extensive central band called the main sequence, astronomers of the 20th century, despite the fact which extends from the upper left corner to lower that he never received any formal academic right corner of the HR diagram. Giant and training in astronomy. When he returned to supergiant stars appear in the upper right portion Hertzsprung, Ejnar 163 of the HR diagram, while the white dwarf stars Observatory. Later that year Schwarzschild be- populate the lower left region. Modern as- came the director of the Astrophysical Obser- tronomers use several convenient forms of the vatory in Potsdam, Germany, and he offered HR diagram to support their visual observations Hertzsprung an appointment as a senior as- and to describe where a particular style fits in the tronomer. Hertzsprung proved to be a patient, overall process of stellar evolution. For example, exacting observer who was always willing to do our parent star, the Sun, is a representative yel- much of the tedious work himself. While at the low dwarf (main sequence) star. Previously, as- Potsdam Observatory, he investigated the tronomers used the term dwarf star to describe Cepheid stars in the Small Magellanic Cloud. any star lying on the main sequence of the HR He used the periodicity relationship for Cepheid diagram. Today, the term main sequence star is pre- variables announced in 1912 by HENRIETTA ferred to avoid possible confusion with white SWAN LEAVITT to help him calculate intergalac- dwarf stars—the extremely dense final evolu- tic distances. Although the currently estimated tionary phase of most low-mass stars. distance (195,000 light-years) to the Small While Hertzsprung was still in Copenhagen, Magellanic Cloud is about six times larger than he also started making detailed photographic in- the value of 32,600 light-years that Hertzsprung vestigations of star clusters. In 1906 he appar- estimated in 1913, his work still had great im- ently constructed his first color versus magnitude portance. It introduced innovative methods for precursor diagrams based on photographic obser- measuring extremely large distances and pre- vations of the Pleiades and subsequently pub- sented an astronomical distance that was signif- lished such data along with companion data for icantly larger than any previously known dis- the Hyades in 1911. This activity represents an tance in the universe. This “enlarged view” of important milestone in the evolution of the the universe encouraged other astronomers, such Hertzsprung-Russell diagram. The Pleidaes is a as HEBER DOUST CURTIS and HARLOW SHAPLEY, prominent open star cluster in the constellation to vigorously debate its true extent. Taurus about 410 light-years distant. The Hyades Hertzsprung left the Potsdam Observatory in is an open cluster of about 200 stars in the con- 1919 and accepted an appointment as associate stellation Taurus, some 150 light-years away. director of the Leiden Observatory in the Astronomers use both clusters as astronomical Netherlands. He became the director of the ob- yardsticks, comparing the brightness of their stars servatory in 1935 and served in that position with the brightness of stars in other clusters. until he retired in 1944. Upon retirement, he re- Hertzsprung would spend the next two decades turned home to Denmark. He remained active making detailed observations of the Pleidaes—a in astronomy, primarily by examining numerous favorite astronomical object used frequently by photographs of binary stars and extracting pre- other astronomers to compare the performance cise position data. The international astronom- of their telescopes in the Carte du Ciel as- ical community recognized his contributions to trophotography program that began in 1887. astronomy through several prestigious awards. In 1909 the German astronomer KARL He received the Gold Medal of the Royal SCHWARZSCHILD invited Hertzsprung to visit Astronomical Society in 1929 and the Bruce him in Göttingen, Germany. Schwarzchild Gold Medal from the Astrophysical Society quickly recognized that Hertzsprung, despite his of the Pacific in 1937. After a full life dedi- lack of formal training in astronomy, possessed cated to progress in observational astronomy, exceptional talents in the field and gave Hertzsprung, the chemical engineer turned as- Hertzsprung a staff position at the Göttingen tronomer, died at the age of 94 on October 21, 164 Hess, Victor Francis 1967, in Roskilde, Denmark. The Hertzsprung- Russell diagram permanently honors his important role in understanding the life cycle of stars.

ᨳ Hess, Victor Francis (1883–1964) Austrian/American Physicist

As a result of ionizing radiation measurements made during perilous high-altitude balloon flights between 1911 and 1912, Victor Hess discovered the existence of cosmic rays that continually bombard Earth from space. Scientists used his discovery to turn Earth’s atmosphere into a giant natural laboratory—a clever research approach that opened the door to many new discoveries in high-energy nuclear physics. Hess was born in Waldstein Castle, near Peg- gau, in Steiermark, Austria, on June 24, 1883. His father, Vinzens Hess, was a royal forester in As a result of his pioneering ionizing radiation detection the service of Prince Öttinger-Wallerstein. Hess measurements made during perilous high-altitude completed his entire education in Graz, Aus- balloon flights between 1911 and 1912, the Austrian- tria—attending secondary school (the Gymna- American physicist Victor Hess discovered the existence sium) from 1893 to 1901 and then the University of Höhenstrahlung (radiation from above). These cosmic rays, as they were later called, are very energetic atomic of Graz, as an undergraduate from 1901 to 1905, particles that continually bombard Earth from space. then as a graduate student in physics, from which Cosmic rays proved extremely important in nuclear he received his Ph.D. degree in 1910. For approx- physics research in the 1920s through the 1950s. They imately a decade after earning his doctorate, Hess also became a special “window to the universe” that allowed scientists to examine direct evidence from investigated various aspects of radioactivity violent astrophysical phenomenon. For his important while working as a staff member at the Institute discovery, Hess shared the 1936 Nobel Prize in physics. of Radium Research of the Viennese Academy of (AIP Emilio Segrè Visual Archives, W. F. Meggers Gallery Sciences. of Nobel Laureates) In 1909 and 1910 scientists had used elec- troscopes (an early nuclear radiation detection from Earth’s surface and the sources of natural ra- instrument) to compare the level of ionizing radioactivity within the planet’s crust, the scien- diation in high places, such as the top of the Eiffel tists expected the observed radiation levels to Tower in Paris, France, or during balloon ascents simply decrease as a function of altitude. They into the atmosphere. These early studies gave a had not anticipated the existence of energetic vague and puzzling, indication that the level of nuclear particles arriving from outer space. ionizing radiation at higher altitudes was actually Hess attacked this mystery by first making greater than the level detected on Earth’s surface. considerable improvements in radiation detec- As they operated their radiation detectors farther tion instrumentation, which he then took on a Hewish, Antony 165 number of daytime and nocturnal balloon as- its newly established Institute of Radiology. As cents to heights up to 5.3 kilometers in 1911 and part of his activities at Innsbruck, he also 1912. The results were similar, as they were in founded a research station on Mount Hafelekar 1912 when he made a set of balloon flight meas- to observe and study cosmic rays. In 1932 the urements during a total solar eclipse. His care- Carl Zeiss Institute in Jena awarded him the ful, systematic measurements revealed that there Abbe Memorial Prize and the Abbe Medal. That was a decrease in ionization up to about an al- same year, Hess became a corresponding mem- titude of one kilometer, but beyond that height ber of the Academy of Sciences in Vienna. the level of ionizing radiation increased consid- But his greatest acknowledgment for his pi- erably, so that at an altitude of five kilometers oneering research came in 1936 when Hess it had twice the intensity than at sea level. Hess shared that year’s Nobel Prize in physics for his completed analysis of his measurements in 1913 discovery of cosmic rays. His fascinating discov- and published his results in the Proceedings of the ery established a major branch of high-energy as- Viennese Academy of Sciences. Carefully ex- trophysics and helped change our understanding amining his measurements, he concluded that of the universe and some of its most violent there was an extremely penetrating radiation, an high-energy phenomena. “ultra radiation,” entering Earth’s atmosphere In 1938 the Nazis came to power in Austria, from outer space. Hess had discovered “cosmic and Hess, a Roman Catholic with a Jewish wife, rays”—a term coined in 1925 by the American was immediately dismissed from his university physicist Robert Millikan (1868–1953). position. The couple fled to the United States Cosmic rays are very energetic nuclear par- by way of Switzerland and later that year, Hess ticles that carry information to Earth from all accepted a position at Fordham University in the over the Galaxy. When a primary cosmic ray par- Bronx, New York, as a professor of physics. He ticle hits the nucleus of an atmospheric atom, became an American citizen in 1944 and retired the result is a cosmic ray “shower” of secondary from Fordham University in 1956. particles that gives nuclear scientists a detailed Victor Hess wrote more than 60 technical look at the consequences of energetic nuclear re- papers and published several books, including actions. The Electrical Conductivity of the Atmosphere and In 1919 Hess received the Lieben Prize from Its Causes (1928) and The Ionization Balance of the Viennese Academy of Sciences for his dis- the Atmosphere (1933). He died on December 17, covery. The following year he received an ap- 1964, in Mount Vernon, New York. pointment as professor of experimental physics at the University of Graz. From 1921 to 1923 he took a brief leave of absence from his position ᨳ Hewish, Antony at the university to work in the United States (1924– ) as the director of the research laboratory of the British U.S. Radium Company in New Jersey and then Radio Astronomer as a consultant to the Bureau of Mines of the U.S. Department of the Interior in Washington, The reception of what were originally thought D.C. to be signals from an extraterrestrial civilization In 1923 Hess returned to Austria and re- led Antony Hewish into a collaborative effort sumed his position as physics professor at the with SIR MARTIN RYLE resulting in the develop- University of Graz. He moved to the University ment of radio-wave-based astrophysics. Hewish’s of Innsbruck in 1931 and became the director of efforts involved the discovery of the pulsar, for 166 Hewish, Antony

British radio astronomers Antony Hewish (left) and Sir Martin Ryle (right) discuss some of their Nobel Prize–winning extraterrestrial radio wave data. They shared the Nobel Prize in physics in 1974 for their accomplishments in radio astronomy. Hewish received the award primarily for his work identifying the first pulsar—a feat that started during an August 1967 survey of galactic radio waves and the detection of a suspicious “alien” radio signal by his graduate student Susan Joceyln Bell Burnell. (AIP Emilio Segrè Visual Archives, Physics Today Collection) which he shared the 1974 Nobel Prize in physics committee inexplicably overlooked Bell’s role in with Ryle. The fascinating story starts in August this major astronomical discovery. 1967, when his graduate student SUSAN JOCELYN Hewish was born on May 11, 1924, in BELL BURNELL detected strangely repetitive Fowey, Cornwall, United Kingdom. He received “alien” radio wave signals from a certain region education at King’s College, Taunton, and then of space during a survey of galactic radio waves. matriculated in 1942 at the University of Subsequent analysis indicated the source as a Cambridge. From 1943 to 1946 he performed pulsar, the first every discovered. Through no war service for Great Britain at the Royal fault of Hewish, the 1974 Nobel Prize awards Aircraft Establishment in Farnborough and at Hewish, Antony 167 the Telecommunications Research Establish- wave interferometers to exploit this idea. With ment in Malvern, Great Britain. During this this new equipment, Hewish was able to perform period, he participated in the development of pioneering measurements that revealed the airborne radar-countermeasure devices and height and physical extent of plasma clouds worked with Ryle. within Earth’s ionosphere. In 1964 Hewish’s He returned to Cambridge University in radio astronomy group at Cambridge University 1946 and completed his undergraduate degree in discovered interplanetary scintillation—the physics at Gonville and Caius College two years twinkling or variation in brightness of a cosmic later. Upon graduation, he joined Ryle’s research radio source due to radio wave scattering by ir- team at the Cavendish Laboratory. In 1952 regularities in the ionized gases within the solar Hewish completed his doctor of philosophy de- wind. Hewish used this discovery to make the gree in physics at Cambridge University and first ground-based measurements of the solar then lectured at Gonville and Caius College wind, and soon space scientists in other coun- until 1961, when he became the director of stud- tries adopted his technique. ies in physics at Churchill College. For the next Between 1965 and 1967 he constructed a three decades, Hewish continued his affiliation large radio telescope at Cambridge with the in- with Cambridge University, progressing through tention of using the facility to survey about positions of increasing academic importance. 1,000 radio galaxies using interplanetary scin- From 1961–69 he served as university lecturer, tillation to provide for scintillating radio from 1969–71 he became a reader, and then from sources. By a stroke of good luck, this large ra- 1971 until his retirement in 1989 he was a pro- dio telescope, consisting of a regular array of fessor of radio astronomy. When Ryle became ill 2,048 dipoles, operated at 3.7 meters wave- in 1977, Hewish assumed leadership of the ra- length—precisely the wavelength needed to dio astronomy group at Cambridge and then di- make astronomical history. On August 6, 1967, rected the Mullard Radio Observatory from one of Hewish’s graduate students, Jocelyn Bell, 1982–88. Upon retirement, Hewish assumed the detected an interesting, rapidly fluctuating ra- title of emeritus professor of radio astronomy. As dio signal that had a periodicity of approxi- of 2004 he remained actively involved in con- mately 1.337 seconds. Hewish initially thought temporary astrophysical research from his office the unusual signal might be a flare star. But sub- in the Cavendish Laboratory. sequent, detailed analysis of the signal indicated His experiences with electronics, antennas, it was a regular radio signal from beyond the so- and radar during World War II influenced lar system. Hewish to conduct research in radio astronomy Because of the regularity of the radio wave following the war. His initial area of interest ad- signal, it was suggested that this could be a mes- dressed the propagation of radio waves through sage from an intelligent extraterrestrial civiliza- inhomogeneous media. Specifically, he recog- tion. So while Hewish puzzled over the nature nized that the scintillation twinkling of signals of this very strange radio signal, both teacher from recently discovered cosmic radio sources and student decided to call the signal LGM— (that is, radio stars) could be used to investigate which stood for “Little Green Man.” As they conditions within Earth’s ionosphere. Earth’s continued to keep track of this signal, Bell de- ionosphere contains various layers of free elec- tected several more pulsed sources. In February trons and ions and extends from approximately 1968 they resolved the mystery and announced 60 kilometers upward to more than 1,000 kilo- that the strange pulsed radio signal belonged to meters altitude. He developed and set up radio the first pulsar ever detected. 168 Hohmann, Walter The pulsar is a rapidly spinning neutron star ᨳ Hohmann, Walter that had been theoretically postulated in 1934 (1880–1945) by WILHELM HEINRICH WALTER BAADE and German FRITZ ZWICKY. By 1974, when Hewish received Engineer, Orbital Mechanics Expert the Nobel Prize in physics for the discovery of the first pulsar (now formerly identified as PSR In his seminal 1925 work, The Attainability of 1919ϩ21 rather than LGM), astronomers had Celestial Bodies (Die Erreichbarkeit der Himme- detected more than 130. lskörper), Walter Hohmann described the math- Astrophysicists now believe that a pulsar is ematical principles that govern space vehicle a very rapidly rotating neutron star, possibly motion, including the most efficient, minimum- formed during a supernova explosion. More than energy orbit transfer path between two orbits in 500 radio pulsars are currently known to exist, the same geometric plane. This widely used orbit with periods ranging from 1.56 millisecond to transfer technique is now called the Hohmann 4 seconds. Jocelyn Bell completed her doctoral transfer orbit in his honor. degree at Cambridge in 1968 (the same year she Hohmann was born to Rudolph and Emma married Martin Burnell) and included the dis- Hohmann on March 18, 1880, in Hardheim, a covery of the pulsar as an appendix in her dis- small German town about 40 kilometers south- sertation. Although she did not get any credit west of Würzburg. His father served as a physi- from the 1974 Nobel Prize committee for her cian and surgeon in the local hospital. The role in the discovery of the pulsar, Hewish pub- Hohmann family moved to Port Elizabeth in licly acknowledged his student’s “care, diligence, South Africa in 1891 and remained there for and persistence” in the data collection that led about six years before returning to Germany. to this discovery, during his Nobel laureate lec- When his family returned to Germany, he en- ture in 1974. rolled in high school at Würzburg. Between 1900 In addition to the 1974 Nobel Prize in and 1904 he studied at the Technical University physics, Hewish received other awards and in Munich and graduated from there as a certi- honors to commemorate his contributions to fied civil engineer with a Diplom-Bauingenieur radio astronomy and astrophysics. His awards degree. include the Eddington Medal of the Royal Upon graduation and for several years there- Astronomical Society (1969), the Franklin after just prior to the start of World War I, Institute’s Michelson Medal (1973), and the Hohmann worked as a civil engineer for various Hughes Medal of the British Royal Society in companies in Austria and Germany. Then, in 1976. Hewish became a fellow of the British 1912, he became the combined equivalent of an Royal Society in 1968, a foreign honorary urban planner and city engineer for the city of member of the American Academy of Arts and Essen, Germany. It was also in 1912 that Sciences in 1977, a foreign Fellow of the Indian Hohmann developed his lifelong interest in National Science Academy in 1982, and an as- space flight and the motion of spaceships on in- sociate member of the Belgian Royal Academy terplanetary trajectories. This fascination with in 1989. As an emeritus professor of radio as- astronautics occurred quite by accident when tronomy at Cambridge University, he still en- the young engineer read an astronomy book. As joys making contributions to astrophysics and the clouds of war descended upon Europe, he du- giving inspiring lectures to the general public tifully undertook a wartime service position in that share the great excitement of scientific dis- 1915 and performed noncombat activities for ap- covery. proximately eight months. Hohmann, Walter 169 He married Luise Juenemann in 1915 and the planets. This useful principle of orbital mechan- couple had two sons, Rudolf (born in 1916) and ics is now called the Hohmann transfer orbit (or Ernst (born in 1918). In 1916, Hohmann sub- sometimes the Hohmann transfer ellipse) in his mitted his dissertation on concrete structures to honor. The technique is not just restricted to the Technical University of Aachen. However, traveling between the planets. It is also used to because of wartime conditions, his work was not efficiently raise (or lower) the altitude of a space- formally accepted and approved until 1919, a year craft in a circular orbit around a primary celes- after World War I ended. Hohmann could now tial body, like planet Earth. A simple description use the more illustrious academic title of “Dr.-Ing. of Hohmann’s widely used minimum energy or- Walter Hohmann”—that is, “Walter Hohmann, bital transfer technique follows below. Doctor of Engineering”—in his professional ac- Consider a spacecraft in a relatively low tivities. altitude, circular orbit around Earth or another After World War I Hohmann sought a pro- celestial body. The Hohmann transfer orbit fessorship in Karlsruhe, but did not succeed. So technique raises the spacecraft to a higher alti- he remained affiliated with Essen as a profes- tude orbit in the same orbital plane with a min- sional civil engineer for the remainder of his imum expenditure of energy and propellant. life. He became a distinguished member of Hohmann’s technique requires two impulsive Verein deutscher Ingenieure, the society of high-thrust burns, or firings, of the spacecraft’s German engineers. The analytical judgments onboard propulsion system. The first burn and mathematical skills he used to discharge his changes the original circular orbit to an ellipti- professional duties also served his work in as- cal one whose perigee is tangent with the lower- tronautics. altitude circular orbit and whose apogee is tan- Hohmann’s personal interest in space flight gent with the higher-altitude circular orbit. was reinforced by the great public interest in After the spacecraft coasts for half of the ellip- science fiction, rocketry, and space travel that tical transfer orbit (that is, half of the Hohmann permeated the Weimar Republic. Some of this transfer orbit) it reaches a position that is tan- enthusiasm can be attributed to HERMANN JULIUS gent with the destination higher-altitude circu- OBERTH, who published an inspirational book, lar orbit. The spacecraft’s propulsion system then The Rocket into Interplanetary Space (Die Rakate performs the second high-thrust firing. When zu den Planetenräumen) in 1923. Just after just the right amount of thrust is applied, this Oberth’s book appeared, Hohmann channeled second firing circularizes the spacecraft’s orbit at his own enthusiasm for astronautics into another the desired new altitude. Hohmann’s technique important book. Using his professional mathe- can be used to lower the altitude of a satellite matical and engineering skills, he related the fun- from one circular orbit to another circular orbit damental principles of orbital mechanics to space of less altitude. The main disadvantage with travel in the classic book Die Erreichbarkeit der Hohmann’s minimum energy orbit transfer ma- Himmelskörper (The Attainability of Celestial neuver is that it takes a great deal of time. Bodies), which was published in 1925. Of par- Throughout the late 1920s Hohmann ex- ticular importance to modern space technology amined the orbital mechanics of interplanetary is Hohmann’s careful enumeration of the most space flight. He actively discussed minimum pro- efficient orbit transfer path between two copla- pellant expenditure, spacecraft design, crew nar circular orbits. Hohmann demonstrated that safety, and maneuver analysis with fellow space an interplanetary trajectory of minimum energy travel enthusiasts in the German Society for is an ellipse that is tangent to the orbits of both Space Travel (Verein für Raumschiffahrt, or VFR). 170 Hubble, Edwin Powell Hohmann was a well-respected professional engineer in service to the city of Essen, so his enthusiastic participation in the VFR and its space travel advocacy served as an important endorse- ment of the society’s interplanetary flight concepts. His relationship with the VFR was a mutually beneficial one. Hohmann found a rich fertile environment for his own innovative astronautics concepts within the VFR because society membership included such space travel pioneers as Hermann Oberth, WERNHER MAGNUS VON BRAUN, and Willy Ley (1906–69)—people who quickly recognized the importance of Hohmann’s work. However, his enthusiasm faded when Adolf The famous American astronomer Edwin Hubble Hitler (1889–1945) and the Nazi Party seized examines the interesting features of a spiral galaxy. power in 1933. From that point on Hohmann After carefully investigating many galaxies in the 1920s, Hubble announced that the universe was began to withdraw from any further German expanding—a premise that now forms the basis for rocket or space activity. He did not join many all modern observational cosmology. (Hale of his former VFR colleagues as they began to Observatories, courtesy AIP Emilio Segrè Visual develop military rockets for the German army, Archives) and he did not become a member of Braun’s rocket research team at Peenemünde. Despite Hohmann’s desire not to support the military or Hubble who determined that other galaxies ex- political objectives of Nazi Germany, the painful ist outside the Milky Way, and that the universe consequences of World War II nevertheless ad- itself, in fact, was expanding. versely affected him and his family. During the Hubble was born on November 20, 1889, in war, he lost his son Ernst, a soldier. On March Marshfield, Missouri, the son of Virginia Lee 11, 1945, exploding Allied bombs claimed James Hubble of Virginia City, Nevada, and in- Hohmann’s life just a week before his 65th birth- surance broker John Powell Hubble of Missouri. day and less than two months before Germany In 1898 his family moved to Chicago, where surrendered. Today, the name of the Hohmann Hubble excelled at sports at Wheaton High transfer orbit commemorates his pioneering School, setting the state record for the high work in orbital mechanics. jump. At the University of Chicago he lettered in track, boxing, and basketball while working at the school’s Yerkes Observatory in Wisconsin. ᨳ Hubble, Edwin Powell During this time he worked as a laboratory as- (1889–1953) sistant to the renowned Robert Millikan American (1868–1953). He earned his B.S. degree in Astronomer, Physicist, Cosmologist physics in 1910, then won a Rhodes scholarship and moved to England to read Roman and Edwin Powell Hubble is generally credited with English law at Queens College, Oxford. creating the greatest change in the perception When he returned to America in 1913, of the universe since GALILEO GALILEI. It was Hubble passed the bar exam and practiced law Hubble, Edwin Powell 171 in Louisville, Kentucky, for a year. His heart was train. It was this groundbreaking first evidence not in it, however, and in 1914 he returned to of the big bang theory that caused ALBERT the University of Chicago to study astronomy, EINSTEIN, who had revised his original calcula- earning a Ph.D. in 1917. Just before getting his tions of an expanding universe because they degree, he was invited by GEORGE ELLERY HALE were too “far-fetched,” to revise his theory again to join the staff at the famous Mount Wilson and make the statement that it was “the great- Observatory, in Pasadena, California, home of est blunder of my life.” the world’s largest telescope at 100 inches. Soon, The redshift discovery propelled Hubble to the United States entered World War I, and the highest ranks of worldwide astronomers and Hubble’s patriotism came to the fore. After earned him unexpected celebrity. He became cramming for his doctoral degree and taking the close friends with several prominent movie stars oral exams the next morning, he enlisted in the and scientists, and was called by Time magazine U.S. Army. He was commissioned a captain in the “toast of Hollywood.” In 1924 Hubble had the 343rd Infantry, 86th Division, stationed in married Grace Burke, and the couple traveled France, and soon after was promoted to major. the world and were honored guests at lavish After cessation of hostilities, Hubble was mus- Hollywod parties during the 1930s and 1940s. tered out of the service in San Francisco and im- When World War II broke out, Hubble wanted mediately headed south to Pasadena, where he to enlist again but became convinced that his presented himself in his major’s uniform and scientific knowledge would do the country more took the job offered by Hale. good in research on the home front. He ulti- At the time, the accepted theory was that mately was awarded a Medal of Merit for his bal- the Milky Way was the boundary of the known listics work at the Aberdeen Proving Ground’s universe and that the fuzzy spots of light in the ultrasonic wind tunnel testing grounds in New night sky were simply islands of star clusters Mexico. within that boundary. However, Hubble used the After the war, Hubble was instrumental in Mount Wilson telescope to measure the distance building the 200-inch Hale telescope at Mount to the Andromeda Galaxy and determined that Palomar, California, and was given the high it was 100,000 times farther away from the near- honor of being the first person to use it. He con- est star than was generally thought, and there- tinued his research at Mount Palomar until his fore had to be its own galaxy. Hubble went on death in Pasadena of a cerebral thrombosis on to measure and classify many galaxies, and September 28, 1953. proved once and for all that the Milky Way is In his distinguished career as one of the 20th only one of millions of galaxies in the cosmos. century’s greatest astronomers, Hubble invented In what was to become a quantum leap in the science of cosmology and completely changed knowledge of the new field of astrophysics, our vision of the universe. His verification of the Hubble then virtually re-created our image of Big Bang theory has caused scientists and the- the universe by discovering the “redshift” and ologians alike to debate the tremendous size of announcing to the world in 1929 that the uni- the cosmos and to theorize about what it was verse was expanding as if it were a gigantic bal- that “banged” in the first place. loon. The redshift was determined to be a Such was Hubble’s fame and impact on as- change in light toward the red end of the spec- tronomy and cosmology that his name is at- trum as galaxies moved away from our own, tached to several parameters and formulae such much like the Doppler effect, which changes the as Hubble’s Law, the Hubble Sequence, Hubble’s tone of a ringing bell as it is passed in a car or Zone of Avoidance, the Hubble Galaxy type, the 172 Huggins, Sir William Hubble Luminosity Law, the Hubble Red-Shift his father became seriously ill. For more than a Distance Relation, the Hubble Radius, as well as decade, Huggins conducted business by day and the Hubble crater on the Moon, and the Hubble astronomy at night. He enjoyed both astronomy Space Telescope. and microscopy, since both of these disciplines gave him an opportunity to pursue original investigations. ᨳ Huggins, Sir William When he was 30, Huggins sold the family (1824–1910) business and dedicated the rest of his life to as- British tronomy. To support this decision, he moved to Astronomer, Spectroscopist an open region called Upper Tulse Hill, south of London, in 1856 and constructed a large private Sir William Huggins, a skilled amateur astro- observatory adjacent to his new house. In 1858 nomer and spectroscopist, helped to revolution- he added a high-quality 8-inch refractor tele- ize observational astronomy in the 19th century. scope, manufactured by the world-famous Using a private astronomical observatory that he American optician ALVAN GRAHAM CLARK. built just outside London, he performed pio- In January 1862 Huggins began a productive neering spectral measurements of the stars and collaboration with W. Allen Miller, a professor then compared the observed stellar spectra to of chemistry at King’s College in London. chemical spectra generated in his laboratory on Huggins wanted to apply to the Kirchhoff- Earth. In 1868 Huggins profoundly influenced Bunsen solar spectroscopy experiment to light the future direction of cosmology when he at- from the distant stars, but he recognized that this tempted to measure a star’s radial velocity by us- was a challenging effort and that Miller’s expe- ing the Doppler shift in its spectrum. Queen rience in chemical spectroscopy would prove in- Victoria knighted him, and he copublished a valuable. However, Miller himself was initially major work on stellar spectra in 1899 with doubtful that Huggins would be successful in de- his talented young wife, Lady Margaret Murray veloping stellar spectroscopy. For one thing, the Huggins. amount of starlight collected by telescope and Huggins was born in London, England, on available for spectral analysis would be only a February 7, 1824. His father was a prosperous very tiny fraction (on the order of millionths to merchant, so he provided his son not only a high billionths) of the amount of sunlight available quality private education but also an important to Kirchhoff and Bunsen when they solved the degree of financial independence. Under such mystery of the Fraunhofer lines. fortunate circumstances, Huggins became one of Despite Miller’s initial misgivings, one of the Great Britain’s most successful and competent great milestones in astronomical spectroscopy private (amateur) astronomers. Throughout his took place in 1864 when Huggins announced lifetime, he was able to contribute productively that the distant stars were composed of the same to astronomy without having a formal attach- chemical elements as the Sun. With Miller as a ment to either a university or an established coauthor, Huggins published a piece entitled observatory. Huggins received his earliest edu- “On the Lines of Some Fixed Stars,” in the cation in the City of London School, but later Philosophical Transactions of the Royal Society. learned mathematics, the physical sciences, and This paper included diagrams of the spectra of several languages at home from private teachers. stars, such as Sirius, Betelgeuse, and Vega. In one At 18 years of age, he passed up a formal college brilliant stroke, spectroscopy became the bridge education to take over the family business when linking terrestrial chemistry to the chemistry of Huggins, Sir William 173 the “unreachable” stars. Unknown to Huggins, While solving one nebula mystery, Huggins the Italian astronomer PIETRO ANGELO SECCHI created another that would remain unresolved for in Rome and others were beginning to conduct about 60 years. In 1866 he observed the spectra similarly important efforts in astronomical spec- of certain nebulas and discovered previously troscopy. This particular effort earned Huggins unidentified bright emission lines that he decided and Miller the 1867 Gold Medal from the Royal to attribute to a new element that he called “neb- Astronomical Society. ulium.” It was not until 1927 that the American Prior to publishing this work, Huggins also astrophysicist Ira Sprague Bowen (1898–1973) attempted to obtain photographs of the spectra of properly explained this puzzling phenomenon. Sirius and Capella in February 1863, but his ef- The bright emission lines did not belong to any forts were greatly limited by contemporary pho- new element; rather, Bowen’s detailed investiga- tographic technology. About a decade later, new tion revealed that the mysterious green lines were photographic materials became available and actually special (forbidden) transitions of the ion- greatly improved the amateur astronomer’s abil- ized gases oxygen and nitrogen. In 1866 the Royal ity to make useful photographic records of stellar Society presented Huggins with its highest award, spectra. the Royal Medal, for his research involving as- Huggins orchestrated another great moment tronomical spectroscopy. in observational astronomy in August 1864 by During the 1860s Huggins also helped turning his stellar spectroscope to study the fuzzy change the direction of modern cosmology when celestial objects called nebulas. At the time, as- he attempted to measure the radial velocity of tronomers were generally divided concerning Sirius by detecting any Doppler shift in its spec- the exact nature of nebulas. Some hypothesized trum. He used his relatively imprecise spectral that they were great gaseous clouds, while oth- measurements (acquired without the aid of pre- ers considered them to be enormous collections cision spectral photography) to conclude that of stars too distant to be individually resolved by there was a redshift in the spectrum of Sirius of a telescope. sufficient magnitude to suggest that this star was On the evening of August 29, Huggins ob- receding from the solar system at about 47 kilo- served a single bright line in the spectrum of a meters per second. He described this work in a nebula in the constellation Draco and immedi- paper, “On the Spectra of the Fixed Stars,” that ately concluded that it was a giant cloud of was coauthored with Miller and belatedly pub- luminous gas. Later, he found a few bright emis- lished in 1868 in Philosophical Transactions of the sion lines in certain other nebulas, including the Royal Society. great nebula in Orion. Huggins also correctly Although this value of radial velocity was noted that certain spiral nebulas, like Messier 31 not close to the value obtained later, Huggins in Andromeda, showed continuous spectra and provided the pioneering concept that encour- must be composed of numerous unresolved stars. aged other astronomers, such as EDWIN POWELL As a historic note, many of these distant spiral HUBBLE, to use the Doppler effect (redshift) in nebulas did indeed turn out to be enormous col- the spectra of distant galaxies. Using this ap- lections of stars—that is, other galaxies, or is- proach, Hubble was eventually able to postulate land universes, as originally suggested by Kant the cosmological model of an expanding and Laplace. However, that particular astro- universe. The radial velocity of a star is simply nomical knowledge would not clearly emerge its motion toward (considered negative) or until decades later, in the early part of the 20th away from (considered positive) the solar sys- century. tem. Contemporary astronomical measurements 174 Huggins, Sir William Despite his lack of formal schooling, his show the star Sirius has radial velocity of Ϫ8 kilometers per second, meaning it is actually ap- epochal astronomical work brought Huggins full proaching the solar system. recognition from learned societies and universi- On May 18, 1866, Huggins became the first ties. He was elected as a member to the Royal astronomer to observe the spectrum of a nova Society in 1865 and received several of its pres- (Nova Coronae 1866), detecting its bright tigious medals, including the Royal Medal hydrogen emission lines. He also applied astro- (1866), the Rumford Medal (1880), and the nomical spectroscopy to comets. In 1868 he ob- Copley Medal (1898). The Royal Astronomical served the spectrum of a comet and reported the Society gave him its distinguished Gold Medal presence of luminous carbon gases. He married twice, in 1867 and again in 1885. The French Margaret Lindsay Murray in 1875 and she im- Academy of Sciences presented him its Lalande mediately became not only a loving wife but also Gold Medal (1872), the Valz Prize (1883), and a most talented collaborator. As he aged, Lady the Janssen Gold Medal (1888). Finally, the U.S. Margaret Huggins, being 24 years younger than National Academy of Sciences awarded him its her husband, did more and more of the actual Henry Draper Medal in 1901. Perhaps the great- observing. In 1899 Lord and Lady Huggins pub- est contribution that this wealthy British ama- lished their award-winning Atlas of Representative teur astronomer made to the development of Stellar Spectra. He was knighted by Queen astronomical spectroscopy was his pioneering effort to interpret stellar observations by using Victoria in 1897 and served as president of the carefully prepared laboratory observations of Royal Society from 1900 to 1905. Sir William chemical spectra. Huggins died in London on May 12, 1910.

particularly interested in the kinetic theory and ᨳ Jeans, Sir James Hopwood thermodynamic behavior of gases, and published (1877–1946) his first major textbook, The Dynamical Theory British of Gasses, in 1904, while recuperating from a Astronomer, Mathematician, Physicist bout with tuberculosis. At the dawn of 20th-century astronomy, Sir James Jeans began his career as a mathematician, Hopwood Jeans proposed the controversial and but made important contributions in such di- now generally ignored tidal theory to explain the verse fields as molecular physics, astrophysics, origin of the solar system. In 1928 he made an- and cosmology. In 1904 he became a lecturer in other bold suggestion that matter was being mathematics at Cambridge University, then in continuously created in the universe. This con- 1905 traveled to the United States to serve as a troversial hypothesis led other scientists to estab- professor of applied mathematics at Princeton lish a steady-state universe model in cosmology. University in New Jersey until 1909. While at Big Bang cosmology has now all but eliminated Princeton he published his second major text- the steady-state model that traces its origins to book, Theoretical Mechanics, in 1906. He became his initial speculations. Following his knighthood a Fellow in the British Royal Society in 1907 in 1928, he focused much of his creative activity and also married an American, Charlotte Tiffany on writing popular books about astronomy. Mitchell, a member of the famous Tiffany fam- Jeans was born in Ormskirk, Lancashire, ily from New York. Jeans published another England, on September 11, 1877, but his family book, The Mathematical Theory of Electricity and moved to London when he was three years old. Magnetism, in 1908. Later the next year he re- He was the son of a journalist and this proba- turned to Great Britain and accepted an ap- bly influenced his strong inclination toward pointment as the Stokes Lecturer in applied writing during childhood. Jeans enrolled at Trinity mathematics at Cambridge University. However, College, Cambridge University, in October 1896. he kept this position only until 1912, before He received a degree in mathematics in 1900 devoting himself entirely to technical writing and became a Fellow of Trinity College in 1901. and research in applied mathematics, especially During this period, he was very active, publish- as related to astronomy and cosmology. ing research on a variety of topics in applied In 1917 Jeans won the Adams Prize from mathematics, astronomy, and physics. He was Cambridge University for an essay titled

175 176 Jeans, Sir James Hopwood “Problems of Cosmogony and Stellar Dynamics” scientists, including Walter Sydney Adams and which was published two years later as a book. ARTHUR HOLLY COMPTON. In this work Jeans mathematically addressed In 1928 Jeans suggested in his book Astronomy the stability of a rotating mass and then took and Cosmogony that matter was being continu- direct issue with the nebular hypothesis of Kant ally created in the universe. This interesting and Laplace as the basis for the formation of conjecture became the foundation of the steady- the planets. He endorsed, instead, a tidal (or state theory of cosmology—a theory champi- catastrophic) theory to explain the formation oned by some scientists in the 1940s and 1950s of the solar system. This interesting theory sug- in opposition to Big Bang cosmology. Today, gests that a rogue star passed close to the Sun steady-state cosmology has been displaced by billions of years ago and gravitationally tugged the general acceptance of an expanding a cigar-shaped wedge of matter out of the Sun universe cosmology based on the Big Bang that eventually condensed into the planets. For hypothesis. more than a decade the tidal theory remained Jeans was elevated to knighthood in 1928, popular in 20th-century astronomy. This the- and starting in 1929 he focused his diverse in- ory implied, however, that planetary systems tellectual talents on writing books that greatly would be rare because their formation would popularized astronomy and science. His most depend on catastrophic encounters of passing famous popular books include: The Universe rogue stars. By the mid-1940s, revitalized ver- around Us (1929), The Mysterious Universe (1930), sions of the nebular hypothesis emerged and The New Background of Science (1933), Through displaced tidal theory from its position of dom- Space and Time (1934), and Physics and Philosophy inance in astrophysics. This took place because (1943). astronomers once again regarded planet for- Jeans received numerous honors and awards. mation as a common, normal part of stellar He received the Gold Medal from the Royal evolution. The recent discovery of extra solar Astronomical Society in 1922 and the Franklin planets provides compelling observational evi- Medal in 1931. He served as the president of dence in support of the refined nebular hypoth- the Royal Astronomical Society from 1925 to esis and justifying the abandonment of the tidal 1927 and as the president of the British hypothesis. Association for the Advancement of Science in By 1917 his excessively high workload be- 1934. He was also awarded the Order of Merit gan to stress his heart and adversely influence in 1939. his health. Therefore, in 1918 Jeans moved his When his first wife died in 1934, Jeans re- family to more relaxed surroundings in Dorking, married a year later. His second wife, Suzanne Surrey, a place where he could devote more time Hock, came from Vienna, Austria, and was an to recreation and music, while still pursuing accomplished musician. Their common interest technical writing at a less hectic pace. However, in music served as the source of inspiration for his interest in astronomy and cosmology also en- Jeans’s popular book Science and Music (1938). couraged him to undertake research at the Mount Jeans died at home in Dorking, England, on Wilson Observatory, in Pasadena, California, and September 16, 1946, due to heart failure. His Jeans enjoyed an extended appointment there numerous publications and bold hypotheses not as a research associate from 1923 to 1944. This only helped shape astrophysics and cosmology position exposed him to stimulating new ideas in the first half of the 20th century but also in astronomy and gave him the opportunity to made astronomy familiar and popular to many personally interact with many notable American less-technical readers. Jones, Sir Harold Spencer 177 worldwide effort to refine the estimate of the ᨳ Jones, Sir Harold Spencer distance from the Earth to the Sun by triangu- (Spencer Jones) lating the distance of Eros 433 as it approached (1890–1960) close to Earth in 1931. Eros 433 was discovered British in 1898 and visited by a NASA spacecraft in Astronomer 2000. A member of the Mars-crossing Amor Sir Harold Spencer Jones was a multitalented group, it is an irregularly shaped minor planet, individual who used the close passage of the approximately 33 × 13 × 13 kilometers in size asteroid Eros 433 in 1931 to achieve precise and resembling a fat banana. In 1931 it came measurements of an important astronomer’s within 26 million kilometers of Earth, and as- “yardstick,” the astronomical unit (AU)—that tronomers at observatories all over the world is, the average distance from the Earth to the photographed the celestial object and recorded Sun. From 1933 to 1955 he served Great Britain accurate data concerning its position. Jones as the 10th Astronomer Royal. He also wrote a gathered these data and then spent the next number of books that popularized astronomy, in- decade reviewing more than 3,000 photographs cluding the pioneering work Life on Other Worlds and making extensive calculations in a tremen- (1940) which opened up all manner of interest- dous effort to refine the estimate of solar paral- ing speculations in the exciting field now known lax—that is, the angle subtended by Earth’s ra- as exobiology. dius when viewed from the center of the Sun. Jones was born in London on March 29, Not until the early 1940s, while World War II 1890. The son of an accountant, he received was raging, did Jones, now back in Greenwich his early education at Latymer Upper School as Astronomer Royal, finally announce his re- and then attended Jesus College at Cambridge fined value for solar parallax as 8.790 Ϯ 0.001 University on a scholarship. Following a distin- arc seconds. Because of the global conflict, much guished undergraduate career, he earned his de- of the significance of his great personal effort es- gree in mathematics in 1911 and in physics in caped the immediate attention of the interna- 1912. In 1913 Jones became the chief assistant tional astronomical community. Today, the IAU at the Royal Greenwich Observatory. Except for defines solar parallax as 8.794148 arc seconds, World War I service with the British Ministry of based on radar measurements. Munitions, he would hold this position at He left South Africa and returned to Great Greenwich until 1923. He was elected a Fellow Britain in 1933 to continue his tenure as of Jesus College in 1914. He married Gladys Astronomer Royal. In addition to refining solar Mary Owens in 1918 and the couple had two parallax, Jones made a second major contribu- sons. In 1923 he replaced Sir Frank Dyson as the tion to astronomy by using more accurate quartz Royal Astronomer at the Cape of Good Hope clocks to study subtle anomalies in Earth’s ro- Observatory in South Africa. tation rate. In 1939 he announced that his In 1928, as Royal Astronomer at the Cape measurements indicated that Earth did not roof Good Hope Observatory, Jones took charge tate regularly, but rather kept time “like an in- of a cooperative international project under the expensive clock.” Specifically, his measurements sponsorship of the International Astronomical indicated that, with respect to other solar sys- Union (IAU) to refine estimates of the astro- tem bodies, Earth was rotating slowly by about nomical unit using positional data for the aster- a second per year—an amount sufficient to ac- oid Eros 433. Following a suggestion originally count for some of the tiny anomalies recorded in made by JOHANN GOTTFRIED GALLE, Jones led a lunar or planetary ephemerides. This work was 178 Jones, Sir Harold Spencer instrumental in the introduction of ephemeris as Worlds without End (1935), Life on Other time in 1958. Worlds (1940), and A Picture of the Universe After World War II, Jones supervised the (1947). He received many honors for his con- plans and activities involved in moving the Royal tributions to astronomy. In 1930 he became a Observatory from Greenwich to Herstmonceux Fellow of the Royal Society of London. He was Castle, in Sussex. Urban light and chemical knighted by King George VI in 1943. He also pollution, detrimental by-products of London’s received the Royal Medal of the British Royal growth, necessitated this change in location. Society (1919), the Gold Medal of the Royal Jones retired in 1955 with the relocation well Astronomical Society (1943), and the Bruce underway. By 1958 the move of the Royal Gold Medal of the Astronomical Society of the Observatory to its new location was successfully Pacific (1949). As a lasting tribute to his life- completed. long service to Great Britain and to the astro- While serving as Astronomer Royal, Jones nomical sciences, Jones was elevated to the rank communicated the excitement and wonder of of Knight of the British Empire in 1955 by astronomy to both technical and nontechnical Queen Elizabeth II. He died at age 70 on readers alike by writing such interesting books November 3, 1960, in London.

where he studied philosophy, mathematics, and ᨳ Kant, Immanuel natural philosophy (physics). He also attended (1724–1804) classes in theology. When his father died in German 1745, Kant found himself in financial difficul- Natural Philosopher, Astronomer ties and served as a private tutor for nine years The great German philosopher Immanuel Kant to earn enough money to finish his studies. In was the first to propose the nebula hypothesis, a 1755 he finally completed the requirements for concept he introduced in his 1755 book, General his degree at the University of Königsberg and History of Nature and Theory of the Heavens. In published General History of Nature and Theory this hypothesis, Kant anticipated modern astro- of the Heavens (Allgemeine naturgeschichte und physics when he suggested that the solar system theorie des himmels) presenting his view of the formed out of a primordial cloud of interstellar physical universe. In this book Kant adhered matter. Kant also introduced the term island uni- strictly to the principle of mechanical causation verses to describe the distant collections of stars (using Newtonian principles) and avoided the that astronomers now call galaxies. He was a truly probing metaphysical speculations that would brilliant thinker, and his works in metaphysics later characterize his great works in philosophy. and philosophy exerted great influence on Western Although Kant is primarily regarded as a thinking far beyond the 18th century. great philosopher and not an astronomer or Kant was born on April 22, 1724, in physicist, his early work addressed Newtonian Königsberg, East Prussia (now Kaliningrad, cosmology and contained several important con- Russia). He lived a very orderly and organized cepts that, amazingly, anticipated future devel- life, so precise that his neighbors would set their opments in astronomy and astrophysics. First, watches by his behavior. Although he was a bril- Theory of the Heavens introduced the nebular hy- liant, popular conversationalist, during his en- pothesis of the formation of the solar system: tire lifetime Kant never ventured more than namely, that the planets formed from a cloud of about 100 kilometers from his birthplace. His fa- primordial interstellar material that slowly col- ther was a poor, but well-respected, saddler, and lected and began swirling around a protosun his mother created a home environment filled under the influence of gravitational attraction with a strict adherence to Protestantism. At age and eventually portions of this rotating disc 16 Kant enrolled at the University of Königsberg, condensed into individual planetary “clumps.”

179 180 Kapteyn, Jacobus Cornelius Laplace independently introduced a similar On the contrary, he was a brilliant conversa- version of Kant’s nebular hypothesis in 1796. tionalist and excellent teacher, who enjoyed a Second, Kant suggested that the Milky Way wide circle of friends who constantly sought his Galaxy was a lens-shaped collection of many views on contemporary intellectual and politi- stars that orbited around a common center, sim- cal issues. He retired from the university in 1796 ilar to the way the rings of Saturn orbited around and died on February 12, 1804, in Königsberg. the gaseous giant planet. Third, he speculated that certain distant spiral nebulas were actually other “island universes”—a term he coined to ᨳ Kapteyn, Jacobus Cornelius describe the modern concept of other galaxies. (1851–1922) Fourth, Kant suggested that tidal friction was Dutch slowing down Earth’s rotation just a bit—a bold Astronomer scientific speculation confirmed by precise measurements in the 20th century. Finally, he also Toward the end of the 19th century, Jacobus suggested the tides on Earth are caused by the Kapteyn made significant contributions to the Moon and that this action is responsible for the emerging new field of astrophotography—that fact the Moon is locked in a synchronous orbit is, taking analysis-quality photographs of celes- around Earth, always keeping the same “face” tial objects. He also pioneered the use of statis- (called the nearside) presented to observers on tical methods to evaluate stellar distributions Earth. Not too bad, for a person who had just and the radial and proper motions of stars. completed his university degree and was about Between 1886 and 1900, Kapteyn carefully scru- to embark on a long and productive academic tinized numerous photographic plates collected career best known for its important philosophi- by SIR DAVID GILL at the Cape of Good Hope cal contributions to Western civilization. Royal Observatory, in South Africa. He then Upon graduating from the University of published these data as a three-volume catalog Königsberg, Kant became a lecturer (Privatdozent) that contained the positions and photographic at the university and served in that capacity for magnitudes of more than 450,000 Southern the next 15 years. During that time, his fame as Hemisphere stars. a brilliant thinker and wonderful teacher grew. Kapteyn was born on January 19, 1851, at In 1770 university officials appointed him to the Barneveld in the Netherlands. From 1869 to chair of logic and metaphysics. This promotion 1875, he studied physics at the University of marked the beginning of a period in which Kant Utrecht. After graduating with his doctorate, wrote a powerful series of books that shaped Kapteyn accepted a position as a member of the Western thinking for the next two centuries. observing staff at the Leiden Observatory. The most important of these works was his During his studies, he had not given any special Critique of Pure Reason (Kritik der reinen attention to astronomy, but this employment Vernunft)—a treatise on metaphysics that is re- opportunity convinced him that studying stel- garded as a classic contribution to philosophy. lar populations and the structure of the universe A full and detailed discussion of Kant’s other was how he wanted to spend his professional great works in metaphysics, ethics, judgment, life. and reason is well beyond the scope of this In 1878 Kapteyn received an appointment book. as the chair of astronomy and theoretical me- Although Kant never married and did not chanics at the University of Groningen. Since venture far from home, he was not a recluse. the university did not have its own observatory, Kapteyn, Jacobus Cornelius 181 Kapteyn decided to establish a special astro- Along with statistical astronomy, Kapteyn nomical center dedicated to the detailed analy- was interested in the general structure of the sis of photographic data collected by other Galaxy. In 1906 he attempted to organize a co- astronomers. The year following this bril- operative international effort in which as- liant career maneuver, he married Catharina tronomers would determine the population of Karlshoven, with whom he had three children. stars of differing magnitude in 200 selected ar- In the mid-1880s Kapteyn interacted with Sir eas of the sky and also measure their radial ve- David Gill, Royal Astronomer at the Cape of locities and proper motions. The radial velocity Good Hope Observatory. The two astronomers of a star is a measure of its velocity along the developed a cordial relationship and Kapteyn line of sight with Earth. Astronomers use the volunteered to make an extensive catalog Doppler shift of a star’s spectrum to indicate of the stars in the Southern Hemisphere, us- whether it is approaching Earth (blueshifted ing the photographs taken by Gill at the Cape spectrum) or receding from Earth (redshifted Observatory. spectrum). The proper motion of a star is the In 1886 Kapteyn’s collaboration with Gill gradual change in the position of a star due to began. Underestimating the true immensity of its motion relative to the Sun. The proper mo- the task for which he had just volunteered, tion (symbol µ) is the apparent angular motion Kapteyn worked for more than a decade in two per year of a star as observed on the celestial small rooms at the University of Groningen. sphere—that is, the change in its position in a During his labor-intensive personal crusade in direction that is perpendicular to the line of sight. photographic plate analysis, he enjoyed support Kapteyn gathered enormous quantities of from just one permanent assistant, several part- data, but World War I interrupted this multi- time assistants, and occasional convict labor national cooperative effort. Nevertheless, he from the local prison. examined the data that was collected but over- The end product of Kapteyn’s massive looked the starlight-absorbing impact of inter- personal effort was the Annals of the Cape stellar dust. So, in the tradition of SIR WILLIAM Observatory—an immense three-volume work HERSCHEL, he postulated that the Milky Way published between 1896 and 1900 that con- must be lens-shaped, with the Sun located tained the position and photographic magni- close to its center. The American astronomer tudes of 454,875 Southern Hemisphere stars. His HARLOW SHAPLEY disagreed with the Dutch pioneering effort led to the creation of the astronomer’s erroneous model and, in 1918, Astronomical Laboratory at the University of conclusively demonstrated that the Galaxy was Groningen, and the establishment of the highly far larger than Kapteyn had estimated and that productive Dutch school of 20th-century as- the Sun actually resided far away from the tronomers. galactic center. In 1904 Kapteyn noticed that the proper Kapteyn’s model of the Galaxy suffered when motion of the stars in the Sun’s neighborhood applied to the galactic plane because he lacked did not occur randomly, but rather moved in two sufficient knowledge about the consequences of different, opposite streams. However, he did not interstellar absorption, not because he was care- recognize the full significance of his discovery. less in his evaluation of observational data. On Years later, one of his students, JAN HENDRIK the contrary, he was a very skilled and careful OORT, demonstrated that the star-streaming phe- analyst who helped found the important field of nomenon first detected by Kapteyn was observa- statistical astronomy. He died in Amsterdam, tional evidence that the Galaxy was rotating. the Netherlands, on June 18, 1922. During his 182 Kepler, Johannes lifetime he received many international awards and medals, including the Gold Medal of the Royal Astronomical Society of London in 1902, the Watson Medal from the American Academy of Sciences in 1913, and the Bruce Gold Medal from the Astronomical Society of the Pacific, also awarded in 1913. Perhaps his greatest overall contribution to astronomical sciences was the creation of the Dutch school of astronomy, which provided many great astronomers who continued his legacy of excellence in data analysis throughout the 20th century.

ᨳ Kepler, Johannes (Johann Kepler) (1571–1630) German Astronomer, Mathematician

Johannes Kepler was a brilliant contemporary of GALILEO GALILEI who helped start the Scientific Revolution. While Galileo’s pioneering use of Johannes Kepler combined painstaking and arduous analyses with simple mathematics to describe the the telescope provided the observational foun- elliptical movement of the known planets around the dations for Copernican cosmology, Kepler’s Sun. With his famous three laws of planetary motion, innovative mathematical contributions to as- Kepler established the mathematical foundations for tronomy provided the theoretical foundations. heliocentric (Copernican) cosmology. His work not only provided the empirical basis for the early Through painstaking and arduous analyses, acceptance of the heliocentric hypothesis, it also Kepler developed his three laws of planetary provided the mathematical starting point from which motion—important physical principles that de- Sir Isaac Newton could develop his law of gravitation. scribe the elliptical of orbits of planets around (AIP Emilio Segrè Visual Archives) the Sun. His work not only provided the empirical basis for the early acceptance of NICOLAS age of three. The disease impaired the use of his COPERNICUS’s heliocentric hypothesis but also hands and affected his eyesight for the remain- the mathematical starting point from which SIR der of his life. When Kepler was five, his father ISAAC NEWTON developed his law of gravitation. left to fight in one of the many local conflicts Kepler gave astronomy its modern, mathematical ravaging Europe at the time, and he never re- foundation. turned home. So Kepler spent the remainder of Kepler was born on December 27, 1571, in his childhood living with his mother at his the small town of Weil der Stadt, Württemberg, grandfather’s inn. Germany (then part of the Holy Roman As a child, his mother took him outside the Empire). His father was a mercenary soldier and walls of the city so he could witness the great his mother was the daughter of an innkeeper.A comet of 1577. This special event appears to have sickly child, Kepler suffered from smallpox at the encouraged his lifelong interest in astronomy. Kepler, Johannes 183 After completing local schooling, he pursued a losophy and mathematics) to the distances of the religious education at the University of Tübingen six known planets from the Sun. This work, of- in the hopes of becoming a Lutheran minister. ten considered the first outspoken defense of the He graduated in 1588 with his baccalaureate de- Copernican hypothesis, also attracted the at- gree and then went on to complete a master’s tention of TYCHO BRAHE, the most famous degree in 1591. (pretelescope) astronomer of the period. While Kepler was a student at the Uni- Kepler married his first wife in 1597. She versity of Tübingen, his professor of astronomy, was a wealthy widow named Barbara Mueller. Michael Maestlin (1550–1632) introduced him However, when all the Protestants were forced to the Copernican hypothesis. Kepler immedi- to leave the Catholic-controlled city of Gratz ately embraced the new heliocentric model of in 1598, Kepler found it extremely difficult to the solar system. As his interest in the motion liquidate her property holdings. Any nuptial of the planets grew, Kepler’s skill in mathemat- financial comfort quickly dissipated, as the ics also emerged. By 1594 partially because he Kepler family hastily departed Gratz and moved alienated church officials after expressing his to Prague in response to Brahe’s invitation. personal disagreement with certain aspects of Kepler joined the elderly Danish astronomer Lutheran doctrine, he totally abandoned any in 1600 as his assistant. When Brahe died the plans for the Lutheran ministry and became a following year, Kepler succeeded him as the mathematics instructor in Gratz (Graz), Austria. imperial mathematician to the Holy Roman As well as an accomplished astronomer and Emperor Rudolf II. As a result, Kepler acquired mathematician, Kepler also maintained a strong all the precise astronomical data Brahe had col- interest in mysticism throughout his life. He ex- lected. These data, especially Brahe’s precise tracted many of his mystical notions from the observations of the motion of Mars, played an early Greeks, including the “music of the celes- important role in the development of Kepler’s tial spheres” that was originally suggested by famous three laws of planetary motion. Pythagoras in the sixth century B.C.E. As was In 1604 Kepler wrote the book De Stella common for many 17th-century astronomers, Nova (The new star), in which he described a Kepler also dabbled in astrology. He often cast bright new star (now known as a supernova) in horoscopes for important benefactors, such as the constellation Ophiuchus. He first observed Emperor Rudolf II (1552–1612) and Duke the event on October 9, 1604. Modern as- (Imperial General) Albrecht von Wallenstein. tronomers sometimes refer to this supernova Astrology provided the frequently impoverished event, the remnants of which form radio source Kepler with a supplemental source of income. 3C 358, as Kepler’s Star. According to early His well-prepared horoscopes also earned Kepler 17th-century astronomical observations that the political protection of many satisfied high- took place in Europe and Korea, this particular ranking officials in the Holy Roman Empire. As supernova remained visible for approximately a result, he was often the only prominent one year. Protestant allowed to live in a German city From 1604 until 1609 Kepler’s main interest under control of a Catholic ruler. was a detailed study of the orbital motion of Mars. In 1596 Kepler published Mysterium Cos- Before his death, Brahe had challenged his young mographicum (The cosmographic mystery)—an assistant with the task of explaining the puzzling intriguing work in which he unsuccessfully motion of the Red Planet. Even accepting the tried to analytically relate PLATO’s five basic geo- Copernican hypothesis, which Kepler did but metric solids (as found in early Greek phi- Brahe did not, a circular orbit around the Sun 184 Kepler, Johannes did not properly fit Brahe’s carefully observed The year 1611 proved extremely difficult for orbital position data. With youthful optimism, Kepler in that his first wife, Barbara, and their Kepler told the older astronomer he would have seven-year-old son died. Then his royal patron, an answer for him in a week, but it took Kepler Emperor Rudolf II, abdicated the throne in fa- eight long and hard years to finally obtain the vor of his brother Matthias. Unlike his brother solution. The movement of Mars could not be Rudolf, Matthias did not believe in tolerance for explained and predicted unless Kepler assumed the Protestants living in his realm. So Kepler, the orbit was an ellipse with the Sun located at along with many other Lutherans, left Prague to one focus. This revolutionary assumption pro- avoid the start of an impending civil war be- duced a major advance in solar system astronomy tween Catholics and Protestants. After burying and provided the first empirical evidence of the his wife and son together, he moved his surviv- validity of the Copernican model. ing children to Linz, where he accepted a posi- Kepler recognized that the other observ- tion as district mathematician and teacher. able planets also followed elliptical orbits In 1613, desperately needing someone to around the Sun. He published this important care for his children, he married Susanna discovery in 1609 in the book Astronomia Nova Reuttinger, herself an orphan. Although his sec- (New astronomy). The book, dedicated to ond marriage was a generally happy one, Kepler Emperor Rudolf II, confirmed the Copernican continued to suffer from misfortune. He had model and permanently shattered 2,000 years chronic financial troubles, experienced the of geocentric Greek astronomy. Kepler became deaths of two infant daughters, and had to re- the first scientist to present a well-written turn to Württemberg to defend his mother, demonstration of the scientific method. This Katharina Kepler, who was being put on trial as work clearly acknowledged the errors and im- a witch. This trial dragged on for three years and perfections in the observational data and then Kepler used all his legal wit and political capi- compensated for these inaccuracies by creating tal to get her released. Her torture and death at a new scientific law (model) that used mathe- the stake were the very likely outcomes that matics to accurately predict the natural phe- Kepler struggled so hard to prevent. Despite nomenon of interest (here the orbital position these personally draining problems, he remained of Mars). In this important document, Kepler a diligent mathematician in Linz until 1628 and announced that the orbits of the planets are el- used his available time to write several books. lipses with the Sun as a common focus. Today, He moved his family in 1628 to Sagan (in astronomers call this statement Kepler’s First Silesia) in order to work for the Imperial general Law of Planetary Motion. Kepler also intro- Albrecht von Wallenstein (1583–1632) as his duced his Second Law of Planetary Motion in court mathematician. With the Thirty Years’ this book. War (1618–48) raging in Germany, in 1630 he German church officials (Lutheran or Cath- had to flee Sagan to avoid religious persecution olic) never officially attacked Kepler for advo- as Wallenstein fell from power. cating the Copernican hypothesis. This was When he published De Harmonica Mundi probably due to his powerful political benefac- (Concerning the harmonies of the world) in tors. However, the same benign neglect did not 1619, Kepler continued his great work involving befall his fiery Italian contemporary, Galileo, the orbital dynamics of the planets. Although who shared the same passion for the Copernican this book extensively reflected Kepler’s fascina- hypothesis and corresponded with Kepler regu- tion with mysticism, it also provided a very sig- larly until about 1610. nificant insight that connected the mean dis- Kepler, Johannes 185 tances of the planets from the Sun with their or- important scientific application of the loga- bital periods. This discovery became known as rithm, a new mathematical function invented Kepler’s Third Law of Planetary Motion. by the Scottish mathematician, John Napier Between 1618 and 1621, despite constant (1550–1617). relocations Kepler summarized all of his plane- Kepler also made important contributions in tary studies in an important seven-volume ef- the field of optics. While in Prague, he wrote fort entitled Epitome Astronomica Copernicanae Optica (Optics) in 1604. Prior to 1610, Galileo (Epitome of Copernican astronomy). This work and Kepler communicated with each other, al- presents all of Kepler’s heliocentric astronomy in though they never met. According to one his- a systematic way. As a point of scientific history, toric account of their relationship, in 1610 Kepler actually based his second law (the law of Kepler refused to believe that Jupiter had four equal areas) on the mistaken (but reasonable for moons that behaved like a miniature solar sys- the time) physical assumption that the Sun ex- tem, unless he personally observed them. When erted a strong magnetic influence on all the a Galilean telescope arrived at his doorstep. planets. Later in the 17th century, Newton pro- Kepler promptly used the device and immedi- vided the right physical explanation when he ately called the four major moons discovered by developed the universal law of gravitation to Galileo “satellites”—a term Kepler derived from identify the force that causes the planetary mo- the Latin word satelles meaning “the people who tion so correctly described by Kepler’s second law. escort or loiter around a powerful person.” In Kepler’s three laws of planetary motion are: 1611 Kepler improved the design of Galileo’s (1) The law of ellipses: the planets move in el- original telescope by introducing two convex liptical orbits with the Sun as a common fo- lenses in place of the one convex lens and one cus; (2) The law of areas: as a planet orbits the concave lens arrangement used by the great Sun, the radial line joining the planet to the Sun Italian astronomer. Kepler’s final published work sweeps out equal areas within the ellipse in equal in Prague was his Dioptrice (Dioptics), which he times; and (3) The harmonic law: the square of completed in 1611. This book is the first scien- the orbital period (P) of a planet is proportional tific work in geometrical optics. to the cube of its mean distance (a) from the Before his death in 1630, Kepler wrote a Sun. The third law states that there is a fixed novel called Somnium (The dream), about an ratio between the time it takes a planet to com- Icelandic astronomer who travels to the Moon, plete an orbit around the Sun and the size of the involving demons and witches who help get the orbit. Astronomers often express this ratio as hero to the Moon’s surface in a dream state. P2/a3, where “a” is the semimajor axis of the Kepler’s description of the lunar surface was ellipse and “P” is the period of revolution around quite accurate. Therefore, many historians treat the Sun. Kepler’s three laws established modern this story, published after his death in 1634, as observational astronomy on a solid mathematical the first genuine piece of science fiction. foundation. Kepler married twice, fathered 13 children, In 1627 Kepler’s Tabulae Rudolphinae (Rudol- constantly battled financial difficulties, and en- phine tables), named after his benefactor dured the turmoil of numerous relocations caused Emperor Rudolf and dedicated to Brahe, pro- by religious persecution. He died on November vided astronomers detailed planetary position 15, 1630, in Regensburg, Bavaria, of a fever con- data. The tables remained in use until the 18th tracted while journeying to see the emperor. century. Kepler used the logarithm to help per- Kepler was trying to collect the payment owed form the tedious calculations, which was the first him for his service as imperial mathematician 186 al-Khwarizmi, Abu and for his effort in producing the Rudolphine In 813 the caliph Al-Ma’mun, who ruled Tables. Newton regarded both Galileo and from 813 to 833, ordered the translation of the Kepler as those “giants” upon whose shoulders work of a man from India who reportedly could he (Newton) stood to see farther into the predict eclipses, and al-Khwarizmi became the mysteries and workings of the mechanical first person to publish astronomical tables based universe. on the Indian’s work. The Indian books, however, were strictly numerical, with limited written explanations. But because India had a numerical ᨳ al-Khwarizmi, Abu (Abu’Jafar system that included the concept of zero, al- Muhammad ibn-Musa al-Khwarizmi) Khwarizmi was able to translate the tables and (ca. 780–850) move into a realm of mathematics that he devised Arabian for the average person to use in everyday life. Mathematician, Astrologer, Astronomer, Al-Ma’mun’s reign was one that both sup- Geographer ported and promoted scientific study, and his excellent skills during a peace negotiation with the The foundation for practical mathematics as it Byzantines made it possible for him to acquire is known and used today is derived from the work PTOLEMY’s original work. Arab scientists again of Abu al-Khwarizmi, who is most renowned as went to work, this time translating Ptolemy, and “the father of algebra.” But as a scholar of his the result was the Almagest, created in about time, broadly estimated between the years of 827. Ptolemy’s influence, and indeed some of his 770 to 850, al-Khwarizmi was a student, prac- exact measurements, can be found in the latter- titioner, and teacher of many scientific disci- day translations of al-Khwarizmi’s writings. plines—mathematics, astrology, astronomy, and During this time, translating involved more geography—because during this time the study than changing the information from one lan- of the stars usually involved an understanding of guage to another. Recalculation of measurements all of these sciences. was equally important, to assure an accurate read- Science first made its appearance in a sig- ing. In essence, al-Khwarizmi was both compil- nificant way in Baghdad under the rule of caliphs. ing information and creating new astronomical During this time, many aspects of life were tables for his time and region. conducted according to astronomy. Physicians Applying geography to the understanding of practiced medicine based on the stars, seeking astronomy, then, was a natural extension of de- stellar guidance for the best time to perform veloping the tables. This led to the creation of medical treatments. Agriculture was tied to as- the first map of the known world, completed in tronomy, as is often the case today when al- 830, under the leadership of al-Khwarizmi with manacs are consulted for the best time to plant the help of 70 other geographers. Determining and harvest. Calendars needed to be devised, the volume and circumference of the newly and the passing of time using a moon-calendar mapped Earth—a scientific blending of geogra- could only be told by looking at the night sky. phy and astronomy—was another task under- Religious rituals, which required praying at taken by al-Khwarizmi for his caliph. precise times and facing an exact direction (ge- A gifted scientist, al-Khwarizmi worked ography), depended on the expert interpreta- within many disciplines as they related to as- tion of the heavens. And the lives and future tronomy and produced significant writings, the destinies of rulers were decided amongst the fundamentals of which have withstood cen- stars. turies. Aside from his most noteworthy work in Kirchhoff, Gustav Robert 187 algebra, Al-Jabrwa-al-Muqabilah, al-Khwarizmi’s scientific writings include his work on geography, Kitab Surat-al-Ard, which is based on Ptolemy’s Geography and provides 2,402 distinct longitude and latitude calculations that are generally agreed to be more accurate than Ptolemy’s calculations; his writing on the Jewish calendar, Istikhraj Tarikh al-Yuhad; his work on sundials, Kitab al-Tarikh and Kitab al-Rukhmat; two works on the astrolabe, an instrument that was used in early times to measure the angle between the horizon and a celestial body; a horoscope of prominent members of society that was written as a political history; and his title on astronomy, Sindhind zij, which covers astrologi- cal tables, calendars, and calculations relating to the Sun, the Moon, and planets, as well as eclipses. Of this work, nearly all of the origi- nals are lost. Abu al-Khwarizmi began his life’s work translating science. It is ironic, then, that all of our knowledge of his scientific discovery comes from translations of his work by other men.

Gustav Kirchhoff was the talented German physicist who collaborated with Robert Bunsen in demonstrating ᨳ Kirchhoff, Gustav Robert the principles of spectroscopy. A major breakthrough (1824–1887) took place when Kirchhoff applied spectroscopy to study the chemical composition of the Sun—especially German the production of the Fraunhofer lines in the solar Physicist, Spectroscopist spectrum. His pioneering work contributed to the development of astronomical spectroscopy—one of the This gifted German physicist collaborated with major tools in modern astronomy. (AIP Emilio Segrè ROBERT WILHELM BUNSEN in developing the Visual Archives, W.F. Meggers Gallery of Nobel fundamental principles of spectroscopy. While Laureates) investigating the phenomenon of blackbody radiation, Kirchhoff applied spectroscopy to study the chemical composition of the Sun—especially the production of the Fraunhofer lines in Friedrich Gauss (1777–1855) at the University the solar spectrum. His pioneering work con- of Königsberg and graduated in 1847. While still tributed to the development of astronomical a student, he extended the work of Georg Simon spectroscopy—one of the major tools in modern Ohm (1787–1854) by introducing his own set astronomy. of physical laws (now called Kirchhoff’s laws) Gustav Robert Kirchhoff was born on to describe the network relationship between March 12, 1824, in Königsberg, Prussia (now current, voltage, and resistance in electrical cir- Kaliningrad, Russia). He was a student of Carl cuits. Following graduation, Kirchhoff taught 188 Kirchhoff, Gustav Robert as an unsalaried lecturer (Privatdozent) at the that the gases in the sodium flame were absorb- University of Berlin and remained there for ap- ing the D-line radiation from the Sun, produc- proximately three years before joining the ing an absorption spectrum. University of Breslau as a physics professor. Four After additional experiments, Kirchhoff also years later, he accepted a more prestigious ap- realized that all the other Fraunhofer lines were pointment as a professor of physics at the actually absorption lines—that is, gases in the University of Heidelberg and remained with Sun’s outer atmosphere were absorbing some of that institution until 1875. At Heidelberg he the visible radiation coming from the solar in- collaborated with the German chemist Bunsen terior thereby creating these dark lines, or “holes” in a series of innovative experiments that sig- in the solar spectrum. By comparing solar spec- nificantly changed observational astronomy tral lines with the spectra of known elements, through the introduction of astronomical spec- Kirchhoff and Bunsen detected a number of el- troscopy. ements present in the Sun, with hydrogen being Prior to his innovative work in spectroscopy, the most abundant. This classic set of experi- Kirchhoff produced a theoretical calculation ments, performed in Bunsen’s laboratory in in 1857 at the University of Heidelberg demon- Heidelberg with a primitive spectroscope as- strating the physical principle that an alter- sembled from salvaged telescope parts, gave nating electric current flowing through a rise to the entire field of spectroscopy, including zero-resistance conductor would flow through astronomical spectroscopy. the circuit at the speed of light. His work be- Bunsen and Kirchhoff then applied their came a key step for the Scottish physicist James spectroscope to resolving elemental mysteries on Clerk Maxwell (1831–79) during his formula- Earth. In 1861 they discovered the fourth and tion of electromagnetic wave theory. fifth alkali metals, which they named cesium Kirchhoff’s most significant contributions to (from the Latin caesium, meaning sky blue) and astrophysics and astronomy were in the field of rubidium (from the Latin rubidus, meaning dark- spectroscopy. Fraunhofer’s work had established est red). Today scientists use spectroscopy to the technical foundations of the science of spec- identify individual chemical elements from the troscopy, but undiscovered was the fact that each light each emits or absorbs when heated to chemical element had its own characteristic incandescence. spectrum. That critical leap of knowledge was Modern spectral analyses trace their her- necessary before physicists and astronomers itage directly back to the pioneering work of could solve the puzzling mystery of the Fraun- Bunsen and Kirchhoff. Astronomers and astro- hofer lines and make spectroscopy an indispen- physicists use spectra from celestial objects in a sable tool in both observational astronomy and number of important applications, including numerous other applications. In 1859 Kirchhoff composition evaluation, stellar classification, achieved that giant step in knowledge, while and radial velocity determination. working in collaboration with Bunsen at the In 1875 Kirchhoff left Heidelberg because University of Heidelberg. In his breakthrough the cumulative effect of a crippling injury he experiment, Kirchhoff sent sunlight through a sustained in an earlier accident now prevented sodium flame and, with the primitive spectro- him from performing experimental research. scope he and Bunsen had constructed, observed Confined to a wheelchair or crutches, he ac- two dark lines on a bright background just where cepted an appointment to the chair of mathe- the Fraunhofer D-lines in the solar spectrum oc- matical physics at the University of Berlin. In curred. He and Bunsen immediately concluded the new less physically demanding position, he Korolev, Sergei Pavlovich 189 pursued numerous topics in theoretical physics lite, Sputnik 1, into orbit around Earth. On for the remainder of his life. During this period October 4, 1957, Korolev became the rocket en- he made significant contributions to the field of gineer who started the Space Age. radiation heat transfer. He discovered that the Korolev was born on January 12, 1907, in emissive power of a body to the emissive power Zhitomir, the Ukraine—at the time part of of a blackbody at the same temperature is equal czarist Russia. Korolev’s birth date sometimes to the absorptivity of the body. His work in appears as December 30, 1906, a date corre- blackbody radiation was fundamental in the de- sponding to an obsolete czarist calendar sys- velopment of quantum theory by MAX KARL tem. As a young boy, Korolev obtained his PLANCK. first ideas about space travel in the inspira- Recognizing his great contributions to tional books of KONSTANTIN EDUARDOVICH physics and astronomy, the British Royal Society TSIOLKOVSKY. After discovering the rocket, elected Kirchhoff as a fellow in 1875. Failing Korolev decided on a career in engineering. health forced him to retire prematurely in 1886 He entered Kiev Polytechnic Institute in 1924 from his academic position at the University of and two years later transferred to Moscow’s Berlin. He died in Berlin on October 17, 1887, Bauman High Technical School, where he and some of his scientific work appeared posthu- studied aeronautical engineering under such famously. While at the University of Berlin, he mous Russian aircraft designers as Andrey prepared his most comprehensive publication, Tupolev. Korolev graduated as an aeronautical Lectures on Mathematical Physics (Vorlesungen engineer in 1929. über mathematische Physik)—a four-volume ef- He began to champion rocket propulsion in fort that appeared between 1876 and 1894. His 1931, when he helped to organize the Moscow collaborative experiments with Bunsen and his Group for the Investigation of Reactive Motion, insightful interpretation of their results started a (Gruppa Isutcheniya Reaktvnovo Dvisheniya) new era in astronomy. (GIRD). Like its German counterpart, the Verein für Raumschiffahrt (VFR), (the German Society for Space Travel), this Soviet technical ᨳ Korolev, Sergei Pavlovich society began testing liquid-propellant rockets of (1907–1966) increasing size. In 1933 GIRD merged with a Ukrainian/Russian similar group from Leningrad (St. Petersburg) Rocket Engineer to form the Reaction Propulsion Scientific Research Institute (RNII). Korolev was very Sergei Korolev is often called the Russian active in this new organization and encouraged WERNHER VON BRAUN, because he was the driv- its members to develop and launch a series of ing technical force behind the initial intercon- rocket-propelled missiles and gliders during tinental ballistic missile (ICBM) and the space the mid-1930s. The crowning achievement of exploration programs of the Soviet Union. In Korolev’s early aeronautical engineering efforts 1954 he started work on the first Soviet ICBM, was his creation of the RP-318, Russia’s first called the R-7. It was a powerful rocket designed rocket-propelled aircraft. to carry a massive nuclear warhead across con- In 1934 the Soviet Ministry of Defense tinental distances. As part of cold war politics, published Korolev’s book Rocket Flight into the Soviet premier Nikita Khrushchev (1894–1971) Stratosphere. Between 1936 and 1938, he super- gave Korolev permission to use that military vised a series of rocket engine tests and winged- rocket to place the world’s first artificial satel- rocket flights within RNII. However, Soviet 190 Korolev, Sergei Pavlovich dictator Joseph Stalin (1879–1953) was elimi- design-efficient nuclear weapons. Responding nating many intellectuals through a series of to this emphasis, Korolev designed the R-7. brutal purges. Despite his technical brilliance, This powerful rocket was capable of carrying a Korolev, along with most of the staff at RNII, 5,000-kilogram payload more than 5,000 kilo- found themselves imprisoned in 1938. During meters. World War II Korolev remained in a scientific With the death of Stalin in 1953, a new labor camp. His particular prison design bureau, leader, Nikita Khrushchev, decided to use called Sharashka TsKB-29, worked on jet-as- Soviet technology accomplishments to empha- sisted take-off (JATO) systems for aircraft. size the superiority of Soviet communism over Freed from the labor camp after the war, Western capitalism. Under Khrushchev, Korolev Korolev resumed his work on rockets. He ac- received permission to send some of his pow- cepted an initial appointment as the chief con- erful military missiles into the heavens on structor for the development of a long-range missions of space exploration, as long as such ballistic missile. At this point in his life, Korolev space missions also had high-profile political essentially disappeared from public view, and all benefits. his rocket and space activities remained a tightly In summer 1955 construction began on a guarded state secret. secret launch complex in a remote area of Following World War II Stalin became Kazakhstan north of a town called Tyuratam. more preoccupied with developing an atomic This central Asian site is now called the bomb than with exploiting captured German V-2 Baikonur Cosmodrome and lies within the po- rocket technology. But he apparently sanctioned litical boundaries of the Republic of Kazakhstan. some work on long-range rockets and also ap- In August and September 1957 Korolev success- proved the construction of a ballistic missile test fully launched the R-7, on long-range demon- range at Kapustin Yar, near the city of Volgograd. stration flights from this location. Encouraged It was this approval that allowed Korolev to form by the success of these test flights, Khrushchev a group of rocket experts to examine captured allowed Korolev to use an R-7 military missile German rocket hardware and to resume the as a space launch vehicle in order to beat the Soviet rocket research program. In late October United States into outer space with the first 1947 Korolev’s group successfully test-fired a artificial satellite. captured German V-2 rocket from the new On October 4, 1957, a mighty R-7 rocket launch site at Kapustin Yar. By 1949 Korolev had roared from its secret launch pad at Tyuratam, developed a new rocket, the Pobeda (Victory- placing Sputnik 1 into orbit around Earth. Korolev, class) ballistic missile. He used Russian-modified the “anonymous” engineering genius, had pro- GermanV-2 rockets and Pobeda rockets to send pelled the Soviet Union into the world spotlight instruments and animals into the upper atmos- and started the Space Age. To Khrushchev’s de- phere. In May 1949 one of his modified V-2 light, a supposedly technically inferior nation rockets lifted a 120-kilogram payload to an alti- won a major psychological victory against the tude of 110 kilometers. United States. With the success of Sputnik 1, As cold war tensions mounted between the space technology became a key instrument of Soviet Union and the United States in 1954, cold war politics and superpower competition. Korolev began work on the first Soviet ICBM. The provocative and boisterous Khrushchev Soviet leaders were focusing their nation’s de- immediately demanded additional high-visibility fense resources on developing very powerful space successes from Korolev. The rocket engineer rockets to carry the country’s much heavier, less responded on November 3, 1957, by placing a Korolev, Sergei Pavlovich 191 much larger satellite into orbit. Sputnik 2 car- interesting follow-on Soyuz spacecraft for future ried the first living space traveler into orbit space projects involving multiple human crews. around Earth. The passenger was a dog named However, he was not allowed to pursue these Laika. Korolev continued to press the Soviet developments in a logical, safe fashion. Union’s more powerful booster advantage by Premier Khrushchev kept demanding other developing the Vostok (one-person) spacecraft space mission “firsts” from Korolev’s team. The to support human space flight. On April 12, Soviet leader wanted to fly a three-person crew 1961, another of Korolev’s powerful military in space before the United States could com- rockets placed the Vostok 1 spacecraft, carry- plete the first flight of its new two-person Gemini ing cosmonaut Yuri Gagarin (1934–68), into capsule. The first crewed Gemini flight occurred orbit around Earth. Gagarin’s brief flight (only on March 23, 1965. Korolev recognized how one orbital revolution) took place just before dangerous it would be to convert his one-person the United States sent its first astronaut, Alan Vostok spacecraft design into an internally B. Shepard Jr. (1923–99), on a suborbital mis- stripped-down “three-seater.” But he also re- sion from Cape Canaveral, Florida, on May 5, membered the painful time he spent in a polit- 1961. ical prison camp for perceived disloyalty to Using Korolev’s powerful rockets like so Stalin’s regime. many trump cards, Khrushchev continued to So, despite strong opposition from his de- reap international prestige for the Soviet Union, sign engineers, Korolev removed the Vostok which had just become the first nation to place spacecraft’s single ejection seat and replaced it a person into orbit around Earth. This particu- with three couches. Without an ejection seat, lar Soviet accomplishment forced U.S. president the cosmonaut crew could not leave the space John F. Kennedy (1917–63) into a daring re- capsule during the final stages of reentry descent, sponse. In May 1961 Kennedy announced his as had been done during previous successful bold plan to land U.S. astronauts on the Moon Vostok missions. To accommodate the demands in less than a decade. From the perspective of of this mission, Korolev came up with several history, Korolev’s space achievements became clever ideas, including a new retro-rocket system the political catalyst by which Braun received a and a larger reentry parachute. To quell the ve- mandate to build more powerful rockets for the hement safety objections from his design team, United States. Starting in July 1969, Braun’s new he also made them an offer they could not refuse: rockets would carry U.S. explorers to the surface If they could design this modified three-person of the Moon—a technical accomplishment that spacecraft in time to beat the Americans, one of soundly defeated the Soviet Union in the great the engineers would be allowed to participate in space race of the 1960s. the flight as a cosmonaut. Following the success of Sputnik, Korolev On October 12, 1964, a powerful military used his rockets to propel large Soviet spacecraft booster sent the “improvised” Voskhod 1 space to the Moon, Mars, and Venus. One of his space- capsule into a 170 kilometer by 409 kilometer craft, Lunik 3, took the first photographic im- orbit around Earth. Voshkod is the Russian word ages of the Moon’s far side in October 1959. for “sunrise.” The flight lasted just one day. The These initial images of the Moon’s long-hidden retrofitted Vostok spacecraft carried three cosmo- hemisphere excited both astronomers and the nauts without spacesuits under extremely cramped general public. Appropriately, one of the largest conditions. Cosmonaut Vladimir Komarov com- features on the Moon’s far side now bears manded the flight; a medical expert, Boris Yegorov, Korolev’s name. He also planned a series of and a design engineer, Konstantin Feoktistov, 192 Kuiper, Gerard Peter accompanied him. Korolev won an extremely ᨳ Kuiper, Gerard Peter (Gerrit Pieter) high-risk technical gamble. His engineering skill (1905–1973) and luck not only satisfied Khrushchev’s insa- Dutch/American tiable appetite for politically oriented space ac- Astronomer complishments, but he also kept his promise of a ride in space to one of his engineers. In 1951 Gerard Kuiper, the Dutch-American Khrushchev responded to Kennedy’s moon planetary astronomer, boldly postulated the race challenge by ordering Korolev’s Experimental presence of thousands of icy planetesimals in an Design Bureau No. 1 (OKB-1) to accelerate its extended region at the edge of the solar system plans for a very large booster. As originally en- beyond the orbit of Pluto. Today, this region of visioned by Korolev, the Russian N-1 rocket was frigid, icy objects has been detected and is called to be a very large and powerful booster for plac- the Kuiper belt in his honor. In 1944 Kuiper dis- ing extremely heavy payloads into Earth’s orbit, covered that Saturn’s largest moon, Titan, had including space stations, nuclear-rocket upper an atmosphere. He continued to revive interest stages, and various military payloads. But after in planetary astronomy by discovering Miranda, Korolev’s untimely death in 1966, the highly the fifth-largest moon of Uranus, in 1948, and secret N-1 rocket became the responsibility of Nereid, the outermost moon of Neptune, in another rocket design group. It suffered four catastrophic failures between 1969 and 1972, and then the project was quietly canceled. From 1962 to 1964, Khrushchev’s continued political use of space technology seriously diverted Korolev’s creative energies from much more important projects, such as new boosters, the Soyuz spacecraft, a Moon-landing mission, and the space station. His design team was just beginning to recover from Khrushchev’s constant interruptions when disaster struck. On January 14, 1966, Korolev died during a botched routine surgery at a hospital in Moscow. He was only 58 years old. Some of Korolev’s contributions to space technology include the powerful, legendary R-7 rocket (1956), the first artificial satellite (1957), pioneering lunar spacecraft missions (1959), the first human space flight (1961), The Dutch-American planetary astronomer Gerard a spacecraft to Mars (1962), and the first space Kuiper was the exceptionally skilled observer who in walk (1965). Even after his death, the Soviet 1944 discovered that Saturn’s largest moon, Titan, had government chose to hide Korolev’s identity by an atmosphere. In the late 1940s he helped revive publicly referring to him only as the “Chief interest in planetary astronomy, when he found Miranda, the fifth largest moon of Uranus in 1948, Designer of Carrier Rockets and Spacecraft.” and Nereid, the outermost moon of Neptune, in Despite this official anonymity, Chief Designer 1949. He also postulated the existence of a large and Academician Korolev is now properly rec- reservoir of small icy bodies beyond the orbit of ognized as the rocket engineer who started the Pluto—now called the Kuiper belt in his honor. (AIP Emilio Segrè Visual Archives, Physics Today Space Age. Collection) Kuiper, Gerard Peter 193 1949. Transitioning to Space Age astronomy, operation in 1939. At the University of Chicago, he served with distinction as a scientific adviser Kuiper progressed up through the academic ranks, to the U.S. National Aeronautics and Space becoming a full professor of astronomy in 1943. Administration (NASA) on the early lunar In an important 1941 technical paper, and planetary missions in the 1960s, especially Kuiper introduced the concept of “contact bi- NASA’s Ranger Project and Surveyor Project. naries”—a term describing close, mass-exchange Gerard Kuiper was born on December 7, binary stars characterized by accretion disks. 1905, in Harenkarspel, the Netherlands. When During World War II, he took a leave of absence he was young, two factors influenced Kuiper’s from the University of Chicago to support vari- interest in astronomy. First, his father gave him ous defense-related projects. His duties included a gift of a small telescope that he used to great special technical service missions as a member advantage because of his exceptional visual of the U.S. War Department’s ALSOS Mission, acuity. Second, he was drawn to astronomy by which assessed the state of science in Nazi the cosmological and philosophical writings of Germany during the closing days of the war. In the great French mathematician René Descartes one of his most interesting adventures, he helped (1596–1650). rescue MAX KARL PLANCK from the advancing While enrolling at the University of Leiden Soviet armies. Kuiper, an astronomer turned in September 1924, Kuiper made the acquain- commando, took charge of a military vehicle and tance of a fellow student, BARTHOLOMEUS JAN driver, dashed across war-torn Germany from the BOK, who would remain a lifelong friend. He com- U.S. lines to Planck’s location in eastern Ger- pleted a bachelor of science degree in 1927 and many, and then spirited the aging German physi- immediately pursued his graduate studies. One of cist and his wife away to a safe location in the Kuiper’s professors at the University of Leiden was western part of Germany near Göttingen. EJNAR HERTZSPRUNG, under whom he did his doc- While performing his wartime service, Kuiper toral thesis on the subject of binary stars. After still managed to make a major contribution to receiving his doctoral degree in 1933, Kuiper trav- modern planetary astronomy, the astronomical eled to the United States under a fellowship and area within which he would become the recog- conducted postdoctoral research on binary stars nized world leader. Taking a short break from his at the Lick Observatory, near San Jose, California. wartime research activities in winter 1943–44, In August 1935 he left California and spent Kuiper conducted an opportunistic spectro- a year at the Harvard College Observatory. scopic study of the giant planets Jupiter and While there, he met and later married (in June Saturn and their major moons at the McDonald 1936) Sarah Parker Fuller, whose family had do- Observatory. To his great surprise, early in 1944 nated the property on which the Harvard Oak he observed methane on the largest Saturnian Ridge Observatory stood. The couple had two moon, Titan—making the large moon the only children: a son and a daughter. In 1936 Kuiper satellite in the solar system with an atmosphere. joined the Yerkes Observatory of the University This fortuitous discovery steered Kuiper into his of Chicago. He became a naturalized American very productive work in solar system astronomy, citizen the following year. He joined other mem- especially the study of planetary atmospheres. bers of the Yerkes staff who worked with the Through spectroscopy he discovered in 1948 University of Texas in planning and developing that the Martian atmosphere contained carbon the McDonald Observatory, near Fort Davis, dioxide. In 1948 he discovered the fifth moon of Texas. The 2.1-meter reflector of this important Uranus, which he named Miranda, and then astronomical facility was dedicated and began Neptune’s second moon, Nereid, in 1949. He 194 Kuiper, Gerard Peter went on to postulate the existence of a region (1961); the Rectified Lunar Atlas (1963); and the of icy planetesimals and minor planets beyond Consolidated Lunar Atlas (1967). the orbit of Pluto. The first members of this re- Kuiper was also a pioneer in applying in- gion, now called the Kuiper belt in his honor, frared technology to astronomy and played a very would be detected in the early 1990s. influential role in the development of airborne Kuiper left the University of Chicago and infrared astronomy in the 1960s and early 1970s. joined the University of Arizona in 1960. At Starting in 1967 Kuiper used NASA’s Convair Arizona, he founded and directed the Lunar 990 jet aircraft, which was equipped with a tel- and Planetary Laboratory, making major con- escope system capable of performing infrared tributions to planetary astronomy at the dawn spectroscopy. As the aircraft flew above 40,000 of the Space Age. He produced major lunar at- feet, Kuiper and his research assistants performed lases for both the U.S. Air Force and NASA. trend-setting infrared spectroscopy measure- His research concerning the Moon in the ments of the Sun and other stars, as well as plan- 1950s and 1960s provided strong support for ets, discovering many interesting phenomena the impact theory of crater formation. Prior to that could not be observed by ground-based as- the Space Age, most astronomers held that the tronomers because of the blocking influence of craters on the Moon had been formed by vol- the denser portions of Earth’s atmosphere. canic activity. Kuiper died on December 24, 1973, while Kuiper promoted a multidisciplinary ap- on a trip to Mexico City with his wife and sev- proach to the study of the solar system, and this eral family friends. As one tribute to his numer- emphasis stimulated the creation of a new as- ous contributions to astronomy, in 1975 NASA tronomical discipline called planetary science. named its newest airborne infrared observatory, He assisted in the selection of the superior a specially outfitted C-141 jet transport air- ground-based observatory site at Mauna Kea, on craft, the Gerard P. Kuiper Observatory (KAO). the island of Hawaii. Because of his reputation This unique airborne astronomical facility oper- as an outstanding planetary astronomer, he ated out of Moffett Field, California, for more served as a scientific adviser on many of NASA’s than two decades until it was retired from service 1960 and 1970 space missions to the Moon and in October 1995. the inner planets. Kuiper was the chief scientist Kuiper received the Janssen Medal in 1947 for NASA’s Ranger Project (1961–65), which from the Astronomical Society of France and the sent robot spacecraft equipped with television Kepler Medal in 1971 from the American cameras crashing into the lunar surface. Later, Association for the Advancement of Science he helped identify suitable landing sites for and the Franklin Institute. He was also elected NASA’s Surveyor robot-lander spacecraft as well as a member of the American Academy of as the Apollo human-landing missions. Sciences in 1950. No astronomer did more in He served as principal author or general ed- the 20th century to revitalize planetary astron- itor on several major works in modern astronomy. Celestial objects carry his name or continue omy, including The Solar System, a four-volume his legacy of discovery across the entire solar sys- series published between 1953 and 1963; Stars tem, from a specially named crater on Mercury, and Stellar Systems, a nine-volume series appear- to Miranda around Uranus, to Nereid around ing in 1960; the famous Photographic Atlas of the Neptune, to an entire cluster of icy minor plan- Moon (1959); the Orthographic Atlas of the Moon ets beyond Pluto.

quipping: “If I had been rich, I probably would ᨳ Lagrange, Comte Joseph-Louis not have devoted myself to mathematics.” (Lodovico Lagrange, Luigi Lagrange, Although given an Italian family name at bap- Giuseppe Luigi Lagrangia) tism, throughout his life Lagrange preferred to (1736–1813) emphasize his French ancestry, derived from his Italian/French father’s side of the family. He would, therefore, Mathematician, Celestial Mechanics sign his name “Luigi Lagrange” or “Lodovico Expert Lagrange”—combining an Italian first name The 18th-century mathematician Joseph Lagrange with a French family name. made significant contributions to celestial me- Lagrange studied at the College of Turin, chanics. In about 1772 he identified certain enjoying instruction in classical Latin and special regions in outer space—now called the ignoring Greek geometry. But after reading SIR Lagrangian libration points—that mark the five EDMUND HALLEY’s treatise on the application of equilibrium points for a small celestial object algebra in optics, Lagrange changed his earlier moving under the gravitational influence of two career plans to become a lawyer and embraced much larger bodies. Other astronomers used his the study of higher mathematics. In 1755 he was discovery of the Lagrangian libration points to appointed professor of mathematics at the Royal find new objects in the solar system, such as the Artillery School in Turin. At the time, Lagrange Trojan Group of asteroids. His influential book, was just 19 years old and already exchanging im- Analytical Mechanics, represented an elegant pressive mathematical notes on his calculus of compendium of the mathematical principles variations with the famous Swiss mathematician that described the motion of heavenly bodies. LEONHARD EULER. In 1757 Lagrange became a Lagrange was born on January 25, 1736, in founding member of a local scientific group that Turin, Italy. His father, Giuseppe Francesco eventually evolved into the Royal Academy of Lodovico Lagrangia, was a prosperous public of- Science of Turin. He published many of his el- ficial in the service of the king of Savoy, but im- egant papers on the calculus of variations in the poverished his family through unwise financial society’s journal, Mélanges de Turin. investments and speculations. Lagrange, a gen- By the early 1760s Lagrange had earned a tle individual with a brilliant mathematical reputation as one of Europe’s most gifted math- mind, recalled his childhood poverty by later ematicians. Yet he was a humble person who did

195 196 Lagrange, Comte Joseph-Louis lunar surface is visible to an observer on Earth over a period of 30 years. This results from a complicated collection of minor perturbations in the Moon’s orbit as it travels around Earth. Soon after that award, he won another prize from the Paris Academy in 1776 for his theory on the motion of Jupiter’s moons. When Euler left Berlin in 1766 to return to St. Petersburg, he recommended to King Frederick II of Prussia that Lagrange serve as his replace- ment. Therefore, in November 1766 Frederick II invited Lagrange to succeed Euler as mathematical director of the Berlin Academy of Science of the Prussian Academy of Sciences. A little less than a year after his arrival in Berlin, Lagrange married Vittoria Conti, a cousin who had lived for an extended time with his family in Turin. The couple had no children. For two decades Lagrange worked in Berlin and during this period produced a steady number of top quality, award-winning mathematical papers. He corresponded frequently with PIERRE- SIMON MARQUIS DE LAPLACE, a contemporary French mathematician living in Paris. Lagrange won prizes from the Paris Academy of Sciences The gifted 18th-century Italian-French mathematician Joseph Lagrange made important contributions to for his mathematics in 1772, 1774, and 1780. He celestial mechanics, extending the work begun by Sir shared the 1772 Paris Academy prize with Euler Isaac Newton. In about 1772 Lagrange identified for his superb work on the challenging three- several special regions in outer space—now called the body problem in celestial mechanics—an effort Lagrangian libration points—that correspond to the five equilibrium points for a small celestial object that involved the existence and location of the moving under the gravitational influence of two much Lagrangian libration points. These five points larger bodies. Later observational astronomers, such as (usually designated as L1,L2,L3,L4, and L5) are Max Wolf, used knowledge of the Lagrangian libration the locations in outer space where a small ob- points to find new objects in the solar system, such as the Trojan Group of asteroids. (AIP Emilio Segrè Visual ject can experience a stable orbit in spite of the Archives, E. Scott Barr Collection) force of gravity exerted by two much more massive celestial bodies when they all orbit about a common center of mass. He won the 1774 not seek fame or position. He just wanted to pur- prize for another brilliant paper on the motion sue the study of mathematics with a modest on the Moon. His 1780 award-winning effort amount of financial security. In 1764 Lagrange discussed the perturbation of cometary orbits by received a prize from the Paris Academy of the planets. Sciences for his brilliant mathematical paper on However, during his 20 years in Berlin, his the libration of the Moon. The Moon’s libration health began to fail. His wife also suffered from is the phenomenon by which 59 percent of the poor health, and she died in 1783 after an Laplace, Pierre-Simon, Marquis de 197 extended illness. Her death plunged Lagrange keep himself absorbed in his thoughts about into a state of depression. After the death of mathematics. He died in Paris on April 10, 1813. Frederick II, Lagrange departed from Berlin to His numerous works on celestial mechanics pre- accept an invitation from the French king Louis pared the way for 19th-century mathematical XVI. In May 1787 Lagrange became a member astronomers to make discoveries using the sub- of the Paris Academy of Sciences, a position he tle perturbations and irregularities in the motion retained for the rest of his career despite the tur- of solar system bodies. moil of the French Revolution. Upon Lagrange’s arrival in Paris, King Louis XVI offered Lagrange apartments in the Louvre, from which comfort- ᨳ Laplace, Pierre-Simon, Marquis de able surroundings he published in 1788 his ele- (1749–1827) gant synthesis of mechanics, entitled Mécanique French analytique (Analytical mechanics), which he had Mathematician, Astronomer, Celestial written in Berlin. Mechanics Expert In May 1790 Lagrange became a member of and eventually chaired the committee of the Called the “French Newton,” Pierre-Simon Paris Academy of Sciences that standardized Laplace’s work in celestial mechanics established measurements and created the international the foundations of 19th-century mathematical system (Système Internationale, or SI) of units astronomy. Laplace extended SIR ISAAC NEWTON’s currently used throughout the world. In 1792 gravitational theory and provided a more com- Lagrange married his second wife, a much plete mechanical interpretation of the solar younger woman, named Renée Le Monnier, the system, including the subtle perturbations of daughter of one of his astronomer colleagues at planetary motions. His mathematical formula- the Paris Academy of Sciences. tions supported the discovery of Uranus (18th Following the Reign of Terror (1793), century), Neptune (19th century), and Pluto Lagrange became the first professor of analysis at (20th century). In 1796, apparently independ- the famous École Polytechnique, founded in ent of IMMANUEL KANT, Laplace introduced March 1794. Though brilliant, the aging mathe- his own version of the nebula hypothesis— matician was not an accomplished lecturer, and suggesting that the Sun and the planets had much of what he discussed sailed over the heads condensed from a primeval interstellar cloud of his audience of inattentive students. Despite of gas. his shortcomings, the notes from his calculus Laplace was born on March 23, 1749, at lectures were collected and published as the Beaumont-en-Auge, in Normandy, France. The Theory of Analytic Functions (1797) and Lessons son of a moderately prosperous farmer, he at- on the Calculus of Functions (1804)—the first tended a Benedictine priory school in Beaumont, textbooks on the mathematics of real analytical a preparatory school for future members of the functions. clergy or military. At age 16 Laplace enrolled in In 1791 the Royal Society in London made the University of Caen, where he studied theol- him a Fellow. Napoleon, the emperor of France, ogy in response to his father’s wishes. However, bestowed many honors upon the aging mathe- after two years at the university, Laplace discov- matician, making him a senator, a member of ered his great mathematical abilities and aban- the Legion of Honor, and a count of the empire. doned any plans for an ecclesiastical career. Despite the lavish political attention, Lagrange At 18 he left the university without receiv- remained a quiet academician who preferred to ing a degree and went to live in Paris. There 198 Laplace, Pierre-Simon, Marquis de applied and refined Newton’s law of gravitation to bodies throughout the solar system. Careful observations of the six known planets and the Moon indicated subtle irregularities in their orbital motions. This raised a very puzzling question: How could the solar system remain stable? Newton, for all his great scientific contributions, considered this particular problem far too complicated to be treated with mathematics. He simply concluded that “divine interven- tion” took place on occasion to keep the entire system in equilibrium. Laplace, however, was determined to solve this problem with his own excellent skills in mathematics. Eighteenth-century astronomers could not explain why Saturn’s orbit seemed to be continually expanding, while Jupiter’s orbit seemed to be getting smaller. Laplace was able to mathematically demonstrate that while there certainly were measured irregularities in the orbital motions of these giant planets, such anomalies were not cumulative, but rather Marquis Laplace is often called the “French Newton.” periodic and self-correcting. His important dis- A brilliant mathematician, his work in celestial mechanics established the foundations of 19th-century covery represented a mathematically and physi- mathematical astronomy. Laplace extended Newton’s cally sound conclusion that the solar system was gravitational theory to provide a more complete actually an inherently stable system. mechanical interpretation of the solar system. He As a result of this brilliant work, Laplace specifically addressed those subtle perturbations in planetary motions that appeared to threaten the long- became recognized as one of France’s great term stability of the solar system. His mathematical mathematicians. In 1773 Laplace became an as- formulations proved that the solar system was stable sociate member of the French Academy of and supported the discovery of Uranus (18th century), Sciences; he became a full member in 1785. Neptune (19th century), and Pluto (20th century). (AIP Emilio Segrè Visual Archives) However, as his fame grew, he more frequently acted the part of a political opportunist rather Laplace met Jean d’Alembert (1717–83) and than a great scientist, tending to forget his hum- greatly impressed the French mathematician and ble roots and rarely acknowledging his many philosopher. D’Alembert secured an appoint- benefactors and collaborators. Good fortune ment for Laplace at the prestigious École came to Laplace in 1784, when he became an Militaire. By age 19 Laplace had become the examiner at the Royal Artillery Corps. He eval- professor of mathematics at the school. uated young cadets who would soon serve in the In 1773 he began to make his important con- French army. While fulfilling this duty in 1785, tributions to mathematical astronomy. Working he had the opportunity to grade the perform- independently of, but cooperatively (through ance of and pass a 16-year-old cadet named correspondence) with COMTE JOSEPH-LOUIS Napoleon Bonaparte. The examiner position LAGRANGE, who then resided in Berlin, Laplace allowed Laplace to make direct contact with Laplace, Pierre-Simon, Marquis de 199 many of the powerful men who would run France Between 1799 and 1825, Laplace summed during its next four politically turbulent decades, up gravitational theory and completed Newton’s including the monarchy of Louis XVI, the rev- pioneering work in a monumental five-volume olution, the rise and fall of Napoleon, and the work, entitled Mécanique Céleste (Celestial restoration of the monarchy under Louis XVIII. mechanics). Laplace provided a complete me- While other great scientists, such as Antoine– chanical interpretation of the solar system and Laurent Lavoisier (1743–94), would quite liter- his application of the law of gravitation. Central ally lose their heads around him, Lagrange main- to this work is Laplace’s great discovery of the tained an ability to correctly change his views invariability of the mean motions of the plan- to suit the changing political events. ets. With this finding, he demonstrated the in- In 1787 Lagrange left Berlin and joined herent stability of the solar system and gained Laplace in Paris. Despite a rivalry between them, recognition throughout his country and the rest the great mathematical geniuses benefited from of Europe as the “French Newton.” their constant exchange of ideas. They both Laplace maintained an extraordinarily high served on the commission of the French Academy scientific output despite the tremendous politi- of Sciences that developed the metric system, al- cal changes taking place around him. He always though Laplace was eventually discharged from demonstrated political adroitness and changed the commission during the Reign of Terror. sides whenever it was to his advantage. Under Laplace married Marie-Charlotte de Courty de Napoleon he became a member and then chan- Romanges in May 1788. His wife was 20 years cellor of the French senate, received the Legion younger than Laplace and bore him two children. of Honor in 1805, and became a count of the Just before the Reign of Terror began, Laplace de- empire in 1806. Yet when Napoleon fell from parted Paris with his wife and two children, and power, Laplace quickly supported restoration of they did not return until after July 1794. the monarchy and was rewarded by King Louis Laplace published Exposition du système du XVIII, who named him a marquis in 1817. monde (The system of the world) in 1796. This Laplace made scientific contributions be- book was a five-volume popular (that is, non- yond his great work in celestial mechanics. He mathematical) treatment of astronomy and ce- provided the mathematical foundation for prob- lestial mechanics. From a historic perspective, it ability theory in two important books. In 1812 also served as the precursor for his more detailed he published his Théorie analytique des probabili- mathematical work on the subject. Laplace used tiés (Analytic theory of probability) in which he this book to introduce his version of the nebu- presented many of the mathematical tools he in- lar hypothesis, in which he suggested that the vented to apply probability theory to games of Sun and planets formed from the cooling and chance and events in nature, including astron- gravitational contraction of a large, flattened omy and collisions of comets and planets. He and slowly rotating gaseous nebula. Apparently, also wrote a popular discussion of probability Laplace was unaware that Kant had proposed a theory, Essai philosophique sur les probabilitiés (A similar hypothesis about 40 years earlier. Laplace philosophical essay on probability) that appeared wrote this book in such exquisite prose that in 1814. in 1816 he won admission to the French Laplace also explored other areas of physi- Academy—an honor only rarely bestowed upon cal science and mathematics between 1805 and an astronomer or mathematician. In 1817 he 1820. These areas included heat transfer, capil- served as president of this distinguished and ex- lary action, optics, the behavior of elastic fluids, clusive literary organization. and the velocity of sound. However, as other 200 Leavitt, Henrietta Swan physical theories began to emerge with their in- the beginning of the 20th century by professor telligent young champions, Laplace’s dominant EDWARD CHARLES PICKERING to make complex position in French science came to an end. He data analyses at the Harvard Observatory, con- died in Paris on March 5, 1827. Throughout tributed to astronomy while suffering almost France and Europe, Laplace was highly regarded total deafness, the same condition as her famous as one of the greatest scientists of all time. He coworker, ANNIE JUMP CANNON. held membership in many foreign societies, in- Leavitt was born on July 4, 1868, in Cambridge, cluding the British Royal Society, which elected Massachusetts, the daughter of a Congregational him a Fellow in 1789. minister. She attended Oberlin College and then Radcliffe College, which was then called the Society for Collegiate Instruction of Women. ᨳ Leavitt, Henrietta Swan She graduated with a B.A. degree from Radcliffe (1868–1921) in 1892, having become interested in astronomy American in her senior year, and, to pursue her new in- Astronomer terest, enrolled in further courses in astronomy. Leavitt suffered a serious illness, however, It is a startling coincidence that Henrietta Swan which left her nearly deaf, forcing her to spend Leavitt, another one of the “computers” hired at a few years at home. Eventually she volunteered

In about 1912, while working at the Harvard College Observatory, the talented American astronomer Henrietta Leavitt discovered the period-luminosity relationship for Cepheid variable stars. Her important finding permitted other astronomers, such as Harlow Shapley, to make more accurate estimates of distances in the Milky Way Galaxy. (Photo courtesy Margaret Harwood, AIP Emilio Segrè Visual Archives, Shapley Collection) Lemaître, Abbé Georges-Édouard 201 to work at the Harvard College Observatory as distance from the Earth to faraway galaxies. She a research assistant, seeking to gather experience was working on a new photographic magnitude as an astronomer. Seven years later, in 1902, scale when she died of cancer in 1921. Four years Professor Pickering hired her at 30 cents an hour later, the Swedish Academy of Sciences recog- to be one of his computers. In this capacity she nized her contribution to science by nominating drifted toward the photometric side of the asher for the Nobel Prize. A crater on the moon tronomy department, and became specialized in was named Leavitt to honor the work of deaf photographing stars as a method of determining astronomers. their magnitude. In 1904, after spending almost all of her time searching photographic plates for Cepheid vari- ᨳ Lemaître, Abbé Georges-Édouard ables, variable stars whose brightness changes due (1894–1966) to alternate expansions and contractions in vol- Belgian ume, Leavitt discovered 152 variables in the Astrophysicist, Cosmologist Large Magellanic Cloud (LMC) and 59 in the Small Magellanic Cloud (SMC). The following Georges-Édouard Lemaître was the innovative year she reported 843 new variables in the SMC. cosmologist who suggested in 1927 that a violent In 1912 Leavitt devised the “period-luminos- explosion might have started an expanding uni- ity” relationship, the direct correlation between verse. He based this hypothesis on his interpreta- the time it took a star to go from brightest to tion of ALBERT EINSTEIN’s general relativity theory dimmest, which allowed astronomers to deter- and upon EDWIN POWELL HUBBLE’s contemporary mine the exact brightness of a star. Today observation of galactic redshifts—an observa- astronomers use the period-luminosity relation- tional indication that the universe was indeed ex- ship to determine the distance of galaxies from panding. Other physicists, such as RALPH ASHER the Earth. ALPHER under the direction of GEORGE GAMOW, With this knowledge, she studied 299 plates built upon Lemaître’s pioneering work and devel- from 13 different telescopes, using logarithmic oped it into the widely accepted big bang theory equations to classify stars over 17 degrees of mag- of modern cosmology. Central to Lemaître’s model nitude and developing a standard of photographic is the idea of an initial superdense primeval atom, measurements, eventually known as the Harvard his “cosmic egg,” that started the universe in a Standard. In 1913 the International Committee colossal ancient explosion. on Photographic Magnitudes accepted the stan- Lemaître was born on July 17, 1894, in dard that Leavitt described. In the course of her Charleroi, Belgium. Prior to World War I, he studies, Leavitt also discovered four novae and studied civil engineering at the University of more than 2,400 variables, approximately half of Louvain. At the outbreak of war in 1914, he the total known to exist at the time. volunteered for service in the Belgian army and Leavitt was a member of Phi Beta Kappa, earned the Belgian Croix de Guerre for his the American Association of University Women, combat activities as an officer in the artillery the American Astronomical and Astrophysical corps. Following the war, he returned to the Society, the American Society for the Advance- University of Louvain where he pursued addi- ment of Science, and an honorary member of the tional studies in physics and mathematics. In the American Association of Variable Star Observers. early 1920s he also responded to another voca- Without Leavitt’s pioneering work, modern tional calling and became an ordained priest in astronomers would not be able to calculate the the Roman Catholic Church in 1923. After 202 Lemaître, Abbé Georges-Édouard ordination, Abbé Lemaître pursued a career distance of galaxies to their observed redshift. devoted to science, especially the area of cos- So Lemaître’s paper, previously ignored, now mology, in which he would make a major 20th- created quite a stir in the astrophysical com- century contribution. munity. He was invited to come to London to Taking advantage of an advanced studies lecture about his expanding-universe concept. scholarship from the Belgian government, During this visit, he not only presented an Lemaître traveled to England to study (1923–24) extensive account of his original theory of with SIR ARTHUR STANLEY EDDINGTON at the the expanding universe, he also introduced solar physics laboratory of the University of his idea about a “primitive atom” (sometimes Cambridge. He continued his travels and came called Lemaître’s “cosmic egg”). He was busy to the United States where he studied at the thinking not only about how to show that the Massachusetts Institute of Technology (MIT) universe was expanding but also about what from 1925–27, earning his Ph.D. in physics. caused the expansion and how this great process While at MIT, Lemaître became familiar with began. the expanding-universe concepts just being de- Lemaître cleverly reasoned that if the galax- veloped by the American astronomers HARLOW ies are now everywhere expanding, then in the SHAPLEY and EDWIN HUBBLE. past they must have been much closer together. In 1927 Lemaître returned to Belgium and In his mind, he essentially ran time backward to joined the faculty of the University of Louvain see what conditions were as the galaxies came as a professor of astrophysics, a position he held closer and closer together in the early universe. for the rest of his life. That year he published his He hypothesized that eventually a point would first major paper related to cosmology. Unaware be reached when all matter resided in a super- of similar work by the Russian mathematician dense primal atom. He further suggested that Alexander Friedmann (1888–1925), Lemaître sum instability within this primal atom would blended Einstein’s general relativity and Hubble’s result in an enormous explosion that would start early work on expanding galaxies to reach the the universe expanding. Big Bang cosmology re- conclusion that an expanding-universe model is sults directly from his concepts, although it took the only appropriate explanation for observed several decades to fully develop and establish redshifts of distant galaxies. Lemaître suggested the Big Bang theory as the currently preferred the distant galaxies serve as “test particles” that cosmological model. clearly demonstrate the universe is in a state of Lemaître’s other significant papers include expansion. Unfortunately, Lemaître’s important “Discussion on the Evolution of the Universe” insight attracted little attention within the as- (1933) and “Hypothesis of the Primeval Atom” tronomical community, mainly because he pub- (1946). His contributions to astrophysics and lished this paper in a rather obscure scientific modern cosmology were widely recognized. In journal in Belgium. 1934 he received the Prix Francqui (Francqui But in 1931 Eddington discovered Lemaître’s Award) directly from the hands of Einstein, paper and, with his permission, had the paper who had personally nominated Lemaître for translated into English and then published in the this prestigious award. In 1936 he became a Monthly Notices of the Royal Astronomical Society. member of the Pontifical Academy of Sciences Eddington also provided a lengthy commentary and then presided over this special papal scien- to accompany the translation of Lemaître’s pa- tific assembly as its president from 1960 until his per. By this time Hubble had formally announced death. In 1941, the Royal Belgian Academy of his famous law (Hubble’s law) that related the Sciences and Fine Art voted him membership. Leverrier, Urbain-Jean-Joseph 203 The Belgian government bestowed its highest award for scientific achievement upon him in 1950, and the British Royal Astronomical Society awarded him the society’s first Eddington Medal in 1953. Lemaître died at Louvain, Belgium, on June 20, 1966. However, he lived long enough to witness the detection by ARNO ALLEN PENZIAS and ROBERT WOODROW Wilson of the microwave remnants of the big bang—an event he had boldly hypothesized almost four decades earlier.

ᨳ Leverrier, Urbain-Jean-Joseph (1811–1877) French Astronomer, Mathematician, Orbital Mechanics Expert

Urbain Leverrier was a skilled celestial mechanics practitioner who mathematically predicted in 1846 (independent of JOHN COUCH ADAMS) the possible location of an eighth, as yet unde- In 1846 the French celestial mechanics practitioner tected, planet in the outer regions of the solar Urbain J. J. Leverrier mathematically predicted the system. Leverrier sent his calculations to the location of the planet Neptune so well that the Berlin Observatory and Neptune was quickly German astronomer Johann Galle was able to quickly discover Neptune by telescopic observation on the discovered by telescopic observation. evening of September 23 of that year. Leverrier’s Leverrier was born on March 11, 1811, in computational effort, accomplished independently of Saint-Lô, France. His father, a local government John Couch Adam’s, is considered to be one of the official, made a great financial sacrifice so that great triumphs of mathematical astronomy in the 19th century. (Courtesy of NASA) his son could receive a good education at the prestigious École Polytechnique. After graduation, Leverrier began his professional life as a all came about rather quickly, when the oppor- chemist. He investigated the nature of certain tunity for academic promotion at the École chemical compounds under the supervision of the Polytechnique presented itself and Leverrier French chemist Joseph Gay-Lussac (1778–1850), seized the moment. who was a professor of chemistry at the École As he settled into this new academic posi- Polytechnique. In 1836 Leverrier accepted an tion, Leverrier began investigating lingering appointment as a lecturer in astronomy at the issues in celestial mechanics. He decided to fo- same institution. Consequently, with neither cus his attention on continuing the work of previous personal interest in nor extensive PIERRE-SIMON MARQUIS DE LAPLACE in mathe- formal training for astronomy, Leverrier sud- matical astronomy and demonstrate with even denly found himself embarking on an astro- more precision the inherent stability of the so- nomically oriented academic career. The process lar system. Following the suggestion given him 204 Leverrier, Urbain-Jean-Joseph in 1845 by DOMINIQUE-FRANÇOIS-JEAN ARAGO, Bristling with success, fame, and good for- he began investigating the subtle perturbations tune, Leverrier pressed his luck in 1846 by ap- in the orbital motion of Uranus, the outer plying mathematical astronomy to explain mi- planet discovered by SIR WILLIAM HERSCHEL nor perturbations in the solar system. This time, some 50 years prior. In 1846 Leverrier, follow- he looked inward at the puzzling behavior in the ing the suggestions of other astronomers orbital motion of Mercury, the innermost known (among them FRIEDRICH WILHELM BESSEL), hy- planet. Unfortunately, Leverrier failed quite pothesized that an undiscovered planet lay be- miserably with his hypothesis that the observed yond the orbit of Uranus. He then examined perturbations in Mercury were due to the pres- the perturbations in the orbit of Uranus and ence of an inner undiscovered planet he called used the law of gravitation to calculate the Vulcan, or possibly even a belt of asteroids or- approximate size and location of this outer biting closer to the Sun. Many 19th-century planet. Unknown to Leverrier, the British as- observational astronomers, including SAMUEL tronomer Adams had made similar calcula- HEINRICH SCHWABE, searched in vain for tions. However, during this period, Sir George Vulcan. ALBERT EINSTEIN’s general relativity Biddell Airy (1801–92), Britain’s Astronomer theory in the early part of the 20th century ex- Royal, basically ignored Couch’s calculations plained the perturbations of Mercury without re- and correspondence about the possible location sorting to Leverrier’s hypothetical planet. of a new outer planet. In 1854 Leverrier succeeded Arago as the In mid-September 1846 Leverrier sent a de- director of the Paris Observatory, founded in tailed letter to the German astronomer JOHANN 1667 by King Louis XIV who appointed GOTTFRIED GALLE at the Berlin Observatory GIOVANNI DOMENICO CASSINI as its first direc- telling Galle where to look in the night sky for tor. This observatory served as the national ob- a planet beyond Uranus. On the evening of servatory of France and was the first such na- September 23, 1846, Galle found Neptune af- tional observatory established in the era of ter about an hour of searching. The French- telescopic astronomy. Leverrier focused his ef- German team of mathematical and observa- forts from 1847 until his death on producing tional astronomers had beaten the British more accurate planetary data tables and on astronomical establishment to one of the 19th creating a set of standard references for use by century’s greatest discoveries. In France Leverrier astronomers. experienced the celebrity that often accompa- Unfortunately, Leverrier was an extremely nies a widely recognized scientific accomplish- unpopular director, who ran the Paris Observatory ment. He received appointment to a specially like a tyrant. By 1870 his coworkers had had created chair of astronomy at the University of enough and he was replaced as director. However, Paris, and the French government made him he was reinstated to the directorship in 1873 an officer in the Legion of Honor. Leverrier when his successor, Charles-Eugene Delaunay received international credit for mathematical (1816–72) died suddenly. This time, however, he discovery of Neptune, which was immediately served under the very watchful authority of a di- followed by controversy. The Royal Society of recting council. London awarded him its Copley Medal in Leverrier died in Paris on September 23, 1846 and elected him a Fellow in 1847. As a 1877. His role in celestial mechanics and the point of scientific justice, Adams received the predictive discovery of Neptune represents one Copley Medal in 1848 for his discovery of of the greatest triumphs of mathematical as- Neptune. tronomy. Lippershey, Hans 205 governing political body that had control of ᨳ Lippershey, Hans (Hans Lippersheim, foreign affair and defense. By 1581 the estates Jan Lippersheim) repudiated allegiance to Spain and formed the (ca. 1570–ca. 1619) Republic of the Seven United Netherlands—the Dutch nucleus of the Dutch republic that grew into a Optician 17th-century naval and economic power. Hans Lippershey is the Dutch optician generally Several historic anecdotes describe how the credited with the invention of the telescope, be- telescope came into being. Hans Lippershey cause he was the first among his contemporaries generally appears at the center of most of these to attempt to patent a simple, two-lens viewing stories by virtue of his being the first person to instrument in 1608. However, once news of actually apply for a patent for a kijker, or “looker.” this new type of optical instrument circulated One of the most popular stories suggests that an through western Europe, creative persons such apprentice in Lippershey’s lens-making shop was as GALILEO GALILEI and JOHANNES KEPLER tinkering with various arrangements of lenses quickly recognized the telescope’s important role and noticed that a special combination two in observational astronomy and spearheaded a short-focus convex lenses placed at the opposite litany of design improvements that continues up ends of a long tube would make distant objects to modern times. appear nearer. Lippershey immediately realized The Dutch lens maker (optician) Lippershey the potential military significance of this device was born in approximately the year 1570 in and applied for a patent from the States-General the town of Wesel, Germany. He moved to through the local government of Zeeland. Middelburg, the capital city of the province of The oldest surviving record concerning the Zeeland, in what is now the modern Kingdom invention of the telescope is a letter, dated of the Netherlands. Practicing his craft as a lens September 25, 1608, from the government of and spectacle-maker, he married there in 1594, the Estate of Zeeland to the States-General of the and became a citizen. At the time, Middelburg Seven United Netherlands, requesting that the was a prosperous city experiencing an influx of States-General assist the bearer of the letter Dutch Protestant refugees who were fleeing from (Lippershey) “who claims to have a certain de- the Spanish invasion of the southern provinces vice by means of which all things at a very great of the Netherlands (now modern Belgium). In distance can be seen as if they were nearby.” the late 16th century this region, like much of Members of the States-General discussed western Europe, was in a state of political and Lippershey’s patent application on October 2, religious turmoil. The Dutch people living in 1608, and then denied the application, stating northern provinces of the region known as the that the basic concept for such a device could Seventeen Provinces of the Netherlands had not be kept secret. embraced Protestantism and were striving for Members of the assembly were quite correct more political freedom from the Catholic king on this point. Upon learning about the Dutch of Spain. Through the Union of Utrecht (1579), telescope from his son, Galileo immediately William the Silent, prince of Orange, led a con- fashioned his own devices in 1609, looked into federation of seven northern provinces called the night sky, and started the field of telescopic estates (Holland, Zeeland, Utrecht, Gelderland, astronomy. However, the States-General of the Overrijssel, Groningen, and Friesland). The es- Seven Netherlands did reward Lippershey for his tates retained individual sovereignty, but were efforts. The governing body awarded him a gen- represented jointly in the States-General, a erous fee (900 florins) to modify his telescope 206 Lockyer, Sir Joseph Norman into a binocular device, which they considered the European Continent, Lockyer began a career more practical for military applications. as a civil servant in the War Office of the British Other Dutch lens makers also claimed credit government. While serving in this capacity for inventing the telescope. As the States- from approximately 1857–69, he also became General was reviewing Lippershey’s patent re- an avid amateur astronomer, enthusiastically quest, another patent request arrived from Jacob pursuing this scientific hobby in every spare mo- Metius (1580–1628), an instrument maker from ment. Following observation of a solar eclipse Alkmaar, a city in the northern part of the in 1858, he constructed a private observatory at Netherlands. Metius sought a patent for his “per- his home. In 1861 while working at the War spicilla” in October 1608, barely two weeks af- Office in London, he married and settled in ter Lippershey initiated his request. Several years Wimbledon. Lockyer made several important as- later, Zacharias Janssen (1580–ca. 1638), an- tronomical discoveries in the 1860s and turned other Dutch optician from Middelburg, claimed to astronomy and science on a full-time basis at credit for inventing the telescope. At this point, the end of that decade. on the basis of surviving historic records, it is While still an amateur astronomer in the impossible to establish exactly who really “in- 1860s, Lockyer decided to apply the emerging vented” the telescope or precisely when the field of spectroscopy to study the Sun. This de- creative moment took place. Lippershey holds cision enabled Lockyer to join two other early the favored position because his request for astronomical spectroscopists, Janssen and SIR patent is the oldest surviving record of the pe- WILLIAM HUGGINS, in extending the pioneering riod. Sometime in 1619, he died in Middelburg. work of ROBERT WILHELM BUNSEN and GUSTAV ROBERT KIRCHHOFF. Lockyer’s efforts directly contributed to development of modern astro- ᨳ Lockyer, Sir Joseph Norman physics. In 1866 he started spectroscopic obser- (1836–1920) vation of sunspots. He observed Doppler shifts British in their spectral lines and suggested that strong Physicist, Astronomer, Spectroscopist convective currents of gas existed in the outer regions of the Sun—a region he named the Helium is the second most abundant element in chromosphere. the universe, yet its existence was totally un- By 1868 he devised a clever method of known prior to the late 19th century. In 1868 acquiring the spectra of the solar prominences the British physicist Sir Joseph Norman Lockyer without waiting for an eclipse of the Sun to take collaborated with the French astronomer Pierre- place. A prominence is a cooler, cloudlike fea- Jules-César Janssen (1824–1907) and discovered ture found in the Sun’s corona. Prominences the element helium through spectroscopic stud- often appear around the Sun’s limb during total ies of solar prominences. However, it was not un- solar eclipses. Lockyer discovered that he could til 1895 that the Scottish chemist Sir William observe the spectra of prominences without Ramsay (1852–1916) finally detected the gas in eclipse conditions if he passed light from the Earth’s atmosphere. Lockyer also founded the very edge of the Sun through a prism. prestigious scientific periodical Nature and pio- Almost simultaneously, but independent of neered the field of archaeological astronomy. Lockyer, the French astronomer Janssen also de- Lockyer was born on May 17, 1836, in veloped this method of obtaining the spectra of Rugby, England. Following a traditional post- solar prominences. Janssen and Lockyer reported secondary education outside of Great Britain on their identical discoveries at the same meeting Lockyer, Sir Joseph Norman 207 of the French Academy of Sciences. Officials of compounds that had dissociated into unusual the academy wisely awarded, 10 years later, both combinations of simpler substances, making men a special “joint medallion” to honor their their spectral signatures unrecognizable. An simultaneous and independent contribution to American astrophysicist, Ira Bowen (1898–1973) solar physics. solved the mystery of “nebulium” in the 1920s, In 1868 Janssen used his newly developed when he demonstrated that the green emission spectroscopic technique to investigate promi- lines from certain nebulas were actually caused nences during a solar eclipse expedition to by forbidden electron transitions taking place in Guntur, India. Janssen reported an unknown oxygen and nitrogen under various excited states bright orange line in the spectral data he col- of ionization. Lockyer’s theory of dissociation lected. Lockyer reviewed Janssen’s report and was definitely on the right track. then compared the position of the reported un- Lockyer was an inspiring lecturer. In 1881 known orange line to the spectral lines of all the he developed an interesting new course in as- known chemical elements. When he could not trophysics at the Royal College of Science (to- find any correlation, Lockyer concluded that this day part of the Imperial College). By 1885 he line was the spectral signature of a yet undis- received an academic promotion to professor of covered element. He named the element he- astrophysics, making him the world’s first pro- lium, after Helios, the sun god in Greek fessor in this discipline. The Royal College also mythology. Because spectroscopy was still in its constructed the Solar Physics Observatory at infancy, most scientists waited for almost three Kensington to support his research and teaching decades before accepting Lockyer’s identification activities. Lockyer served as the observatory’s di- of a new element in the Sun. Wide scientific ac- rector until approximately 1913, when the fa- ceptance of Lockyer’s discovery of helium took cility moved to a new location at Cambridge place only after Ramsay detected the presence University. of this elusive gas within Earth’s atmosphere During travel to Greece and Egypt in the in 1895. early 1890s, Lockyer noticed how many ancient In 1869 Lockyer won election as a fellow to temples had their foundations aligned along an the Royal Society. He decided to abandon his east-west axis—a consistent alignment that sug- civil service career so he could pursue astron- gested to him some astronomical significance omy and science full time. That year he founded with respect to the rising and setting Sun. To the internationally acclaimed scientific journal pursue this interesting hypothesis, Lockyer vis- Nature; he would serve as its editor for almost 50 ited Karnack, one of the great temples of ancient years. Between 1870 and 1905, Lockyer remained Egypt. He discussed the hypothesis in his 1894 an active solar astronomer and personally partici- book, The Dawn of Astronomy. This book is of- pated in eight solar eclipse expeditions. ten regarded as the beginning of archaeological In 1873 Lockyer turned his attention to stel- astronomy—the scientific investigation of the lar spectroscopy and introduced his theory of astronomical significance of ancient structures atomic and molecular dissociation in an attempt and sites. to explain puzzling green lines in the spectra of As part of this effort, Lockyer studied certain nebulas. He disagreed with fellow British Stonehenge, an ancient site located in south spectroscopist Huggins who suggested that the England. However, he could not accurately de- green lines came from an unknown element he termine the site’s construction date. As a result, called “nebulium.” Instead, Lockyer hypothe- he could not confidently project the solar cal- sized that they might actually be from terrestrial endar back to a sufficiently precise moment in 208 Lowell, Percival history that would reveal how the curious cir- primarily to support his personal interest in cular ring of large vertical stones topped by Mars and his aggressive search for signs of an capstones might be connected to some astro- intelligent civilization there. Driving Lowell nomical practice of the ancient Britons. was his misinterpretation of GIOVANNI VIRGINIO Lockyer’s visionary work clearly anticipated the SCHIAPARELLI’s use of the word canali in an 1877 results of modern studies of Stonehenge—results technical report in which the Italian astronomer that suggest the site could have served as an an- discussed his telescopic observations of the cient astronomical calendar around 2000 B.C.E. Martian surface. Lowell took this report as early Lockyer was a prolific writer. His best-known observational evidence of large, water-bearing published works include Studies in Spectrum canals built by intelligent beings. Lowell wrote Analysis (1872), The Chemistry of the Sun (1887), books, such as Mars and Its Canals (1906) and and The Sun’s Place in Nature (1897). In 1874 Mars As the Abode of Life (1908) to commu- the Royal Society of London recognized his nicate his Martian civilization theory to the important achievements in solar physics and public. While his nonscientific (but popular) astronomical spectroscopy and awarded him its interpretation of observed surface features on Rumford Medal. Mars proved quite inaccurate, his astronomical In 1897 Lockyer joined the Order of Knight instincts were correct for another part of the so- Commander of the Bath (KCB), a royal honor lar system. Based on perturbations in the orbit bestowed upon him by Britain’s Queen Victoria of Neptune, Lowell predicted in 1905 the exis- for his discovery of helium and lifetime contri- tence of a planet-sized, trans-Neptunian object. butions to science. After the Solar Physics In 1930 CLYDE WILLIAM TOMBAUGH, working at Observatory at the Royal College was moved the Lowell Observatory, discovered Lowell’s from Kensington to Cambridge University, Sir Planet X and called the tiny planet Pluto. Lockyer remained active in astronomy by con- Lowell was born on March 13, 1855, in structing his own private observatory in 1912 in Boston, Massachusetts, into an independently Sidmouth, Devonshire. This facility, called the wealthy family. His brother Abbott Lowell be- Norman Lockyer Observatory, currently oper- came president of Harvard University and his ates under the supervision of an organization of sister Amy became an accomplished poet. amateur astronomers. Following graduation with honors from Harvard Lockyer, the British civil servant who en- University in 1876, Lowell devoted his time to tered astronomy in the 1850s as a hobby and business and to traveling throughout the Far became one of the great pioneers in astrophysics East. Based on his experiences between 1883 and and stellar spectroscopy, died on August 16, 1895, Lowell published several books about the 1920, at Salcombe Regis, Devonshire. Far East, including: Chosön (1886), The Soul of the Far East (1888), Noto (1891) and Occult Japan (1895). ᨳ Lowell, Percival He was not especially attracted to astron- (1855–1916) omy until later in life, when he discovered an American English translation of Schiaparelli’s 1877 Mars Astronomer observation report that presented the Italian word canali. As originally intended by Schiaparelli, Late in the 19th century Percival Lowell estab- canali simply meant “channels.” In the early lished a private astronomical observatory, the 1890s Lowell unfortunately became erroneously Lowell Observatory, near Flagstaff, Arizona, inspired by the thought of artificially constructed Lowell, Percival 209 canals on Mars, the presence of which he then intelligent civilization on Mars struggling to dis- extended to imply the existence of an advanced tribute water from the planet’s polar regions with alien civilization. From this point on, Lowell a series of elaborate giant canals. While most decided to become an astronomer and dedicate planetary astronomers shied away from such un- himself to a detailed study of Mars. founded speculation, science fiction writers Unlike other observational astronomers, flocked to Lowell’s hypothesis—a premise that however, Lowell was independently wealthy and survived in various forms until the dawn of the already had a general idea of what he was search- Space Age. On July 14, 1965, NASA’s Mariner ing for—evidence of an advanced civilization of 4 spacecraft flew past the Red Planet and re- the Red Planet. To support this quest, he spared turned images of its surface that shattered all pre- no expense and sought the assistance of profes- vious speculations and romantic myths about a sional astronomers. William Henry Pickering series of large canals built by a race of ancient (1858–1938) from the Harvard College Obser- Martians. vatory, and his assistant ANDREW ELLICOTT Since the Mariner 4 encounter with Mars, DOUGLASS helped Lowell find an excellent “see- an armada of other robot spacecraft have also ing” site upon which to build a private observa- studied Mars in great detail. No cities, canals, tory for the study of Mars, which Lowell nor intelligent creatures have been found on the constructed near Flagstaff, Arizona. Called the Red Planet. What has been discovered, however, Lowell Observatory, it was opened in 1894 and is an interesting “halfway” world. Part of the housed a top quality 24-inch refractor telescope Martian surface is ancient, like the surfaces of that allowed Lowell to perform some excellent the Moon and Mercury, while part is more planetary astronomy. However, his “observations” evolved and Earthlike. In the 21st century, ro- tended to anticipate the things he reported, like bot spacecraft and eventually human explorers oases and seasonal changes in vegetation. Other will continue Lowell’s quest for Martians—but astronomers, including Douglass, would label this time they will hunt for tiny microorgan- these blurred features simply indistinguishable isms possibly living in sheltered biological natural markings. As Lowell more aggressively niches or else possible fossilized evidence of an- embellished his Mars observations, Douglass cient Martian life-forms from the time when began to question Lowell’s interpretation of these the Red Planet was a milder, kinder and wetter data. Perturbed by Douglass’s scientific challenge, world. Lowell simply fired him in 1901 and then hired While Lowell’s quest for signs of intelligent Vesto M. Slipher to fill the vacancy. life on Mars may have lacked scientific rigor by In 1902 the Massachusetts Institute of a considerable margin, his astronomical instincts Technology (MIT) gave Lowell an appointment about “Planet X”—his name for a suspected icy as a nonresident astronomer. He was definitely world lurking beyond the orbit of Neptune— an accomplished observer, but often could not proved technically correct. In 1905 Lowell be- resist the temptation to greatly stretch his in- gan to make detailed studies of the subtle per- terpretation of generally fuzzy and optically turbations in Neptune’s orbit and predicted the distorted surface features on Mars into observa- existence of a planet-sized trans-Neptunian tional evidence of artifacts from an advanced object. He then began an almost decade-long civilization. With such books as Mars and Its telescopic search, but he failed to find this elu- Canals Lowell became popular with the general sive object. In 1914, near the end of his life, public, which drew excitement from his specu- he published the negative results of his search for lative (but scientifically unproven) theory of an Planet X and bequeathed the task to some future 210 Lowell, Percival astronomer. Lowell died in Flagstaff, Arizona, on a major private astronomical observatory. An of- November 12, 1916. ten forgotten milestone in astronomy took place In 1930, Tombaugh, a farm boy turned am- at the Lowell Observatory in 1912, when Slipher ateur astronomer, fulfilled Lowell’s quest. Hired made early measurements of the Doppler shift of by Slipher to work as an observer at the Lowell distant nebulas. He found many to be receding Observatory and search for Planet X, Tombaugh from Earth at a high rate of speed. Slipher’s work made use of the blinking comparator technique provided EDWIN POWELL HUBBLE the basic di- to find the planet Pluto on February 18, 1930. rection he needed to discover the expansion of The Lowell Observatory still functions today as galaxies.

the return of comet Halley sometime in 1758 and ᨳ Messier, Charles made his own calculations in an attempt to be (1730–1817) the first to detect its latest visit. French Delisle assigned the task of searching for Astronomer Halley’s comet to his young clerk. Messier searched Charles Messier, the first French astronomer to diligently throughout 1758 but mostly in the spot comet Halley during its anticipated return wrong location, because Delisle’s calculations in 1758, was an avid “comet hunter.” He per- were in error. However, in August of that year, sonally discovered at least 13 new comets and Messier discovered and tracked a different comet assisted in the codiscovery of at least six others. for several months. He detected a distant fuzzy In 1758 he began compiling a list of nebulas object that he thought was the anticipated and star clusters that eventually became the comet Halley. However, to Messier’s frustration, famous noncomet Messier Catalogue. He assem- the object did not move, so he realized it had to bled this list of “unmoving” fuzzy nebulas and be a nebula. On September 12, 1758, he care- star clusters primarily as a tool for astronomers fully noted its position in his observation log. engaged in comet searches. This particular “fuzzy patch” was actually the Messier was born in Badonviller, Lorraine, Crab Nebula—a fuzzy celestial object previously France, on June 26, 1730. His father died when discovered by another astronomer. Messier was a young boy and the family was Cometography, that is, “comet hunting,” thrust into poverty. The appearance of a multi- was one of the great triumphs of 18th-century tailed comet and the solar eclipse of 1748 stim- astronomy. Messier enjoyed the thrill and ex- ulated his childhood interest in astronomy. citement that accompanied a successful quest Messier went to Paris in 1751 and became a clerk for a new “hairy star”—the early Greek name for Joseph Nicolas Delisle (1688–1768), who (κοµετεζ) for a comet. The young clerk- was then the astronomer of the French navy. astronomer also realized that fuzzy nebulas and Messier’s ability to carefully record data attracted star clusters caused time-consuming false alarms. Delisle’s attention, and soon the young clerk was He had the solution—prepare a list of noncomet cataloging observations made at Hôtel de Cluny, objects, such as nebulas and star clusters. In the including the transit of Mercury in May 1753. 18th century, astronomers used the word nebula Delisle, like many other astronomers, anticipated to describe any fuzzy, blurry, luminous celestial

211 212 Michelson, Albert Abraham object that could not be sufficiently resolved by tions have generally been superseded by the available telescopes. The fuzzy object he mistook designations presented in the New General for a comet in late August 1758 eventually be- Catalogue of Nebulae and Clusters of Stars (NGC) came object number one (M1) in the Messier published in 1888 by the Danish astronomer Catalogue—namely, the great Crab Nebula in Johan Dreyer (1852–1926). the constellation Taurus. In 1764 Messier was elected as a foreign Despite false alarms caused by nebulas and member of the Royal Society of London. In 1770 his discovery of another comet, Messier kept vig- he became a member of the Paris Academy of orously searching for comet Halley throughout Sciences, and the astronomer of the French 1758. Then, on the evening of December 25, navy, officially assuming the position formerly Christmas Day, an amateur German astronomer held by Delisle, who had retired six years earlier. named Georg Palitzch became the first observer However, Messier lost this position during the to catch a glimpse of the greatly anticipated French Revolution and his observatory at the comet, as it returned to the inner portions of the Hôtel de Cluny fell into general disrepair. solar system. About a month later, on the In 1806 Napoleon Bonaparte (1769–1821) evening of January 21, 1759, Messier succeeded awarded Messier the cross of the Legion of in viewing this comet and became the first Honor—possibly because Messier had openly French astronomer to have successfully done so and rather unscientifically suggested in a tech- during the comet’s 1758–59 journey through nical paper that the appearance of the great perihelion. His work earned him recognition at comet of 1769 correlated with Napoleon’s birth. the highest levels. The French king Louis XV This politically inspired act of astrology is the fondly referred to Messier as “the comet ferret.” last known attempt by an otherwise knowledge- After the passage of comet Halley, Messier able astronomer to tie the appearance of a comet continued to search for new comets and to as- to a significant historic event on Earth. Messier semble his noncomet list of nebulas and star clus- died in Paris on April 11, 1817. Most of the ters. By 1764 this list contained 40 objects, 39 of comets he so eagerly sought have been forgot- which he personally verified through his own ob- ten, but his famous noncomet list of celestial observations. Within the resolution limits of the jects serves as a permanent tribute to one of the telescopes of his day, Messier’s objects included 18th century’s most successful “comet hunters.” nebulas, star clusters, and distant galaxies. By 1771 he had completed the first version of his famous noncomet list and published it as ᨳ Michelson, Albert Abraham the Catalogue of Nebulae and of Star Clusters in (1852–1931) 1774. This initial catalog contained 45 Messier German/American objects. He completed the final version of his Physicist noncomet list of celestial objects in 1781. It contained 103 objects (seven additional were How fast does light travel? Physicists have pon- added later) and was published in 1784. Messier dered that challenging question since GALILEO designated each of the entries in the list by a GALILEI’s time. In the late 1880s Albert Michelson separate number, prefixed by the letter M. For provided the first very accurate answer—a ve- example, Messier object M1 represented the locity slightly less than 300,000 kilometers per Crab Nebula, and object M31 represented the second. He received the 1907 Nobel Prize in Andromeda Galaxy. His designations persist to physics for his innovative optical measurements the present day, although the Messier designa- and precision measurements. Michelson, Albert Abraham 213 study advanced optics in Europe. In Germany he visited the University of Berlin and the Uni- versity of Heidelberg. He also studied at the Collège de France and the École Polytechnique in Paris. In 1881 he resigned from the U.S. Navy and then returned to the United States to accept an appointment as a professor of physics at the Case School in Applied Science in Cleveland, Ohio. Michelson had conducted some preliminary experiments in measuring the speed of light in 1881 at the University of Berlin. Once settled in at Case, he refined his experimental techniques and obtained a value of 299,853 kilometers per second. This value remained a stan- The Nobel laureate Albert Michelson had a lifelong dard within physics and astronomy for more than passion for precision optical instruments (like the type two decades and changed only when Michelson he is inspecting in the photograph) and extremely himself improved the value in the 1920s. accurate measurements of the velocity of light. He In the early 1880s, with financial support was the first American scientist to receive a Nobel Prize in physics and experienced this great honor in from the Scottish-American inventor Alexander 1907 for his innovative optical experiments and Graham Bell (1847–1922), Michelson con- precision measurements. (AIP Emilio Segrè Visual structed a precision optical interferometer—an Archives) instrument that splits a beam of light into two paths and then reunites the two separate beams. Michelson was born in Strelno, Prussia (now Should either beam experience travel across dif- Strzelno, Poland) on December 19, 1852. When ferent distances or at different velocities (due to he was two years old, his family immigrated to passage through different media), the reunited the United States, settling first in Virginia City, beam would appear out of phase and produce a Nevada, and then in San Francisco, California, distinctive arrangement of dark and light bands where he received his early education. In 1869 called an interference pattern. Using an inter- Michelson received an appointment from ferometer in 1887, Michelson collaborated President Grant to the U.S. Naval Academy in with the American physicist William Morley Annapolis, Maryland. More skilled as a scientist (1838–1923) to perform one of the most im- than as a seaman, he graduated from Annapolis portant “failed” experiments ever undertaken in in 1873 and received his commission as an en- science. sign in the U.S. Navy. Following two years of Now generally referred to as the Michelson- sea duty, Michelson became an instructor in Morley experiment, this experiment used an in- physics and chemistry at the academy, then in terferometer to test whether light traveling in 1879 an assignment to the navy’s Nautical the same direction as Earth through space moves Almanac Office in Washington, D.C. There he more slowly than light traveling at right angles met and worked with SIMON NEWCOMB who, to Earth’s motion. Their failure to observe ve- among many other things, was attempting to locity differences in the perpendicular beams of measure the velocity of light. light dispelled the prevailing concept that light After about a year at the Nautical Almanac traveled through the universe using some sort of Office, Michelson took a leave of absence to invisible “cosmic ether” as the medium. Michelson 214 Michelson, Albert Abraham had reasoned that when rejoined in the inter- pathway between two mountain peaks in California ferometer the two beams of light should be out that he had carefully surveyed to an accuracy of of phase due to Earth’s motion through the pos- less than 2.5 centimeters. With a specially de- tulated ether. But their very careful measure- signed revolving eight-sided mirror, he measured ments failed to detect any interfering influence the velocity of light as 299,798 kilometers per of the hypothetical, all-pervading ether. Of second. After retiring from the University of course, the real reason their classic experiment Chicago in 1929, Michelson joined the staff of failed is now very obvious—there isn’t any “cos- the Mount Wilson Observatory in California. In mic ether.” Michelson’s work was exact, precise, the early 1930s he bounced light beams back and and provided a very correct, albeit null, result. forth in an evacuated tube to produce an ex- The absence of ether gave ALBERT EINSTEIN im- tended 16-kilometer pathway to measure optical portant empirical evidence upon which he con- velocity in a vacuum. The final result, an- structed his special relativity theory in 1905. nounced in 1933, after his death, was a velocity The Michelson-Morley experiment provided the of 299,794 kilometers per second. To appreciate first direct evidence that light travels at a con- the precision of Michelson’s work, the currently stant speed in space—the very premise upon accepted value of the velocity of light in a vac- which all of special relativity is built. uum is 299,792.5 kilometers per second. From 1889 to 1892 Michelson served as a Michelson died in Pasadena, California, on professor of physics at Clark University in May 9, 1931. His most notable scientific works Worcester, Massachusetts. He then left Clark include Velocity of Light (1902), Light Waves and University to accept a position in physics in the Their Uses (1899–1903) and Studies in Optics newly created University of Chicago. He re- (1927). In addition to being the first American mained affiliated with this university until his scientist to win a Nobel Prize, Michelson re- retirement in 1929. In 1907 Michelson became ceived numerous other awards and international the first American scientist to receive the Nobel recognition for his contributions to physics. He Prize in physics. He received this distinguished became a member (1888) and served as presi- international award because of his excellence in dent of (1923–27) the American National the development and application of precision Academy of Sciences. The Royal Society of optical instruments. London made him a foreign Fellow in 1902 During World War I, he rejoined the U.S. and presented him its Copley Medal in 1907. Navy. Following this wartime service, Michelson He also received the Draper Medal from the returned to the University of Chicago and turned American National Academy of Sciences in his attention to astronomy. Using a sophisticated 1912, the Franklin Medal from the Franklin improvement of his optical interferometer, he Institute in Philadelphia in 1923, and the Gold measured the diameter of the star Betelgeuse in Medal of the Royal Astronomical Society in 1920. His achievement represented the first ac- 1923. His greatest scientific accomplishment curate determination of the size of a star, ex- was the accurate measurement of the velocity cluding the Sun. In 1923 he resumed his lifelong of light—a physical “yardstick” of the universe quest to improve the measurement of the velocity and an important constant throughout all of of light. This time he used a 35-kilometer-long modern physics.

libraries in Washington, D.C., Newcomb began ᨳ Newcomb, Simon to study mathematics extensively on his own. By (1835–1909) 1857 Newcomb’s mathematical aptitude caught Canadian/American the attention of the great American physicist Astronomer, Mathematician Joseph Henry (1797–1878), who helped him Simon Newcomb was one of the 19th century’s find employment as a computer (that is, a per- leading mathematical astronomers. While work- son who does precise astronomical calculations) ing for the Nautical Almanac Office of the U.S. at the U.S. Nautical Office, then located at Naval Observatory, he prepared extremely ac- Harvard University in Cambridge, Massachusetts. curate tables that predicted the position of solar In 1858 Newcomb graduated from Harvard system bodies. Before the arrival of navigation University with a bachelor of science degree; he satellites, sailors found their way at sea using an continued there for three years afterward as a accurate knowledge of the positions of natural graduate student. celestial objects, such as the Sun, the Moon, and Newcomb received an appointment as a other planets. The more accurate the available professor of mathematics for the U.S. Navy in nautical tables, the more precisely sea captains 1861 and was assigned to duty at the U.S. Naval could chart their voyages. In 1860 Newcomb Observatory in Washington, D.C. A year earlier presented a trend-busting astronomical paper in he had made his initial mark on mathematical which he correctly speculated that the main-belt astronomy when he presented a paper demon- asteroids did not originate from the disinte- strating that the orbits of the asteroids (minor gration of a single ancient planet, as was then planets) did not diverge from a single point. His commonly assumed. careful calculations dismantled the then-popular Newcomb was born on March 12, 1835, in hypothesis in solar system astronomy that the Wallace, Nova Scotia, Canada. As the son of main belt of minor planets between Mars and an itinerant teacher, he received little formal Jupiter was the remnants of a single ancient schooling, and what education he did experience planet that tore itself apart. Unfortunately, in childhood took place privately. Newcomb Newcomb’s interesting paper was quickly over- moved to the United States in 1853 and, much shadowed by the start of the Civil War in April like his father, worked as a teacher in Maryland 1861 and the pressing needs of the U.S. Navy between 1854 and 1856. While proximate to the for more accurate nautical charts.

215 216 Newcomb, Simon Observatory’s new 26-inch telescope, which had recently been authorized by Congress. Newcomb also planned the tower and dome, and supervised construction. Later, he assisted in the development of the Lick Observatory in California. Although primarily a mathematical astronomer rather than a skilled observer, Newcomb participated in a number of astronomical expeditions while serving the U.S. Naval Observatory. He traveled to Gibraltar in 1870–71 to observe an eclipse of the Sun and to the Cape of Good Hope, at the southern tip of Africa, in 1882 to observe a transit of Venus. In 1877 he received promotion to senior professor of mathematics in the U.S. Navy (a position with the equivalent naval rank of captain) and was in charge of the office of an important publication, the American Ephemeris and Nautical Almanac. Newcomb had a number of military and civilian assistants helping him produce the Nautical Almanac, including ASAPH HALL, the American astronomer who discovered the two tiny moons of Mars in 1877 while a staff member at the U.S. Naval Observatory. By the 1890s, as American naval power reached around the globe, Newcomb supported its needs for improved navigation by producing the highest-quality nautical almanac yet devel- This photograph shows one of the 19th century’s oped. To accomplish this, he supervised a large leading mathematical astronomers, Simon Newcomb, staff of astronomical computers (that is, human at his desk. As the superintendent of the American Nautical Almanac Office until his retirement in 1897, beings) and enjoyed control of the largest ob- Newcomb prepared extremely accurate tables that servatory budget in the world. To support the predicted the position of solar system bodies. His production of a high-quality Nautical Almanac, efforts led to a global standardization of astronomical Newcomb pursued, produced, and promoted a reference data and supported great improvements in navigation at sea. (AIP Emilio Segrè Visual Archives, new and more accurate system of astronomical W. F. Meggers Gallery of Nobel Laureates) constants that became the world standard by 1896. He retired from his position as superintendent of the U.S. Nautical Almanac Office in At the U.S. Naval Observatory, Newcomb 1897 and received promotion to the rank of rear focused all his mathematical talents and ener- admiral in 1905. gies on preparing the most accurate nautical Newcomb was also a professor of mathemat- charts ever made (before the era of electronic ics and astronomy at Johns Hopkins University computers). One of his first major responsibili- between 1884 and 1893. He served as editor of ties was to negotiate the contract for the Naval the American Journal of Mathematics for many years Newton, Sir Isaac 217 and as president of the American Mathematical Society from 1897–98. He was a founding member and the first president (1899–1905) of the American Astronomical Society. He wrote numerous technical papers, including “An Investigation of the Orbit of Uranus, with General Table of Its Motion” (1874) and “Measurement of the Velocity of Light” (1884)— a paper that brought him in contact with a brilliant young scientist named ALBERT ABRAHAM MICHELSON. A gifted writer, Newcomb published books on various subjects for audiences of varying levels, including Popular Astronomy (1877), Principles of Political Economy (1886), and Calculus (1887). As a gifted mathematical astronomer, New- comb received many honors and won election to many distinguished societies. In 1874 he received the Gold Medal of the Royal Astronomical Society in Great Britain. He also became a Fellow of the Royal Society of London in 1877 When the brilliant English physicist and mathematician and received that society’s Copley Medal in Isaac Newton published his great work The Principia in 1687, he single-handedly transformed the practice 1890. The Astronomical Society of the Pacific of physical science and completed the scientific made him the first Bruce Gold Medallist in revolution started by Copernicus, Galileo, and Kepler. 1898. He is considered one the greatest scientific minds that He died in Washington, D.C., on July 11, ever lived. (Original engraving by unknown artist, courtesy AIP Emilio Segrè Visual Archives, Physics 1909, and was buried with full military honors Today Collection) at Arlington National Cemetery. To commemorate his great contributions to the United States in the field of mathematical astronomy Isaac Newton, who made perhaps the biggest and nautical navigation, the navy named a contribution of all time to the field of astron- surveying ship the USS Simon Newcomb. omy with the scientific notions he devised as a 22-year-old on his family’s farm. December 25, 1642, Christmas Day, was a ᨳ Newton, Sir Isaac day to be remembered in astronomy. In Italy, the (1642–1727) famous mathematician and scientist GALILEO British GALILEI passed away, blind from too many ob- Mathematician, Physicist servations of the Sun, and under house arrest by the Roman Catholic Church—courtesy of the Only one scientist has been simultaneously Inquisition for his beliefs in a heliocentric uni- thought of in such diverse ways as “the greatest verse, which he was forced to recant 10 years genius that ever existed,” and “as a man, he was earlier to avoid being tortured to death. As one a failure; as a monster he was superb.” This ge- great life ended, another began in Woolsthorpe, nius monster was the famous mathematician Sir England, where on this day Isaac Newton was 218 Newton, Sir Isaac born—the first child of the recently widowed century before Newton was born. It states that Hannah Ayscough. Newton was named for his an object at rest stays at rest, and an object in father, an illiterate but wealthy farmer who had motion stays in motion in a straight line and at died three months earlier. a constant speed unless an outside influence or From age two, the young Newton was passed force acts upon that object. More scientifically, around among his relatives after his mother re- it is written, “In the absence of outside forces, married, living mostly with his grandparents. the momentum of a system remains constant.” Newton hated his stepfather, Barnabus Smith, Momentum can be simply defined as the prod- once even threatening to burn his house down uct of mass and velocity: momentum ϭ mass ϫ with his mother and stepfather in it. After Smith velocity. died when Newton was 10, the boy was reunited The Second Law of Motion deals with with his mother and her three children by Smith, force, and so is about change in momentum. It and then promptly sent away to school. His first states, “If a force acts upon a body, the body ac- attempt at education was brief—he was pulled celerates in the direction of the force, its mo- out of school after just a few months because he mentum changing at a rate numerically equal lacked any visible ability to learn. But at age 13, to that force.” As with the first law, if there is after failing miserably at taking over the task of no force, there is no change in momentum. running his mother’s estate, Newton was sent Acceleration is the rate at which velocity back to school, and this time he enjoyed learn- changes, and so force is often the product of mass ing so much that he wrote it must be “a sin.” and acceleration: force ϭ mass ϫ acceleration. At the very late age of 18, in 1661, Newton But if the mass of a body changes—for exam- entered Trinity College at Cambridge. With no ple, if the weight of a rocket diminishes as fuel financial backing from his mother, Newton was burns out of it—then the formula is not quite obliged to work as a “sizar”—a servant to the so simple. wealthier students in exchange for financial aid If the acceleration to a body occurs in the to attend the university. In 1663 he got his first same direction as the velocity of the body, then look at Euclid’s Elements, and he suddenly be- the object speeds up. An example of this is the came entranced with mathematics. He graduated force of gravity accelerating the momentum of in 1665, the university closed because of the a falling object, which occurs at a rate of 32 plague, and Newton went back to his family’s feet per second2. If a force is accelerating in farm where he spent the next year and a half do- the opposite direction of the momentum of a ing nothing spectacular—nothing but devising body, then it slows the object down, for ex- the laws that changed the world’s understanding ample, the force of friction. Newton also ex- of the universe. plained the computations for two or more As a 22-year-old on the farm, Newton had forces acting on one object; and if two forces time to let his scientific mind conjure up the cancel each other, then the body does not ac- creative ideas for which he is known today, in- celerate but instead stays in a state of equilib- cluding calculus, the laws of motion, and the rium. Universal Law of Gravity. Newton’s laws of mo- Newton’s Third Law of Motion is the famous tion consist of three laws that deal with mass and “reaction” law: “For every action, there is an force and are the basis for Newtonian mechanics, equal and opposite reaction.” This was an orig- both on Earth and in space. inal concept in which Newton states that all The First Law of Motion is based on iner- forces happen in pairs that are mutually equal tia, a concept Galileo introduced around a half- and opposite to one another. Newton, Sir Isaac 219 Newton also needed to explain the idea of of his calculus or any other work when he re- circular momentum, because if a force on a body turned to Cambridge. causes the object to accelerate in a straight line, Instead, Newton was interested in optics, how could anything travel in a circular path? For and he soon discovered that white light is made this to happen, there has to be a constant force of a spectrum of colors—red, orange, yellow, of acceleration toward the center of the circle. green, blue, indigo, and violet—and can be seen This is called centripetal acceleration, or cen- when a ray of light is bent, or refracted, for ex- tripetal force. Both Newton and a Dutch physi- ample through a glass prism. This discovery con- cist, Christiaan Huygens (1629–95), arrived at cerned Newton about the optics of refracting this idea independently—Newton in 1666, which telescopes, so he invented a reflecting telescope. of course he did not publish, and Huygens in Then, in 1672, he gave one of his new telescopes 1673, which he published. The equation is that to the Royal Society. In honor of his gift, he was force is equal to the product of mass and vol- elected as a member to the society and was al- ume squared, divided by the radius of the circle: lowed to publish his first paper on optics and the F ϭ mv2/r. properties of light. The Universal Law of Gravitation is the Trouble soon followed. Mathematician Robert famous “apple falling off the tree” law that chil- Hooke had discussed his ideas on light with dren are taught when they first learn about Newton, and when Hooke saw these concepts gravity in school. The laws of motion, the for- in print he accused Newton of stealing his work. mula for centripetal force, and JOHANNES Huygens didn’t agree with Newton’s science. KEPLER’s laws helped Newton arrive at the Law And the Jesuits saw his ideas as an attack on of Gravitation. The formula shows that the Christianity and sent him a barrage of violent force between two bodies is the constant letters. After years of badgering, Newton could of gravitation times the mass of each of the no longer stand the pressure, and in 1678 he two bodies separated by the distance squared: suffered his first nervous breakdown. 2 F ϭ G(m1m2/d ). Newton stated it as “Between After such disastrous results with publishing, any two objects anywhere in space there exists a it is surprising that any of Newton’s later work force of attraction that is in proportion to the ever made it into print. But the famous as- product of the masses of the objects and in tronomer SIR EDMUND HALLEY, who sought inverse proportion to the square of the distance Newton’s help to work on the problem of orbits, between them.” discovered that Newton had developed the laws Newton’s laws are generally acceptable for of motion and gravity and had the calculus to most, but not all, natural physics. The two back it up. He pushed Newton to publish his exceptions are relativity, explained by ALBERT work, and Newton agreed only after Halley of- EINSTEIN, and quantum theory, which Newtonian fered to pay for the printing with his own mechanics cannot describe. money. In 1687 the first edition of 2,500 copies In order to give all of the necessary compu- of Philosophiae Naturalis Principia Mathematica tations for his laws, Newton created calculus (Mathematical principles of natural philosophy) during his stay on the farm. Then, in 1667, he was published, and Principia, as it became returned to Cambridge to work on his master’s known, put Newton in the ranks of the greatest degree, and two years later became Lucasian scientific minds ever to grace the planet. Professor in mathematics, a position that would But Newton was busy with the politics of also be held 300 years later by SIR STEPHEN the university and the state, publicly fighting WILLIAM HAWKING. Newton made little mention King James II’s decree to fill the university’s 220 Newton, Sir Isaac teaching positions with academically unquali- inventor. Leibniz was never allowed to give any fied Catholics. When William of Orange ousted evidence in his defense, and the issue became a James II, Newton was rewarded for his stance hotly debated international incident. with a seat in Parliament. From 1689 to 1693 Newton died in 1727, and two years later, 42 Newton filled his time with both the university years after its original publication, Principia was work and his new work in government, but translated from its original Latin into English. again the pressures of life took hold of him, and Newton was buried in Westminster Abbey, with he suffered another nervous breakdown. It took a Latin inscription on his tomb that reads, several years for him to get back on his feet, but “Mortals! Rejoice at so great an ornament to the when he did, in 1696, he became extremely human race.” The Leibniz incident followed wealthy as the head of the Royal Mint. both Newton and Leibniz all the way to their The Royal Society elected Newton as pres- graves, and remained an international debate ident in 1703, and in 1704, after Hooke’s death, years after their deaths (Leibniz and Newton are he published his entire work on optics, part of now considered to have independently invented which had caused the scandal with Hooke ear- calculus). lier in his career. For Newton’s now famous work The French mathematician COMTE JOSEPH- in science, Queen Anne knighted him in 1705, LOUIS LAGRANGE called Newton “the greatest giving him the honor of being the first man ever genius that ever existed,” and SUBRAHMANYAN knighted for scientific achievement. CHANDRASEKHAR considered his brilliance sec- In 1711 controversy struck again, this time ond to none, not even Einstein. But in Newton’s in a disastrous scandal involving the famous math- case, scientific brilliance had its “equal and op- ematician Gottfried Wilhelm Leibniz (1646–1716), posite” dark side in a mean-spirited and evil tem- who was commonly regarded as the inventor perament. Newton ordered several counterfeit- of calculus. An article published by the Royal ers executed by the state, and he had nasty Society, of which Newton was then president, ac- public fights with other important figures, not cused Leibniz of plagiarism and declared Newton the least of whom was the Astronomer Royal as the inventor of calculus. Newton was known John Flamsteed. Newton was superbly mon- for being a horrid man, and in a position of power strous, an observation written by the literary he could do whatever he wanted to guarantee that philosopher Aldous Huxley (1894–1963) and a things went his way. He announced that he was view shared by many, both during and after appointing an “impartial committee” to deter- Newton’s lifetime. Yet his professional contribu- mine who really invented calculus, then wrote an tions to astronomy were nothing short of genius. anonymous decision on behalf of the Royal To his credit, Newton has said, “If I have seen Society in favor of himself, and promptly closed farther than others, it is because I was standing the case, officially pronouncing himself the true on the shoulders of giants.”

(part of the Austro-Hungarian Empire). His par- ᨳ Oberth, Hermann Julius ents were members of the historically German- (1894–1989) speaking community of the region. His father, Romanian/German Julius, was a prominent physician who tried to Mathematician, Physicist, (Theoretical) influence his son in a career in medicine. But Rocket Engineer Hermann was a free-spirited thinker who pre- The Transylvanian-born German physicist Her- ferred to ponder the future while challenging mann Oberth was a theoretician who helped the ideas held by the current scientific estab- establish the field of astronautics early in the 20th lishment. century. He originally worked independently of At age 11 Oberth discovered the works of KONSTANTIN EDUARDOVICH TSIOLKOVSKY and Jules Verne, especially De la terre à la lune (From ROBERT HUTCHINGS GODDARD in his advocacy of the Earth to the Moon). In his famous 1865 rockets for space travel, but later discovered and novel, Verne was first to provide young readers acknowledged their prior efforts. Unlike Tsi- like Oberth a somewhat credible account of a olkovsky and Goddard, however, Oberth made human voyage to the Moon. Verne’s travelers are human beings an integral part of the space blasted on a journey around the Moon in a spe- travel vision. His inspirational 1923 publication cial hollowed-out capsule fired from a large can- The Rocket into Interplanetary Space provided a non. Verne correctly located the cannon at a comprehensive discussion of all the major low-latitude site on the west coast of Florida aspects of space travel, and his 1929 award-win- called “Tampa Town.” By coincidence, this fic- ning book, Roads to Space Travel, popularized titious site is about 120 kilometers to west of the concept of space travel for technical and Launch Complex 39 at the NASA Kennedy nontechnical readers alike. His technical publi- Space Center from which Apollo astronauts ac- cations and inspiring lectures exerted a tremen- tually left for journeys to the Moon between dous career influence on many young Germans, 1968 and 1972. including the legendary WERNHER MAGNUS Oberth read this novel many times and VON BRAUN. then, while remaining excited about space Oberth was born on June 25, 1894, in the travel, questioned the story’s technical plausi- town of Hermannstadt in a German enclave bility. He soon discovered that the acceleration within the Transylvanian region of Romania down the barrel of this huge cannon would have

221 222 Oberth, Hermann Julius

Hermann Oberth, one of the founding fathers of astronautics, appears in the forefront of this 1956 photograph, accompanied by officials of the U.S. Army Ballistic Missile Agency at Huntsville, Alabama. Included behind Oberth (from left to right) are Ernst Stuhlinger (seated), Major General H. N. Toftoy (uniformed, standing), Wernher von Braun (seated on table), and Eberhard Rees (standing, far right). General Toftoy was the American military officer responsible for “Project Paperclip”—the operation that took rocket scientists and engineers (including Oberth, von Braun, and Stuhlinger) out of Germany after World War II and relocated them in the United States so they could help design U.S. rockets during the cold war. (Courtesy of NASA) Oberth, Hermann Julius 223 crushed the intrepid explorers and that the cap- studied at the University of Göttingen then at sule itself would have burned up in Earth’s at- the University of Heidelberg before becoming mosphere. But Verne’s story made space travel certified as a secondary-school mathematics and appear technically possible, and this important physics teacher in 1923. At this point in his life, idea thoroughly intrigued Oberth. So, after iden- he was unaware of the contemporary rocket the- tifying the technical limitations in Verne’s fic- ory work by Tsiolkovsky in Russia and Goddard tional approach, he started searching for a more in the United States. In 1922 he presented a practical way to travel into space. That search doctoral dissertation on rocketry to the faculty quickly led him to the rocket. at the University of Heidelberg, but the univer- In 1909, at age 15, Oberth completed his sity committee rejected his dissertation. first plan for a rocket to carry several people. His Still inspired by space travel, he revised this design for a liquid-propellant rocket that burned work and published it in 1923 as Die Rakete zu hydrogen and oxygen came three years later. He den Planetenräumen (The rocket into interplane- graduated from the Gymnasium (high school) in tary space). This modest book provided a thor- June 1912, receiving an award in mathematics. ough discussion of the major aspects of space The next year he entered the University of travel, and its contents inspired many young Munich with the intention of studying medi- German scientists and engineers to explore rock- cine, but World War I interrupted his studies. etry, including WERNHER MAGNUS VON BRAUN. As a soldier, he was wounded and transferred to Oberth worked as a teacher and writer in the a military medical unit. To the great disap- 1920s. He discovered and acknowledged the pointment of his father, Oberth’s three years of rocketry work of Goddard and Tsiolkovsky in duty in this medical unit reinforced his decision the mid-1920s and became the organizing figure not to study medicine. around which the practical application of rock- During World War I Oberth tried to inter- etry developed in Germany. He served as a lead- est the Imperial German War Ministry in de- ing member of Verein für Raumschiffahrt (VFR), veloping a long-range military rocket. In 1917 the German Society for Space Travel. Members he submitted his specific proposal for a large of this technical society conducted critical ex- liquid-fueled rocket. He received a very abrupt periments in rocketry in the late 1920s and response for his efforts. Certain Prussian arma- early 1930s, until the German army absorbed ments “experts” within the ministry quickly their efforts and established a large military rejected his plan and reminded him that their rocket program. experience clearly showed that military rockets Fritz Lang (1890–1976), the popular Austrian could not fly farther than seven kilometers. Of filmmaker, hired Oberth as a technical adviser course, these officials were limited by their own during the production of his 1929 film Die experience with contemporary military rockets Frau im Mond (The woman in the moon). that used inefficient black powder for propellant. Collaborating with Willy Ley (1906–69), Oberth They totally missed Oberth’s breakthrough provided for the film an exceptionally prophetic idea involving a better-performing liquid-fueled two-stage cinematic rocket that startled and de- rocket. lighted audiences with its impressive blastoff. Undaunted, Oberth returned to the univer- Lang, ever the showman, also wanted Oberth sity and continued to investigate the theoretical to build and launch a real rocket as part of a problems of rocketry. In 1918 he married publicity stunt to promote the new film. Mathilde Hummel and a year later went back to Unfortunately, with little engineering experi- the University of Munich to study physics. He ence, Oberth accepted Lang’s challenge, but 224 Olbers, Heinrich Wilhelm Matthäus was soon overwhelmed by the arduous task of years before returning to Germany in 1958 and turning theory into practical hardware. Shocked retiring. and injured by a nearly fatal liquid-propellant Of the three founding fathers of astronau- explosion, Oberth abandoned Lang’s publicity tics, only Oberth lived to see some of his rocket and retreated to the comfort and safety pioneering visions come true. These visions in- of writing and teaching mathematics in his cluded the dawn of the Space Age (1957, with native Romania. Sputnik 1), human space flight (1961), the first Oberth was a much better theorist and tech- human landing on the Moon (1969), the first nical writer than nuts-and-bolts rocket engineer. space station (1971), and the first flight of a In 1929 Oberth expanded his ideas concerning reusable launch vehicle—NASA’s Space Shuttle the rocket for space travel and human space flight (1982). He died in Nuremberg, Germany, on in a book entitled Wege zur Raumschiffahrt (Roads December 29, 1989. Oberth studied the theo- to space travel). The Astronomical Society of retical problems of rocketry and outlined the France gave Oberth an award for this book, technology needed for people to live and work which helped popularize the concept of space in space. The last paragraph of his 1954 book, travel for both technical and nontechnical audi- Man into Space, addresses the important ques- ences. As newly elected president of the VFR, tion: “Why space travel?” His eloquently philo- Oberth used some of his book’s prize money to sophical response is, “This is the goal: To make fund rocket engine research within the society. available for life every place where life is possi- Young engineers like Braun had a chance to ex- ble. To make inhabitable all worlds as yet unin- periment with liquid-propellant engines, includ- habitable, and all life purposeful.” ing one of Oberth’s concepts, the Kegeldüse (conic) engine design. In this visionary book, Oberth also anticipated the development of ᨳ Olbers, Heinrich Wilhelm Matthäus electric rockets and ion propulsion systems. (1758–1840) Throughout the 1930s, Oberth continued to German work on liquid-propellant rocket concepts and on Astronomer (Amateur) the idea of human space flight. In 1938 Oberth joined the faulty at the Technical University of Sometimes a person is primarily remembered for Vienna. There, he participated briefly in a rocket- asking an interesting question that baffles the related project for the German air force. In 1940 best scientific minds of the time. The German he became a German citizen. The following year, astronomer Heinrich Wilhelm Matthäus Olbers he joined Braun’s rocket development team at was just such a person. To his credit as an ob- Peenemünde. servational astronomer, he discovered the main- Oberth worked only briefly with Braun. In belt asteroids Pallas in 1802 and Vesta in 1807. 1943 he transferred to another location to work Today he is best remembered for formulating the on solid-propellant antiaircraft rockets. At the interesting philosophical question now known end of World War II, Allied forces captured him as Olber’s paradox. In about 1826 he challenged and placed him in an internment camp. Upon his fellow astronomers by posing the following release, he left a devastated Germany and sought seemingly innocent question: “Why isn’t the rocket-related employment as a writer and lec- night sky with its infinite number of stars not as turer in Switzerland and Italy. In 1955 he joined bright as the surface of the Sun?” Braun’s team again, this time at the U.S. Army’s Olbers was born on October 11, 1758, at Redstone Arsenal. He worked there for several Ardbergen (near Bremen), Germany. The son of Olbers, Heinrich Wilhelm Matthäus 225 a Lutheran minister, he entered the University suggested in 1811 that a comet’s tail points away of Göttingen in 1777 to study medicine, but also from the Sun during perihelion passage because took courses in mathematics and astronomy. By the material ejected by the comet’s nucleus is in- 1781 he became qualified to practice medicine fluenced (pushed) by the Sun. He remained an and established a practice in Bremen. By day, he active observational astronomer and discovered served his community as a competent physician; four more comets, including one in 1815 that in the evening he pursued his hobby of astron- now bears his name. omy. He converted the upper floor of his home Olbers is best remembered, however, for into an astronomical observatory and used sev- popularizing the question “Why is the night sky eral telescopes to conduct regular observations. dark?” He presented a technical paper in 1826 “Comet hunting,” or cometography, was a that attempted to solve this interesting puzzle. favorite pursuit of 18th-century astronomers, Previous astronomers in the 17th and 18th cen- and Olbers, a dedicated amateur astronomer, tury were certainly aware of this question, which eagerly engaged in this quest. In 1796 he dis- is sometimes traced back to the writings of the covered a comet and then used a new mathe- 17th-century astronomer JOHANNES KEPLER,or matical technique he had developed to compute to a 1744 publication by the Swiss astronomer its orbit. His technique, often referred to as Jean-Philippe Loys de Chéseaux. However, Olber’s method, proved computationally efficient Olbers’s paper represents the most enduring for- and was soon adopted by many other astronomers. mulation of the question, which is now known At the start of the 19th century, Olbers contin- as Olber’s paradox. ued to successfully practice medicine in Bremen, Within the perspective of 19th-century cos- but he also became widely recognized as a skilled mology, the basic problem can be summarized as astronomer. follows: If the universe is infinite, unchanging, At the end of the 18th century, astronomers homogeneous, and therefore filled with stars (in began turning their attention to the interesting the early 20th century “galaxies” was included), gap between Mars and Jupiter. At the time, pop- then the entire night sky should be filled with ularization of the Titius-Bode law—actually just light and as bright as daytime. Of course, Olbers an empirical statement of relative planetary dis- saw that night sky was obviously not bright as tances from the Sun—caused astronomers to the day—so what accounted for this inconsis- speculate that a planet should have been in this tency or paradox between observation and the- gap. Responding to this wave of interest, ory? Olbers explanation suggested that the dust GIUSEPPE PIAZZI discovered the first and largest and gas in interstellar space blocked much of the of the minor planets, which he named Ceres, on light traveling to Earth from distant stars. the first of January in 1801. Unfortunately, Piazzi Unfortunately, he was wrong in this particular soon lost track of Ceres. However, based on suggestion, because within his cosmological Piazzi’s few observations, the brilliant German model, such absorbing gas would have heated up mathematician Carl Friedrich Gauss (1777– to incandescent temperatures and glowed. 1855) was able to calculate its orbit. Consequently, To solve this apparent contraction, Olbers a year later, on January 1, 1802, Olbers relocated needed to discard the prevalent infinite, static, Ceres. While observing Ceres, Olbers also dis- homogeneous model of the universe and discovered another minor planet, Pallas. He contin- cover Big Bang cosmology, with its expanding, ued looking in the gap and found the third finite, and inhomogeneous universe. Modern as- main-belt asteroid, Vesta, in 1807. Anticipating tronomers now provide a reasonable explanation the discovery of solar radiation pressure, he of Olber’s paradox with the assistance of an 226 Oort, Jan Hendrik expanding, finite universe model. Some suggest that as the universe expands the very distant stars and galaxies become obscure due to extensive redshift—a phenomenon that weakens their apparent light and makes the night sky dark. Other astrophysicists declare that the observed redshift to lower energies is not a sufficient reason to darken the sky. They suggest that the finite extent of the physical, observable universe and its changing time-dependent nature provide the reason the night sky is truly dark—despite the faint amounts of starlight reaching Earth. Today, modern cosmology explains that the universe is dynamic and not statically filled up with unchanging stars and galaxies. Finally, as inherently implied within Big Bang cosmology, since the universe is finite in extent and the speed of light is assumed constant, there has not even been a sufficient amount of time for the light from those galaxies beyond a certain range (called the observable universe) to reach Earth. Olbers died in Bremen, Germany, on March 2, 1840. The chief astronomical legacy of this The Dutch astronomer Jan Oort, shown here at his successful German physician and accomplished desk in 1986, made pioneering studies of the amateur astronomer is Olber’s paradox—a co- dimensions and structure of the Milky Way Galaxy in herent response to which helps scientists high- the 1920s. He also boldly speculated in 1950 that a light some of the most important aspects and im- large swarm of comets (now called the Oort cloud) encircles the Sun at a great distance—somewhere plications of modern cosmology. between 50,000 and 100,000 astronomical units. (Photo by Ron Doel, courtesy AIP Emilio Segrè Visual Archives) ᨳ Oort, Jan Hendrik (1900–1992) very distant, postulated reservoir of icy bodies as Dutch the Oort cloud in his honor. Astronomer Oort was born in the township of Franeker, in Friesland Province, the Netherlands, on April An accomplished astronomer, Jan Oort made 28, 1900. At age 17 he entered the University pioneering studies of the dimensions and struc- of Groningen where he studied stellar dynamics ture of the Milky Way Galaxy in the 1920s. under JACOBUS CORNELIUS KAPTEYN. He com- However, he is now most frequently remembered pleted his doctoral coursework in 1921 and re- for the interesting hypothesis he extended in mained at the university as a research assistant 1950 when he postulated that a large swarm of for Kapteyn for about one year. He then comets circles the Sun at a great distance— performed astrometry-related research at Yale somewhere between 50,000 and 100,000 astro- University between 1922 and 1924. Upon re- nomical units. Today astronomers refer to this turning to Holland in 1924, he accepted an Oort, Jan Hendrik 227 appointment as a staff member at Leiden tronomy and a joint director of the observatory. Observatory and remained affiliated with the In 1945, at the end of World War II, he received University of Leiden in some capacity for the a promotion to full professor and the position of remainder of his life. the director of its observatory. He continued his Following completion of all the require- university duties until retirement in 1970. ments for his doctoral degree in 1926, Oort However, after retirement from the university, he began making important contributions to our un- still continued to work regularly at the Leiden derstanding of the structure of the cosmos. During Observatory and produced technical papers un- seven decades of productive intellectual activity, til just before his death on November 5, 1992. Oort made significant contributions to the rap- Despite the research-limited conditions that idly emerging body of astronomical knowledge. characterized German-occupied Holland during At the start of his career, the universe was con- World War II, Oort saw the important galactic sidered to be contained within just the Milky Way research potential of the newly emerging field Galaxy—a vast collection of billions of stars of radio astronomy. He therefore strongly en- bound within some rather poorly defined borders. couraged his graduate student Hendrik van de When he published his last paper in 1992, Oort Hulst (1918–2000) to investigate whether hy- was busy describing some of the interesting char- drogen clouds might emit a useful radio fre- acteristics of an expanding universe now con- quency signal. In 1944 van de Hulst was able sidered comprised of billions of galaxies whose to theoretically predict that hydrogen should space and time dimensions extending in all di- have a characteristic radio wave emission at a rections to the limits of observation. wavelength of 21 centimeters. In 1927 he revisited Kapteyn’s star stream- After Holland recovered from World War II ing data, while also building upon the recent and the University of Leiden returned to its nor- work of the Swedish astronomer Bertil Lindblad mal academic functions, Oort was able to form (1895–1965). This approach produced a classic a Dutch team, including van de Hulst, which paper in which Oort demonstrated that the discovered in 1951 the predicted 21-centimeter differential systematic motions of stars in the wavelength radio frequency emission from neu- solar neighborhood could be explained in terms tral hydrogen in outer space. By measuring the of a rotating galaxy hypothesis. The paper, distribution of this telltale radiation, Oort and “Observational Evidence Confirming Lindblad’s his colleagues mapped the location of hydrogen Hypothesis of a Rotation of the Galactic gas clouds throughout the Galaxy. Then, they System,” served as Oort’s platform for introduc- used this application of radio astronomy to find ing his concept of differential galactic rotation. the large-scale spiral structure of the Galaxy, the Differential rotation occurs when different location of the galactic center, and the charac- parts of a gravitationally bound gaseous system teristic motions of large interstellar clouds of rotate at different speeds. This implies that the hydrogen. various components of a rotating galaxy share in Throughout his career as an astronomer, the overall rotation around the common center comets remained one of Oort’s favorite topics. to varying degrees. Oort continued to pursue ev- Oort supervised completion of research by a idence for differential galactic rotation and was postwar doctoral student who was investigating able to establish the mathematical theory of the origin of comets and the statistical distri- galactic structure. bution of the major axes of their elliptical or- Starting in 1935, Oort served the University bits. Going beyond this student’s research, Oort of Leiden as both an associate professor of as- decided to investigate the consequences that 228 Oort, Jan Hendrik passing rogue stars might have on cometary deflected comets then collected in a swarm or orbits. cloud that extended in distance from the Sun of As early as 1932, the Estonian astronomer between 30,000 and 100,000 astronomical units. Ernst Öpik (1893–1985) had suggested that the At this extreme range of distances (from about long-period comets that occasionally dashed 20 to 30 percent of the way to the nearest star, through the inner solar system might reside in Proxima Centuri) the perturbations within some gravitationally bound cloud at a great dis- other stars and gas clouds helped shape the he- tance from the Sun. In 1950 Oort revived and liocentric orbits so that only an occasional extended the concept of a heliocentric reservoir comet now pops out of the cloud on a visit back of icy bodies in orbit around the Sun. This reser- through the inner solar system. Oort’s theory has voir is now called the Oort cloud. become a generally accepted model for the origin In refining his comet reservoir model, Oort of very long-period comets. first suggested that in the early solar system these He received numerous awards for his theory icy bodies formed at a distance of less than 30 of galactic structure, including the Bruce Medal astronomical units from the Sun—that is, within of the Astronomical Society of the Pacific in the orbit of Neptune. But then, they diffused 1942 and the Gold Medal of the Royal outward as a result of gravitational interaction Astronomical Society in 1946. However, it is the with the giant gaseous planets Jupiter and Oort cloud—his comet cloud hypothesis—that Saturn. According to Oort’s hypothesis, these gives his work a permanent legacy in astronomy.

before the outbreak of World War II and escaped ᨳ Penzias, Arno Allen almost certain death in one of Hitler’s concentra- (1933– ) tion camps. In 1939 his parents placed Arno and German/American his younger brother on a special refugee train to Physicist, Radio Astronomer Great Britain and then traveled there under sep- Sometimes the world’s greatest scientific discov- arate exit visas to join their sons. Once reunited, eries take place when least expected. While col- the family sailed for the United States in Decem- laborating in the mid–1960s with ROBERT ber and arrived in New York City in January WOODROW WILSON, a fellow radio astronomer at 1940. Penzias followed the education route Bell Laboratories, Arno Penzias went about the taken by many thousands of upwardly mobile task of examining natural sources of extraterres- immigrants. He used hard work and the New trial radio wave noise that might interfere with York City public school system as his pathway to transmissions from communication satellites. To a better life. In 1954 he graduated from the City his great surprise, he and Wilson quite by acci- College of New York (CCNY) with a bachelor of dent stumbled upon the “Holy Grail” of modern science degree in physics. After graduation he cosmology—the cosmic microwave background. married, then joined the U.S. Army, where he This all-pervading microwave background radia- served in the Signal Corps for two years. He tion resides at the very edge of the observable then enrolled at Columbia University in 1956 universe and is considered the cooled remnant and graduated from that institution with a mas- (about three kelvins) of the ancient big bang ter of arts degree in 1958 and a Ph.D. degree in explosion. They carefully confirmed the data 1962. that rocked the world of physics and gave cos- His technical experience in the army’s Sig- mologists the first empirical evidence pointing to nal Corps allowed him to obtain a research a very hot, explosive phase at the beginning of assistantship in the Columbia Radiation Labo- the universe. Penzias and Wilson shared the 1978 ratory. There he met and studied under Charles Nobel Prize in physics for this most important Townes (b. 1915), the American physicist and discovery. Nobel laureate who developed the first opera- Penzias was born in Munich, Germany, on tional maser (microwave amplification by stim- April 26, 1933. Of Jewish heritage, his family was ulated emission of radiation)—the forerunner one of the last to successfully flee Nazi Germany to the laser. For a doctoral research project,

229 230 Penzias, Arno Allen

Shown here in front of their historic radio telescope at the Bell Laboratories in New Jersey are the Noble laureates Robert Woodrow Wilson (left, background) and Arno Penzias (right, foreground). In the mid-1960s, while performing other experiments with this facility, the two radio astronomers serendipitously detected the cosmic microwave background—the cooled remnant of the “big bang” at the edge of the observable universe. Their discovery provided cosmologists the first direct evidence of a very hot, explosive phase at the beginning of the universe. For this great achievement, they shared the 1978 Nobel Prize in physics. (Lucent Technologies’ Bell Laboratories, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection)

Professor Townes assigned Penzias the challeng- surprise, the director of the Radio Research ing task of building a maser amplifier suitable Laboratory offered him a permanent position. for use in a radio astronomy experiment of his Penzias quickly accepted the radio astronomer own choosing. position and subsequently remained a member Upon completion of his thesis work in 1961, of Bell Laboratories in various technical and Penzias sought temporary employment at Bell management capacities until his retirement in Laboratories in Holmdel, New Jersey. To his May 1998. Penzias, Arno Allen 231 In 1963 Penzias met another radio astro- echoing effects of pigeon droppings from a pair nomer, Wilson, who had recently been hired to of birds that made a portion of the antenna work at Bell Laboratories after graduating from their home. Nothing explained this persistent, the California Institute of Technology (Cal- omnidirectional, uniform microwave signal. By tech). The two scientists embarked on the task early 1965 Penzias and Wilson had completed of using a special horn-reflector antenna 20 feet their initial data collection with their antenna, in diameter that had just been constructed at but were still no closer to unraveling the true Bell Laboratories to serve as an ultra-low-noise physical nature of this persistent signal. Their receiver for signals bounced from NASA’s Echo careful analysis indicated the signal was definitely One satellite—the world’s first passive com- “real”—but what was it? munications satellite experiment, launched in Then the mystery unraveled quickly when, August 1960. At the time, this ultrasensitive six- during a meeting with another physicist in spring meter horn-reflector was no longer needed for 1965, Penzias casually mentioned his recent satellite work, so both Penzias and Wilson began radio astronomy work and the interesting noise- to modify the instrument for radio astronomy. like signal he and Wilson had collected. The As modified with traveling-wave maser ampli- physicist suggested that Penzias contact Robert fiers, their modest-sized horn reflector became Dicke (1916–97) and members of his group at the most sensitive radio telescope in the world at Princeton University who were exploring the the time. Both radio astronomers were eager to physics of the universe and something called extend portions of their doctoral research with the big bang hypothesis. Penzias contacted this newly converted radio telescope. Their ini- Dicke who soon visited Bell Laboratories. After tial objective was to measure the intensity of he reviewed their precise work, Dicke immedi- several interesting extraterrestrial radio sources ately realized that Penzias and Wilson had, totally at a radio frequency wavelength of 7.53 cen- by accident, beaten all the other astrophysicists timeters—a task with potential value in both and cosmologists, including Dicke, in detecting the development of satellite-based telecommu- evidence of the hypothesized microwave remnant nications and radio astronomy. of the big bang. Recognizing the scientific impor- On May 20, 1964, Wilson and Penzias made tance of this work, they agreed to publish letters a historic measurement that later proved to be in the Astrophysical Journal. As a result, Volume the very first to clearly indicated the presence of 142 of the Astrophysical Journal contains two his- the cosmic microwave background—the remnant toric letters that appear side by side. In one letter, “cold light” from the dawn of creation. At the Dicke and his team at Princeton University dis- time, neither was sure why this strange back- cuss the cosmological implications of the cosmic ground “noise” at around three degrees Kelvin microwave background; in the other letter, Pen- equivalent temperature kept showing up in all zias and Wilson present their cosmic microwave the measurements. As excellent scientists do, background measurements without elaborating they checked every potential source for this on the cosmological significance of the data. unexplained signal. They ruled out equipment Once the Penzias and Wilson data began to error (including antenna noise due to faulty circulate within the astronomical community, its joints), the lingering effects of a previous nuclear true significance quickly emerged. Scientists re- test in outer space, the presence of human-made visited the earlier big bang hypothesis work of radio frequency signals (including those ema- RALPH ASHER ALPHER and engaged in a series of nating from New York City), sources within corroborating measurements. For providing the the Milky Way Galaxy, and even the possible first definitive evidence of the cosmic microwave 232 Piazzi, Giuseppe background, Penzias and Wilson shared the ᨳ Piazzi, Giuseppe 1978 Nobel Prize in physics with the Russian (1746–1826) physicist Pyotr Kapitsa, who received his award Italian for unrelated achievements in low-temperature Astronomer physics. While responding to the research needs and In the late 18th century this intellectually gifted priorities of Bell Laboratories in the 1960s and Italian monk was a professor of mathematics at 1970s, Penzias and Wilson also continued to par- the academy in Palermo and also served as the ticipate in pioneering radio astronomy research. director of the new astronomical observatory In 1973, while investigating molecules in inter- constructed in Sicily in 1787. Piazzi was a skilled stellar space, they discovered the presence of the observational astronomer and discovered the deuterated molecular species DCN and were first asteroid on New Year’s Day in 1801. Fol- then able to use this molecular species to trace lowing prevailing astronomical traditions, he the distribution of deuterium in the Galaxy. In named the newly found celestial object Ceres, 1972 Penzias became head of the Radio Physics after the patron goddess of agriculture in Roman Research Department at Bell Laboratories, and mythology. early in 1979 his management responsibilities Giuseppe Piazzi was born at Ponte, in Val- increased when he received a promotion to tellina, Italy, on July 16, 1746. Early in his life head the laboratory’s Communications Sciences he decided to enter the Theatine Order, a reli- Research Division. At the end of 1981, he re- gious order for men founded in southern Italy in ceived another promotion and became vice pres- the 16th century. Upon completing his initial ident of research as the Bell System experienced religious training, Piazzi accepted the order’s a major transformation. While discharging his strict vow of poverty. As a newly ordained responsibilities in this new executive position, monk, he pursued advanced studies at colleges Penzias began to concentrate on the creation in Milan, Turin, Genoa, and Rome. Piazzi and effective use of new technologies. In 1989 emerged as a professor of theology and a profes- he published a book, Ideas and Information, sor of mathematics. In the late 1770s he taught which discussed the impact of computers and briefly at the university on the island of Malta other new technologies on society. In May 1998 and then returned to a college post in Rome to Penzias retired from his position as chief scientist serve with distinction as a professor of dogmatic at Bell Laboratories, now a division of Lucent theology. His academic colleague in Rome was Technologies. another monk named Luigi Chiaramonti, who Best known as the radio astronomer who was later elected Pope Pius VII (1800–23). In codiscovered the cosmic microwave background, 1780 his religious order sent Piazzi to the acad- Penzias received many awards and honors in ad- emy in Palermo to assume the chair of higher dition to his 1978 Nobel Prize. Some of his other mathematics. awards include the Henry Draper Medal of the While working at this academy in Sicily, American National Academy of Sciences (1977) Piazzi obtained a grant from the viceroy of Sicily, and the Herschel Medal of the Royal Astronomical Prince Caramanico, to construct an observatory. Society (1977). He also received membership in As part of the development of this new obser- many distinguished organizations, including the vatory, he traveled to Paris in 1787 to study as- National Academy of Sciences, the American tronomy with Joseph Lalande (1732–1807) and Academy of Arts and Sciences, and the American then went on to Great Britain the following year Physical Society. to work with England’s fifth Astronomer Royal, Pickering, Edward Charles 233

Nevil Maslelyne (1732–1811). As a result of his asteroid hunter, HEINRICH WILHELM MATTHÄUS travels, Piazzi gathered new astronomical equip- OLBERS, to relocate the minor planet on January ment for the observatory in Palermo. Upon re- 1, 1802. Olbers then went on to find the aster- turning to Sicily, he set up the new equipment oids Pallas (1802) and Vesta (1807). on top of a tower in the royal palace between When Piazzi died in Naples, Italy, on July 1789 and 1790. 22, 1826, only four asteroids were known to ex- All was soon ready and Piazzi began to make ist in the gap between Mars and Jupiter. But is astronomical observations in May 1791. He his pioneering discovery of Ceres in 1801 stim- published his first astronomical reports in 1792. ulated renewed attention on this interesting His primary goal was to improve the stellar po- region of the solar system—a gap that should sition data in existing star catalogs. Piazzi paid contain a missing planet according to the Titus- particular attention to compensating for errors Bode law. In 1923 astronomers named the 1,000th induced by such subtle phenomenon as the asteroid discovered “Piazzia” to honor the Italian aberration of starlight, discovered in 1728 by astronomer’s important achievement. the British astronomer JAMES BRADLEY. The monk-astronomer was a very skilled observer who was soon able to publish a refined positional ᨳ Pickering, Edward Charles list of approximately 6,800 stars in 1803. He fol- (1846–1919) lowed this initial effort with the publication of American a second star catalog containing about 7,600 Astronomer, Physicist stars in 1814. Both of these publications were well received within the astronomical commu- Starting in 1877, Edward Charles Pickering dom- nity and honored by prizes from the French inated American astronomy for the last quarter academy. of the 19th century. He served as the director of However, Piazzi is today best remembered as the Harvard College Observatory for more than the person who discovered the first asteroid (or four decades, and in this capacity supervised the minor planet). He made this important discov- production of the Henry Draper Catalogue by ery on January 1, 1801, from the observatory ANNIE JUMP CANNON,WILLIAMINA PATON that he founded and directed in Palermo. To STEVENS FLEMING,HENRIETTA SWAN LEAVITT, please his royal benefactors while still maintain- and other astronomical “computers.” This impor- ing astronomical traditions, he called the new tant work listed more than 225,000 stars accord- celestial object Ceres, after the ancient Roman ing to their spectra, as defined by the newly goddess of agriculture who was once widely wor- introduced Harvard Classification System. He shiped on the island of Sicily. Ceres (asteroid 1) also vigorously promoted the exciting new field is the largest asteroid, with a diameter of about of astrophotography, and in 1889 discovered the 935 kilometers. However, because of its very low first spectroscopic binary star system—two stars albedo (about 10 percent), Ceres cannot be so visually close together that they can be observed by the naked eye. After just three good distinguished only by the Doppler shift of their telescopic observations in early 1801, Piazzi lost spectral lines. the asteroid in the Sun’s glare. Yet Piazzi’s care- Pickering was born on July 19, 1846, in fully recorded positions enabled the brilliant Boston, Massachusetts. After graduating from German mathematician Carl Friedrich Gauss Harvard University in 1865, he taught physics (1777–1855), to accurately predict the asteroid’s for approximately 10 years at the Massachusetts orbit. Gauss’s calculations allowed another early Institute of Technology (MIT). To assist in his 234 Pickering, Edward Charles the Harvard Observatory. With the funds provided by HENRY DRAPER’s widow, Ann Palmer Draper (1839–1914), Pickering employed Cannon, Fleming, Antonia Maury, Leavitt, and others to work at the observatory. He then supervised these talented and well qualified women as they produced the contents of the Henry Draper Cata- logue. This catalogue, published in 1918, was primarily compiled by Cannon and presented the spectra classification of some 225,000 stars based on Cannon’s Harvard Classification System, in which the stars were ordered in a sequence that corresponded to the strength of their hydrogen absorption lines. In 1884 Pickering produced a new catalog called the Harvard Photometry. This work presented the photometric brightness of 4,260 stars using the North Star (Polaris) as a reference. Pickering revised and expanded this effort in 1908. He was an early advocate of astrophotography, and in 1903 he published the first photographic map of the entire sky. To achieve his goals in astrophotography he also sought the assistance of his younger brother, William Henry Pickering As director of the Harvard College Observatory, (1858–1938), who established the Harvard Col- Edward Charles Pickering dominated American astronomy in the last quarter of the 19th century. lege Observatory’s southern station in Peru. Inde- He supervised the production of the Henry Draper pendent of the German astronomer Hermann Catalogue (by Anne Jump Cannon, Williamina Vogel (1841–1907), Pickering discovered the Fleming, Henrietta Leavitt, and other astronomical first spectroscopic binary star system, Mizar, in “computers”) and vigorously promoted the exciting new field of astrophotography. (AIP Emilio Segrè Visual 1889. Archives) He was a dominant figure in American astronomy and a great source of encouragement to physics lectures, he constructed the first instruc- amateur astronomers. He founded the American tional physics laboratory in the United States. Association of Variable Star Observers and re- Then, in 1876, at just 30 years of age, he became ceived a large number of awards for his contribu- a professor of astronomy and the director of the tions to astronomy, including the Henry Draper Harvard College Observatory. He remained in Medal of the National Academy of Sciences this position for 42 years and used it to effectively (1888), the Rumford Prize of the American shape the course of American astronomy through Academy of Arts and Sciences (1891), the Gold the last two decades of the 19th century and the Medal of the Royal Astronomical Society (1886 first two decades of the 20th century. and 1901), and the Bruce Gold Medal of the One important innovation was Pickering’s Astronomical Society of the Pacific (1908). He decision to hire women to work as observational died in Cambridge, Massachusetts, on February astronomers and “astronomical computers” at 3, 1919. Planck, Max Karl 235 whom he lived happily until her death in 1909. ᨳ Planck, Max Karl The couple had two sons and twin daughters. In (1858–1947) 1910 Planck married his second wife, Marga von German Hösling. He remained a professor of physics at the Physicist University of Berlin until his retirement in 1926. Modern physics, with its wonderful new approach Good fortune and success would smile upon to viewing both the most minute regions of inner Planck’s career as a physicist in Berlin, but tragedy space and the farthest regions of outer space, has would stalk his personal life. two brilliant cofounders: Max Planck and ALBERT EINSTEIN. Many other intelligent people have built upon the great pillars of 20th-century physics— quantum theory and relativity—but these two giants of scientific achievement hold the distinction of leading the way. Planck was born in Kiel, Germany, on April 23, 1858. His father was a professor of law at the University of Kiel and gave his son a deep sense of integrity, fairness, and the value of intellectual achievement—important traits that characterized Planck throughout his life. When Planck was a young boy, his family moved to Munich, where he received his early education. A gifted student who could easily have become a great pianist, Planck studied physics at the Universities of Munich and Berlin. In Berlin he had the opportunity to directly interact with such famous scientists as GUSTAV ROBERT KIRCHHOFF and RUDOLF JULIUS EMMANUEL CLAUSIUS. Kirchhoff introduced Planck to sophisticated, classical interpretations of blackbody radiation, while Clausius challenged him with the profound significance of the second law of thermodynamics and the elusive concept of entropy. In 1879 Planck received his doctoral degree in physics from the University of Munich. From 1880 to 1885 he remained in Munich as a Max Planck was the gentle, cultured German physicist Privatdozent (lecturer) in physics at the university. who introduced quantum theory in 1900, transforming He became an associate professor in physics at the physics and the world in the process. His powerful University of Kiel in 1885 and remained in that new theory suggested the transport of electromagnetic radiation in discrete energy packets or quanta. Amid position until 1889, when he succeeded Kirchhoff great personal tragedy, Planck received the 1918 Nobel as professor of physics at the University of Berlin. Prize in physics for his world-changing scientific His promotion to associate professor in 1885 pro- accomplishment—an achievement representing one of vided Planck with the income to marry his first the two great pillars of modern physics. (The other is Albert Einstein’s theory of relativity.) (AIP Emilio Segrè wife, Marie Merck—a childhood friend with Visual Archives) 236 Planck, Max Karl While teaching at the University of Berlin (Annals of physics), contained Planck’s most im- at the end of the 19th century, Planck began to portant work and represented a major turning address the very puzzling problem involved with point in the history of physics. The introduc- the emission of energy by a blackbody radiator tion of quantum mechanics had profound im- as a function of its temperature. A decade ear- plications on all modern physics from the way lier, JOSEF STEFAN had performed important heat scientists treated subatomic phenomena to the transfer experiments concerning blackbody ra- way they modeled the behavior of the universe diators. However, classical physics could not ad- on cosmic scales. equately explain his experimental observations. Yet Planck himself was a reluctant revolu- To make matters more puzzling, classical elec- tionary. For years, he felt that he had only created tromagnetic theory incorrectly predicted that a the quantum postulate as a “convenient means” blackbody radiator should emit an infinite amount of explaining his blackbody radiation formula. of thermal energy at very high frequencies—a However, other physicists were quick to seize paradoxical condition referred to as the “ultra- Planck’s quantum postulate and then to go forth violet catastrophe.” and complete his revolutionary movement— Early in 1900, two British scientists, Lord displacing classical physics with modern physics. Rayleigh (1842–1919) and SIR JAMES HOPWOOD Einstein used Planck’s quantum postulate to JEANS, introduced their mathematical formula explain the photoelectric effect in 1905, and (called the Rayleigh-Jeans formula) to describe Niels Bohr (1885–1962) applied quantum the energy emitted by a blackbody radiator as a mechanics in 1913 to create his world-changing function of wavelength. While their formula ad- model of the hydrogen atom. equately predicted behavior at long wavelengths Planck received the 1918 Nobel Prize in (for example, at radio frequencies), their model physics in recognition of his epoch-making in- failed completely in trying to predict blackbody vestigations into quantum theory. He also pub- behavior at shorter wavelengths (higher fre- lished two important books: Thermodynamics quencies)—the portion of the electromagnetic (1897) and The Theory of Heat Radiation (1906) spectrum of great importance in astronomy, since that summarized his major efforts in the physics stars approximate high-temperature blackbody of blackbody radiation. He was a well-respected radiators. physicist even after his retirement from the Planck solved the problem when he de- University of Berlin in 1926. That same year, the veloped a bold new formula that successfully British Royal Society honored his contributions described the behavior of a blackbody radiator to physics by electing him a foreign member and over all portions of the electromagnetic spec- awarding him its prestigious Copley Medal. trum. To reach his successful formula, Planck as- But as Planck climbed to the pinnacle of sumed that the atoms of the blackbody body professional success, his personal life was marked emitted their radiation only in discrete indi- with deep tragedy. At the time Planck won the vidual energy packets that he called quanta. In Nobel Prize in physics, his oldest son, Karl, died a classic paper that he published in late 1900, in combat in World War I, and both his twin Planck presented his new blackbody radiation daughters, Margarete and Emma, died about a formula. He included the revolutionary idea that year apart in childbirth. the energy for a blackbody resonator at a fre- In the mid–1930s, when Adolf Hitler seized quency (␯) is simply the product h ␯, where h is power in Germany, Planck, in his capacity as the a universal constant, now called Planck’s con- elder statesperson for the German scientific stant. This paper, published in Annalen der Physik community, bravely praised Einstein and other Plato 237 German-Jewish physicists in open defiance of because of broad shoulders (from Platon, meaning the ongoing Nazi persecutions. Planck even met “broad”)—was the first to create the ideas that personally with Hitler to try to stop the sense- grew into the science of the universe—a science less attacks against Jewish scientists. But Hitler that would cause the death of many astronomers simply flew into a tirade and ignored the pleas in the centuries to come who questioned the from the aging Nobel laureate. As a final protest, philosophies that became the religious “truths” Planck resigned in 1937 as the president of the of the Christian church. Kaiser Wilhelm Institute—the leadership posi- Plato was a student of the philosopher tion in German science and one in which he Socrates (470–399 B.C.E.), who was a Sophist. had proudly served with great distinction since This sect of philosophers considered themselves 1930. In his honor, that institution is now called “masters of wisdom,” and traveled from country the Max Planck Institute. to country and town to town as orators espous- During the closing days of World War II, ing their philosophies. The Sophist view was his second son, Erwin, was brutally tortured and that there are two kinds of philosophy—natural then executed by the Nazi Gestapo for his role and moral. Natural philosophy, that is, nature or in the unsuccessful 1944 assassination attempt science, was considered a complete waste of time against Hitler. Just weeks before the war ended, and mental attention. The only philosophy wor- Planck’s home in Berlin was completely thy of human thought was moral philosophy be- destroyed by Allied bombing. In the very last cause it dealt with the abstract, and abstract wis- days of the war, U.S. troops launched a daring dom was the only kind of knowledge that served rescue across war-torn Germany to keep Planck to strengthen the soul. Socrates took this view and his second wife, Marga, from being of moral philosophy one step further, saying the captured by the advancing Russian army. The most important knowledge of all was to “know Dutch-American astronomer GERARD PETER thyself.” His teachings centered on this premise. KUIPER, was a participant in this military Socrates, Plato, and the others who consid- action that allowed Planck to live the remain- ered themselves Sophists were changing the der of his life in the relative safety of the Allied- then-accepted views of the Ionians—a sort of occupied portion of a divided Germany. On competitive group of philosophers. The Ionians October 3, 1947, at age 89, the brilliant expanded on the views of Thales (624–546 physicist who ushered in a revolution in physics B.C.E.), who declared that the Earth was flat with his quantum theory died peacefully in and in essence afloat in an endless sea of space. Göttingen, Germany. This notion of a flat planet managed to resur- face some centuries later, and was ultimately disproved to the “general public” once and for ᨳ Plato (Aristocles, Platon) all—some 2,000 years after its original introduc- (ca. 427–347 B.C.E.) tion—by Christopher Columbus. He navigated Greek his ships by the stars, and thankfully did not fall Philosopher off the “edge” of the Earth during any of his explorations. The ancient Greek philosopher born Aristocles The next evolution of the state of all in Athens around 427 B.C.E., was not interested things heavenly came from a student of Thales in science. In fact, he is said to have despised named Anaximander (610–547 B.C.E.). He in- it. Ironically, this pagan philosopher known troduced the idea of a sphere around the Earth as Plato—a nickname picked up as a child in which all of the stars were held, and he 238 Plato expanded the shape of the Earth from a pan- Pythagoras claimed that the entire system was cake to a cylinder. But since the Ionians were spherical—the Sun, Moon, stars, and planets— natural philosophers, not moral philosophers, and, by the way, so was the Earth. This was truly they were attempting to explain the nature of a new concept. Plato picked up the cosmic ball the universe, which the Sophists were adamantly and ran with it, so to speak, giving credence to against. In fact, Socrates warned his followers the idea of an entirely spherical universe—a uni- that if they succumbed to the kind of thinking verse that, of course, revolved around the spher- subscribed to by the Ionians, it would “expose ical Earth. Plato then went one step further still, [their] mental eyes to total and irreparable describing the entire system, in whole and in blindness.” every part, as a living organism. In 409 Plato became a disciple of Socrates. The world according to Plato consisted of When Socrates was executed by the government four elements—earth, air, fire, and water. The in 399, for “corrupting youth” by teaching them heavens consisted of one—quintessence. The the “art of words,” Plato left Athens, stating in perfection of the heavens was a result of the per- his writings that the entire system would re- fect one who created them. And since the heav- main corrupt until “kings were philosophers or ens were perfect, it stood to reason that they had philosophers were kings.” to move in the most perfect of paths—in the shape Plato’s travels took him to Italy and Africa. of a circle. It was reasonable, then, that they At some point during his journey, he became resided in perfect shapes—crystalline spheres— familiar with the Pythagoreans and their belief that held everything in place. In fact, Plato that everything could be explained with mathe- believed that the entirety of the heavens existed matics. In Plato’s time, mathematics was not in perfect geometric form. With his new ideas on considered a science because it dealt with motion and shape, mathematics and astronomy abstracts. As abstract thought, mathematics, became forever intertwined. then, was the most worthy kind of thought to Plato’s writings were created as dialogues— ponder. discussions between his teacher, Socrates, and In 387 Plato found his way back to Athens one of his students—in which Plato crafted the and set up the first institute for higher learning. explanations of his philosophies. Plato delved Plato’s Academy, built on land once owned by into the order of the universe in his work a man named Academus, was dedicated to ab- Timaeus, in which an astronomer named Timaeus stract thought—truly considered higher learn- explains the universe to Socrates. “What is that ing—and since mathematics was purely abstract, which always is and has no becoming; and what Plato became such a proponent of it that he had is that which is always becoming and never a sign inscribed above the Academy’s entrance is? . . . Was the world, I say, always in existence that read, “Let no one ignorant of mathematics and without beginning? Or created and had it a enter here.” This foundation of mathematics beginning?” It is in this writing that Plato puts built into Plato’s teachings was strong enough to forth the concept of the circular motions and hold the philosophy of the cosmos—ideas that spherical shape of the universe. were proposed initially by Plato then built upon In another dialogue, Republic, Plato deter- by his most famous student, ARISTOTLE—for the mines the order in which the celestial orbs lie next 1,500 years. closest to the Earth, but he changes that order Plato learned in his travels that Pythagoras in Timaeus, ultimately settling on the Moon, the (ca. 582–497 B.C.E.) had gone even further with Sun, Mercury, Venus, and Mars. He describes the sphere concept proposed by Anaximander. four concentric spheres that relate to the four Ptolemy 239 elements, and then explains the sizes of the Plato’s Academy, the first university ever spheres as they relate to the size of Earth. In this, established, was in operation for 900 years. The the Earth has a radius of one, water’s radius is Christian leader, the Roman emperor Justinian, two, air’s radius is five, and fire has a radius of closed the pagan institution in 529. Plato died 10 and is the sphere that contains the stars. He at age 82, supposedly peacefully, in his sleep af- then tells the distances of the spheres of the ter attending a feast in honor of the wedding of planets from the Earth in terms of the number a student. The crater Plato is located in the value he has given the four elements. For ex- Alpine Valley region of the Moon. Nearby lie ample, the distance to the moon is 8, which the craters Eudoxus and Aristoteles. equals 1 ϩ 2 ϩ 5, or earth ϩ water ϩ air. But Plato’s ideas had many flaws. For starters, orbits are not circular, there are no crys- ᨳ Ptolemy (Claudius Ptolemy, talline spheres holding the universe together, Claudius Ptolemaeus, Claudius and the entire cosmos does not revolve around Ptolemaios) the Earth. As his students expanded upon Plato’s (ca. 100–178) ideas, complications grew. One such student, Greek Eudoxus of Cnidus, declared that there were 26 Philosopher, Astronomer, Astrologer, rotating spheres in the heavens. Another stu- Cartographer, Geographer, dent, Aristotle, determined that there were in Mathematician fact 54 crystal spheres holding the universe together and keeping it all moving in perfect or- As with many of the ancients, little is known der. As these ideas of the universe expanded, it about the famous Greek philosopher Claudius became pretty evident that they did not always Ptolemy. Believed to have been a Roman citi- work. In order to make sure these philosophies zen, and born in Alexandria, Egypt, he has appeared to work, adjustments had to be made. been described as a man of average build who These adjustments were called “saving the ap- had a penchant for horsemanship. It was his pearances,” and were performed throughout the mastery of natural (that is, scientific) philosoph- reign of the geocentric, or Earth-centered, realm ical thought and writing that made his work the that explained the structure of the universe ac- prevailing doctrine of astronomy for approxi- cording to Aristotle, by way of Plato’s teach- mately 1,500 years after his death, building on ings. Things did not change until the works of many great thinkers who came before him, includ- NICOLAS COPERNICUS,JOHANNES KEPLER, and ing PLATO, Eudoxus of Cnidus (409–356 B.C.E.), GALILEO GALILEI became recognized as the true ARISTOTLE, and of course Hipparchus (190– nature of the universe. 120 B.C.E.). In Epinomis, another writing credited to Ptolemy created ancient encyclopedic vol- Plato (although there has been controversy umes on astronomy in the dawn of recorded sci- surrounding its authorship), a fifth element, entific study. His goals were very clear in creat- aether—the quintessence—was introduced, and ing his first writing, Megale Mathematike Syntaxis it is this writing that is said to bridge the transi- (Great mathematical composition), which cen- tion from the four elements and Plato’s universe turies later became known as Almagest. “We shall to the expanded view of the cosmos explained set out everything useful for the theory of the by Aristotle. Here, Plato tells us that the Sun is heavens in the proper order . . . (and) recount larger than the Earth, and that the sphere of stars what has been adequately established by the is immense in size. ancients,” he wrote. 240 Ptolemy The “ancients” were the Mesopotamians, universe, around which everything else revolved. whose work was known from about 2,000 years This followed Aristotle’s teachings, which had prior to Ptolemy’s time. Their studies of the heav- become the accepted view of how the universe ens included classifications of stars, determining worked, despite the fact that, around 287 B.C.E., the length of seasons, observations and theories of ARISTARCHUS OF SAMOS introduced a heliocen- lunar cycles, the relationship between the Moon tric model after studying at Aristotle’s Lyceum and planets, planetary observations (particularly in Alexandria. This concept fell out of favor and of Venus), and creating the signs of the zodiac that was not revived until the 16th century, when the are familiar today and often credited to Ptolemy. Polish cleric NICOLAS COPERNICUS worked on They also determined that the universe was made simplifying Ptolemy’s complicated model of the up of a system of eight concentric spheres. heavens. Ptolemy was a student of astronomy, and it Ptolemy’s work in astronomy was his Megale is generally agreed that Ptolemy’s most influen- Mathematike Syntaxis (Great mathematical com- tial “teacher” lived years before he was born. In position), simply called Megiste (Greatest), which the second century B.C.E., Hipparchus (ca. 160– was translated into Arabic as al-Majisti (the great- 125 B.C.E.) was a highly regarded philosopher est), and finally became Almagest. The work con- and mathematical astronomer who worked sists of 13 volumes—a treatise with mathemati- mostly on the island of Rhodes, and was the first cal computations, observations, and theories on person to use longitude and latitude to designate all things regarding the workings of the universe. the location of a city. Access to Hipparchus’s Ptolemy stated, “We shall try to note down work was naturally available to Ptolemy through everything which we think we have discovered the great libraries in Alexandria, as was the up to the present time.” This included mathe- work of the philosopher Aristotle, who ex- matical computations for how the geocentric panded on the work of his teacher Plato, who model works, using mostly trigonometry, in was a disciple of Socrates. which he defines an approximate value of pi as One of the biggest distinctions between 3.14166, and an introduction to a theorem (now Ptolemy and his predecessors is that most of his called Ptolemy’s theorem) that states that for a major works have survived. Ptolemy’s writings quadrilateral inscribed in a circle (a cyclic have undergone a number of translations through- quadrilateral), the sum of the products of the out the centuries—by Persian mathematician and two pairs of opposite sides are equal to the prod- astronomer Nasir ad-Din at-Tusi (1201–74); uct of its two diagonals, written as AC ϫ BD ϭ philosopher and scholar George of Trebizond (AD ϫ BC) ϩ (AB ϫ CD). (1396–1486), who wrote his own commentary on In the Almagest Ptolemy explains that the the Almagest that was as long as Ptolemy’s work, Earth is fixed and the other heavenly spheres but whose translation was criticized by the pope rotate around the Earth, and he explains how for its inaccuracies; and most notably German to predict the positions of the Sun, the Moon, astronomer Johannes Regiomontanus (1436–76), and the planets. He includes his determination who translated Ptolemy’s work from Greek to of the length of the year, a theory of the Moon, Latin from 1460 to 1463, creating Epitome of the theory of eclipses, theory of the Sun, theory of Almagest, the definitive translation of the work for planets, creates a star catalog with more than the 15th and 16th centuries. 1,000 stars, and then creates a very complicated Ptolemy’s astronomical work centered on his model to fit his observations. belief that the universe was geocentric in nature; It is very hard to say which part of this in other words, the Earth was the center of the caused the most trouble for astronomers over the Ptolemy 241 centuries. The problems are, of course, based on planetary movement. Astrology was the culmi- the fact that his premise is wrong—the Earth is nation of Almagest. As Ptolemy saw it, Almagest not at the center of the universe. Even this was was meant to explain how the heavenly bodies obvious to Ptolemy; he tried to fix it by moving worked, and Astrology explained how they af- the Earth slightly off center from the spheres fected people’s lives. Other astronomy-related ti- that rotated around it. tles were Analemma, which explained the math- Other problems arose as well. The value he ematics necessary to make a sundial, and 1 1 gave for the length of the year was 365 ⁄4— ⁄300 Planesphaerium, which delved into how to map of a day, which is not accurate (the actual value the celestial sphere onto a plane. Optics, a col- 1 is less than ⁄28 of a day). He notes in Almagest lection of five books, explored light in terms of that there are small discrepancies—that his reflection and refraction. model does not match the observed sky. He Another major contribution to science was states that everything in the heavens revolves in Ptolemy’s Geography, a compilation of eight perfect circular motion. books in which he undertakes the daunting task To give it all some sense, Ptolemy had to do of giving the coordinates (approximately 8,000) things like add complicated spheres within to map the entire known world by longitude and spheres. And while moving the Earth off center latitude. The three continents then known were was a strict violation of Aristotle’s teachings, it Europe, Asia, and Africa, and the maps included seemed to be acceptable because it was only the Tropics of Cancer and Capricorn. His maps slightly different, and with the other adjust- did not survive, but the text did, and scholars in ments, it seemed to work—for the most part. But the 15th century re-created his maps based on it was this kind of fudging that would eventually his instructions in the book. arouse some heated opinions from astronomers in Almagest gave a historical, philosophical, centuries to come. GALILEO GALILEI gave perhaps and scientific perspective on the early views of the most gentle argument against Ptolemy’s astronomy, though it was fraught with mistakes. model in his work Dialogue Concerning the Two Even Ptolemy himself knew that the work had Chief World Systems, Ptolemaic and Copernican, problems. The complications were huge, and in written in 1632. SIR ISAAC NEWTON, however, many places the text was contradictory. At least was a little more blatant in his distaste of Ptolemy felt compelled to address these issues: Ptolemy’s work, saying that Ptolemy was a fraud, “Let no one seeing the difficulty of our devices, and that his work was “a crime committed by a find troublesome such hypotheses. For it is not scientist against fellow scientists and scholars, a proper to apply human things to divine things.” betrayal of the ethics and integrity of his pro- Almagest proposed a view that, unfortunately, fession” and that every observation Ptolemy became dogma. But it did what Ptolemy said he wrote in Almagest was completely made up. was hoping to accomplish: It gave all of the de- Several pieces of the Almagest resulted in tails of what was known at the time. Ptolemy spin-off works. Handy Tables gave updated calcu- added original thought about planetary move- lations for planetary, solar, and lunar positions, ments, created a star catalog that became the eclipses of the Sun and Moon, and was generally primary source for star maps for the next 1,400 used for astrology purposes. Planetary Hypothesis years, and most important, defined astronomy as consisted of two books on Ptolemy’s theories of a science.

the third receiver that, in 1938, picked up the ᨳ Reber, Grote elusive radio emissions Reber was searching for at (1911–2002) 160 megahertz. By 1940, and again in 1944, he American had accumulated enough information to publish Radio Astronomer a series entitled “Cosmic Static” in the Astro- From the beginning of recorded time, amateur physical Journal, and the study of radio astronomy astronomers have contributed significantly to was officially under way. The year 1944 was a the study of the cosmos. One such astronomer busy one for this important discoverer, as he also of the 20th century was Grote Reber, a pioneer located radio emissions coming from the Sun and in radio astronomy. from the nearby Andromeda Galaxy. A graduate of the Illinois Institute of Around the middle of the 20th century, Technology in 1933, Reber became intrigued Grote Reber moved his operations to an estate with the concept of radio astronomy when, dur- in Tasmania, Australia, but first he donated his ing the same year, Karl Jansky announced his original radio telescope to the National Radio discovery of radio waves emanating from space. Astronomy Observatory in Green Bank, Virginia, The young Reber embarked on his career as an where it is still on display. His relocation to engineer and spent the next 17 years working Tasmania was, as he wrote, to “build a more for radio manufacturers in Chicago, giving him elaborate structure capable of being called a the opportunity to conduct radio research on his radio telescope.” By the time he was through, own. Reber spent the summer of 1937 building Reber had constructed an array of 192 dipoles, a 31-foot (9-meter) tiltable radio telescope in his or antennas, that spanned an area of 3,520 feet backyard in Wheaton, Illinois, becoming the in diameter. He focused his efforts on the low- first person to make such an instrument. This frequency radio waves that he was able to best was during the Great Depression, and Reber re- receive in this part of the world. portedly spent six months’ salary for the neces- Reber achieved several firsts in his field. In sary parts and equipment to build the parabolic addition to building the first radio telescope, dish reflector, which he designed himself. some of his most notable work includes classify- Over the next several years, Reber con- ing radio signals by density and brightness, and structed three different detectors in an effort to using his findings of radio frequency to create and find radio signals at the right wavelengths. It was publish contour maps of space. This work was

242 Rees, Sir Martin John 243 significant enough to earn him the Catherine Wolfe Bruce Gold Medal, awarded by the Astro- nomical Society of the Pacific in 1962. Reber became only the second amateur astronomer to receive the award since the organization’s beginnings in 1889. Reber continued his work in Australia as a pioneer in long wavelength radio astronomy. The year 1962 was a big one for accolades in Reber’s life. In addition to the Bruce Medal, he received an honorary doctorate from Ohio State University, the Cresson Gold Medal from the Franklin Institute of Pennsylvania, and the American Astronomical Society’s Henry Norris Russell Lectureship. Additional honors include the Jansky Prize from the National Radio Astronomy Observatory (NRAO) in 1976, and the Jackson-Gwilt Medal, in 1983, from the Royal Astronomical Society. Beginning in 1938, Reber published more than 50 papers on his work. “Reber was the first to systematically study the sky by observing something other than visible light,” according to Fred Lo, director of the NRAO. Reber’s sci- Sir Martin John Rees, the 15th Astronomer Royal of entific papers are all in the NRAO’s library. In Great Britain, was among the first astrophysicists to suggest that enormous black holes could power his honor, the SETI Institute in Mountain View, quasars. His previous investigations of the distribution California, published a song in their League of quasars helped discredit steady-state cosmology. Songbook to the tune of If You’re Happy and You (AIP Emilio Segrè Visual Archives, John Irwin Know It, a short version of the life and times of Collection) this beloved amateur. On December 20, 2002, Reber died in Australia, just two days before his 91st birthday. theories of galaxy formation and studied the nature of the so-called dark matter of the universe. Dark matter is matter believed present ᨳ Rees, Sir Martin John throughout the universe that cannot be observed (1942– ) directly because it emits little or no electromag- British netic radiation. Contemporary cosmological Astrophysicist models suggest that this “missing mass” controls the ultimate fate of the universe. In 1995 Sir Rees Sir Martin John Rees was among the first accepted an appointment to serve Great Britain astrophysicists to suggest that enormous black as the 15th Astronomer Royal—a position he still holes could power quasars. His investigation of held as of 2004. the distribution of quasars helped discredit steady- Rees was born on June 23, 1942, in York, state cosmology. He has also contributed to the England. He received his formal education at 244 Rossi, Bruno Benedetto Cambridge University. Rees graduated from Trin- principle—the somewhat controversial premise ity College in 1963 with a bachelor of arts degree that suggests the universe evolved in just the in mathematics and then continued on for his right way after the big bang to allow for the emer- graduate work, completing a Ph.D. degree in gence of life, especially intelligent human life. 1967. Before becoming a professor at Sussex Uni- One of Rees’s greatest talents is his ability versity in 1972, he held various postdoctoral to effectively communicate the complex topics positions in both the United Kingdom and the of modern astrophysics to both technical and United States. In 1973 Rees became the nontechnical audiences. He has written more Plumian Professor of Astronomy and Experi- than 500 technical articles, mainly on cosmol- mental Philosophy at Cambridge and remained ogy and astrophysics, and several books, includ- in that position until 1991. During this period, ing Cosmic Coincidences (1989), and Gravity’s he also served two separate terms (1977–82 and Fatal Attraction: Black Holes in the Universe 1987–91) as director of the Institute of Astronomy (1995); Just Six Numbers (2000), New Perspectives at Cambridge. Among his many professional in Astrophysical Cosmology (2000), and Our affiliations, Rees became a fellow of the Royal Cosmic Habitat (2001). Rees has received nu- Society of London in 1979, a foreign associate of merous awards for his contributions to modern the United States National Academy of Sciences astrophysics, including the Gold Medal of the in 1982, and a member of the Pontifical Acad- Royal Astronomical Society (1987), the Bruce emy of Sciences in 1990. He is currently a Royal Gold Medal from the Astronomical Society of Society Professor and a fellow of King’s College the Pacific, the Science Writing Award from at Cambridge University. He is also a visiting the American Institute of Physics (1996), the professor at the Imperial College in London. Bower Science Medal of the Franklin Institute In 1992 he became president of the Royal (1998), and the Rossi Prize of the American Astronomical Society, and Queen Elizabeth II Astronomical Society (2000). conferred knighthood upon him. By royal decree in 1995, Sir Martin Rees became Great Britain’s Astronomer Royal, the 15th distin- ᨳ Rossi, Bruno Benedetto guished astronomer to hold this position since (1905–1993) the English king Charles II created the post in Italian/American 1675. Physicist, Astronomer, Space Scientist As an eminent astrophysicist, he has modeled quasars and studied their distribution— Attracted to high-energy astronomy, Bruno Rossi important work that helped discredit the steady- investigated the fundamental nature of cosmic state universe model in cosmology. He was one rays in the 1930s. Using special instruments car- of the first astrophysicists to postulate that enor- ried into outer space by sounding rockets, he col- mous black holes might power these powerful and laborated with RICCARDO GIACCONI and other sci- puzzling compact extragalactic objects that were entists in 1962 and discovered the X-ray sources first discovered in 1963 by MAARTEN SCHMIDT. outside the solar system. In the first decade of the Sir Rees maintains a strong research interest in Space Age, Rossi made many important contri- many areas of contemporary astrophysics, in- butions to the emerging fields of X-ray astronomy cluding gamma ray bursts, black hole formation, and space physics. To honor these important con- the mystery of dark matter, and anthropic cos- tributions, NASA renamed the X-ray astronomy mology. One of today’s most interesting cosmo- satellite successfully launched in December 1995 logical issues involves the so-called anthropic the Rossi X-ray Timing Explorer (RXTE). Rossi, Bruno Benedetto 245 to 1938. However, in 1938 the Fascist regime of Benito Mussolini suddenly dismissed Rossi from his position at the university. That year, Fascist leaders went about purging the major Italian universities of many “dangerous” intellectuals who might challenge Italy’s totalitarian government and question Mussolini’s alliance with Nazi Germany. Like many other brilliant Euro- pean physicists in the 1930s, Rossi became a political refugee from fascism. Together with his new bride, Nora Lombroso, he departed Italy in 1938. The couple arrived in the United States in 1939, after short stays in Denmark and the United Kingdom. Rossi eventually joined the faculty at Cornell University in 1940 and remained with that university as an associate professor until 1943. In spring 1943 Rossi’s official immigration status as an “enemy alien” was changed to “cleared to top secret,” and he joined the many other refugee nuclear physicists at the Los Alamos National Laboratory, in New Mexico. There Rossi collaborated with other gifted scientists from Europe, as they developed the atomic bomb under the top-secret As part of his investigation of cosmic rays in the Manhattan Project. Rossi used all his skills in 1930s, the Italian-American physicist Bruno Rossi radiation detection instrumentation to provide developed pioneering electronic instrumentation that supported both nuclear particle physics and high- his colleague, the great nuclear physicist Enrico energy astrophysics. He collaborated with Giacconi Fermi (1901–54), an ultrafast measurement of and others in 1962 and helped discover the first X-ray the exponential growth of the chain reaction in sources outside the solar system. During the first the world’s first plutonium bomb (called Trinity) decade of the Space Age, Rossi continued to make made many other important contributions to the that was tested near Alamogordo, New Mexico, emerging fields of X-ray astronomy and space physics. on July 16, 1945. In a one-microsecond oscil- (AIP Emilio Segrè Visual Archives) loscope trace, Rossi’s instrument captured the rising intensity of gamma rays from the bomb’s supercritical chain reaction—marking the pre- Bruno Rossi was born on April 13, 1905, in cise moment in world history before and after Venice, Italy. The son of an electrical engineer, the age of nuclear weapons. he began his college studies at the University of After World War II, Rossi left Los Alamos Padua and received his doctorate in physics from in 1946 to become a professor of physics at the the University of Bologna in 1927. He began his Massachusetts Institute of Technology (MIT). In scientific career at the University of Florence 1966 he became an institute professor—an ac- and then became the chair in physics at the Uni- ademic rank at MIT reserved for scholars of versity of Padua, serving in that post from 1932 great distinction. Upon retirement in 1971, the 246 Rossi, Bruno Benedetto university honored his accomplishments by be- and X-ray astronomy. In 1958 he focused his at- stowing upon him the distinguished academic tention on the potential value of direct meas- rank of institute professor emeritus. urements of ionized interplanetary gases by space Early in his career, Rossi’s experimental in- probes and Earth-orbiting satellites. He and his vestigations of cosmic rays and their interaction colleagues constructed a detector (called the with matter helped establish the foundation of MIT plasma cup) that flew into space onboard modern high-energy particle physics. Cosmic NASA’s Explorer X satellite. Launched in 1961, rays are extremely energetic nuclear particles this instrument discovered the magnetopause— that enter Earth’s atmosphere from outer space the outermost boundary of the magnetosphere, at velocities approaching that of light. When beyond which Earth’s magnetic field loses its cosmic rays collide with atoms in the upper at- dominance. mosphere, they produce cascades of numerous Then, in 1962, Rossi collaborated with short-lived subatomic particles like mesons. Riccardo Giacconi (then at American Science Rossi carefully measured the nuclear particles and Engineering, Inc.) and launched a sounding associated with such cosmic ray showers and rocket from White Sands, New Mexico, with an effectively turned Earth’s laboratory into one early grazing incidence X-ray mirror as its pay- giant nuclear physics laboratory. load. With funding from the U.S. Air Force, the Rossi began his detailed study of cosmic rays scientists primarily hoped to observe any X-rays in 1929, when only a few scientists had an inter- scattered from the Moon’s surface as a result of est in them or realized their great importance. interactions with energetic atomic particles That year, to support his cosmic ray experiments, from the solar wind. To their great surprise, the he invented the first electronic circuit for record- rocket’s payload detected the first X-ray source ing the simultaneous occurrence of three or more from beyond the solar system—Scorpius X-1, the electrical pulses. This circuit is now widely known brightest and most persistent X-ray source in as the Rossi coincidence circuit. It not only be- the sky. Rossi’s fortuitous discovery of this in- came one of the fundamental electronic devices tense cosmic X-ray source marks the beginning used in high-energy nuclear physics research, but of extrasolar (cosmic) X-ray astronomy. Other also was the first electronic AND circuit—a ba- astronomers performed optical observations of sic element in modern digital computers. Scorpius X-1 and found a binary star system, While at the University of Florence, Rossi consisting of a visually observable ordinary dwarf demonstrated in 1930 that cosmic rays were ex- star and a suspected neutron star. In this type of tremely energetic, positively charged nuclear so-called X-ray binary, matter drawn from the particles that could pass through a lead shield normal star becomes intensely heated and emits over a meter thick. Through years of research, X-rays as it falls to the surface of its neutron star Rossi helped remove much of the mystery sur- companion. rounding the Höhenstrahlung (“radiation from Rossi was a member of many important sci- above”) first detected by VICTOR FRANCIS HESS entific societies, including the National Acad- in 1911–12. emy of Sciences and the American Academy of By the mid-1950s large particle accelerators Arts and Sciences. He was a very accomplished had replaced cosmic rays in much of contempo- writer. Rossi’s books included High Energy Parti- rary nuclear particle physics research, so Rossi cles (1952), Cosmic Rays (1964), Introduction to used the arrival of the Space Age (late 1957) to the Physics of Space (coauthored with Stanislaw became a pioneer in two new fields within Olbert in 1970), and the insightful autobiogra- observational astrophysics: space plasma physics phy, Moments in the Life of a Scientist (1990). He Russell, Henry Norris 247 received numerous awards, including the Gold Medal of the Italian Physical Society (1970), the Cresson Medal from the Franklin Institute (1974), the Rumford Award of the American Academy of Arts and Sciences (1976), and the U.S. National Medal of Science (1985). Rossi’s scientific genius laid many of the foundations of high-energy physics and astrophysics. He died at home in Cambridge, Massachusetts, on November 21, 1993.

ᨳ Russell, Henry Norris (1877–1957) American Astronomer, Astrophysicist

Henry Norris Russell was one of the most influential astronomers in the first half of the 20th century. As a student, professor, and observatory director, he worked for nearly 60 years at Prince- ton University—a truly productive period that also included vigorous retirement activities as professor emeritus and observatory director emeritus. Primarily a theoretical astronomer, he The American astronomer Professor Henry Norris made significant contributions in spectroscopy Russell lecturing at Princeton University. Independent and to astrophysics. Independent of EJNAR of the Danish astronomer Ejnar Hertzsprung, Russell HERTZSPRUNG, Russell investigated the relation- developed the famous Hertzsprung-Russell (HR) ship between absolute stellar magnitude and a diagram that helps astronomers and astrophysicists understand stellar life cycles. (Courtesy of AIP Emilio star’s spectral class. By 1913 their complemen- Segrè Visual Archives, Margaret Russell Edmondson tary efforts resulted in the development of the Collection) famous Hertzsprung-Russell (H–R) diagram, which is of fundamental importance to all modern astronomers who wish to understand the minister, Russell received his first introduction theory of stellar evolution. Russell also per- to astronomy at age five, when his parents formed pioneering studies of eclipsing binaries showed him the 1882 transit of Venus across the and made preliminary estimates of the relative Sun’s disk. He completed his undergraduate ed- abundance of elements in the universe. Often ucation at Princeton University in 1897, gradu- called “the dean of American astronomers,” ating with the highest academic honors ever Russell served the astronomical community very awarded by that institution—namely, insigni well as a splendid teacher, writer, and research cum laude (with extraordinary honor). Russell adviser. remained at Princeton for his doctoral studies in Russell was born on October 25, 1877, in astronomy, again graduating with distinction Oyster Bay, New York. The son of a Presbyterian (summa cum laude) in 1900. 248 Russell, Henry Norris Following several years of postdoctoral re- have experienced gravitational collapse at the search at Cambridge University, he returned to end of their life cycle. Princeton in 1905 to accept an appointment as Following his pioneering work in stellar an instructor in astronomy. He remained affili- evaluation, Russell engaged in equally signifi- ated with Princeton for the remainder of his cant work involving eclipsing binaries. An life. He became a full professor in 1911 and the eclipsing binary is a binary star that has its or- following year became director of the Princeton bital plane positioned with respect to Earth in Observatory. He remained in these positions such a way that each component star is totally until his retirement in 1947. Starting in 1921, or partially eclipsed by the other star every or- Russell also held an additional appointment bital period. With his graduate student HARLOW as a research associate of the Mount Wilson SHAPLEY, Russell analyzed the light from such Observatory, in the San Gabriel Mountains stars to estimate stellar masses. Later he collab- just north of Los Angeles, California. In 1927 orated with another assistant, Charlotte Emma he received an appointment to the newly en- Moore Sitterly (1898–1990), in using statistical dowed C. A. Young Research Professorship at methods to determine the masses of thousands Princeton, a special honor bestowed upon him of binary stars. by his undergraduate classmates from the class Before the discovery of nuclear fusion, of 1897. Russell tried to explain stellar evolution in Starting with his initial work at Cambridge terms of gravitational contraction and continual University on the determination of stellar dis- shrinkage and used the H-R diagram as a flow- tances, Russell began to assemble data from dif- chart. When HANS ALBRECHT BETHE and other ferent classes of stars. He noticed that these data physicists began to associate nuclear fusion related spectral type and absolute magnitude and processes with stellar life cycles, Russell aban- soon concluded that there were actually two doned his contraction theory of stellar evolution. general types of stars: giants and dwarfs. However, the basic information he presented in The Hertzsprung-Russell (H-R) diagram is the H-R diagram still remained very useful. actually just an innovative graph that depicts the In the late 1920s Russell performed a de- brightness and temperature characteristics of tailed analysis of the Sun’s spectrum showing stars. However, since its introduction by Russell that hydrogen was a major constituent. He noted at a technical meeting in 1913, it has become the presence of other elements, as well as their one of the most important tools in modern as- relative abundances. Extending this work to trophysics. So-called dwarf stars, including the other stars, he postulated that most stars exhibit Sun, lie on the main sequence of the H-R dia- a similar general combination of relative ele- gram—the well-populated region that runs mental abundances (dominated by hydrogen from the top left to lower right portions of this and helium) that became known as the “Russell graph. Giant and supergiant stars lie in the up- mixture.” This work reached the same general per right portion of the diagram above the main conclusion that was previously suggested in 1925 sequence band. Finally, huddled down in the by the British astronomer Cecilia Helena Payne- lower left portion of the H-R diagram below Gaposchkin. the main sequence band are the extremely Russell was an accomplished teacher, and dense, fading cores of burned-out stars known his excellent two-volume textbook, Astronomy, collectively as “white dwarfs.” This term is jointly written with Raymond Dugan and John sometimes misleading because it actually ap- Stewart, appeared in 1926–27. It quickly plies to a variety of compact, fading stars that became a standard text in astronomy curricula Ryle, Sir Martin 249 at universities around the world. Russell’s Solar radio frequency systems for the Royal Air Force. System and Its Origin (1935) served as a pioneer- His wartime service in the Telecommunications ing guide for future research in astronomy and Research Establishment gave him valuable en- astrophysics. Even after his retirement from gineering experience that he would soon apply Princeton in 1947, Russell remained a domi- in innovative ways in radio astronomy. After the nant force in American astronomy. Honored war Ryle received a fellowship to conduct radio with appointments as both an emeritus profes- wave research at the Cavendish Laboratory of sor and an emeritus observatory director, he the University of Cambridge. The research pursued interesting areas in astrophysics for the group he joined at the laboratory was just start- remainder of his life. ing to investigate radio emissions from the Sun. He received recognition from many organi- He and his team developed pioneering interfer- zations, including the Gold Medal of the Royal ometry techniques to precisely locate radio- Astronomical Society (1921), the Henry Draper emitting regions on the Sun, so other scientists Medal from the National Academy of Sciences could correlate the radio frequency emissions (1922), the Rumford Prize from the American with visible light emissions. These were exciting Academy of Arts and Sciences (1925), and the research times, as Ryle began to apply wartime Bruce Gold Medal from the Astronomical advances in radio frequency and electronic tech- Society of the Pacific (1925). He died in Princeton, nologies to the embryonic field of radio astron- New Jersey, on February 18, 1957. omy. In 1947 he married Rowena Palmer and the couple eventually had three children: two daughters and a son. ᨳ Ryle, Sir Martin It was mainly due to Ryle and his colleagues (1918–1984) that Cambridge became one of the leading cen- British ters in the world for astronomical research. In Physicist, Radio Astronomer 1948 Ryle received an appointment to lecture in physics at the university, and the following year Sir Martin Ryle was the British scientist who es- he was elected as a fellow at Trinity College. tablished an important center for radio astron- Between 1948 and 1952 Ryle formed a winning omy at Cambridge University after World War radio astronomy research team that included II. By 1960 his pioneering activities in radio as- Hewish. With this team, Ryle started using ra- tronomy allowed him to introduce the technique dio interferometry to carefully map the radio known as aperture synthesis. He shared the 1974 sky—an essential task that led to the establish- Nobel Prize in physics with ANTONY HEWISH for ment of radio astronomy as a very fertile field their pioneering achievements in radio astron- for astronomical research and discovery. He su- omy, specifically Ryle’s invention of aperture pervised the development and publication of a synthesis and Hewish’s identification of the first series of extraterrestrial radio source catalogs. By pulsar. Ryle also served Great Britain as the 12th the time the Third Cambridge Catalogue was pub- Astronomer Royal from 1972 to 1982. lished in 1959, it contained the positions and Ryle was born in Brighton, Sussex, England, strengths of more than 500 radio sources. This on September 27, 1918. Son of a well-respected document, and timely updates to it, became an physician, he received education in physics at essential reference for all radio astronomers. Bradfield College and Oxford University, grad- In the late 1950s Cambridge formally recog- uating in 1939. During World War II Ryle nized the important work Ryle and his team were worked on the development of radar and other accomplishing in radio astronomy. He became the 250 Ryle, Sir Martin director of the Mullard Radio Astronomy Obser- the Ryle Telescope to honor the pioneering vatory in 1957, and then received an appoint- radio astronomer. ment to a new chair in radio astronomy. This Ryle became a fellow of the Royal Society in promotion made him the university’s first profes- 1952 and Queen Elizabeth II knighted him in sor of radio astronomy. 1966. When he shared the Nobel Prize in physics As part of his pioneering efforts in radio with Hewish in 1974, they became the first sci- astronomy in the 1950s, Ryle learned how to use entists to receive this prestigious award for several small radio telescopes to mimic the per- achievements in astronomy. Ryle also served as formance of a much larger instrument by selec- the 12th Astronomer Royal of England from tively sampling portions of just the wave front 1972 to 1982. His most important publication of interest from an arriving extraterrestrial radio was the Third Cambridge Catalogue (1959)—an frequency signal. He called this invention essential reference in radio astronomy that, “aperture synthesis” and constructed two major among many other contributions, assisted the dis- aperture synthesis radio telescopes at Cam- covery of the first quasar. His other awards bridge to support the university’s expanding included the Gold Medal of the Royal Astronom- astronomical effort. These two facilities were ical Society (1964), the Henry Draper Medal of called the One Mile Telescope and the Five the American National Academy of Sciences Kilometer Telescope. (1965), the Royal (Gold) Medal of the Royal Strange, repetitive radio signals collected by Society (1973), and the Bruce Gold Medal from the One Mile Telescope led to the discovery and the Astronomical Society of the Pacific (1974). identification of the first pulsar by Hewish and Ryle died on October 14, 1984, in Cambridge, his graduate student, SUSAN JOCELYN BELL England. As a pioneer of radio astronomy, he BURNELL, in 1967. The Five Kilometer Telescope, developed revolutionary radio telescope systems consisting of four movable 13-meter dishes and using aperture synthesis. With these new tele- four fixed 13-meter dishes, opened in 1972 and scopes, he and his colleagues observed some of soon became the main instrument of the Mullard the universe’s most distant galaxies and puzzling Radio Astronomy Observatory. It is now called extragalactic objects.

A masterful storyteller and eager host of ᨳ Sagan, Carl Edward innumerable conferences, meetings, and radio (1934–1996) and TV shows, Sagan published more than 600 American scientific papers and articles and more than 20 Astronomer, Astrophysicist, Physicist books. His book Dragons of Eden won the Pulitzer Perhaps no other person in the 20th century was Prize in 1978. The paperbound edition of his as responsible for bringing the science of astro- book Pale Blue Dot: A Vision of the Human Future nomy and space exploration into the public eye in Space was a worldwide best seller. His best- and educating hundreds of millions of people selling novel Contact was made into a major worldwide about the nature of the cosmos as motion picture coproduced by Sagan and his Carl Sagan. wife and frequent collaborator, Ann Druyan. Sagan was born in 1934 in Brooklyn, New All in all, books written or cowritten by Sagan York. In 1951 he entered the University of were on the New York Times best-seller list eight Chicago, where he received a bachelor’s degree times. in 1955 and a master’s degree in 1956, both in Sagan’s translation of science into commonly physics, and then a Ph.D. in astronomy and as- understood terms and concepts is possible best trophysics in 1960. He then taught at Harvard remembered by his TV series on PBS, Cosmos, University through the 1960s and went to an Emmy– and Peabody Award–winning show Cornell University in Ithaca, New York, in 1971, that became the most watched series in PBS his- where he remained for the rest of his life. tory, seen by more than 500 million people in Sagan’s research highlights were many. He 60 countries. The accompanying book, Cosmos, postulated the greenhouse effect on Venus was on the New York Times best-seller list for 70 before space probes proved it. He predicted that weeks and became the best-selling book about the apparent seasonal changes on the surface of science ever published. Mars were the result of windblown dust. Sagan Needless to say, Sagan’s awards and hon- identified organic aerosols on Titan, the major orary degrees are almost too numerous to list. He moon of Saturn. He described in great detail the received 22 honorary degrees from American long-term environmental consequences of nu- institutions. For his leading role in NASA’s clear war, and he wrote extensively on the ori- Mariner, Viking, Voyager, and Galileo missions gin of life on Earth. to other planets, he was awarded NASA medals

251 252 Scheiner, Christoph for Exceptional Scientific Achievement and at the Jesuit college in Landsberg before he twice received the Distinguished Public Service entered the then-young Jesuit order in 1595. and the NASA Apollo Achievement Award. Scheiner studied mathematics, Hebrew, and Most notable of his other awards are the John F. metaphysics at the university in Ingolstadt, and Kennedy Astronautics Award of the American in 1610 he joined the faculty at the Jesuit Astronautical Society; the Explorers Club 75th College in Ingolstadt as a professor of mathe- Anniversary Award; the Konstantin Tsiolkovsky matics and Hebrew. medal of the Soviet Cosmonauts Federation; At first, Scheiner became an expert in the and the Mazursky Award of the American Astro- mathematics of sundials, but when the telescope nomical Society. He received the highest award came into wide use he obtained one and turned given by the National Academy of Sciences, the his studies toward the Sun. Using colored glass Public Welfare Medal. He was Distinguished and observing for the most part on somewhat Visiting Scientist at the Jet Propulsion Labora- foggy days, Scheiner first observed sunspots in tory in Pasadena, California. 1611. As the chief proponents of traditional Sagan was editor of Icarus—a professional Aristotelian cosmology, and hailed by many as journal devoted to planetary research—for 12 the intellectual champions of the Catholic years, and was a cofounder of the Planetary Church, the Jesuits and the Catholic Church in Society, the largest space-interest organization general adhered to the “purity” of the universe in the world, with 100,000 members. and PTOLEMY’s geocentric view of the Earth’s po- At the time of his death on December 20, sition in the heavens. However, the Copernican 1996, of pneumonia resulting from myelodisplasia heliocentric view was becoming popular, and sci- in a hospital in Seattle, Washington, Sagan was entists such as Galileo were beginning to prove the David Duncan Professor of Astronomy and him right. Space Sciences, and the director of the Laboratory Largely because of his religion’s insistence for Planetary Studies at Cornell University. The that the heavens were unchangeable and the Sun asteroid 2709 Sagan is named after him. was “virginal,” Scheiner concluded that sunspots were shadows cast on the Sun’s surface by small planets closely circling it inside Mercury’s orbit. ᨳ Scheiner, Christoph Using a pseudonym, he sent three letters to his (1573–1650) friend Marcus Wexler, an Augsburg banker and German Jesuit patron, describing his conclusions, and Astronomer, Mathematician Wexler showed the letters, called “Three Letters on Solar Spots,” to Galileo, inviting him to Born in Wald, near Mindelheim, in what is now comment on them. southwest Germany, Christoph Scheiner is best Thus began a correspondence in which the known for his protracted controversy with two scientists argued voluminously with one an- GALILEO GALILEI over the nature of sunspots— other. Galileo, to Scheiner’s consternation, in- Scheiner thought they were shadows cast by the sisted that sunspots were actually on the Sun’s Sun’s satellites, while Galileo was convinced surface, changing their shape and appearing and they were irregular phenomena on the Sun’s reappearing at irregular intervals. That the Sun surface. In his later years, Scheiner gave in and was not perfect was a heretical position, and con- admitted that Galileo was right. tributed seriously to Galileo’s falling out with As a boy, Scheiner entered the Jesuit Latin Rome and the Jesuit order. Nevertheless, and school in Augsburg, then continued his studies although he seems to have taken pains not to Schiaparelli, Giovanni Virginio 253 insult Scheiner, Galileo was ultimately proven Copernicus versus Ptolemy argument. Scheiner correct, and in his publication Rosa Ursina, died on June 18, 1650, in Neisse. which was to remain the standard work on sunspots for more than a century, Scheiner eventually capitulated to Galileo. ᨳ Schiaparelli, Giovanni Virginio After his first observations, Scheiner con- (1835–1910) tinued to study sunspots for 15 years, and in Rosa Italian Ursina he also described new methods of repre- Astronomer senting the motions of sunspots across the Sun’s surface. Scheiner also published several works on Giovanni Schiaparelli was the 19th-century atmospheric refraction and performed detailed Italian astronomer whose misinterpreted words studies on the optics of the human eye, describing stimulated undue excitement about civilization the functions of the retina, pupil, and iris. He on Mars. An excellent astronomer, he had care- elaborated on the previous optical work of fully observed Mars in the 1870s and made a de- JOHANNES KEPLER, and built what he called a tailed map of its surface, including some straight “helioscope” for projecting images of the Sun, markings that he dutifully described as canali— improving on the projection methods described meaning “channels” in Italian. Unfortunately, by Galileo and Castelli. This instrument is the when his description of Martian surface features earliest known equatorially mounted projector. was translated into English, the word canali While conducting his sunspot research, became “canals.” Some astronomers, most no- Scheiner was a mathematics instructor to Arch- tably the wealthy American astronomer PERCIVAL duke Maximilian, brother of Emperor Rudolph LOWELL, completely misunderstood the true mean- II. This endeared him to royalty and in 1621 he ing of Schiaparelli’s observations and launched became confessor to Archduke Karl, brother of a zealous telescopic search for the supposed the new emperor, Ferdinand II. At this time he canals that represented the handiwork of a founded a new Jesuit college at Neisse, in Sile- neighboring intelligent alien civilization on the sia. When the archduke died in 1624, Scheiner Red Planet. journeyed to Rome, remaining there for eight Schiaparelli was born on March 14, 1835, years and continuing to observe the Sun at the in Savigliano, Italy. He graduated from the observatory of the Gregoriana. After charting University of Turin in 1854 with a degree in civil the movements of sunspots, he calculated the engineering. After graduation, he engaged in the rotation of the Sun at 25 days near the equator private study of astronomy, foreign languages, and 31 days at the poles. Using this informa- and mathematics. In 1856 he received an ap- tion, he then calculated the equator and the pointment to teach mathematics in an elemen- rotation axis, discovered solar flares, and tary school in Turin—an experience that he did observed the granulation of the photosphere. not particularly enjoy. By 1857, government of- While in Rome, he published the famous Rosa ficials of the Piedmont region of Italy recognized Ursina. his talents and interest in astronomy and so they In 1633 Scheiner went back to Bavaria, provided Schiaparelli with a modest fellowship where he spent the rest of his life in the area of to pursue additional efforts in observational as- Vienna, both supervising the new college in tronomy. Much to his parents’ dismay, he aban- Neisse and working on a refutation of Copernican doned his teaching appointment, accepted the theory. The latter work went virtually unknown small stipend, and studied astronomy under and is reported to have little effect on the Johann Encke (1791–1865) in Berlin and Otto 254 Schmidt, Maarten Struve (1819–1905) at the Pulkova Observatory solar system astronomy. Yet, this erroneous in- in St. Petersburg, Russia. terpretation of his canali in an otherwise excel- When Schiaparelli returned to Italy in 1860, lent observational report about Mars is how he became the second astronomer at the Brera most people remember the Italian astronomer. Observatory in Milan. Two years later, he became If Schiaparelli had never published his now in- the observatory’s director and retained that posi- famous 1877 Mars report, he might still have tion until he retired in 1900. In 1861 Schiaparelli, won many international awards. He received an exceptionally skilled observer, used the anti- the Gold Medal of the Royal Astronomical quated equipment he found at the Brera Society in 1872 and the Bruce Gold Medal from Observatory as best he could and managed to dis- the Astronomical Society of the Pacific in 1902. cover the asteroid Hesperia. Over the years he In 1900 he decided to retire as directory of struggled to upgrade the observatory facilities, the Brera Observatory because of his failing eye- while still making significant contributions to as- sight. However, even though he could no longer tronomy. He linked the periodic meteor shower practice astronomical observing, he still con- called the Perseids to the remnants of a comet, and tributed to the field of astronomy by researching he conducted observational and theoretical stud- the history of ancient astronomy and writing the ies concerning the shapes of comet tails. Through book Astronomy in the Old Testament in 1903. He careful and patient observation, he also showed died on July 4, 1910, in Milan, Italy. that Venus and Mercury rotated very slowly. He also studied the planet Mars and made detailed observations during its 1877 opposi- ᨳ Schmidt, Maarten tion, when the Red Planet approached within (1929– ) about 56 million kilometers of Earth. From Dutch/American these careful observations, Schiaparelli made a Astronomer, Astrophysicist detailed map of Mars, even using his knowledge of classical literature and the Bible to name var- Modern astronomers are constantly discovering ious surface features. Schiaparelli’s keen eye that the universe is filled with interesting and for details caused him to note certain straight strange objects. In 1963 the joy of discovering features as canali. The mistaken translation of the unusual touched astronomer Maarten canali appearing in Schiaparelli’s 1877 Mars re- Schmidt as he analyzed the enormous redshift in port spurred another astronomer, the wealthy radio source 3C 273 and found the first quasar. Lowell, to build a private observatory at Schmidt’s analysis of the unexpectedly large Flagstaff, Arizona, and diligently study Mars in redshift in the hydrogen lines of this strange an attempt to prove through a set of carefully object’s spectrum indicated that it was very selected (but improperly interpreted) observa- young and very distant and traveling away from tions that the “canals” on Mars were manifes- Earth at more than 15 percent of the speed of tations of the presence of an ancient Martian light. civilization. Lowell even suggested the un- Schmidt was born in Groningen, the founded, but very popular, hypothesis that this Netherlands, on December 28, 1929. He com- race of Martians was struggling to transport wa- pleted his undergraduate education at the Uni- ter from the poles to water-starved regions of versity of Groningen in 1949 and then earned their dying planet. his doctoral degree in 1956 at the University of Schiaparelli never endorsed Lowell’s exten- Leiden under the research supervision of JAN sive extrapolation of some of his best work in HENDRIK OORT. After performing about three Schmidt, Maarten 255 years of postdoctoral research at the University reason he is generally credited with identifying of Leiden, Schmidt came to the United States to the first quasar. He recognized that certain broad accept an appointment at the California Insti- emission lines in the corresponding optical spec- tute of Technology (Caltech) as a staff member trum of radio source 3C 273 were actually hy- at the Hale Observatories (Palomar Observa- drogen lines in the Balmer series that had been tory) northeast of San Diego. Schmidt initially redshifted an enormous amount, approximately accepted this position primarily to continue that of an object receding from Earth at about investigating the structure and dynamics of the 16 percent of the velocity of light. Assuming Milky Way Galaxy. But when the German- that this enormous redshift was the result of an American astrophysicist Rudolph Minkowski expanding universe, Schmidt estimated 3C 273 (1895–1976) retired, Schmidt assumed respon- to be about a billion light-years away. This sibility for his project of taking optical spectra strange, compact object was not very far away. of distant objects that had been found to emit It also had the energy output of perhaps 100 radio wave signals. galaxies. At the time, astrophysicists were puzzling In 1964 Schmidt became a professor of as- over several compact radio sources, originally tronomy at Caltech and remained affiliated identified in SIR MARTIN RYLE’s Third Cambridge with that institution as of 2004. Following his Catalogue, published in 1959. In the early 1960s breakthrough work on identifying 3C 273 as the American astronomer Alan Sandage (b. the first quasar, Schmidt studied the evolution 1926), discovered a mysterious class of radio- and distribution of quasars throughout the ob- loud objects (that is, celestial objects that emit servable universe. He soon discovered that detectable radio wave signals) with an ultravio- quasars were more abundant when the universe let excess in color. At the time, no one really was younger, a fact that challenged the steady- knew what these strange objects might be, state universe hypothesis and supported Big because they were starlike in size and had vari- Bang cosmology. His current research interests able brightness, yet were radio sources. It was not center around the spatial distribution and until radio source 3C 273 was identified as one luminosity function of quasars in the radio fre- of these puzzling and bizarre radio sources that quency, optical, and X-ray portions of the elec- interesting things began to happen in the astro- tromagnetic spectrum. He also maintains an nomical community. Astronomers originally interest in the nature of the extragalactic X-ray called the objects “quasi-stellar radio sources”— background, the statistics associated with quasars—because of their starlike appearance gamma-ray bursts, and the distribution of mass (hence “quasi-stellar”) and the fact they were within the Galaxy. strong radio sources. However, subsequent dis- Since identifying the first quasar in 1963, coveries forced astrophysicists to change the Schmidt’s astronomical endeavors have earned term to “quasi-stellar object” (QSO)—expand- him numerous awards and international recog- ing the meaning to include a compact extra- nition. These awards include the Rumford Prize galactic object that appears like a point source of the American Academy of Arts and Sciences of light but emits more energy than 100 or so (1968), the Jansky Prize from the National galaxies. Radio Astronomy Observatory of the United In 1963 Schmidt examined the correspon- States (1979), the Gold Medal of the Royal ding optical spectrum of the brightest quasar, Astronomical Society (1980), and the Bruce called 3C 273. His insight and calculations Gold Medal from the Astronomical Society of helped unravel this cosmic mystery, and for this the Pacific (1992). Professor Schmidt continues 256 Schwabe, Samuel Heinrich to perform creative research at the frontiers of Vulcan that some professional astronomers pos- astrophysics at Caltech. tulated resided close to the Sun inside the orbit of Mercury. While trying to catch a glimpse of this nonexistent planet as it traveled across the ᨳ Schwabe, Samuel Heinrich face of the Sun, Schwabe also noticed and (1789–1875) sketched sunspots—thereby establishing a very German careful record of their population and patterns Astronomer (Amateur) as a function of time. He made very detailed sunspot records, but the sunspots themselves Professional astronomers are not the only people were of only secondary interest. Weather condi- who have made interesting astronomical discov- tions permitting, he observed the Sun almost eries. Samuel Heinrich Schwabe was a German daily. pharmacist who spent most of his free time as an By 1843, however, his quest for Vulcan amateur astronomer. Starting in 1825, he began proved fruitless. At this point, inspiration making systematic observations of the Sun and struck Schwabe. As he reviewed almost 17 years continued this activity for many years. He was of carefully recorded sunspot data, he suddenly primarily searching for the hypothetical planet noticed that there was an approximate 10-year of Vulcan believed to be inside the orbit of Mer- (now established more precisely as 11 years) cury. However, instead of finding this fictitious periodicity in the number of sunspots on the planet, he discovered that sunspots have a cycle solar disk. Later that year, he announced this of about 10 years or so. He announced his find- important astronomical observation in an arti- ings in 1843, but German scientists generally cle titled “Solar Observations during 1843” that ignored his discovery. It was only after the appeared in the German journal Astronomische sunspot cycle was rediscovered and confirmed by Nachrichten. At first, the German scientific professional astronomers in the 1850s that establishment completely ignored Schwabe’s Schwabe received some recognition for his discovery, possibly because he was an amateur excellent work. astronomer with no formal academic status in Schwabe was born on October 25, 1789, in physics or astronomy. the town of Dessau, near Berlin, Germany. He But Schwabe’s careful record of sunspots and studied pharmacology in Berlin and then re- his conjecture about an apparent 10-year perio- turned to Dessau in 1812 to assume management dicity emerged out of obscurity and gained of his family’s apothecary shop. While studying long-overdue scientific recognition in 1851 to become a pharmacist, Schwabe also became when the famous German naturalist Baron interested in astronomy and soon immersed him- Alexander von Humboldt (1769–1859) in- self in various astronomical studies as a hobby. cluded these data in the third volume of his In 1825, according to one biographical anec- monumental work, Kosmos, a vast encyclopedia dote, Schwabe won his first telescope in a lot- of natural knowledge. Once Humboldt recog- tery. He soon ordered a more powerful viewing nized the value of Schwabe’s work, other scien- instrument from the famous German optician tists immediately began to examine the sunspot JOSEPH VON FRAUNHOFER. cycle and to relate the periodicity of solar activ- In October 1825 Schwabe began his sys- ity to geomagnetic activity of Earth. In a very tematic observations of the Sun—a dedicated real sense, this rediscovery of Schwabe’s sunspot effort that extended for more than 17 years. His cycle hypothesis represents the beginning of primary objective was to discover the planet modern solar-terrestrial physics. Schwabe, the Schwarzschild, Karl 257 pharmacist-astronomer, personally likened his serendipitous discovery to the biblical account of Saul, who went out in search of his father’s donkey and found a kingdom. In 1831 Schwabe became the first astronomer, amateur or professional, to provide a detailed description and drawing of Jupiter’s Great Red Spot. The British Royal Astronomical Society awarded Schwabe its prestigious Gold Medal in 1857 and elected him as a foreign member in 1868—an honor rarely bestowed on an amateur astronomer. He died in Dessau, Germany, on April 11, 1875. As part of his legacy to astronomy, the Swiss astronomer Johann Rudolf Wolf (1816–93) immediately built upon Schwabe’s many years of detailed solar disk observations and was able to announce in 1857 a refined value for sunspot periodicity at slightly more than 11 years.

ᨳ Schwarzschild, Karl (1873–1916) The German astronomer Karl Schwarzschild poses German here in full academic regalia early in the 20th century. Astronomer, Astrophysicist Decades ahead of his time, Schwarzschild brilliantly applied Einstein’s relativity theory to very high-density objects and singularities (point masses)—thereby Karl Schwarzschild was the talented German as- starting black hole astrophysics. In 1916 he introduced tronomer who started black hole astrophysics. the idea of an event horizon (now called the He did this by applying ALBERT EINSTEIN’s rela- Schwarzschild radius) around a super-dense, tivity theory to a very high-density object: a gravitationally collapsing star, from which nothing, not even light, can escape. (Photo by Robert Bein, point mass. In 1916 while voluntarily serving in courtesy AIP Emilio Segrè Visual Archives) the German army in Russia, he developed the concept of the Schwarzschild radius—the zone or “event horizon” around a superdense, gravitationally collapsing star from which nothing, University of Strasbourg and then transferred to not even light itself, can escape. the University of Munich in 1893, completing He was born in Frankfurt, Germany, on his doctor of philosophy degree there in 1896. October 9, 1873. The son of a prosperous Jewish After graduation Schwarzschild worked in businessman, Schwarzschild showed his mathe- Vienna from 1896 to 1899 at the Kuffner matical aptitude and interest in astronomy early Observatory. He then spent some time lecturing in life. At age 16 he published a significant ce- and writing before he joined the faculty at the lestial mechanics paper that addressed the University of Göttingen in 1901 as an associate problem of binary orbits. Encouraged to pursue professor. He remained at the university until a scientific career, he began his studies at the 1909, quickly reaching rank of full professor and 258 Secchi, Pietro Angelo becoming the director of the observatory. death, represent the theoretical start of black During this period, he explored the possibility hole astrophysics. that space might be non-Euclidean (that is, Unfortunately, the brilliant German as- have curvature), he investigated radiative equi- tronomer contracted a fatal skin disease while librium processes in the Sun’s outer atmosphere, serving in Russia during World War I. The and he promoted the use of astrophotography— German army discharged the stricken scientist particularly to support the study of the rela- and shipped him home, where he died shortly tionship between a star’s spectral type and its after his return to Potsdam, on May 11, 1916. color. However, his son, the German-born American In 1909 he left the University of Göttingen astrophysicist Martin Schwarzschild (1912–97), to accept the position of director of the would continue making important contributions Astrophysical Observatory at Potsdam. Although to astronomy. Following in his father’s scientific already in his early 40s when World War I broke footsteps, Martin left Germany after World out, he volunteered for military service in the War II and became a professor at Princeton Kaiser’s imperial army. Starting in 1914, he University, where he pioneered the use of digi- served with the German army in Belgium, tal computers to perform theoretical studies of France, and finally Russia. While on duty in stellar structure and evolution. Russia in 1916, he stayed in touch with scientific developments by writing two excellent papers that dealt with Einstein’s newly introduced ᨳ Secchi, Pietro Angelo (1915) general theory of relativity. One of (1818–1878) Schwarzschild’s papers presented the first exact Italian solution of Einstein’s general gravitational equa- Astronomer, Spectroscopist tions, providing a description of how gravity curves space and time around a single, very com- The 19th-century astronomer and Jesuit priest pact object. In his second paper, Schwarzschild Pietro Angelo Secchi was the first person to sys- introduced the concept of the event horizon tematically apply spectroscopy to astronomy. By around a black hole, beyond which nothing, not the mid-1860s he completed the first major as- even light, can escape. Schwarzschild demon- tronomical spectroscopic survey and then pub- strated that according to general relativity, if an lished a catalog that contained the spectra of object’s gravity is sufficiently strong, the space- more than 4,000 stars. After examining these time continuum around that body becomes so data, in about 1867 he placed stellar spectra into highly curved and warped that light itself can- four basic classes. This represented what was later not escape from the object. He further explained referred to as the Secchi classification system. He that this condition occurs when the radius of a also supported advances in astrophotography, massive body is less than a certain critical value, primarily by photographing solar eclipses—pio- now called the Schwarzschild radius. Today, as- neering work that assisted in the study of solar trophysicists call the Schwarzschild radius the phenomena such as prominences. “event horizon” or “boundary of no return” for Secchi was born on June 29, 1818, in the a black hole. Anything that falls inside this ra- Lombardian town of Reggio, Italy. In 1833 he dius can never escape. The event horizon repre- entered a religious order known as the Society sents the start of a special region that is totally of Jesus (Jesuits), and began lecturing on physics disconnected from normal space and time. and mathematics at the Jesuit Roman College Schwarzschild’s papers, written weeks before his in 1839. He started his formal theological stud- Shapley, Harlow 259 ies in 1844 and was ordained as a priest in the Soleil (The Sun) first appeared in Paris in 1870. Roman Catholic Church in 1847. Due to ex- Secchi enjoyed a wide international reputation treme antireligious political unrest that occurred as a skilled observer and excellent astronomer. in Rome in 1848, he left Italy and traveled to He was consequently allowed to operate his ob- Great Britain and then on to the United States, servatory in Rome despite the political turmoil where he taught natural sciences at Georgetown and anti-Jesuit politics that swept Italy in the University in Washington, D.C. By 1849 order early 1870s. He enjoyed membership in the was restored in Rome and Secchi returned to British Royal Society, the Royal Astronomical become a professor of astronomy and the direc- Society, the French Academy of Sciences, and tor of the observatory at the Roman College. the Imperial Russian Academy of St. Petersburg. Finding the old observatory in great disrepair Pietro Secchi, a true pioneer of astronomical and poorly equipped, he started construction of spectroscopy, died in Rome on February 26, a new observatory dome on top of the firm vault 1878. of the Church of Saint Ignatius at the college. From this refurbished observatory he became one of the first astronomers to carry out research ᨳ Shapley, Harlow that concentrated on the physical properties of (1885–1972) the stars rather than simply their positions. He American also conducted pioneering work in meteorology Astronomer and terrestrial magnetism. Soon after ROBERT WILHELM BUNSEN and Early in his career, astronomer Harlow Shapley GUSTAV ROBERT KIRCHHOFF introduced the single-handedly more than doubled the size of concept of astronomical spectroscopy in the the known universe in 1914, when he used a de- early 1860s, Secchi became the first astronomer tailed study of variable stars (especially Cepheid to adapt spectroscopy to astronomy in a rigor- variables) to establish more accurate dimensions ous, systematic manner. In the mid-1860s he for the Milky Way Galaxy. He discovered that conducted the first spectroscopic survey of the the Sun was actually two-thirds of the way out heavens by using visual observation to their in the rim of our spiral galaxy. Up until then, spectra to classify more than 4,000 stars. He di- astronomers assumed the Sun enjoyed a favored vided these stars into four general groups, in- location near the center of the Galaxy. In 1920 troducing a system that later became known as Shapley engaged in a well-publicized, though the Secchi classification. His pioneering work inconclusive, debate with fellow astronomer anticipated the more precise photographic HEBER DOUST CURTIS concerning the nature of work of EDWARD CHARLES PICKERING,ANNIE distant spiral nebula and the true size of the JUMP CANNON, and others who developed the Milky Way Galaxy. As director of the Harvard Harvard Classification System, which appeared College Observatory, Shapley made many use- in the 1890s. ful contributions to astronomy, including stud- Secchi was also extremely active in solar ies of the Magellanic Clouds and clusters of physics. He investigated prominences during so- galaxies. lar eclipses, using both visual and spectroscopic Shapley was born on November 2, 1885, in observations. He proved that prominences were Nashville, Missouri. He started out in professional features on the Sun itself and not an ancillary life as a journalist and then decided to switch to phenomenon associated with the Moon or the astronomy. He changed careers during that ex- eclipse period. His influential monograph Le citing and intellectually turbulent period in the 260 Shapley, Harlow vast expanding universe. Prior to entering the University of Missouri, Shapley had worked for two years as a newspaper reporter. However, once exposed to astronomy during his undergraduate education, he embraced the field and quickly became one of its rising young stars. He completed his undergraduate degree in astronomy at the University of Missouri in 1910, followed a year later by his master of arts degree from the same institution. Shapley then went to Princeton University where he studied for his Ph.D. under the great American astronomer HENRY NORRIS RUSSELL. Shapley’s doctoral research involved a careful study of the orbits of 90 eclipsing binaries. It was a major effort, supervised by Russell, through which Shapley essentially created a special branch of binary star astronomy. In the process of completing his doctoral research, Shapley distinguished Cepheid variables from eclipsing binaries and then correctly suggested Cepheid variability was due to pulsations. Following completion of his doctoral degree in 1914, Shapley worked at the Mount Wilson Observatory, near Los Angeles, California, until The American astronomer Harlow Shapley at his desk 1921. There he investigated globular clusters at the Harvard College Observatory. In 1914 Shapley and was able to calibrate the period-luminosity started a detailed study of variable stars in an effort to relation for Cepheid variables discovered by establish more accurate dimensions for the Milky Way Galaxy. This work encouraged him to engage in a HENRIETTA SWAN LEAVITT in 1912. He boldly great public debate with fellow astronomer Heber and correctly postulated that the distribution of Curtis. They disagreed about the actual size of the these globular clusters served as an outline for Milky Way and the true nature of distant spiral the Milky Way Galaxy. Using Cepheid variables nebulas. In 1929, however, Edwin Hubble presented his hypothesis of an expanding universe filled with as an astronomical “yardstick,” he speculated spiral and other types of distant galaxies, collapsing that the Milky Way Galaxy was actually much many of Shapley’s key debate points and resolving the larger than previously believed. He further noted highly contested discussions. (AIP Emilio Segrè Visual that because of the observed asymmetric distri- Archives, Shapley Collection) bution of these globular clusters, the Sun was not near the center of the Galaxy, as had been early part of the 20th century when great astro- assumed, but rather resided many light-years nomical discoveries, including his important away from the center. Shapley, initially unaware contributions, displaced the Sun from its long- of the dimming influence of interstellar gas and assumed position near the center of the Galaxy. dust, estimated that the Sun was about 50,000 Astronomers also recognized that the Milky Way light-years from the galactic center. He later cor- Galaxy was but one of millions of others in a rected this overestimate and placed the Sun at Shapley, Harlow 261 about 30,000 light-years from the galactic be separate. In the 1930s astronomers such as center—a value independently confirmed by Oort proved that Shapley’s comments were more JAN HENDRIK OORT and now generally accepted. accurate concerning the actual size of the Milky Shapley’s pioneering work at Mount Wilson also Way and the Sun’s relative location within it. prepared him to participate in debates about the Therefore, when viewed from the perspective of size of the Galaxy and the true nature of distant science history, both eminent astronomers had spiral galaxies. inconclusively argued their positions using par- Many astronomers, including Shapley, op- tially faulty and fragmentary data. The most posed Curtis’s hypothesis about the extragalac- important consequence of the Curtis-Shapley tic nature of spiral nebulas. On April 26, 1920, debate was that it triggered a new wave of as- Curtis and Shapley engaged in their famous tronomical inquiry in the 1920s. This burst of “Great Debate” on the scale of the universe and inquiry encouraged astronomers, Hubble among the nature of the Milky Way Galaxy at the them, to determine the true size of the Milky National Academy of Sciences in Washington, Way and to recognize that it is but one of many D.C. At the time, the vast majority of as- other galaxies in an incredibly vast, expanding tronomers considered the extent of the Milky universe. Way Galaxy synonymous with the size of the Upon the death of EDWARD CHARLES universe—that is, most thought the universe PICKERING, Shapley was offered the directorship was just one big galaxy. However, because of of the Harvard College Observatory. He ac- incomplete knowledge, neither astronomer in- cepted, left Mount Wilson in 1921, and remained volved in this highly publicized debate was com- as the director of the Harvard Observatory until pletely correct. Curtis argued that spiral nebu- his retirement in 1952. During his directorship, las were other galaxies similar to the Milky Shapley created an outstanding graduate school Way—a bold hypothesis later proven to be in astronomy, performed his own studies of the correct—but he also suggested that the Galaxy Magellanic Clouds, and wrote many interesting was small and that the Sun was near its center, articles and books about astronomy, including both of which ideas were subsequently proven the popular autobiographical work Through incorrect. Shapley, on the other hand, incor- Rugged Ways to the Stars (1969). In the 1930s rectly opposed the hypothesis that spiral nebu- Shapley discovered the first two dwarf galaxies las were other galaxies. He argued that the within the Local Group and also discovered the Galaxy was very large (in fact, much larger than grouping of clusters of galaxies, or superclus- it actually is) and that the Sun was far from the ters—the most prominent of which is now called galactic center. the Shapley concentration. It was not until the mid-1920s that the great Shapley’s contributions to astronomy earned American astronomer EDWIN POWELL HUBBLE, numerous awards, including the Henry Draper helped resolve one of the main points of con- Medal of the National Academy of Sciences troversy. He did this by using the behavior of (1926), the Rumford Prize of the American Cepheid variable stars to estimate the distance Academy of Arts and Sciences (1933), the Gold to the Andromeda Galaxy. Hubble showed that Medal of the Royal Astronomical Society (1934), this distance was much greater than the size of and the Bruce Gold Medal of the Astronomical the Milky Way Galaxy proposed by Shapley. So, Society of the Pacific (1939). The astronomer as Curtis had suggested, the great spiral nebula who helped displace the Sun from its historically in Andromeda, like other spiral nebulas, could assumed position near the center of the universe not be part of the Milky Way and therefore must died in Boulder, Colorado, on October 20, 1972. 262 Sitter, Willem de his mathematical talents and his newly acquired ᨳ Sitter, Willem de astronomy techniques, de Sitter studied the mo- (1872–1934) tions of the major moons of Jupiter and calcu- Dutch lated their masses and the mass of Jupiter itself. Astronomer, Mathematician After working with Gill for more than two Willem de Sitter was born May 6, 1872, at years, de Sitter returned to the Groningen Sneek, in Friesland, a province in the northern Astronomical Laboratory. In 1908 he was ap- part of the Netherlands. His early education was pointed professor of astronomy at the Uni-ver- at the Gymnasium at Arnhem, where his father sity of Leiden, the oldest university in the was a judge. In 1891 he entered the University Netherlands, established in 1575, and whose of Groningen, where he intended to study math- observatory, established in 1633, is the oldest ematics. However, while there he became inter- operating university observatory in the world. ested in physics and astronomy and worked in In this position, de Sitter made observa- the Groningen Astronomical Laboratory, then tions in 1913 of double-star systems and became under the direction of the famous Professor the first astronomer to prove that the velocity JACOBUS CORNELIUS KAPTEYN. of light had nothing to do with the velocity of In 1896 SIR DAVID GILL, who was the Royal its source. Also while at Leiden, de Sitter be- (British) Astronomer at the observatory at the came familiar with the newly promulgated the- Cape of Good Hope, South Africa, paid a visit ory of general relativity of ALBERT EINSTEIN, to Kapteyn at the Groningen laboratory and was then director of the Kaiser Wilhelm Institute introduced to de Sitter as one of Kapteyn’s bril- of Physics in Berlin. Einstein visited de Sitter liant mathematics students. At the time, de at Leiden, but the political situation in Europe, Sitter was at a measuring instrument, making as war was fast approaching, prevented the two computations on a photographic plate. The fol- scientists from working together. Einstein be- lowing morning, de Sitter was having breakfast gan sending his correspondence to de Sitter, in his room when he received a summons to who in turn sent them to SIR ARTHUR STANLEY meet with Gill in the laboratory. There, with EDDINGTON at the Royal Observatory in Mrs. Kapteyn acting as interpreter, Gill invited Greenwich, England. de Sitter to visit the South African observatory De Sitter then published a series of three pa- and offered him a job as assistant. After ex- pers entitled “On Einstein’s Theory of Gravitation plaining that he was a mathematician and not and Its Astronomical Consequences.” The first an astronomer, and requesting (and receiving) two papers explained Einstein’s theories, and the another year’s time in order to complete his doc- third proposed his own interpretation of the as- toral degree, de Sitter agreed. Thus was born the tronomical consequences of Einstein’s theory. astronomy career of de Sitter. One biographer states that while Einstein, who Arriving at the Cape observatory in August knew little of astronomy, wondered how astron- 1897, de Sitter began his initial work in parallax omy could be applied to his theory, de Sitter be- and triangulation computations with a heliome- came the first scientist to apply the theory of ter. He observed the colors of stars and was first general relativity to astronomy. Indeed, de to determine that stars near the plane of the Sitter’s solution in 1917 to Einstein’s field equa- Milky Way are always bluer than those away from tions showed that a practically empty universe the plane. But his main interest soon became ob- was expanding, instead of contracting, as was the servations of the moons of Jupiter. Combining common theory at the time. Somerville, Mary Fairfax 263 Later, with the war over and the political Self-taught, with only one year of formal edu- climate eased, de Sitter and Einstein published cation at a boarding school when she was 10 a joint paper in which they proposed there may years old, the prolific Mary Somerville became be in the universe large amounts of matter that one of the most scientifically influential persons does not emit light and consequently has not of the 19th century and, as one contemporary been detected. This became known as “dark observer put it, “one of the most remarkable matter” and has since been shown to exist; how- women of her generation.” ever, its exact nature is still under investigation. She was born in 1780 at Jedburgh, Rox- In 1919 de Sitter was named director of the burghshire, Scotland, to Margaret Charters Fair- Leiden Observatory and, under the guidance of fax and naval officer Sir William George Fairfax, Kapteyn, expanded and modernized it adding an who later became vice-admiral of the Scottish astrophysical division dedicated to the spec- navy. However, Jedburgh was just a stopover; the troscopy and photometry of stars, and a theo- family home was in Burntisland, in the county of retical division, which he headed himself. De Fife. The social mores of the time dictated that Sitter also had the wisdom to hire EJNAR boys got the education and girls learned needle- HERTZSPRUNG, who would succeed him and co-invent the famous Hertzsprung-Russell dia- point. Somerville’s mother did teach her to read, gram of stars, still in use today. While director using the family Bible, but saw no reason for her daughter to learn how to write. When she was at Leiden, de Sitter also hired the man who 10, Somerville was sent to Miss Primrose’s would become the most famous of all Leiden Boarding School, where she spent a dismal and astronomers, JAN HENDRIK OORT. unhappy year, but did learn to write. When she De Sitter was awarded the Watson Medal of returned home, she had such a craving for the National Academy of Science in 1929, the knowledge that she began to read every book in Bruce Gold Medal of the Astronomical Society the house, to the point where she was criticized of the Pacific and the Gold Medal of the Royal by family members for her “unladylike” preoc- Astronomical Society in 1931. During the pe- cupation. Consequently, she was sent to a spe- riod 1925–28 he was president of the Inter- cial school to learn needlework. She also took national Astronomical Union. piano lessons and had lessons in painting from The chance meeting in 1896 of Gill and de the artist Alexander Naysmyth. Sitter changed the course of the latter’s life from Visiting an uncle in Jedburgh, Mary casually mathematics to theoretical astronomy and gave mentioned to him that she was teaching herself the world new knowledge of Jupiter and its Latin. The uncle, perhaps the only family mem- moons and the first interpreter and analyst of ber to appreciate her quest for knowledge, en- Einstein’s revolutionary theories. De Sitter died couraged her, and together they studied Latin of pneumonia on November 19, 1934, at whenever she visited. Leiden. In her early teens she became interested in mathematics when her art teacher, Naysmyth, taught her the basics of perspective in painting ᨳ Somerville, Mary Fairfax by using Euclid’s Elements. She immediately (1780–1872) read the whole book, which led to her interest British in astronomy. However, it was not proper for Astronomer, Geographer, young ladies to buy science books in those days, Mathematician so Somerville prevailed upon her brother to 264 Somerville, Mary Fairfax smuggle her his science books. She also began Royal Society, which led them into another tight visiting her brother’s tutor to learn more. circle of the leading scientists of the day associ- Her next passion was algebra. While read- ated with the University of Cambridge and ing puzzles in a friend’s woman’s magazine, she several prominent scientific societies, both in found her curiosity piqued by the strange sym- London and on the Continent. bols in an algebra problem, and she borrowed Somerville published her first paper in algebra texts from the tutor. She became so im- 1826, at age 46: “The Magnetic Properties of mersed in algebra and other mathematical the Violet Rays of the Solar Spectrum.” It at- branches that her parents worried about her tracted interest at the time, but its premise was health. eventually refuted. However, it gained her her At age 24 she married a Russian naval offi- first attention as a serious scientific investiga- cer, Samuel Grieg, who had a low opinion of tor, and the next year Lord Brougham, of the her interest in education. They settled in Society for the Diffusion of Useful Knowledge, London, and when Grieg died, only three years asked Somerville to translate Mécanique Celeste later, he left her financially independent and for popular consumption. Instead, she explained she seized her newfound free time to pursue her in minute detail the mathematics used by the interest on her own. Now the mother of two Frenchman Laplace, which was unfamiliar to children, she had a circle of friends in London most English mathematicians of the day. Her who encouraged her pursuit of science, includ- “translation” eventually became a ponderous ing a professor of natural philosophy at Edinburgh tome, too big for the society to publish, and it University named John Playfair, who intro- was published in 1831 as The Mechanism of the duced her by mail to William Wallace, a pro- Heavens. fessor of mathematics at the Royal Military The book was a smashing success both College at Great Marlow. In their letters he critically and financially, and boosted her rep- taught her how to solve mathematical problems utation immensely. She spent a year in Paris, to the point where she eventually won a silver meeting even more prominent scientists, and medal for her solution to a problem published wrote her second book, The Connection of the in Mathematical Repository. In accepting the Physical Sciences. Her discussion in the book of medal, she sought the advice of the editor of the a theoretical planet perturbing Uranus led JOHN magazine for the proper course of mathematical COUCH ADAMS to his discovery of Neptune. study, which led to her reading of SIR ISAAC This produced a shower of honors. She and NEWTON’s Principia and PIERRE SIMON MARQUIS CAROLINE LUCRETIA HERSCHEL were the first DE LAPLACE’s Mécanique Celeste, as well as sev- women elected to the Royal Astronomical eral other prominent astronomical and mathe- Society in 1835. The Société de Physique et matical textbooks. d’Histoire Naturelle de Genève gave her an hon- In a big turning point in her life, she mar- orary membership, and the Royal Irish Academy ried William Somerville in 1812. He was a sur- did the same. geon in the Royal Navy who was supportive of In 1838 William’s health deteriorated and her interest in science. By this time Somerville the family moved to Italy, where William sur- also was fluent in French and Greek, and in vived for 22 more years while Mary wrote books Edinburgh both she and her husband studied ge- at a prolific rate. Her most important later pub- ology and traveled in a close circle of physicists lication was Physical Geography, which was pub- and mathematicians. William Somerville was lished when she was 68, in 1848, and it became transferred to London and accepted into the her most successful textbook, used in secondary Slipher, Vesto Melvin 265 schools and universities until the turn of the 20th century. This book got her elected to the American Geographical and Statistical Society and the Italian Geographical Society. In 1870, at 90 years of age, she received the Victoria Gold Medal of the Royal Geographical Society. Somerville did more to publicize mathematics and astronomy than any other woman of her time, and, for obvious reasons, was a devout supporter of women’s suffrage and women’s education. When John Stuart Mill, the great British philosopher and economist, encouraged the British parliament to give women the vote, he amassed a huge petition to submit to them. The first name on his list was Mary Fairfax Somerville.

ᨳ Slipher, Vesto Melvin (1875–1969) American Astronomer The American astronomer Vesto Slipher worked at the Lowell Observatory and in about 1912 performed Behind many great scientific breakthroughs, the initial spectroscopic studies of spiral nebulas there is usually some generally unrecognized (galaxies) that revealed Doppler redshifts. His work pathfinder who first marked the trail for others became the foundation upon which Edwin Hubble to travel and achieve technical glory. The and others pursued the concept of an expanding universe. Later, as director of the Lowell Observatory, astronomer Vesto Slipher was the pathfinder for he hired a young Kansas farm boy, Clyde Tombaugh, the famous American astronomer EDWIN POW- and assigned him the arduous task of searching for ELL HUBBLE. In 1912 Slipher began his impor- Percival Lowell’s Planet X. Tombaugh delivered on tant series of spectroscopic studies involving the February 18, 1930, when he discovered the planet Pluto. (AIP Emilio Segrè Visual Archives) light from objects called “spiral nebula” at the time, which are now recognized as distant galaxies. He noticed that the spectroscopic data developed the modern concept of an expanding he collected at the Lowell Observatory exhib- universe. ited interesting Doppler shift phenomena. The Slipher was born on November 11, 1875, in predominant number of spectral redshifts he Mulberry, Indiana. He received all his educa- observed in the spiral nebulas under study sug- tion at the University of Indiana at gested that these objects were receding from Bloomington. There he received his bachelor of Earth at very high speed. Although his data arts degree in mechanics and astronomy in were generally ignored when he presented them 1901, his M.A. degree in 1903, and his Ph.D. in the late 1910s, his pioneering spectroscopic degree in 1909. studies provided the framework around which In August 1901 Slipher started working at Hubble and other astronomers eventually the Lowell Observatory, in Flagstaff, Arizona. He 266 Slipher, Vesto Melvin became the assistant of the observatory in 1915, shifted spectral lines and only four blueshifted and when PERCIVAL LOWELL died in 1916, Slipher spectral lines. Slipher also measured radial became the acting director of the observatory. In velocities in excess of many thousands of kilo- 1926, he became its director and served in that meters per second. position until his retirement in 1954. The mystery presented by these data puz- Slipher was not only an excellent spectro- zled him and other astronomers including scopist but he also proved to be a competent HARLOW SHAPLEY. However, unable to resolve administrator. One of his early decisions as di- the mystery astronomers preferred to simply ig- rector was to hire a young farm boy named CLYDE nore these important data, often suggesting WILLIAM TOMBAUGH in the late 1920s and as- that Slipher’s experimental technique was sign him the task of searching the night skies for faulty or his interpretation of the data in error. Lowell’s Planet X. On March 13, 1930, in his But one great astronomer did not ignore the in- capacity as director of the Lowell Observatory, credibly important implications of Slipher’s Slipher had the pleasure of announcing to the work. Hubble used Slipher’s work as a starting astronomical world that Tombaugh had discov- point to develop his cosmology of an expand- ered the planet Pluto. ing universe filled with millions of galaxies re- But about three decades earlier, Slipher had ceding from Earth. Hubble presented these made his own great contribution to astronomy at ideas in the late 1920s and changed forever our the Lowell Observatory—a generally overlooked view of the vast size and dynamic nature of the discovery that changed the trajectory of modern universe. cosmology. Starting in about 1912, he used spec- As a very skilled astronomer, Slipher ap- troscopic measurements and exposure times as plied spectroscopic techniques at the Lowell long as 80 hours to measure the enormous radial Observatory to prove the existence of vast quan- velocities of spiral nebulas. Slipher determined tities of dust and gas in interstellar space and to the radial velocities of these so-called spiral neb- investigate the atmospheric composition of the ulas (now known to be galaxies beyond the gaseous giant planets Jupiter, Saturn, Uranus, Milky Way) by measuring the displacement of and Neptune. In the early 1930s he also inves- their spectral lines. The Doppler effect, for ex- tigated the phenomenon of zodiacal light—the ample, will shift spectral lines toward the red faint cone of light extending upward from (longer wavelength) portion of the visible spec- Earth’s horizon in the direction of the ecliptic trum if the object is going away (receding) from caused by the reflection of sunlight from tiny Earth and toward the blue or violet portion of pieces of interplanetary dust in orbit around the the spectrum if the object is approaching at high Sun. velocity. Numerous awards marked Slipher’s contri- In 1913 Slipher examined the spectral butions to astronomy, including the Lalande lines from the great spiral nebula in Andromeda Prize and Gold Medal from the French Academy (also known as Messier catalogue number M31 of Sciences (1919), the Henry Draper Medal of or the Andromeda Galaxy) and, to his surprise, the National Academy of Sciences (1932), the discovered this object was approaching Earth Gold Medal of the Royal Astronomical Society (indicated by blueshifted spectral lines) at (1933), and the Bruce Gold Medal from the approximately 300 kilometers per second. He Astronomical Society of the Pacific (1935). The extended this work to many other spiral astronomer whose pioneering spectroscopic nebulas and soon discovered that out of the 40 studies of spiral nebulas led to our modern un- he had carefully observed, 36 displayed red- derstanding of the expanding universe died in Stefan, Josef 267 Flagstaff, Arizona, on November 8, 1969, just Stefan carefully investigated thermal energy losses four days short of his 94th birthday. from hot bodies, such as heated platinum wires, and he became the first scientist to effectively quantify the phenomenon of radiation heat trans- ᨳ Stefan, Josef fer. In 1879 he noted that the rate of thermal en- (1835–1893) ergy loss was proportional to the fourth power of Austrian an object’s absolute temperature. For example, if Physicist the temperature of an object doubled, say from 1,000 to 2,000 kelvins, the amount of thermal en- In about 1879 Josef Stefan experimentally ergy it radiated increased 16-fold. demonstrated that the energy radiated per unit In 1884 one of his former students, Boltz- time by a blackbody was proportional to the mann, provided the theoretical basis for Stefan’s fourth power of that body’s absolute temperature. empirical observations. Boltzmann used thermo- When LUDWIG BOLTZMANN provided the theo- dynamic principles to develop the famous physi- retical foundations for this relationship in 1884, cal law that is now called the Stefan-Boltzmann the collaboration of the two Austrian physicists law. This law states that the luminosity, or radi- resulted in the formulation of the famous Stefan- ant power, of a blackbody is proportional to the Boltzmann law—a physical principle of great fourth power of the blackbody’s absolute temper- importance to astronomers and astrophysicists. ature. Astronomers and astrophysicists often use Stefan was born on March 24, 1835, in St. this law to describe and compare the radiant Peter, near Klagenfurt, Austria. He received his properties and temperatures of stars, because to a childhood education in Klagenfurt and then en- good approximation stars closely approximate tered the University of Vienna to study physics the behavior of blackbody radiators. For conven- and mathematics. Upon graduation in 1858, he ience, astronomers will also frequently use the received an appointment as lecturer in mathe- luminosity, radius, and absolute surface tempera- matical physics at the university. By 1866 he ture of the Sun as their reference and then apply earned the rank of professor of mathematics and the Stefan-Boltzmann law to form a ratio that physics and also became the director of the compares the corresponding values for another Physical Institute in Vienna. He stayed affiliated star to this solar baseline. with the university for the remainder of his life. During his lifetime, Stefan was honored He was an excellent experimental physicist and with special appointments, including those of a very well-liked instructor. One of his most Rector Magnificus at the University of Vienna famous students was Boltzmann. in 1876 and vice president of the Viennese As an experimental physicist, Stefan had a Academy of Sciences in 1885. He died on wide range of research interests, including opti- January 7, 1893, in Vienna, Austria. His radia- cal interference, the kinetic theory of gases, election heat transfer research provided a major tromagnetic induction, diffusion, thermomag- breakthrough in the understanding of blackbody netic phenomena, and the cooling rate of hot radiation and set the stage for MAX KARL bodies. He is best remembered for his pioneering PLANCK and his development of the quantum work with respect to radiation heat transfer. theory of thermal radiation.

Fortunately for Tereshkova, they decided that ᨳ Tereshkova, Valentina this woman must be a parachutist. (1937– ) One of only five women to be considered for Russian the role, Tereshkova was selected for the Vostok Cosmonaut 6 flight in May 1963 by Premier Khrushchev The early race into space between the Soviets himself, who was pushing the space race to beat out the United States with as many Soviet “firsts” and the Americans produced a win for the as possible. The following month, she had her Soviets and for women in space exploration historic moment in space. The event lasted 70 when Valentina Tereshkova became the first hours, 50 minutes, allowing Tereshkova to orbit woman to fly into space on June 16, 1963. the Earth once every 88 minutes. Parachuting From her humble beginnings in the Russian came into play when, upon reentering the at- village of Masslenikovo, where she was born to mosphere, she jumped from the spacecraft and farmworkers on March 6, 1937, young Tereshkova landed in central Asia. could easily have been considered least likely to While she never ventured into space again, become a world-renowned figure. At age 18, the Tereshkova played a pivotal role for women in young woman left school to work in a textile mill. astronomy as the first woman to physically enter In hindsight, one of the most important decisions this new frontier. She has since received two to her future career came when she joined a para- Order of Lenin awards, as well as the United chutists’ club. Her first jump, at age 22, would do Nations Gold Meal of Peace, the Simba far more than propel her from a plane. It International Women’s Movement Award, and would ultimately help launch her into the Russian the Joliot-Curie Gold Medal. space program. In 1961 Tereshkova decided to become a cosmonaut. Her timing was good: Since Gher- ᨳ Tombaugh, Clyde William man Titov had recently made a flight into space, (1906–1997) the Russian government was contemplating American something new—sending a woman into space. Astronomer

268 Tombaugh, Clyde William 269

Clyde Tombaugh was the “farm boy astronomer” SLIPHER, the director of the Lowell Observatory, who discovered the planet Pluto on February 18, hired him in 1929 as a junior astronomer. Slipher 1930. He did this while working as a junior also placed Tombaugh on a rendezvous trajectory astronomer at the Lowell Observatory near with astronomical history when he assigned the Flagstaff, Arizona. His success came through young “farm boy astronomer” to the monumen- very hard work, perseverance, and Tombaugh’s tal task of searching the night sky for Planet X. skilled use of the “blinking comparator”—an As early as 1905, Lowell had noticed subtle per- innovative approach to astrophotography based turbations in the orbits of Neptune and Uranus, on the difference in photographic images taken which he attributed to the gravitational tug of a few days apart. His discovery of the elusive some undetected planet farther out in the solar trans-Neptunian planet also helped fulfill the system. After several more years of investigation, dreams of the observatory’s founder, PERCIVAL Lowell boldly predicted in 1915 the existence of LOWELL, who had predicted the existence of a this “Planet X” and began to conduct a detailed “Planet X” decades earlier. photographic search in candidate sections of the Clyde Tombaugh was born on February 4, sky from his newly built observatory in Flagstaff. 1906, on a farm near Streator, Illinois. When Unfortunately, Lowell died in 1916 without find- he was in secondary school, his family moved ing his mysterious Planet X. to the small farming community of Burdett in Using a 13-inch photographic telescope at the western portion of Kansas. When Tombaugh the Lowell Observatory, Tombaugh embarked on graduated from Burdett High School in 1925, a systematic search for the planet. He worked he had to abandon any immediate hope of at- through the nights in a cold, unheated dome, tending college, because crop failures had re- making pairs of exposures of portions of the sky cently impoverished his family. While growing with time intervals of two to six days. He then up on the farm, he acquired a very strong in- carefully examined these astrographs (star pho- terest in amateur astronomy from his father. To tographs) under a special device called the blink- complement this interest, he taught himself comparator in the hope of detecting the small mathematics and physics. In 1927 he con- shift in position of one faint point of light among structed several homemade telescopes, includ- hundreds of thousands of points of light—the ing a 9-inch reflector built from discarded farm sign of Planet X among a field of stars. On the machinery, auto parts, and handmade lenses and nights of January 23 and 29, 1930, Tombaugh mirrors. Using this reflector telescope under the made two such photographs of the region of the dark skies of western Kansas, he spent evenings sky near the star Delta Geminorum. On the af- observing and made detailed drawings of Mars ternoon of February 18, 1930, he triumphed. and Jupiter. Searching for advice and comments While viewing these photographic plates under about his observations, Tombaugh submitted his the blink-comparator, Tombaugh detected the drawings in 1928 to the professional planetary telltale shift of a faint starlike object. Slipher and astronomers at the Lowell Observatory in other astronomers at the observatory verified the Flagstaff, Arizona. To his great surprise, the as- results and rejoiced in Tombaugh’s discovery. tronomers were very impressed with his detailed However, caution was urged and time was taken drawings, which revealed his great talent as a for Tombaugh to confirm this important discov- careful and skilled astronomical observer. ery. The discovery of Pluto was confirmed with So despite the fact that Tombaugh lacked a subsequent photographic measurements and an- formal education in astronomy, VESTO MELVIN nounced to the world on March 13, 1930. 270 Tombaugh, Clyde William With the announcement of this discovery, in astronomy in 1939. He frequently told the story Tombaugh joined an exclusive group of as- of his perplexed astronomy professor who did not tronomers who observed and then named major want a “planet discoverer” in his basic astronomy planets in the solar system. Of the many thou- course. sands of astronomers in history who have Upon graduation, he returned to the Lowell searched the heavens with telescopes, only the Observatory and continued a rigorous program of following accompany Tombaugh in this very elite sky watching that resulted in his meticulous cat- group—SIR WILLIAM HERSCHEL, who discovered aloging of more than 30,000 celestial objects, in- Uranus in 1781, and JOHANN GOTTFRIED GALLE, cluding hundreds of variable stars, thousands of who discovered Neptune in 1846 (credit for this new asteroids, and two comets. He also engaged discovery is shared by JOHN COUCH ADAMS and in a search for possible small natural satellites en- URBAIN-JEAN-JOSEPH LEVERRIER). In keeping with circling Earth. However, save for the Moon, he astronomical tradition, Tombaugh had the right could not find any natural satellites of Earth that as the planet’s discoverer to give the distant ce- were large enough or bright enough to be detected lestial body a name. He chose Pluto, god of dark- by means of photography. ness and the underworld in Roman mythology. During World War II, Tombaugh taught nav- Pluto is a tiny, frigid world, very different from igation to military personnel from 1943 to 1945 the gaseous giant planets that occupy the outer at Arizona State College (now called Northern solar system. For that reason there is some debate Arizona University). Following World War II, the within the astronomical community as to Lowell Observatory did not rehire him as an as- whether Pluto is really a “major planet” or per- tronomer, because of funding reductions. Instead haps should be regarded as an icy moon that es- Tombaugh went to work for the military at the caped from Neptune or perhaps a large Kuiper White Sands Missile Range, in Las Cruces, New belt object. As more and more trans-Neptunian Mexico. There he supervised the development objects are discovered beyond the orbit of Pluto, and installation of the optical instrumentation this debate will most likely intensify in the 21st used during the testing of ballistic missiles, in- century. But for now, Pluto is regarded as the cluding WERNHER VON BRAUN’s V-2 rockets that ninth major planetary body in the solar system had been captured in Germany by the U.S. Army and Tombaugh’s discovery represents a marvelous at the close of the war. accomplishment in 20th-century observational Tombaugh left his position at the White astronomy. Sands Missile Range in 1955 and joined the fac- After discovering Pluto, Tombaugh remained ulty at New Mexico State University in Las with the Lowell Observatory for the next 13 years. Cruces. He helped this university establish a plan- During this period, he also entered the University etary astronomy program and remained an active of Kansas on scholarship in 1932 to pursue the observational astronomer. Upon retirement from undergraduate education he had been forced to the university in 1973, he went on extensive lec- delay because of financial constraints. In 1934, ture tours throughout the United States and while attending the university, he met and mar- Canada, accompanied by his wife, to raise money ried Patricia Edson of Kansas City. The couple re- for scholarships in astronomy at New Mexico mained married for more than 60 years and raised State University. Several weeks before his 91st two children. While observing during the sum- birthday, Tombaugh died on January 17, 1997, in mers at the Lowell Observatory, Tombaugh Las Cruces. earned his bachelor of science degree in astron- Tombaugh was recognized around the world omy in 1936 and then his master of arts degree as the discoverer of Pluto, and the only American Tsiolkovsky, Konstantin Eduardovich 271 to discover a planet. He became a professor emer- At age 16 Tsiolkovsky ventured to Moscow, itus in 1973 at New Mexico State University and where he studied mathematics, astronomy, me- published several books, including The Search for chanics, and physics. He used an ear trumpet to Small Natural Earth Satellites (1959) and Out of the listen to lectures and struggled with a meager al- Darkness: The Planet Pluto (1980), coauthored lowance of just a few kopecks (pennies) each with Patrick Moore. week for food. Three years later Tsiolkovsky returned home. He soon passed the schoolteacher’s examination and began his teaching career at a ᨳ Tsiolkovsky, Konstantin Eduardovich rural school in Borovsk, located about 100 kilo- (1857–1935) meters from Moscow. In Borovsk he met and mar- Russian ried his wife, Varvara Sokolovaya. He remained Physicist, (Theoretical) Rocket Engineer a provincial schoolteacher in Borovsk for more The nearly deaf Russian schoolteacher than a decade. Then, in 1892, Tsiolkovsky moved Konstantin Eduardovich Tsiolkovsky was a theo- to another teaching post in Kaluga, where he re- retical rocket expert and space travel pioneer mained until he retired in 1920. light-years ahead of his time. At the beginning of As he began his teaching career in rural the 20th century, Tsiolkovsky worked independ- Russia, Tsiolkovsky also turned his fertile mind to ent of ROBERT HUTCHINGS GODDARD and science, especially concepts about rockets and HERMANN JULIUS OBERTH, toward their common space travel. Despite his severe hearing impair- vision: the use of rockets for interplanetary travel. ment, Tsiolkovsky’s tenacity and self-reliance al- This brilliant schoolteacher lived a simple life in lowed him to become an effective teacher and isolated, rural towns in czarist Russia. Yet he wrote also to make significant contributions to the fields with such uncanny accuracy about modern rock- of aeronautics and astronautics. ets and space that he cofounded astronautics. But teaching in rural Russian villages in the Primarily a theorist, Tsiolkovsky never con- late 19th century physically isolated Tsiolkovsky structed any of the rockets he proposed in his re- from the mainstream of scientific activities, both markably prophetic books but they inspired many in his native country and elsewhere in the world. future Russian cosmonauts, space scientists, and He independently worked out the kinetic theory rocket engineers, including SERGEI PAVLOVICH of gases in 1881, then proudly submitted a manu- KOROLEV, whose powerful rockets helped fulfill script concerning this original effort to the Russ- Tsiolkovsky’s predictions. ian Physico-Chemical Society. Unfortunately for Tsiolkovsky was born on September 17, Tsiolkovsky, the famous chemist Dmitri 1857, in the village of Izhevskoye, in the Ryazan Mendeleyev (1834–1907) informed him that the Province of Russia. His father, Eduard theory had been developed a decade earlier. How- Ignatyevich Tsiolkovsky, was a Polish noble by ever, the originality and quality of Tsiolkovsky’s birth, but now in exile working as a provincial paper impressed Mendeleyev and the other forestry official. His mother, Mariya Yumasheva reviewers, and they invited him to become a Tsiolkovskaya was Russian and Tartar. At age member of the society. nine a near-fatal attack of scarlet fever left him While teaching in Borovsk, Tsiolkovsky almost totally deaf. With his loss of hearing, he used his own meager funds to construct the first adjusted to a lonely, isolated childhood in which wind tunnel in Russia. He did this so he could books became his friends. He also learned to ed- experiment with airflow over various stream- ucate himself and in the process acquired a high lined bodies. He also began making models of degree of self-reliance. gas-filled, metal-skinned dirigibles. His interest 272 Tsiolkovsky, Konstantin Eduardovich in aeronautics served as a stimulus for his more habitats in space, the use of solar energy, and visionary work involving the theory of rockets closed life support systems. and their role in space travel. As early as 1883, In the first two decades of the 20th century, he accurately described the weightlessness con- things seemed to go from bad to worse in dition of space in an article entitled “Free Tsiolkovsky’s life. In 1908 an overflowing river Space.” In his 1895 book, Dreams of Earth and flooded his home and destroyed many of his notes Sky, Tsiolkovsky discussed the concept of an ar- and scientific materials. Undaunted, he salvaged tificial satellite orbiting Earth. By 1898 he cor- what he could, rebuilt, and pressed on with teach- rectly linked the rocket to space travel and con- ing and writing about space. cluded that it would have to be a liquid-fueled Following the Russian Revolution of 1917, rocket to achieve the necessary escape velocity. the new Soviet government grew interested in The escape velocity is the minimum velocity an rocketry and rediscovered Tsiolkovsky’s amazing object must acquire in order to overcome the work, honoring him for his previous achieve- gravitational attraction of a large celestial body, ments in aeronautics and astronautics and such as planet Earth. To completely escape from encouraging him to continue his pioneering Earth’s gravity, for example, a spacecraft would research. He received membership in the Soviet need to reach a minimum velocity of approxi- Academy of Sciences in 1919, and the govern- mately 11 kilometers per second. ment granted him a pension for life in 1921 in Many of the fundamental principles of astro- recognition of his teaching and scientific contri- nautics were described in his seminal work, butions. Tsiolkovsky used the free time of Exploration of Space by Reactive Devices. This im- retirement to continue to make significant con- portant theoretical treatise showed that space tributions to astronautics. In 1924 he published travel was possible using the rocket. Another pi- his book Cosmic Rocket Trains, in which he rec- oneering concept found in the book is a design ognized that a single-stage rocket would not be for a liquid-propellant rocket that used liquid hy- powerful enough to escape Earth’s gravity on its drogen and liquid oxygen. Tsiolkovsky delayed own, so he developed the concept of a staged publishing the important document until 1903. rocket, which he called a rocket train. Tsi- One possible reason for the delay is the fact that olkovsky’s visionary writings inspired many Tsiolkovsky’s son, Iganty, had committed suicide future cosmonauts and aerospace engineers, in 1902. including Korolev. Because of Tsiolkovsky isolation his impor- Tsiolkovsky died in Kaluga on September 19, tant work in aeronautics and astronautics went 1935. His epitaph conveys the important message essentially unnoticed by the world. Few in Russia “Mankind will not remain tied to Earth forever.” cared about space travel in those days and he As part of the Soviet Union’s centennial cele- never received significant government funding to bration of Tsiolkovsky’s birth, one of Korolev’s en- pursue any type of practical demonstration of his visioned powerful rockets launched Sputnik 1, the innovative concepts. His suggestions included the world’s first artificial satellite—starting the Space space suit, space stations, multistage rockets, large Age on October 4, 1957.

With funding from an American-Scandinavian ᨳ Urey, Harold Clayton Foundation fellowship, Urey traveled to Denmark, (1893–1981) where he spent a year in postdoctoral research American at Niels Bohr’s Institute of Theoretical Physics. Chemist, Exobiologist Upon his return to the United States, he became Harold Urey was the American physical chemist an associate professor in chemistry at Johns who won the 1934 Nobel Prize in chemistry for Hopkins University. his discovery of the hydrogen isotope deuterium. In 1929 Urey accepted an appointment as In World War II he contributed to uranium iso- an associate professor in chemistry at Columbia topic enrichment efforts as part of the U.S. University. There, in 1931, while engaging in re- atomic bomb program known as the Manhattan search on diatomic gases, he devised a method to Project. Then, starting in the early 1950s, he concentrate any possible heavy hydrogen isotopes made a very exciting contribution to the emerg- by the fractional distillation of liquid hydrogen. ing field of planetary sciences by conducting His efforts led to the discovery of deuterium (D), one of the first experiments in exobiology—a the nonradioactive heavy isotope of hydrogen classic experiment often known as the Urey- that forms heavy water (D2O). He became a full Miller experiment. professor at Columbia in 1934. From 1940 to 1945 He was born on April 29, 1893, in Walkerton, Urey also served as the director of War Research, Indiana, the son of a minister and the grandson Atomic Bomb Project, at Columbia University. of one of the pioneers who originally settled the After World War II he moved to the University area. Following his early education in rural of Chicago and served there as a distinguished schools and high school graduation in 1911, professor of chemistry until 1955. Urey taught for three years in country schools. While at the University of Chicago in the Then, in 1914, he enrolled in the University of early 1950s, he made a dramatic break away from Montana and earned his bachelor of science de- his previous Nobel Prize–winning efforts in ter- gree in zoology in 1917. He spent the next two restrial chemistry and began to investigate the years as an industrial research chemist and then possible origins of life on Earth and elsewhere in returned to Montana to teach chemistry. In the universe from the perspective of extraterres- 1921 he entered the University of California trial chemistry. As one of the first exobiologists, and graduated in 1923 with a Ph.D. in chemistry. he introduced some of the basic ideas in this field

273 274 Urey, Harold Clayton

The American chemist and Nobel laureate Harold Urey at work in his laboratory. Early in his career, Urey discovered the nonradioactive isotope of ordinary hydrogen called deuterium. He received the 1934 Nobel Prize in chemistry for this accomplishment. Later in his career, he became one of the earliest exobiologists as he investigated the origins of life on Earth and the possibility of life in other worlds. In 1953, together with his student Stanley Miller, Urey performed the classic exobiology experiment in which gaseous mixtures that simulated Earth’s primitive atmosphere were subjected to various energy sources. To their pleasant surprise, life- forming organic compounds (amino acids) appeared in the solutions. (Argonne National Laboratory, courtesy AIP Emilio Segrè Visual Archives)

with his 1952 book The Planets: Their Origin and ulating Earth’s primitive atmosphere, and then Development. In 1953, together with his gradu- subjected these mixtures to various energy ate student Stanley Miller (b. 1930), Urey per- sources, such as ultraviolet radiation and light- formed the famous exobiology experiment that ning discharges. Within days, life-precursor or- is now widely known as the “Urey-Miller ex- ganic compounds known as amino acids began periment.” They created gaseous mixtures, sim- to form in some of the test beakers. Urey, Harold Clayton 275 The intriguing question that other scien- The 1934 Nobel Prize in chemistry highlighted tists began to seriously ask after the Urey-Miller his achievements as a terrestrial chemist, but his experiment was: “If life started in a primordial innovative work in extraterrestrial chemistry chemical soup here on Earth, does (or can) life may have far greater technical consequences. start on other worlds that have similar primi- Thanks to Urey’s supervision of pioneering ex- tive environments?” The question of whether periments at the University of Chicago, exobiol- life is unique to Earth or common throughout ogy has become a credible part of contemporary the Galaxy remains unanswered in the 21st space science programs—most notably reflected century. today by NASA’s continued search for micro- In 1958 Urey accepted a position at the scopic life on Mars and the space organization’s University of California in La Jolla, and he re- planned search for possible alien life in the sus- mained with that institution until he retired in pected subsurface liquid water ocean on the 1970. He died on January 5, 1981, in La Jolla. Jovian moon Europa.

the premier U.S. space scientist at the beginning ᨳ Van Allen, James Alfred of the Space Age. (1914– ) In 1942 Van Allen transferred to the Applied American Physics Laboratory at Johns Hopkins University Physicist, Space Scientist to work on rugged vacuum tubes. He received a The pioneering space scientist James Van Allen wartime commission that autumn in the U.S. placed the Iowa cosmic ray experiment on the Navy, and served as ordnance specialist for the re- first U.S satellite, Explorer 1, and with this in- mainder of World War II. One of his primary con- strument discovered the inner portion of tributions was the development of an effective Earth’s trapped radiation belts in early 1958. radio proximity fuse—one that detonated an ex- Today, space scientists call this distinctive plosive shell when the ordnance came near its zone of magnetically trapped atomic particles target. Following combat duty in the Pacific, he around Earth the Van Allen radiation belts in returned to the laboratory at Johns Hopkins his honor. University in Maryland. One afternoon in March Van Allen was born in Mount Pleasant, Iowa, 1945, he quite literally ran into his future wife, on September 7, 1914. During his sophomore year Abigail, during a minor traffic accident. Six at Iowa Wesleyan College, he made his first meas- months later both drivers were married and their urements of cosmic ray intensities. After gradua- fortuitous traffic encounter eventually yielded five tion in 1935, he attended the University of Iowa, children and a house full of grandchildren. where he earned his master’s degree in 1936 and In the postwar research environment, Van completed his doctoral degree in physics in 1939. Allen began applying his wartime engineering From 1939 to 1942 Van Allen worked at the experience to miniaturize the rugged new elec- Carnegie Institution of Washington as a physics tronic equipment. He used this small, but tough, research fellow in the department of terrestrial equipment in conjunction with his pioneering magnetism. As a Carnegie Fellow, he received rocket and satellite scientific instrument pay- valuable cross-training in geomagnetism, cosmic loads. By spring 1946 the navy transferred rays, nuclear physics, solar-terrestrial physics, and Lieutenant Commander Van Allen to its inac- ionospheric physics. All of this scientific cross- tive reserve and he resumed his war-interrupted training prepared him well for his leading role as research work at Johns Hopkins. He remained

276 Van Allen, James Alfred 277 at the Applied Physics Laboratory until 1950, providing a rugged Geiger-Muller tube to the Jet when he returned to the University of Iowa as Propulsion Laboratory, which was on contract head of the physics department. with the U.S. Army to construct the upper stage- While at Johns Hopkins, Van Allen per- spacecraft portion of Explorer 1. Van Allen’s formed a series of preliminary space science ex- scientific instrument was sturdy enough to periments that anticipated his great discovery at survive the ride into space on a rocket and then the dawn of the U.S. space program. He designed start collecting interesting geophysical data and constructed rugged, miniaturized instru- that was transmitted back to Earth by the host ments to collect geophysical data at the edge of spacecraft. space, using rides on captured German V-2 rock- All was ready on January 31, 1958. The U.S. ets, Aerobee sounding rockets, and even rockets Army hastily pressed a Jupiter C rocket into launched from high altitude balloons (rock- service as a launch vehicle, with a cleverly im- oons). One of his prime interests was the meas- provised configuration designed by WERNHER urement of the intensity of cosmic rays and any MAGNUS VON BRAUN. Flawlessly, the rocket other energetic particles arriving at the top of rumbled into orbit from Cape Canaveral, Earth’s atmosphere from outer space. He carried Florida. Soon the first U.S. satellite, Explorer 1, these research interests back to the University traveled in orbit around Earth. As the satellite of Iowa and over the years established an inter- glided though space, Van Allen’s ionizing radi- nationally recognized space physics program. ation detector, primarily designed to measure On October 4, 1957, the Soviet Union cosmic ray intensity, jumped off scale. As a great shocked the world by sending the first artificial surprise to Van Allen and other scientists, this satellite, Sputnik 1, into orbit around Earth. In instrument had unexpectedly detected the inner addition to starting the Space Age, this satellite portion of Earth’s trapped radiation belts. forced the United States into a hotly contested The Explorer II spacecraft, launched into space technology race. In a desperate attempt orbit on March 26, 1958, carried an augmented to win the race, both the Soviets and the version of Van Allen’s Iowa cosmic-ray instru- Americans started pumping large quantities of ment. That spacecraft harvested an enormous money into the construction of military and quantity of data about the radiation environ- scientific (civilian) space systems. ment in space and confirmed the presence of Fortune often favors the prepared. As a trapped energetic charged-particle belts (mainly gifted scientist, Van Allen was well prepared for electrons and protons) within Earth’s magne- the great opportunity that suddenly came his tosphere. These belts are now called the Van way. With the dramatic failure of the first Allen radiation belts. Soon an armada of space- Vanguard rocket vehicle at Cape Canaveral, craft poked and probed the region of outer space Florida, in early December 1957, senior U.S. near Earth, defining the extent, shape, and com- government officials made an emergency deci- position of Earth’s trapped radiation belts. Van sion to launch the country’s first satellite with a Allen became an instant scientific celebrity. military rocket. A scientific payload that was Because of his widely recognized space science rugged enough to fly on a rocket was needed at accomplishments, he has since met eight U.S. once. Van Allen’s Iowa cosmic-ray experiment presidents. was available and quickly selected to become the In the 1960s and 1970s he assisted the principal component of the payload on Explorer National Aeronautics and Space Adminis- 1. He responded to this great opportunity by tration in planning, designing, and operating 278 Van Allen, James Alfred

Pioneering space scientist James Van Allen was part of the jubilant team that launched the first American satellite, Explorer I, on January 31, 1958. Appearing in this photograph are: (left) William H. Pickering, former director of the Jet Propulsion Laboratory, which built and operated the satellite; (center) James Van Allen, who designed and built the satellite’s space science instruments; and (right) Wernher von Braun, who built the launch vehicle that successfully sent the satellite into orbit around Earth. They are holding a model of Explorer I, whose instruments made scientific history by detecting Earth’s trapped radiation belts—now called the Van Allen belts. (NASA) energetic particle instruments on planetary ex- missions. Members of this group have published ploration spacecraft to Mars, Venus, Jupiter, and major papers dealing with Jupiter’s intensely Saturn. Since Explorer 1, Van Allen and his powerful magnetosphere, the discovery and pre- team of researchers and graduate students at the liminary survey of Saturn’s magnetosphere, and University of Iowa have actively participated the energetic particles population in interplan- in many other pioneering space exploration etary space. Van Allen, James Alfred 279 Van Allen retired from the department of building appropriately named Van Allen Hall. physics and astronomy at the University of Iowa His space physics efforts not only thrust the in 1985. However, as the Carver Professor of University of Iowa into international promi- Physics Emeritus, he still pores over interesting nence but he also served his nation as a truly in- space physics data in his office in the campus spirational scientific hero.

California, and today the largest university- ᨳ Wilson, Robert Woodrow operated radio observatory in the world. For (1936– ) Wilson, graduate research in radio astronomy American provided a nice mixture of electronics and Physicist, Radio Astronomer physics. His decision to pursue this area of re-

Robert Wilson collaborated with ARNO ALLEN search placed him on a highly productive career PENZIAS at Bell Laboratories in the mid-1960s path in radio astronomy. However, in 1958 he and made the most important discovery in 20th- briefly delayed his entry into radio astronomy to century cosmology. By detecting cosmic mi- return to Houston so he could court and marry crowave background radiation, they provided his wife, Elizabeth Rhoads Sawin. the first empirical evidence in support of the Big In 1959 Wilson took his first astronomy Bang theory presented as a doctoral thesis in courses at Caltech and began working at the 1948 by RALPH ASHER ALPHER. Owens Valley Radio Observatory during breaks Robert Woodrow Wilson was born in in the academic calendar. He completed the last Houston, Texas, on January 10, 1936. His child- part of his thesis research under the supervision hood visits to the company shop with his father, of MAARTEN SCHMIDT, who was exploring a chemist working for the oil industry, provided quasars at the time. Following graduation with Wilson with his lifelong interest in electronics his doctoral degree, Wilson stayed on at Caltech and machinery. In 1957 he received his bache- as a postdoctoral researcher and completed sev- lor of arts degree with honors in physics from eral other projects. In 1963 he joined Bell Rice University in Houston and then enrolled Laboratories and soon met Penzias, the only for graduate work in physics at the California other radio astronomer at the laboratory. Institute of Technology (Caltech). At the time Between 1963 and 1965 the two collabo- Wilson was not decided about what area of rated in applying a special antenna six meters physics he wanted to pursue for his doctoral re- in diameter to investigate the problem of search. However, fortuitous meetings and dis- radio noise from the sky. At this time, Bell cussions on campus led him to become involved Laboratories had a general interest in detecting in interesting work at Caltech’s Owens Valley and resolving any cosmic radio noise problems Radio Observatory—then undergoing develop- that might adversely affect the operation of the ment in the Sierra Nevada near Bishop, early communication satellites. Expecting radio

280 Wolf, Maximilian 281 noise to be less severe at shorter wavelengths, ᨳ Wolf, Maximilian (Max Wolf) Wilson and Penzias were surprised to discover (1863–1932) that the sky was uniformly “bright” at 7.3 cen- German timeters wavelength in the microwave region. Astronomer Discussions with Robert Dicke (1916–97) in spring 1965 indicated that Wilson and Penzias Max Wolf was an asteroid hunter who pioneered had stumbled upon the first direct evidence of the use of astrophotography to help him in his the cosmic microwave background—the “Holy search for these elusive solar system bodies. He Grail” of Big Bang cosmology. Wilson and discovered more than 200 minor planets, in- Penzias estimated the detected cosmic “radio cluding asteroid Achilles in 1906—the first of noise” to be about three kelvins. Measurements the Trojan group of asteroids. This group of mi- performed by NASA’s Cosmic Background nor planets moves around the Sun in Jupiter’s Explorer (COBE) spacecraft between 1989 and orbit, but at the Lagrangian libration points of 1990 indicated that the cosmic microwave 60 degrees ahead and 60 degrees behind the background closely approximates a blackbody giant planet. radiator at a temperature of 2.735 kelvins. For Wolf was born on June 21, 1863, in this great (though serendipitous) discovery, Heidelberg, Germany, the city where he spent Wilson shared one half of the 1978 Nobel Prize almost his entire lifetime. His father was a re- in physics with Penzias. The other half of the spected physician and the family was comfort- award that year went to the Russian physicist ably wealthy. When Wolf was a young boy, his Pyotr Kapitsa for unrelated work in low- father encouraged him to develop an interest in temperature physics. science and astronomy by building him a private In the late 1960s and early 1970s, Wilson observatory adjacent to the family’s residence. and Penzias used techniques in radio astron- His father’s investment was a good one. Wolf omy at millimeter wavelengths to investigate completed his doctoral degree in mathematical molecular species in interstellar space. They studies at the University of Heidelberg in 1888 were excited to unexpectedly find large quan- and then went to the University of Stockholm tities of carbon monoxide (CO) behind the for two years of postdoctoral work. He returned Orion Nebula, and soon found that this mol- to Heidelberg in 1890 and began lecturing in as- ecule was rather widely distributed throughout tronomy at the university as a Privatdozent (un- the Galaxy. paid instructor). In 1893 Wolf received a dual From 1976 to 1990 Wilson served as the appointment from the University of Heidelberg head of the Radio Physics Research Department to serve as a special professor of astrophysics at Bell Laboratories. He was elected to the U. S. and to direct the new observatory being con- National Academy of Sciences in 1979. In ad- structed at nearby Königsstuhl. In 1902 he be- dition to the 1978 Nobel Prize, Wilson also re- came the chair of astronomy at the university ceived the Herschel Medal from the Royal and, along with his directorship of the Königsstuhl Astronomical Society (1977) and the Henry Observatory, remained in these positions until Draper Medal from the American National his death. Academy of Sciences (1977). Wilson’s major Wolf performed important spectroscopic contribution to astronomy was his codiscovery work concerning nebulas and published 16 lists of the cosmic microwave background—the lin- of nebulae containing a total of about 6,000 ce- gering remnant of the Big Bang explosion that lestial objects. But he is best remembered as be- started the universe. ing the first astronomer to use photography to 282 Wolf, Maximilian find asteroids. In 1891 he demonstrated the abil- 200 new asteroids, including asteroid 588, Achilles. ity to photograph a large region of the sky with Wolf found and named Achilles in 1906, noting a telescope that followed the “fixed” stars pre- that it orbited the Sun at the L4 Lagrangian cisely as the Earth rotated. The stars therefore point 60 degrees ahead of Jupiter. The Trojan appeared as points, while the minor planets he group is the collection of minor planets found at hunted appeared as short streaks on the photo- the two Lagrangian libration points lying on graphic plate. On September 11, 1898, he dis- Jupiter’s orbital path around the Sun. The name covered his first asteroid with this photographic comes from the fact that many of these asteroids technique and named the celestial object Brucia were named after the mythical heroes of the (also called asteroid 323) to honor the American Trojan War. philanthropist Catherine Wolfe Bruce. She had Wolf was an avid asteroid hunter and a pi- donated money for Wolf’s new telescope at the oneer in astrophotography. In recognition of his Königsstuhl Observatory. She also established contributions to astronomy, he received the the Bruce Gold Medal as the award presented Gold Medal of the Royal Astronomical Society annually to an astronomer in commemoration in 1914 and the Bruce Gold Medal from the of his or her lifetime achievements. Astronomical Society of the Pacific in 1930. By the end of 1898, Wolf had discovered He held membership in both the American nine other minor planets using astrophotogra- Astronomical Society and the Royal Astro- phy. Over the next three decades, this technique nomical Society of Great Britain. He died in allowed him to personally discover more than Heidelberg on October 3, 1932.

Zwicky was also enrolled there as a student, ᨳ Zwicky, Fritz science historians often suggest that he was a (1898–1974) student of Einstein. Without question, Zwicky Swiss was a very creative and intelligent physicist, so Astrophysicist he could certainly have engaged in interesting

Shortly after EDWIN POWELL HUBBLE introduced scientific discussions with Einstein, as both a stu- the concept of an expanding universe in the late dent in Switzerland and then after graduation, 1920s, Fritz Zwicky pioneered the early search for when he became a professor at the California the “dark matter” (that is, the missing mass) of Institute of Technology (Caltech). However, the the universe. While collaborating with WILHELM truth is not known. What is clear is that Zwicky HEINRICH WALTER BAADE in 1934, he coined the had a dark side to his technical genius. He was term supernova to describe certain very cata- very abrasive and fond of using rough language clysmic nova phenomena. Zwicky, a visionary and intimidating colleagues and students alike. with an extremely eccentric and often caustic per- Only a few extremely tolerant individuals, such sonality, also postulated that the by-product of as Baade, could or would overlook his eccentric this supernova explosion would be a neutron star. and difficult personality in order to encounter Fritz Zwicky was born on February 14, 1898, the bursts of genius that occasionally could be in Varna, Bulgaria. A lifelong Swiss citizen, he found within Zwicky’s characteristically caustic spent his childhood in Mollis, a village in the comments. Canton (state) of Glarus, Switzerland. He re- At the invitation of the Nobel laureate ceived his education in physics at the Federal physicist Robert Millikan (1868–1953), Zwicky Institute of Technology in Zürich, graduating came to the United States in 1925 to work as with a Ph.D. in 1922. While a graduate student, a postdoctoral fellow at Caltech. Claiming he Zwicky interacted with the Swiss physicist enjoyed the mountains near Pasadena, Zwicky Auguste Piccard (1884–1962) and performed his remained affiliated with that institution and dissertation research under a Nobel laureate, the stayed in California for the rest of his life. Dutch-American physical chemist Peter Deybe However, despite living and working for almost (1884–1966). five decades in the United States, Zwicky re- Since ALBERT EINSTEIN was a physics in- tained his Swiss citizenship and never chose to structor at the Federal Institute in Zurich when apply for U.S. citizenship.

283 284 Zwicky, Fritz antics are legendary. When encountering an unfamiliar student on campus, Zwicky would often suddenly stop, stare in his or her face, and loudly inquire: “Who the hell are you?” Similarly, during a lecture on campus, he might suddenly stand up and leave the room, pausing at the door to turn around and inform the startled speaker that he (Zwicky) had already solved the particular problem under discussion. Without question, many on the campus breathed a sigh of relief when Zwicky committed much of his time between 1943 and 1946 to direct research at the Aerojet Corporation in Azusa, California, in support of jet engine development and other defense-related activities. Despite his extensive involvement with astronomers, many of them also fell victim to his aggressive social behavior. While working at the Mount Wilson Observatory or at the Palomar Observatory, Zwicky would often inject one of his favorite exclamations, that all astronomers The Swiss astrophysicist Fritz Zwicky lecturing at the were “spherical bastards.” Why spherical? Well, California Institute of Technology (Caltech). In the late according to Zwicky, astronomers “looked the 1920s he pioneered the early search for the “dark matter” (that is, the missing mass) of the universe. same when viewed from any direction.” But be- While collaborating with Walter Baade in 1934, he hind this difficult personality was a gifted astro- coined the term supernova to describe certain very physicist who helped establish the framework of cataclysmic nova phenomena. Zwicky, a visionary modern cosmology. with an extremely eccentric and often caustic personality, also postulated that the by-product of In 1933, while investigating the Coma this supernova explosion would be a neutron star. Cluster—a rich cluster of galaxies in the (AIP Emilio Segrè Visual Archives) Constellation Coma Berenices (also known as Berenice’s Hair)—Zwicky observed that the velocities of the individual galaxies in this clus- In 1927 he became a professor of theoreti- ter were so high that they should definitely cal physics and retained that academic position have escaped from each other’s gravitational at Caltech until he became a professor of astro- attraction long ago. Zwicky, never afraid of physics there in 1942. He retired from Caltech controversy, quickly came to the pioneering in 1972 given the status of professor emeritus in conclusion that the amount of matter actually recognition of his lifelong service to the univer- in that cluster had to be much greater than sity and to astrophysics. While at Caltech what could be accounted for by the visible Zwicky interacted with many of the world’s best galaxies alone—an amount estimated to be astronomers, including Baade, who came to only about 10 percent of the mass needed to Southern California to use the Mount Wilson gravitationally bind the galaxies in the cluster. Observatory, located in the nearby San Gabriel Zwicky then focused a great deal of his atten- Mountains. On campus at Caltech, Zwicky’s tion on the problem of this “missing mass” or, Zwicky, Fritz 285 as it is now more commonly called, the prob- brilliance, not all supernovas are visible to naked- lem of “dark matter.” eye observers on Earth. The most famous naked- To support his research in dark matter, eye supernovas include the very bright new star Zwicky and his collaborators started to use the reported by Chinese and Korean astronomers in 18-inch Schmidt telescope at the Palomar 1054; Tyco’s star, appearing in 1572; Kepler’s Observatory near San Diego in 1936 to investi- star, appearing in 1604; and supernova 1987A, gate and then catalog numerous clusters of the most recent event, which took place in the galaxies. Between 1961 and 1968 Zwicky pub- Large Magellan Cloud on February 23, 1987. lished the results of this intense effort as a six- Zwicky recognized that supernovas were incred- volume work called Catalog of Galaxies and of ibly interesting, yet violent celestial events. Clusters of Galaxies. Sometimes simply referred During a supernova explosion, the dying star to as the Zwicky catalog, this important work might become more than 1 billion times brighter contained about 10,000 clusters (classified as than the Sun. either compact, medium compact, or open) and In 1932 the British physicist Sir James approximately 31,000 galaxies. Chadwick (1891–1974) experimentally discov- While investigating bright novas with ered the neutron. Zwicky recognized the astro- Baade in 1934, Zwicky coined the term super- nomical significance of Chadwick’s discovery nova to describe the family or new class of no- and boldly presented an extremely visionary vas that appeared to be far more energetic and “neutron star” hypothesis in 1934. Specifically, cataclysmic than any of the more frequently Zwicky proposed that a neutron star might be encountered novas. The classical nova phe- formed as a by-product of a supernova explosion. nomenon involves a sudden and unpredictable He reasoned that the violent explosion and sub- increase in the brightness (perhaps up to 10 sequent gravitational collapse of the dying star’s orders of magnitude) of a binary star system. In core should create a compact object of such in- a typical spiral galaxy like the Milky Way, as- credible density that all the electrons and pro- trophysicists expect about 25 such eruptions to tons become so closely packed together that they occur each year. As Zwicky noted, the supernova become neutrons. However, his daring hypoth- was a much more violent and rare stellar event. esis was essentially ignored for about three A star undergoing a supernova explosion tem- decades. Then, in 1968, astronomers confirmed porarily shines with a brightness that is more the presence of the first suspected neutron star, than 100 times more luminous than an ordinary a young optical pulsar, in the cosmic debris of nova. The supernova occurs in a galaxy like the the great supernova event of 1054. The discov- Milky Way only about two or three times per ery proved that the eccentric Zwicky was years century. From 1937 to 1941 Zwicky engaged in ahead of his contemporaries in suggesting a link- an extensive search for such events beyond the age between supernovas and neutron stars. Milky Way and personally discovered 18 extra- Zwicky also published the creative book galactic supernovas. Until then, only about 12 Morphological Cosmology in 1957. He received such events had been recorded in the entire his- the Gold Medal from the Royal Astronomical tory of astronomy. Society in 1973 for his contributions to modern Since this early work by Zwicky and Baade, cosmology. After spending almost five decades other astrophysicists have discovered more than in the United States, Zwicky died on February 800 extragalactic supernovas. Despite their 8, 1974, in Pasadena, California.

ENTRIES BY FIELD

ASTRONAUTICS Beg, Muhammed Taragai Herschel, Sir John Frederick Braun, Wernher Magnus von Ulugh William Ehricke, Krafft Arnold Bell Burnell, Susan Jocelyn Herschel, Sir William Goddard, Robert Hutchings Bessel, Friedrich Wilhelm Hertzsprung, Ejnar Hohmann, Walter Bode, Johann Elert Hewish, Antony Korolev, Sergei Pavlovich Bok, Bartholomeus Jan Hubble, Edwin Powell Lagrange, Comte Joseph-Louis Bradley, James Huggins, Sir William Laplace, Pierre-Simon, Marquis Brahe, Tycho Jeans, Sir James Hopwood de Burbidge, Eleanor Margaret Jones, Sir Harold Spencer Leverrier, Urbain-Jean-Joseph Peachey Kant, Immanuel Oberth, Hermann Julius Campbell, William Wallace Kapteyn, Jacobus Cornelius Tereshkova, Valentina Cannon, Annie Jump Kepler, Johannes Tsiolkovsky, Konstantin Cassini, Giovanni Domenico al-Khwarizmi, Abu Eduardovich Charlier, Carl Vilhelm Kuiper, Gerard Peter Ludvig Laplace, Pierre-Simon, Marquis ASTRONOMY Clark, Alvan Graham de Adams, John Couch Copernicus, Nicolas Leverrier, Urbain-Jean-Joseph Adams, Walter Sydney Curtis, Heber Doust Lockyer, Sir Joseph Norman Alfonso X Douglass, Andrew Ellicott Lowell, Percival Ångström, Anders Jonas Drake, Frank Donald Messier, Charles Arago, Dominique-François- Draper, Henry Newcomb, Simon Jean Dyson, Sir Frank Watson Olbers, Heinrich Wilhelm Argelander, Friedrich Fleming, Williamina Paton Matthäus Wilhelm August Stevens Oort, Jan Hendrik Aristarchus of Samos Galilei, Galileo Penzias, Arno Allen Aryabhata Galle, Johann Gottfried Piazzi, Giuseppe Baade, Wilhelm Heinrich Gill, Sir David Pickering, Edward Charles Walter Hall, Asaph Ptolemy Barnard, Edward Emerson Halley, Sir Edmund Reber, Grote Battani, al- Hawking, Sir Stephen William Rossi, Bruno Benedetto Bayer, Johannes Herschel, Caroline Lucretia Russell, Henry Norris

286 Entries by Field 287

Ryle, Sir Martin COSMOLOGY Halley, Sir Edmund Sagan, Carl Edward Alfvèn, Hannes Olof Gösta Hawking, Sir Stephen Scheiner, Christoph Alpher, Ralph Asher William Schiaparelli, Giovanni Gamow, George Herschel, Sir John Frederick Virginio Hawking, Sir Stephen William William Schmidt, Maarten Hubble, Edwin Powell Jeans, Sir James Hopwood Schwabe, Samuel Heinrich Lemaître, Abbé Georges- Kepler, Johannes Schwarzschild, Karl Êdouard al- Khwarizmi, Abu Secchi, Pietro Angelo Lagrange, Comte Joseph-Louis Shapley, Harlow ENGINEERING Laplace, Pierre-Simon, Sitter, Willem de Braun, Wernher Magnus von Marquis de Slipher, Vesto Melvin Ehricke, Krafft Arnold Leverrier, Urbain-Jean-Joseph Somerville, Mary Fairfax Hohmann, Walter Newcomb, Simon Tombaugh, Clyde William Korolev, Sergei Pavlovich Newton, Sir Isaac Wilson, Robert Woodrow Oberth, Hermann Julius Wolf, Maximilian ENVIRONMENTAL SCIENCE Ptolemy Douglass, Andrew Ellicott Scheiner, Christoph ASTROPHYSICS Sitter, Willem de Alpher, Ralph Asher EXOBIOLOGY Somerville, Mary Fairfax Ambartsumian, Viktor Arrhenius, Svante August Amazaspovich Urey, Harold Clayton OPTICAL SCIENCE AND INSTRUMENTATION Bell Burnell, Susan Jocelyn Clark, Alvan Graham Bethe, Hans Albrecht HISTORY Draper, Henry Burbidge, Eleanor Margaret Alfonso X Fraunhofer, Joseph von Peachey Hale, George Ellery Chandrasekhar, LITERATURE Lippershey, Hans Subrahmanyan Aratus of Soli Newton, Sir Isaac Eddington, Sir Arthur Stanley Scheiner, Christoph Giacconi, Riccardo MATHEMATICS Hale, George Ellery Adams, John Couch Lemaître, Abbé Georges- Arago, Dominique-François- PHILOSOPHY Êdouard Jean Aristotle Rees, Sir Martin John Aristarchus of Samos Bruno, Giordano Russell, Henry Norris Aryabhata Herschel, Sir John Frederick Sagan, Carl Edward Battani, al- William Schmidt, Maarten Beg, Muhammed Taragai Kant, Immanuel Schwarzschild, Karl Ulugh Plato Zwicky, Fritz Brahe, Tycho Ptolemy Cassini, Giovanni Domenico CHEMISTRY Charlier, Carl Vilhelm Ludvig PHYSICS Arrhenius, Svante August Dirac, Paul-Adrien-Maurice Alfvén, Hannes Olof Gösta Bunsen, Robert Wilhelm Doppler, Christian Andreas Alpher, Ralph Asher Cavendish, Henry Euler, Leonhard Alvarez, Luis Walter Urey, Harold Clayton Galilei, Galileo Anderson, Carl David 288 A to Z of Scientists in Space and Astronomy

Ångström, Anders Jonas Hertz, Heinrich Rudolf Tsiolkovsky, Konstantin Arago, Dominique-François- Hess, Victor Francis Eduardovich Jean Hubble, Edwin Powell Van Allen, James Alfred Boltzmann, Ludwig Jeans, Sir James Hopwood Wilson, Robert Woodrow Cavendish, Henry Kirchhoff, Gustav Robert Clausius, Rudolf Julius Lockyer, Sir Joseph SPACE SCIENCES Compton, Arthur Holly Norman Alfvén, Hannes Olof Gösta Dirac, Paul Adrien Maurice Michelson, Albert Abraham Van Allen, James Alfred Einstein, Albert Newton, Sir Isaac Rossi, Bruno Benedetto Euler, Leonhard Oberth, Hermann Julius Fowler, William Alfred Penzias, Arno Allen SPECTROSCOPY Fraunhofer, Joseph von Pickering, Edward Charles Bunsen, Robert Wilhelm Galilei, Galileo Planck, Max Karl Fraunhofer, Joseph von Gamow, George Rossi, Bruno Benedetto Huggins, Sir William Goddard, Robert Hutchings Ryle, Sir Martin Kirchhoff, Gustav Robert Halley, Sir Edmund Sagan, Carl Edward Lockyer, Sir Joseph Norman Hawking, Sir Stephen William Stefan, Josef Secchi, Pietro Angelo

ENTRIES BY COUNTRY OF BIRTH

ARMENIA Laplace, Pierre-Simon, Scheiner, Christoph Ambartsumian, Viktor Marquis de Schwabe, Samuel Heinrich Amazaspovich Leverrier, Urbain-Jean-Joseph Schwarzschild, Karl Messier, Charles Wolf, Maximilian AUSTRIA Boltzmann, Ludwig GERMANY (INCLUDES PRUSSIA) GREAT BRITAIN Doppler, Christian Baade, Wilhelm Heinrich Adams, John Couch Andreas Walter Bell Burnell, Susan Jocelyn Hess, Victor Francis Bayer, Johannes Bradley, James Stefan, Josef Bessel, Friedrich Wilhelm Burbidge, Eleanor Margaret Bethe, Hans Albrecht Peachey BELGIUM Bode, Johann Elert Cavendish, Henry Lemaître, Abbé Georges- Braun, Wernher Magnus von Dirac, Paul Adrien Maurice Êdouard Bunsen, Robert Wilhelm Dyson, Sir Frank Watson Ehricke, Krafft Arnold Eddington, Sir Arthur Stanley BULGARIA Einstein, Albert Fleming, Williamina Paton Zwicky, Fritz Fraunhofer, Joseph von Stevens Galle, Johann Gottfried Gill, Sir David CANADA Herschel, Caroline Lucretia Halley, Sir Edmund Newcomb, Simon Herschel, Sir William Hawking, Sir Stephen William Hertz, Heinrich Rudolf Herschel, Sir John Frederick DENMARK Hohmann, Walter William Brahe, Tycho Kant, Immanuel Hewish, Antony Hertzsprung, Ejnar Kepler, Johannes Huggins, Sir William Kirchhoff, Gustav Robert Jeans, Sir James Hopwood EGYPT Lippershey, Hans Jones, Sir Harold Spencer Ptolemy Michelson, Albert Abraham Lockyer, Sir Joseph Norman Olbers, Heinrich Wilhelm Newton, Sir Isaac FRANCE Matthäus Rees, Sir Martin John Arago, Dominique-François- Penzias, Arno Allen Ryle, Sir Martin Jean Planck Max Karl Somerville, Mary Fairfax

289 290 A to Z of Scientists in Space and Astronomy

GREECE PERSIA UKRAINE Aratus of Soli Beg, Muhammed Taragai Ulugh Gamow, George Aristarchus of Samos al-Khwarizmi, Abu Korolev, Sergei Pavlovich Aristotle Plato POLAND UNITED STATES Clausius, Rudolf Julius Alpher, Ralph Asher INDIA Emmanuel Alvarez, Luis Walter Aryabhata Copernicus, Nicolas Anderson, Carl David Chandrasekhar, Subrahmanyan Barnard, Edward Emerson ROMANIA Campbell, William ITALY Oberth, Hermann Julius Wallace Bruno, Giordano Cannon, Annie Jump Cassini, Giovanni Domenico RUSSIA Clark, Alvan Graham Galilei, Galileo Tereshkova, Valentina Compton, Arthur Holly Giacconi, Riccardo Tsiolkovsky, Konstantin Curtis, Heber Doust Lagrange, Comte Joseph-Louis Eduardovich Douglass, Andrew Ellicott Piazzi, Giuseppe Drake, Frank Donald Rossi, Bruno Benedetto SPAIN Draper, Henry Schiaparelli, Giovanni Alfonso X Fowler, William Alfred Virginio Goddard, Robert Hutchings Secchi, Pietro Angelo SWEDEN Hale, George Ellery Alfvèn, Hannes Olof Gösta Hall, Asaph LITHUANIA Ångström, Anders Jonas Hubble, Edwin Powell Argelander, Friedrich Arrhenius, Svante August Lowell, Percival Wilhelm Charlier, Carl Vilhelm Ludvig Pickering, Edward Charles Reber, Grote NETHERLANDS SWITZERLAND Russell, Henry Norris Bok, Bartholomeus Jan Euler, Leonhard Sagan, Carl Edward Kapteyn, Jacobus Shapley, Harlow Cornelius SYRIA Slipher, Vesto Melvin Kuiper, Gerard Peter Adams, Walter Sydney Tombaugh, Clyde William Oort, Jan Hendrik Urey, Harold Clayton Schmidt, Maarten TURKEY Van Allen, James Alfred Sitter, Willem de Battani, al- Wilson, Robert Woodrow

ENTRIES BY COUNTRY OF MAJOR SCIENTIFIC ACTIVITY

AUSTRALIA GERMANY Dirac, Paul Adrien Maurice Reber, Grote Argelander, Friedrich Dyson, Sir Frank Watson Wilhelm August Eddington, Sir Arthur AUSTRIA Bayer, Johannes Stanley Boltzmann, Ludwig Bessel, Friedrich Wilhelm Halley, Sir Edmund Doppler, Christian Andreas Bode, Johann Elert Herschel, Caroline Lucretia Hess, Victor Francis Bunsen, Robert Wilhelm Herschel, Sir William Stefan, Josef Clausius, Rudolf Julius Herschel, Sir John Frederick Emmanuel William BELGIUM Fraunhofer, Joseph von Hewish, Antony Lemaître, Abbé Georges- Galle, Johann Gottfried Huggins, Sir William Êdouard Hertz, Heinrich Rudolf Jeans, Sir James Hopwood Hohmann, Walter Jones, Sir Harold Spencer DENMARK Kant, Immanuel Lockyer, Sir Joseph Norman Brahe, Tycho Kepler, Johannes Newton, Sir Isaac Hertzsprung, Ejnar Kirchhoff, Gustav Robert Rees, Sir Martin John Oberth, Hermann Julius Ryle, Sir Martin EGYPT Olbers, Heinrich Wilhelm Somerville, Mary Fairfax Ptolemy Matthäus Planck, Max Karl GREECE FRANCE Scheiner, Christoph Aratus of Soli Arago, Dominique-François- Schwabe, Samuel Heinrich Aristarchus of Samos Jean Schwarzschild, Karl Aristotle Cassini, Giovanni Domenico Wolf, Maximilian Plato Lagrange, Comte Joseph- Louis GREAT BRITAIN INDIA Laplace, Pierre-Simon, Adams, John Couch Aryabhata Marquis de Bell Burnell, Susan Jocelyn Leverrier, Urbain-Jean- Bradley, James ITALY Joseph Cavendish, Henry Bruno, Giordano Messier, Charles Chandrasekhar, Subrahmanyan Galilei, Galileo

291 292 A to Z of Scientists in Space and Astronomy

Piazzi, Giuseppe SWEDEN Drake, Frank Donald Schiaparelli, Giovanni Alfvén, Hannes Olof Gösta Draper, Henry Virginio Ångström, Anders Jonas Ehricke, Krafft Arnold Secchi, Pietro Angelo Arrhenius, Svante August Einstein, Albert Charlier, Carl Vilhelm Fleming, Williamina Paton NETHERLANDS Ludvig Stevens Kapteyn, Jacobus Cornelius Dirac, Paul Adrien Maurice Fowler, William Alfred Lippershey, Hans Gamow, George Oort, Jan Hendrik SWITZERLAND Giacconi, Riccardo Sitter, Willem de Einstein, Albert Goddard, Robert Hutchings PERSIA SYRIA Hale, George Ellery Beg, Muhammed Taragai Battani, al- Hall, Asaph Ulugh Hubble, Edwin Powell al-Khwarizmi, Abu UNITED STATES Kuiper, Gerard Peter Adams, Walter Sydney Lowell, Percival POLAND Alpher, Ralph Asher Michelson, Albert Copernicus, Nicolas Alvarez, Luis Walter Abraham Anderson, Carl David Newcomb, Simon RUSSIA Baade, Wilhelm Heinrich Penzias, Arno Allen Ambartsumian, Viktor Walter Pickering, Edward Charles Amazaspovich Barnard, Edward Emerson Reber, Grote Euler, Leonhard Bethe, Hans Albrecht Rossi, Bruno Korolev, Sergei Pavlovich Bok, Bartholomeus Jan Benedetto Tereshkova, Valentina Braun, Wernher Russell, Henry Norris Tsiolkovsky, Konstantin Magnus von Sagan, Carl Edward Eduardovich Burbidge, Eleanor Margaret Schmidt, Maarten Peachey Shapley, Harlow SPAIN Campbell, William Wallace Slipher, Vesto Melvin Alfonso X Cannon, Annie Jump Tombaugh, Clyde Chandrasekhar, William SOUTH AFRICA Subrahmanyan Urey, Harold Clayton Gill, Sir David Clark, Alvan Graham Van Allen, James Alfred Herschel, Sir John Frederick Compton, Arthur Holly Wilson, Robert William Curtis, Heber Doust Woodrow Sitter, Williem de Douglass, Andrew Ellicott Zwicky, Fritz

ENTRIES BY YEAR OF BIRTH

499–400 B.C.E. 1500–1599 Laplace, Pierre-Simon, Plato Bayer, Johannes Marquis de Brahe, Tycho Messier, Charles

399–300 B.C.E. Bruno, Giordano Olbers, Heinrich Wilhelm Aratus of Soli Galilei, Galileo Matthäus Aristarchus of Samos Kepler, Johannes Piazzi, Giuseppe Aristotle Lippershey, Hans Schwabe, Samuel Heinrich Scheiner, Christoph Somerville, Mary Fairfax

100–0 B.C.E. 1600–1699 1800–1809 Ptolemy Bradley, James Doppler, Christian Andreas Cassini, Giovanni Domenico 400–499 Halley, Sir Edmund 1810–1819 Aryabhata Newton, Sir Isaac Adams, John Couch Ångström, Anders Jonas 700–799 1700–1799 Bunsen, Robert Wilhelm al-Khwarizmi, Abu Arago, Dominique-François- Galle, Johann Gottfried Jean Leverrier, Urbain-Jean-Joseph 800–900 Argelander, Friedrich Wilhelm Secchi, Pietro Angelo Battani, al- August Bessel, Friedrich Wilhelm 1820–1829 Bode, Johann Elert Clausius, Rudolf Julius 1200–1299 Cavendish, Henry Emmanuel Alfonso X Euler, Leonhard Hall, Asaph Fraunhofer, Joseph von Huggins, Sir William 1300–1399 Herschel, Caroline Lucretia Kirchhoff, Gustav Robert Beg, Muhammed Taragai Herschel, Sir William Ulugh Herschel, Sir John Frederick 1830–1839 William Clark, Alvan Graham 1400–1499 Kant, Immanuel Draper, Henry Copernicus, Nicolas Lagrange, Comte Joseph-Louis Lockyer, Sir Joseph Norman

293 294 A to Z of Scientists in Space and Astronomy

Newcomb, Simon Hertzsprung, Ejnar Korolev, Sergei Pavlovich Schiaparelli, Giovanni Jeans, Sir James Hopwood Kuiper, Gerard Peter Virginio Russell, Henry Norris Oort, Jan Hendrik Stefan, Josef Schwarzschild, Karl Rossi, Bruno Benedetto Sitter, Willem de Tombaugh, Clyde William 1840–1849 Slipher, Vesto Melvin Boltzmann, Ludwig 1910–1919 Gill, Sir David 1880–1889 Alvarez, Luis Walter Pickering, Edward Charles Eddington, Sir Arthur Braun, Wernher Magnus von Stanley Burbidge, Eleanor Margaret 1850–1859 Goddard, Robert Hutchings Peachey Arrhenius, Svante August Hess, Victor Francis Chandrasekhar, Barnard, Edward Emerson Hohmann, Walter Subrahmanyan Fleming, Williamina Paton Hubble, Edwin Powell Ehricke, Krafft Arnold Stevens Shapley, Harlow Fowler, William Alfred Hertz, Heinrich Rudolf Reber, Grote Kapteyn, Jacobus Cornelius 1890–1899 Ryle, Sir Martin Lowell, Percival Baade, Wilhelm Heinrich Van Allen, James Alfred Michelson, Albert Abraham Walter Planck, Max Karl Compton, Arthur Holly 1920–1929 Tsiolkovsky, Konstantin Jones, Sir Harold Spencer Alpher, Ralph Asher Eduardovich Lemaître, Abbé Georges- Hewish, Antony Êdouard Schmidt, Maarten 1860–1869 Oberth, Hermann Julius Campbell, William Wallace Urey, Harold Clayton 1930–1939 Cannon, Annie Jump Zwicky, Fritz Drake, Frank Donald Charlier, Carl Vilhelm Ludvig Giacconi, Riccardo Douglass, Andrew Ellicott 1900–1909 Penzias, Arno Allen Dyson, Sir Frank Watson Alfvén, Hannes Olof Gösta Sagan, Carl Edward Hale, George Ellery Ambartsumian, Viktor Tereshkova, Valentina Wolf, Maximilian Amazaspovich Wilson, Robert Woodrow Anderson, Carl David 1870–1879 Bethe, Hans Albrecht 1940–1949 Adams, Walter Sydney Bok, Bartholomeus Jan Bell Burnell, Susan Jocelyn Curtis, Heber Doust Dirac, Paul Adrien Maurice Hawking, Sir Stephen William Einstein, Albert Gamow, George Rees, Sir Martin John CHRONOLOGY

295 296 A to Z of Scientists in Space and Astronomy

1750 1800 1850 1900 1950 2000

Johann Elert Bode Marquis Pierre-Simon de Laplace Caroline Lucretia Herschel Heinrich Wilhelm Matthäus Olbers Mary Fairfax Somerville Friedrich Wilhelm Bessel Dominique-François-Jean Arago Joseph von Fraunhofer Samuel Heinrich Schwabe Sir John Frederick William Herschel Friedrich Wilhelm August Argelander Christian Andreas Doppler Urbain-Jean-Joseph Leverrier Robert Wilhelm Bunsen Johann Gottfried Galle Anders Jonas Ångström Pietro Angelo Secchi John Couch Adams Rudolf Julius Emmanuel Clausius Gustav Robert KirchhoffKirchhoff Sir William Huggins Asaph Hall Alvan Graham Clark Simon Newcomb Giovanni Virginio Schiaparelli Josef Stefan Sir Joseph Norman Lockyer Henry Draper Sir David Gill Ludwig Boltzmann Edward Charles Pickering Jacobus Cornelius Kapteyn Albert Abraham Michelson Percival Lowell Heinrich Rudolf Hertz Williamina Paton Stevens Fleming Edward Emerson Barnard KonsKonstantintantin Eduardovich Tsiolkovsky Max Karl Planck Svante August Arrhenius Carl Vilhelm Ludvig Charlier William Wallace Campbell Maximilian Wolf Chronology 297 298 A to Z of Scientists in Space and Astronomy

BIBLIOGRAPHY

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INDEX

Note: Page numbers in boldface indicate main topics. Page numbers in italic refer to illustrations.

A Airy, George Biddell 2–4, American Academy of Arts 156 and Sciences 103, 168, Aachen Technical University Albategnius 38–40 232, 246. See also Rumford 169 Albert Einstein World Award Gold Medal Abbe Medal/Memorial Prize of Science Medal 71 American Academy of 165 Albert Medal 68 Sciences 194 aberration of starlight 58–59, Albertus University 45 American Association for 74, 104, 106, 233 Aldrin, Edwin (Buzz) 64 the Advancement of Academia des Ciencias de Alexander the Great (king of Science (AAAS) 35, 89, Lisboa 96 Macedonia) 25, 27 94, 103, 201. See also Alexander VII (pope) 76 Kepler Medal Académie des Sciences 20, Alfonso X (king of León and American Association of 67, 77, 97, 146, 196–199, Castile) 7–8 University Women 70–71, 212, 259, 266. See also Alfvén, Hannes Olof Gösta 76, 201 Janssen Medal; Lalande 8–10, 9 American Association of Medal; Paris Academy; Alfvén waves 8–9 Variable Star Observers Poncelet Prize Allegheny Observatory, 201, 234 Academy of Mines and Curtis and 94 American Astronautical Forests 98 The Almagest (Ptolemy) Society 252 Accademia delle Scienze di 38–39, 186, 239–241 American Astronomical and Torino 96 Alpha Centauri 41 Astrophysical Society 201 Accademia Nazionale dei Alpher, Ralph Asher 10–12, American Astronomical Lincei (Rome) 97, 125 128 Society 44, 70, 83, 94, 217, Achilles 281–282 Alvarez, Luis Walter 12–15, 243–244, 252, 282 Adams, John Couch 1–5, 2, 13 American Chemical Society 155 Alvarez, Walter 12–14 Willard Gibbs Medal 29 Adams, Walter Sydney 5, Alvarez hypothesis 12–15 American Institute of Physics 5–7 Amalthea 36 244 Adams Prize, Cambridge Ambartsumian, Viktor American Institute of the University 175–176 Amazaspovich 15–16 City of New York 18

305 306 A to Z of Scientists in Space and Astronomy

American Mathematical Arizona, University of Australian National Society 217 99–100, 194 University 55 American Physical Society Arizona State College 270 89, 96, 119, 232 Armenian Academy of American Society of Swedish Sciences 16 B Engineers 18 Armstrong, Neil 64 Amyntas III (king of Arrhenius, Johan 27 Baade, Wilhelm Heinrich Macedonia) 25 Arrhenius, Svante August Walter 31–34, 283–285 Analytical Society 153 27, 27–29 Babbage, Charles 153–154 Anaximander 237–238 Aryabhata 29–30 background radiation 11–12, Anderson, Carl David asteroids 127, 129, 149, 229–232, 16–18 Alvarez and 12–15 280–281. See also blackbody androcell, Ehricke and Baade and 31, 34 radiation 109–110 Bessel and 47 Baikonur Cosmodrome 190 Andromeda Galaxy 32–33, Bode and 53 Barnard, Edward Emerson 266 Galle and 127 34–38, 84 androsphere 109 Gill and 133 Barnard Astronomical Ångström, Anders Jonas Jones and 177 Society 37 18–20, 19 Newcomb and 215 Barnard Medal for Anne (queen of Great Olbers and 224 Meritorious Service to Britain) 145, 220 Piazzi and 53, 232–233 Science 113, 119 Annie J. Cannon Award in Sagan and 252 Barnard’s Star 37 Astronomy 70–71, 76 Schiaparelli and 254 Basel, University of 115 anthropic principle 244 Wolf and 281–282 Battani, al- 38–40 Antigonus Gonatus (king of astrolabe 187 Bayer, Johannes 40–41 Macedonia) 22 Astronomical Society of Beatrice M. Tinsley Prize 44 antimatter 17–18, 96 France 118, 224 Becquerel, A. Henri 28 aperture synthesis 250 Astronomical Society of Beg, Muhammed Taragai aphelion point 39 London 154, 159 Ulugh 41–42 Apollo Project 61 Astronomical Society of Belgian Royal Academy 168 Applied Physics Laboratory Mexico 118 Bell, Alexander Graham 276–277 Astronomical Society of the 213 Arago, Dominique-François- Pacific 94, 102. See also Bellarmine, Robert 125 Jean 2, 20–22, 204 Bruce Gold Medal Bell Burnell, Susan Jocelyn Aratus of Soli 22 astronomical unit (AU) 51, 42–44, 166–168 Archimedes 24, 90 127, 132, 177 Bell Laboratories 230–232 Arecibo Observatory 102 Astronomische Gesellschaft Bergman, Lorraine 18 Argelander, Friedrich 23, 82–83, 103 Berlin, University of 62, 85, Wilhelm August 22–24 astrophotography 34, 133, 112, 126, 160, 188–189, Aristarchus of Samos 24, 180–182, 258, 269, 281 213, 235–236 90–91, 240 astrophysics, term 142 Berlin Academy of Sciences Aristocles. See Plato astropolis 109–110 45, 47, 50, 115, 196 Aristotle 24–27, 123–126, Atkinson, Robert d’Escourt Berliner Astronomisches 239–240 48 Jahrbuch 50, 52–53 Index 307

Berlin Institute of Braid, James W. 35 Ryle and 250 Technology 62 Brashear, J. A. 140–141 Schiaparelli and 254 Berlin Observatory 51, 53, Braun, Wernher Magnus von Schmidt and 255 126, 203–204 61, 61–64, 108, 191, 222, Shapley and 261 Berlin Technical University 223, 278 Sitter and 263 108 Brera Observatory 254 Slipher and 266 Bernoulli, Johann 115 Breslau, University of 188 Wolf and 282 Bessel, Friedrich Wilhelm Breslau Observatory 127 Brucia 282 23, 44–47 Bristol, University of 95 Bruno, Giordano 64–66, 92 Bethe, Hans Albrecht 11, British Association for the Bunsen, Robert Wilhelm 66, 47–50 Advancement of Science 66–68, 187–189 big bang theory 10–12, 49, 3, 155, 176 Bunsen burner 66–67 127–129, 147, 171, British Chemical Society Burbidge, Eleanor Margaret 201–203, 231–232, 255 Faraday Medal 29 Peachey 68–71, 69, 119 binary stars 154, 159, 193 Broughman, Henry 80 Burbidge, Geoffrey 68–70 blackbody radiation 11–12, Bruce, Catherine Wolfe 37, Burke, Grace 171 189, 236, 267. See also 282 Burnell, Martin 43, 168 background radiation Bruce, Eliza 5 Burnham, S. W. 35–37 black holes 147, 149, Bruce Gold Medal, Byurakan Astrophysical 243–244, 257 Astronomical Society of Observatory 15–16 blinking comparator 269 the Pacific 282 Bode, Johann Elert 50–53 Adams and 7 Bode-Flamsteed atlas 53 Ambartsumian and 16 C Bohr, Neils 81, 96, 128, 236 Baade and 34 Bok, Bartholomeus Jan Barnard and 37 Caen, University of 197 53–55, 54, 193 Bethe and 50 calculus, Newton and Bologna, University of 76, 245 Bok and 55 218–220 Bolton, John 34 Burbidge and 71 California, University of Boltzmann, Ludwig 28, Campbell and 74 9–10, 13–14, 70, 72–74, 55–58, 56, 267 Charlier and 83 102, 273, 275 Bond, George Phillips 142 Dyson and 105 California Institute of Bond, William 142 Eddington and 107 Technology (Caltech) Bonn, University of 23, 86, Fowler and 119 17–18, 69, 118–119, 142, 161 Giacconi and 131 255–256, 280, 283–284 Bonnet, Charles 51 Gill and 133–134 California State University Bonn survey 23 Hertzsprung and 163 109 Born, Max 96 Jones and 178 Calvert, Rhoda 35 Bouguer, Pierre 21 Kapteyn and 182 Cambridge Observatory 2, Bowen, Ira Sprague 173, 207 Newcomb and 217 5 Bower Science Medal 244 Oort and 228 Cambridge University Bradley, James 46, 58–59 Pickering and 234 Adams and 1–2, 5 Brahe, Otto 60 Reber and 243 Bell Burnell and 43 Brahe, Tycho 40, 59–61, Rees and 244 Bethe and 47 183 Russell and 249 Cavendish and 78 308 A to Z of Scientists in Space and Astronomy

Cambridge University Fleming and 117 circular cosmology. See (continued) Gill and 133 spherical cosmology Chandrasekhar and 80–81 Halley and 144 City College of New York Dirac and 95–97 Herschel and 151–152, 229 Dyson and 104 156, 158–159 Clark, Alvan Graham Eddington and 106 Kapteyn and 180–181 83–85 Hawking and 147 Messier and 211–212 Clark University 136–138, Herschel and 153 Newcomb and 216 214 Hewish and 166–168 Piazzi and 233 classification systems. See Jeans and 175 Ryle and 249–250 catalogs Jones and 177 Secchi and 258 Clausius, Rudolf Julius Lemaítre and 202 Zwicky and 285 Emmanuel 57, 85, 85–87, Newton and 218–219 Catherine II (empress of 235 Rees and 244 Russia) 116 Clavius, Christopher 39 Russell and 248 Cavendish, Henry 78–80 Clement IX (pope) 77 Ryle and 249 Cavendish Laboratory 68, Cocconi, Giuseppi 101 Campani, Giuseppe 77 80, 88, 128, 167, 249 Colgate University 18 Campbell, Betsey (Bess) 72, Celsius, Anders 19 College of the Pacific 92 74 Centaurus A 34 Collier Trophy in Aviation 15 Campbell, William Wallace Centaur vehicle 107, 109 Colorado, University of 72, 72–74, 73 Cepheid variables 32–33, 129 Cannon, Annie Jump 201, 260 Columbia University 229, 74–76, 75 Ceres 53, 232–233 273 Cape of Good Hope cesium 68, 188 Columbus, Christopher 237 Observatory 132–133, Chadwick, James 285 Coma Cluster 284 154–155, 177, 180–181, 262 Challis, James 2–4 comets Carnegie Institution Chandrasekhar, Barnard and 35–36 100–101, 142, 276 Subrahmanyan (Chandra) Bessel and 46 Carnot, Sadi 86 80–82, 85, 107, 220 Bode and 52 Caroline (queen of Great Chandrasekhar’s limit Galle and 126 Britain) 146 80–82, 149 Halley and 144–146 Carte du Ciel project 104, 133 Charles II (king of England) Herschel (Caroline) and Case School in Applied 144 150, 152, 159 Science 213 Charlier, Carl Vilhelm Kepler and 182 Cassini, Giovanni Domenico Ludvig 82–83 Messier and 211–212 76–78, 144 Chéseaux, Jean-Philippe Loys Olbers and 224 catalogs de 224 Oort and 227–228 Argelander and 22–24 Chiaramonti, Luigi 232 Compton, Arthur Holly 87, Bayer and 40–41 Chicago, University of 13, 87–89 Beg and 42 81, 88, 141, 170–171, Conklin, Evelina 141 Bessel and 46–47 193–194, 214, 251, 273. See contact binaries 193 Bode and 50, 52–53 also Yerkes Observatory Conti, Vittoria 196–197 Campbell and 74 Christina (queen of Sweden) Copenhagen, University of Cannon and 74–76 77 60–61 Index 309

Copenhagen Polytechnic Jeans and 175 Dicke, Robert 231, 281 Institute 162 Kant and 179 Die Frau im Mond 62, 108, Copernicus, Nicolas 8, Kapteyn and 181 223 89–92, 90, 122, 125, Kepler and 182–186 Dione 77 182–184, 253 Lemaître and 201–203 Dirac, Gabriel Andrew 96 Copley Medal, Royal Society Plato and 238–239 Dirac, Paul Adrien Maurice Arago and 21 Ptolemy and 240–241 95–97 Bunsen and 68 Crab Nebula, Messier and Disney, Walt 63 Cavendish and 80 211–212 Doppler, Christian Andreas Clausius and 87 Cracow, University of 89–90 97–99 Dirac and 96 Cresson Gold Medal, Franklin Doppler effect 74, 97–99, Einstein and 113 Institute 18, 243, 247 171, 173, 254, 266 Herschel and 154–155 Crick, Francis 129 Doraiswamy, Lalitha 81 Hubble and 174 Curie, Marie 28 Dornberger, Walter 62 Leverrier and 204 Curie, Pierre 28 Doroschkevich, A. G. 11 Michelson and 214 Curtis, Heber Doust 32–33, Douglass, Andrew Ellicott Newcomb and 217 92, 92–94, 93, 93, 94, 259, 99–101, 209 Planck and 236 261 Drake, Frank Donald Cordoba Survey 24 Curtis, Mary D. Rapier 94 101–102 Cornell University 48, 50, Draper, Ann Palmer 234 101–102, 245, 251–252 Draper, Henry 102–103 Cosimo II (grand duke of D Draper, John William 102 Tuscany) 125 Dreyer, Johan 212 Cosmic Background Explorer Daguerre, Louis 21 Dreyer, L. E. 156 (COBE) 12, 149, 281 d’Alembert, Jean 198 Druyan, Ann 251 cosmic egg 201–202 Dançay, Charles 60 Dudley Observatory 12 cosmic rays 17, 89, 164–165, dark matter 243, 263, Dugan, Raymond 248 244, 246, 276–277 283–285 Dunlop, James 34 cosmology. See also Big Bang dark stars 47 Dutcher, Mary 119 theory; heliocentric d’Arrest, Heinrich Ludwig 4, dwarf galaxies 261 cosmology 126 dwarf stars 6, 163, 248 Alfvén and 9–10 Dartmouth College 6 Dyson, Frank Watson Aratus and 22 Darwin, Charles 153–154 104–105, 106 Aristotle and 26 Davy Medal, Royal Society Aryabhata and 29–30 29, 68 Battani and 38–39 Dawes, William 3 E Bruno and 65 Dearborn Observatory 84, 140 Charlier and 83 Deimos 84, 142–143 eclipsing binaries 248, 260 Clausius and 85–87 Delaunay, Charles-Eugene École Militaire 198 Copernicus and 89–92 204 École Polytechnique 20, 197, Galileo and 122, Delisle, Joseph Nicolas 211 203, 213 124–125 Desaga, Peter 67 Eddington, Arthur Stanley Hawking and 146–150 Descartes, René 193 82, 106–107, 107, 147, Hubble and 170–172 Deybe, Peter 283 202, 262 310 A to Z of Scientists in Space and Astronomy

Eddington Medal, Royal Faraday, Michael 21, Fraunhofer lines 67, Astronomical Society 119, 153–154 120–121, 188 168, 203 Faraday Medal, British Frederick II (king of Edinburgh Medal 44 Chemical Society 29 Denmark) 60 Edlund, Eric 28 Federal Institute of Frederick II (king of Prussia) Edson, Patricia 270 Technology 283 196–197 education, Einstein on Feoktistov, Konstantin Frederick the Great (king of 110–111 191–192 Prussia) 115–116 Ehricke, Ingebord 109 Ferdinand II (Holy Roman Fresnel, Augustine 20–21 Ehricke, Krafft Arnold Emperor) 253 Friedmann, Alexander 202 107–110 Ferdinand (king of Sicily) Friedrich Wilhelm III (king Einstein, Albert 110–114, 53 of Prussia) 45 171, 202, 283 Ferguson, James 151, 157 Friedrich Wilhelm IV (king Einstein, Elsa 113 Fermi, Enrico 89, 245 of Prussia) 23 Elizabeth I (queen of Fizeau, Armand 98 Frost, Edwin B. 6 England) 65 Fizeau, Hippolyte 22 Fuller, Sarah Parker 193 Elizabeth II (queen of Great Flamsteed, John 23, 41, 52, Britain) 178, 244, 250 59, 144–146, 152, 220 Ellerman, Ferdinand 37 Fleming, James 117 G elliptical orbits 144–145, Fleming, Williamina (Mina) 184–185 Paton Stevens 117–118 Gagarin, Yuri 191 Enceladus 159 Flora 127 Galilei, Galileo 4, 26, 92, Encke, Johann Franz 126, 253 Florence, University of 122–126, 123, 184–185, entropy 57, 85–87 245–246 205, 241, 252 Erikson, Kerstin Maria 9 Florida State University 97 Galilei, Vincenzo 122 Euclid 263 Ford, Gerald 119 Galle, Johann Gottfried 4, Eudoxus of Cnidos 22, Fordham University 165 126–127, 204 25–26, 239 Fortin, Jean 52–53 Gamba, Marina 124 Euler, Leonhard 114–116, Foucault, Léon 22 gamma rays 44, 87–89 195–196 Fowler, Ralph H. 80, 95 Gamow, George 10–11, Europa 275 Fowler, William Alfred 127–129, 128 European Southern 118–120 Gassendi, Pierre 61 Observatory 131 France, Collège de 213 Gauss, Carl Friedrich 187, event horizon 257 Franck, James 96 224, 233 Explorer I 64, 276–277, 278 Francqui Award 202 Gauss, Johann 45 extraterrestrial life 27, 29, Frankfurt, University of 47 Gay-Lussac, Joseph 203 101–102, 147, 149–150, Franklin Institute. See Bower Geiger, Hans Wilhelm 108 208–210, 273–275 Science Medal; Cresson Gemini project 191 Gold Medal; Franklin general relativity theory 7, Medal; Kepler Medal 113, 258 F Franklin Medal, Franklin George III (king of Great Institute 89, 214 Britain) 151–152, 158 Fairfield, Priscilla 54 Fraunhofer, Joseph von George of Trebizond 240 Fälthammar, Carl-Gunne 9 120–121 Georgetown University 259 Index 311

George VI (king of Great Rees and 244 Gustavus Adolphus College Britain) 178 Russell and 249 18 George Washington Ryle and 250 Gylden, Johan A. H. 82 University 10, 128 Schiaparelli and 254 Giacconi, Riccardo Schmidt and 255 129–132, 130, 244, 246 Schwabe and 257 H giant stars 6, 81, 248 Shapley and 261 Gill, David 132–134, Sitter and 263 Hale, George Ellery 6, 180–181 Slipher and 266 36–37, 84, 140–142, 171 Gill, Isabel 132–133 Wolf and 282 Hale Observatories 255 Glasgow, University of 42 Zwicky and 285 Hale Solar Laboratory 6–7 Goddard, Robert Hutchings Gold Medal, Royal Society Hall, Asaph 84, 142–143, 134–139, 135, 223 113 216 Gold Medal, Académie des Goodricke, John 32–33 Halle, University of 85 Sciences 266 Göttingen, University of 31, Halley, Edmund 144–146, Gold Medal, American 34, 45, 66, 128, 223–224, 195, 219 Institute of the City of New 257 Halley’s Comet 44, 146, 155, York 18 Göttingen Observatory 163 211–212 Gold Medal, Italian Physical gravitation Hamburg Observatory 31 Society 247 Cavendish and 79 Hangen, Johanna 45 Gold Medal, Royal Chandrasekhar and 81 Harriot, Thomas 44 Astronomical Society Einstein and 112–113 Harun al-Rashid (caliph of (Britain) Galileo and 123 Baghdad) 38 Adams and 7 Laplace and 197–199 Harvard Boyden Station 55 Ambartsumian and 16 Newton and 218–219 Harvard Classification Baade and 34 Sitter and 262 System 233–234 Barnard and 37 Graz, University of 56, Harvard College Observatory Bessel and 47 164–165 Bok and 54–55 Campbell and 74 Gregory, David 51 Cannon and 74 Dyson and 105 Gregory XIII (pope) 39 Douglass and 99 Giacconi and 131 Grieg, Samuel 264 Fleming and 117 Gill and 133 Groningen, University of 54, Hale and 141 Hall and 143 180–181, 226, 254, 262 Hall and 142–143 Herschel and 152, 154 Groningen Astronomical Kuiper and 193 Hertzsprung and 163 Laboratory 262 Leavitt and 200–201 Hubble and 174 Gsell, Abigail 116 Lowell and 209 Huggins and 173 Gsell, Katharina 115–116 Pickering and 233–234 Jeans and 176 Guadalupa Almendaro Medal Shapley and 259, 261 Jones and 178 118 Harvard-Smithsonian Center Kapteyn and 182 Guggenheim, Daniel 139 for Astrophysics 131 Michelson and 214 G. Unger Verlesen Prize 119 Harvard Southern Newcomb and 217 Gunter Löser Medal, Hemisphere Observatory Oort and 228 International Astronautical 99–100, 234 Pickering and 234 Federation 110 Harvard Standard 201 312 A to Z of Scientists in Space and Astronomy

Harvard University 101, Herschel, Caroline Lucretia Humboldt, Alexander von 143, 208, 215, 233, 251 150–153, 153–154, 256 Hawaii, University of 36 156–159 Hume, David 112 Hawking, Stephen William Herschel, John Frederick Hummel, Mathilde 223 95, 146–150 William 3–4, 47, 152, Huxley, Aldous 220 Hebrew University 114 153–156 Huygens, Christiaan 219 Heidelberg, University of 67, Herschel, Mary Pitt Huygens Medal, Holland 188, 213, 223, 281 153–154, 159 Academy of Sciences 87 Heisenberg, Werner 95 Herschel, William 1, 52, Hyades 163 Helen B. Warner Prize for 150–153, 156–160 hydrogen 20, 78–80 Astronomy 70 Herschel Medal, Royal heliocentric cosmology 24, Astronomical Society 44, 89–92, 122, 124–125, 232, 281 I 182–186 Hertz, Heinrich Rudolf 160, helium 206–207 160–161 Iapetus 77 Helmholtz, Herman von 160 Hertzsprung, Ejnar Icarus 34 Helsinki Observatory 23 161–164, 162, 193, 263 Icarus project 252 Henri III (king of France) 65 Hertzsprung-Russell (HR) Imperial Academy of Henry, Joseph 215 diagram 161–164, 247–249 Sciences, Vienna 98 Henry Draper Catalog 76, Hesperia 254 Imperial College 244 103, 117, 234 Hess, Victor Francis 164, Imperial Russian Academy Henry Draper Medal, 164–165 259 National Academy of Hevelius, Johannes 52 Index Liber Prohibitorum Sciences Hewish, Antony 43, 65–66, 92 Adams and 7 165–168, 166, 249 Indiana, University of 265 Campbell and 74 Hidalgo 31 Indian Academy of Science Cannon and 76 Hipparchus 22, 239–240 96 Hubble and 174 Hock, Suzanne 176 Indiana University 129 Michelson and 214 Hohmann, Walter 168–170 Indian National Science Penzias and 232 Holden, Edward 35–36 Academy 168 Pickering and 234 Holland Academy of inertia 218 Russell and 249 Sciences 87 Innsbruck, University of 165 Ryle and 250 Hooke, Robert 219 Institut de France 96 Shapley and 261 Hösling, Marga von 235, 237 Institute of Astronomy Slipher and 266 Houtermans, Fritz 48 (Cambridge University) Wilson and 281 Hoyle, Fred 11, 49, 68, 119 244 Henry Draper Memorial Fund Hubble, Edwin Powell 5, Institute of Theoretical 75, 103 92–94, 170, 170–172, 266 Physics 273 Herman, Robert 11–12 Huggins, William 172–174, International Astronautical Hermes Project 63 207 Federation, Gunter Löser Herpyllis 25 Hughes Medal, Royal Society Medal 110 Herschel, Alexander 151, 89, 168 International Astronomical 156–157 Hulst, Hendrik van de 227 Union 16, 54, 177, 263 Index 313

International Council of Joliot-Curie Gold Medal 268 Kepler’s Star 183, 285 Scientific Unions 16 Jones, Bryn 52 Keyser, Pietr Dirksz 40 Io 36 Jones, Harold Spencer 133, Khrushchev, Nikita Ionian philosophers 237–238 177–178 189–192, 268 Iowa, University of 276–279 Jörgensdatter, Kirsten 60 Khwarizmi, Abu al- iridium anomaly 14 Juenemann, Luise 169 186–187 Iris 133 Juno I 64 Kiel, University of 160, 235 island universes, Kant and Jupiter 77, 82, 122, 124, 185, Kiev Polytechnic Institute 179–180 262 189 Italian Physical Society 247 Justinian (emperor of Rome) Kirchoff, Gustav Robert 239 66–67, 187, 187–189, 235 Kisk, Esther Christine 136, J 138–139 K Koehler, Johann Gottfried Jackiw, R. W. 50 52 Jackson-Gwilt Medal, Royal Kaiser Wilhelm Institute 237 Kohlschütter, Arnold 6 Astronomical Society 243 Kalinga Prize 129 Komarov, Vladimir 191 James II (king of Great Kansas, University of 270 Königsberg, University of 23, Britain) 219–220 Kant, Immanuel 179–180 179–180, 187 Jansky, Karl 242 Kapitsa, Pyotr 232, 281 Königsberg Observatory 23, Jansky Prize 243, 255 Kapteyn, Jacobus Cornelius 45–47 Janssen, Pierre-Jules-César 133, 180–182, 226, Königsstuhl Observatory 21, 206–208 262–263 281–282 Janssen, Zacharias 206 Karlshoven, Catharina 181 Korolev, Sergei Pavlovich Janssen Medal, Académie des Karlsruhe Polytechnic 160 189–192 Sciences 16, 174, 194 Kassel, University of 67 KT boundary 14 Jeans, James Hopwood 5, Keeler, James 35 Kuffner Observatory 257 175–176, 236 Kellogg Radiation Laboratory Kuiper, Gerard Peter 84–85, jet-assisted takeoff (JATO) 118 192, 192–194, 237 139, 190 Kelvin, William Thompson Jet Propulsion Laboratory 86 (JPL) 64, 102, 252 Kennedy, John F. 18, 64, L Jewitt, David C. 36 191–192 Johansson, Maria 28 Kenwood Physical Lacaille, Nicolas-Louis de 52 John Ericsson Medal, Observatory 141 Lacroix, Sylvestre 153 American Society of Kepler, Johannes 40, 61, 92, Lagrange, Joseph-Louis Swedish Engineers 18 124–125, 182, 182–186, 195–197, 196, 198–199, John F. Kennedy Astronautics 219 220 Award 252 Kepler, Katharina 184 Laistre, Genevieve de 77 John Paul II (pope) 126 Kepler Medal, American Lalande, Joseph-Jérôme Le Johns Hopkins University Association for the Français de 4, 232 216, 273, 276–277 Advancement of Science Lalande Medal 74, 84, 154, Johnson, Lyndon B. 15 194 174, 266 314 A to Z of Scientists in Space and Astronomy

Lambert, Johann 50 Lindblad, Bertil 227 Halley 146 Lamont, Johann von 4 Lippershey, Hans 205–206 Herschel (Caroline) 153 Landis, Janet L. 13 liquid propellant rockets Herschel (John) 156 Lang, Fritz 62, 108, 223 107, 109, 135, 138–139 Herschel (William) 160 Laplace, Pierre-Simon, Lo, Fred 243 Hubble 172 marquis de 196, 197–200, Lockyer, Joseph Norman Korolev 191 198, 264 206–208 Leavitt 201 Lassell, William 3 Lombroso, Nora 245 Plato 239 Lauritsen, Charles C. 118 London, University of 68 Lund, University of 83 Lavoisier, Antoine-Laurent longitude 77, 145–146, 187 Lunik 3 191 de 79, 155, 199 Los Alamos National Luther, Martin 91 Leavitt, Henrietta Swan 32, Laboratory. See Manhattan 75, 200, 200–201 Project Legion d’Honneur 119, 197, Louis XIV (king of France) M 199, 204, 212 77, 204 Leibniz, Gottfried Wilhelm Louis XV (king of France) MacDonald Observatory 70 146, 220 212 Mach, Ernest 57, 112 Leiden, University of 54, Louis XVI (king of France) Maestlin, Michael 183 193, 227, 254–255, 262 197, 199 Magellanic Premium Award, Leiden Observatory 163, Louis XVIII (king of France) American Philosophical 180, 227, 263 199 Society 12, 44 Leipzig, University of 56–57, Louvain, University of main sequence stars 163 60, 162 201–202 Malmquist, Karl 83 Leissner, Siri Dorotea 83 Lovell, Bernard 42 Malvasia, Cornelio 76 Lemaître, Georges-Édouard Lowell, Percival 84, 99, Ma’mun, al- (caliph of 201–203 208–210, 253–254, 269 Baghdad) 38, 186 Le Monnier, Renée 197 Lowell Observatory 84, 99, Manchester, University of Leningrad, University of 208–210, 265, 269–270 48, 106 15–16, 127–128 Lunar and Planetary Manhattan Project 13, 49, Leonids 5 Observatory 194 89, 245, 273 Leverrier, Urbain-Jean- lunar crater names Maragheh Observatory 41 Joseph 2–4, 126–127, 203, Arago 22 Marconi, Guglielmo 161 203–204 Aristotle 27, 239 Maric, Mileva 111, 114 Ley, Willy 63, 108, 223 Aryabhata 30 Mariner 4 209 Libby, Willard 100 Baade 34 Marischal College 155 Lick Observatory 35, 72–74, Beg 42 Marius, Simon 32 73, 74, 84, 92–93, 93, 141, Bessel 47 Mars 193, 216 Bode 53 Barnard and 36 Lieben Prize, Hess and 165 Cannon 76 Braun and 64 light velocity 212–214, 217, Cavendish 80 Campbell and 74 262 Eddington 107 Cassini and 77 light waves 21–22 Einstein 114 Douglass and 99 Lilienthal Observatory 45 Eudoxus 239 Hall and 142–143 Lindbergh, Charles 139 Fleming 118 Kepler and 183–184 Index 315

Korolev and 192 Milikan, Robert 17, 165, Morrison, Philip 101 Kuiper and 193 170, 283 motion 26, 123, 182–186, Lowell and 208–210 Milky Way Galaxy 31–32, 218–220 Schiaparelli and 253–254 53–55, 92–94, 159, 171, Mount Palomar Observatory Marsburg, University of 67 180–181, 226–227, 171, 255, 285 Martian crater names 259–261 Mount Stromlo Observatory Arago 22 Miller, Adeline L. 6 34, 55 Halley 146 Miller, Stanley 273–275 Mount Wilson Observatory Herschel 156 Miller, W. Allen 172–173 5, 5, 6–7, 31–32, 34, 68–69, Maskelyne, Nevil 46, 158, Milne, Edward A. 80 142, 171, 176, 214, 248, 233 Mimas 159 260–261 Massachusetts Institute of Minkowski, Rudolf Leo Mueller, Barbara 183–184 Technology 13, 49, 141, Bernhard 31, 34, 111–112 Mullard Radio Astronomy 202, 209, 233, 245–246 Minnesota, University of 88 Laboratory 43–44, 167, Mauna Kea Observatory 194 Miranda 159, 192–194 250 Maury, Antonia 234 Missouri, University of 260 Munich, University of 47, Max (rocket) 62 Mitchell, Charlotte Tiffany 56, 160, 223, 235, 257 Maxwell, James Clerk 57, 175–176 Munich Technical University 79, 111, 132, 160–161, 188 Mitterrand, François 119 168 Maxwell-Boltzmann Mocenigo, Zuane 65 Münster, University of 31 distribution 57 momentum 218 Murray, Margaret Lindsay Mayer, Tobias 52 Montana, University of 273 172, 174 Mazursky Award 252 Moon. See also lunar crater McCloskey, Betty 88 names McDonald Observatory 193 Adams and 4–5 N Melanchthon 91 Aryabhata and 30 Memorial Medal, Royal Bradley and 59 Napa College 92 Physiographic Society 83 Braun and 64 Napier, John 185 Mendeleev, Dmitri 67, 271 Cassini and 77 Napoleon Bonaparte 45, Merck, Marie 235 Draper and 102–103 197–199, 212 Mercury 194 Ehricke and 109–110 National Academy of Arts Messier, Charles 32, 158, Euler and 115–116 and Sciences 96 211–212 Galileo and 124 National Academy of Metius, Jacob 206 Gill and 132 Sciences (U.S.). See also Miami, University of 97 Halley and 146 Henry Draper Medal; Michell, John 149 Kant and 180 Public Welfare Medal; Michelson, Albert Abraham Kepler and 185 Watson Gold Medal 141, 212–214, 213 Korolev and 191–192 Adams and 7 Michelson Medal 44, 168 Kuiper and 194 Anderson and 18 Michelson-Morley Lagrange and 196 Burbidge and 70 experiment 213–214 Oberth and 221 Campbell and 74 Michigan, University of 72, Moore, Patrick 271 Curtis and 93 92, 94, 142 Moritz (rocket) 62 Dirac and 96 Milan, University of 129 Morley, William 213–214 Draper and 103 316 A to Z of Scientists in Space and Astronomy

National Academy of Neher, Victor 17 Novorossysky University 127 Sciences (U.S.) (continued) Nell 139 nuclear weapons 96, 114. Fowler and 119 Neptune 1–5, 21, 53, See also Manhattan Gamow and 129 126–127, 155, 203–204 Project Hawking and 150 Nereid 192–194 nutation 58–59 Penzias and 232 neutron star hypothesis 285 Rees and 244 Newcomb, Simon 84, Rossi and 246 215–217, 216 O Shapley and 261 New Mexico State University Wilson and 281 270 Oberlin College 200 National Aeronautics and Newton, Isaac 83, 111, Oberon 159 Space Administration 144–146, 179, 182, 186, Oberth, Hermann Julius 62, (NASA) 197–199, 217, 217–220, 108, 169, 221–224, 222 Alpher and 10 241 occultation 144 Braun and 61, 64 New York University 103 Ohio State University 118, Chandrasekhar and 82 Niepce, Nicéphor 21 243 Compton and 87–88 Nobel Institute 9, 28–29 Ohm, Georg Simon 187 and Einstein 131 Nobel Prize laureates Olbers, Heinrich Wilhelm Giacconi and 130–131 Alfvén 8–9 Matthäus 44–47, and Goddard 139 Alvarez 12, 14–15 224–226 Kuiper and 193–194 Anderson 18 Olbert, Stanislaw 246 Rossi and 244 Arrhenius 27–28 Olmsted, Ardiane Foy 119 and Sagan 251–252 Bethe 49 Oort, Jan Hendrik 226, and Van Allen 277–278 Chandrasekhar 81 226–228, 254, 263 National Institute of Sciences Compton 88–89 Open University 44 of India 96 Dirac 96 Öpik, Ernst 228 National Medal of Science Einstein 113 Oppenheimer, Robert 49, 96, (U.S.) 15, 71, 82, 119, Fowler 119 149 247 Giacconi 129 Oppenheimer Prize 44 National Radio Astronomy Hess 165 optics 20–21, 185, 212–214, Observatory (NRAO) 101, Hewish 166, 168 219–220, 241, 253 131, 242–243 Michelson 212, 214 Order of Lenin 268 Naval Observatory, U.S. 84, Penzias 229, 232 Order of Merit (British 142–143, 215–216 Planck 236 honor) 97, 176 Naval Research Laboratory Raman 80–81 Oriani, Barnabas 52 130 Ryle 249–250 Orion Nebula 102–103 Naysmyth, Alexander 263 Urey 273, 275 Oslander, Andreas 91 nebula hypothesis 176, Wilson 281 Ostwald, Wilhelm 162 179–180, 197 Norman Lockyer Observatory Owens, Gladys Mary 177 nebulas 37, 50, 52, 173, 208 Owens College 106 211–212 Northern Arizona University Owens Valley Radio nebulium 173, 207 270 Observatory 280 Neddermey, Seth 18 novas 33, 174 Oxford University 58, 76, Néel, Louis 9 Novikov, Igor 11 145–147, 170, 249 Index 317

P pi 30, 50 Princeton University 44, 88, Piazzi, Giuseppe 53, 96, 114, 175, 231, 247, 249, Padua, University of 90, 124, 232–233 258 245 Picard, Jean 78 Prix Francqui 202 Palermo Academy 47 Piccard, Auguste 283 Procyon 47 Palermo Observatory 233 Pickering, Edward Charles Project Ozma 101 Palitzch, Georg 212 74–76, 117, 141, 200–201, prominence 206 Pallas 224 209, 233–234, 234 Prony, Gaspard de 21 Palmer, Anna Mary 103 Pickering, William Henry Proxenus of Atarneus 25 Palmer, Rowena 249 234, 278 Prussian Academy of panspermia hypothesis Pigott, Edward 52 Sciences 115 27–29 Pike’s Peak experiment 18 Ptolemy, Claudius 8, 22, Panzano Observatory 76 pi mesons 49 38–39, 90–91, 125, parallax 5–7, 46–47, 58, 77, Pisa, University of 122–124 186–187, 239–241 132–134 Pius VII (pope) 232 Public Welfare Medal, Paris, University of 204 Planck, Max Karl 193, 235, National Academy of Paris Academy (Académie 235–237 Sciences 252 royale des sciences de Paris) planetary motion 182–186, Pulitzer Prize 251 115 197 Pulkovo Astronomical Paris Observatory 2, 77–78, Planetary Society 252 Observatory 15–16, 23, 82, 204 Plato 25, 183, 237–239 84, 254 Parsbjerg, Manderup 60 Playfair, John 264 pulsars 42–44, 165–168 Pauli, Wolfgang 81 Pleiades 82, 163 Pythagoras 183, 238 Paul V (pope) 125 Plutarch 24 Pythias 25 Payne-Gaposchkin, Cecilia Pluto 53, 84, 208–210, 266, Helena 248 268–271 Peacock, George 153 Poncelet Prize, Académie des Q Pearman, J. Peter 101 Sciences 87 Pellepoix, Antoine Darquier Pontifical Academy of quadrant 42 de 52 Sciences 96, 202, 244 quantum theory 95–97, 111, Penrose, Roger 49, 147, 149 Potsdam Astrophysical 113, 149, 236–237 Penzias, Arno Allen Observatory 163, 258 quasars 43, 70, 243–244, 229–232, 230, 280–281 Pound, James 58 254–255 Perseids 254 Prague, University of 98 quasi-stellar object (QSO) Phobos 84, 142–143 precession 39 255 photography 21, 35–37, 75, Presidential Certificate of Quistorp, Maria von 63 102–103, 132, 154–155, 173 Merit 18 photometry 21–22, 82 Presidential Medal of Merit Physical Engineering 119 R Institute 97 President’s Science Advisory Physical Institute, Swedish Committee 49 Radcliffe College 75, 200 Academy of Sciences 28 Prime Mover 26 radio astronomy 43, Physical Society 107 primitive atom 202 101–102, 165–168, Physics Museum, Munich 121 Princeton Observatory 248 242–243, 280–281 318 A to Z of Scientists in Space and Astronomy

Radiological Society of North Royal Academy of Sciences Royal Society (of London). America 89 of Uppsala 20 See also Copley Medal; radio waves 160–161 Royal Astronomical Society Davy Medal; Hughes Raman, Chandrasekhara (Britain). See also Medal; Royal Medal; Venkata 80–81 Eddington Medal; Gold Rumford Medal Ramsay, William 79, 206 Medal; Herschel Medal; Adams and 5 Ranger Project 193–194 Jackson-Gwilt Medal Ångström and 20 Rayleigh, John William Adams (John Crouch) Bessel and 46 Strutt 236 and 5 Bunsen and 67 Rayleigh-Jeans formula 236 Adams (Walter Sydney) Cavendish and 79–80 Reagan, Ronald 71 and 7 Chandrasekhar and 80, 82 Reber, Grote 242–243 Bell Burnell and 44 Clausius and 87 Rees, Eberhard 222 Bessel and 47 Dirac and 96 Rees, Martin John 243, Chandrasekhar and 81 Dyson and 104 243–244 Curtis and 94 Eddington and 107 Regiomontanus, Johannes Eddington and 107 Halley and 144–146 240 Fleming and 118 Hawking and 150 Reinhold, Erasmus 8 Fowler and 119 Herschel (Caroline) and Reinmuth, Karl Wilhelm 53 152 Gill and 133 relativity theory 106, Herschel (John) and Hale and 141 110–114, 147–149, 153–154 Jeans and 176 257–258, 262 Herschel (William) and Rees and 244 Reuttinger, Susanna 184 151, 158 Secchi and 259 Rhea 77 Hubble and 174 Somerville and 264 Rheticus 91 Jeans and 175 Rice University 280 Wolf and 282 Jones and 178 Rimpam, Adelheid 86 Royal College of Science Kirchoff and 189 rockets 61–64, 107–110, 207 Lagrange and 197 134–139, 189–192, Royal Danish Academy 97, Leverrier and 204 223–224, 271–272, 277 129 Lockyer and 207–208 Roemer, Olaus 59 Royal Greenwich Messier and 212 Roentgen, Wilhelm 161 Observatory 70, 104–106, Michelson and 214 Romanges, Marie-Charlotte 144, 146, 160, 177–178 Newcomb and 217 de Courty de 199 Royal Institute of Newton and 219–220 Roope, P. M. 138 Technology, Stockholm Rees and 244 Rosenberg, Peter Vok 61 9–10 Ryle and 250 Rosenfeld, Léon 81 Royal Irish Academy 96, Secchi and 259 Rossi, Bruno Benedetto 152, 264 Somerville and 264 244–247, 245 Royal Medal, Royal Society Royal Swedish Academy 20 Rossi Prize 244 82, 96, 107, 154–155, 174, rubidium 68, 188 Rostock, University of 60 178, 250 Rudeck, Sofia 28 Royal Academy of Science of Royal Society of Edinburgh Rudolf II (Holy Roman Turin 195 96 Emperor) 61, 183–185 Index 319

Rumford Gold Medal, Schroter, Johann 45 Somerville, Mary Fairfax American Academy of Schultz, Herman 82 263–265 Arts 89, 234, 247, 249, Schwabe, Samuel Heinrich Somerville, William 264 255, 261 256–257 Sommerfeld, Arnold 47, 110, Rumford Medal, Royal Schwarzschild, Karl 6, 163, 113–114 Society 20, 174, 208 257, 257–258 Sophist philosophers Russell, Henry Norris Schwarzschild, Martin 258 237–238 162–163, 247, 247–249, science fiction 62, 134, 185, Southampton, University 260 221 43–44 Rutherford, Ernest 88, 128 Search for Extra-Terrestrial Soviet Academy of Sciences Ryle, Martin 165, 166, 167, Intelligence (SETI) 16, 96, 272 249–250 101–102 Soviet Cosmonauts Secchi, Pietro Angelo Federation, Sagan and 252 258–259 Space Telescope Science S Shapley, Harlow 32–33, Institute 131 54–55, 92–94, 162, 248, space travel 61–64, 134, 136, Sachs, Henry 138 259, 259–261, 260, 261 168–170, 189, 221–224, Sagan, Carl Edward 102, Shepard, Alan B., Jr. 191 272 251–252 Sheppard, Scott S. 36 special theory of relativity Sagan, Linda 102 Siding Spring Observatory 112–113 St. Helena Observatory 144 55 spectrography 103 St. Petersburg, University of. Simba International spectroheliograph 141 See Leningrad, University Women’s Movement Award spectroscopy of 268 Adams and 5–7 St. Petersburg Academy of Sirius 47, 173–174 Ångström and 19 Sciences 115 Sirius B 5–7, 84 Bunsen and 66–68 Sandage, Alan 255 Sitter, Willem de 262–263 Campbell and 72, 74 Sappho 133 Sitterly, Charlotte Emma Cannon and 75 satellites 185, 192 Moore 248 Fraunhofer and 120–121 Saturn 77–78, 126, 143, 159 Slee, Bruce 34 Hale and 141 Saturn project 64 Slipher, Vesto Melvin Herschel and 154 Sawin, Elizabeth Rhoads 280 209–210, 265, 265–266, Huggins and 172–174 Schaeberle, John 47 269 Kirchoff and 187–189 Scheiner, Christoph Smithsonian Institution 137, Kuiper and 193 252–253 139 Lockyer and 206–208 Schiaparelli, Giovanni Smithwick, Geraldine 13 Secchi and 258–259 Virginio 208–209, Sobel, Dava 102 Slipher and 266 253–254 Société de Physique et spherical cosmology 26, 30, Schiff, Leonard I. 118 d’Histoire Naturelle de 183, 238–239, 241 Schmidt, Bernhard V. 31 Genève 264 spiral galaxies 50, 53 Schmidt, Maarten 254–256, Society for Collegiate spiral nebulas 93, 265–266 280 Instruction of Women 200 Sputnik project 63–64, Schönfeld, Eduard 23 Socrates 237–238 190–191, 272, 277 Schrödinger, Erwin 96 Sokolovaya, Varvara 271 Stack, Sophie 86 320 A to Z of Scientists in Space and Astronomy

Stalin, Joseph 190 Scheiner and 252 Thales 237 Stanley, G. 34 Schwabe and 256 thermodynamics, laws of Stefan, Josef 267 superclusters 261 85–86, 147 Stefan-Boltzmann Law supergiant stars 248 Thetys 77 55–57, 267 supernovas 33, 60, 124, 183, Thomas, Robert Baily 151 stellar association 15–16 283, 285 Thomas Aquinas 26 stellar composition 106–107 Surveyor Project 193–194 Throop Polytechnic Institute. stellar energy 47–50, 56–57 Sussex University 244 See California Institute of stellar evolution 161 Swedish Academy of Technology stellar motion 72, 146 Sciences 28–29, 201. See Tikhov, Gavriil Adrianovich stellar nucleosynthesis 119 also Nobel Prize laureates; 84 stellar streaming 181 Physical Institute time travel 147, 149 Steward, Margaret Brodie 154 Swift, Jonathan 143 Titan 192–193 Steward Observatory 54, 55, Titania 159 99–100 Titius, Johann 51 Stewart, John 248 T Titov, Gherman 268 Stockholm, University of 281 Toftoy, H. N. 222 Stockholm Academy 47 Talbot, William Henry Fox Tombaugh, Clyde William Stockholm Observatory 82 155 84, 208, 210, 266, 268–271 Stockholm Technical Tamm, Igor 96 Tooke, Mary 144 University 28 Tebbutt’s comet 103 Townes, Charles 229–230 Stoic philosophers 22 telescopes Trojan asteroid group Stonehenge 207–208 Baade and 34 281–282 Strasbourg, University of 257 Barnard and 35–36 Truman, Harry S. 119 Strato of Lampsacus 24 Clark and 83–85 Tsiolkovsky, Konstantin Stromberg, Gustav 83 Strutt, John William 236 Galileo and 124–125 Eduardovich 189, 223, Struve, Otto 81, 101, Hale and 140 271–272 253–254 Herschels and 151, 157, Tübingen University 48, 183 Struve, Friedrich Georg 159–160 Tupolev, Andrey 189 Wilhelm von 15, 23 Hewish and 167 Turin, College of 195 Stuhlinger, Ernst 222 Huggins and 172 Turin, University of 253 Stuttgart, University of 47 Kepler and 185 Turku Observatory 23 Sufi, Abd-al-Rahman al- 32 Kuiper and 193 Turner, Herbert Hall Sun Lippershey and 205–206 117–118 Ångström and 19–20 Newton and 219 Tusi, Nasir al-Din 41, 240 Herschel and 155, 159 Ryle and 250 Tycho’s Star 33, 285 Lockyer and 206 Schwabe and 256 Secchi and 259 Tombaugh and 269 sunspots Teller, Edward 49, 128 U Alfvén and 8 Temple University 18 Ambartsumian and 15 Tereshkova, Valentina 268 Uhuru satellite 131 Douglass and 99–100 test particles 202 Umbriel 159 Galileo and 125 Thackeray, William G. 104 Union College 12 Index 321

United Nations Gold Medal Vienna, Physical Institute of Willard Gibbs Medal, of Peace 268 267 American Chemical universe expansion, Hubble Vienna, Technical University Society 29 and 172–174 of 224 William Herschel Museum universe size, Curtis and Vienna, University of 56–57, 152–153, 159 92–94 98, 267 William III (king of Great University College, London Vienna Polytechnic Institute Britain) 145, 220 44, 79 97–98 William the Silent (prince of University Observatory 162 Viennese Academy of Orange) 205 Uppsala, University of 8, Sciences 164–165, 267 Wilson, Charles 88 19–20, 27–28, 82 Virginia, University of 93 Wilson, Robert Woodrow Uppsala Observatory 19, 82 Vitruvius 24 229–232, 230, 280–281 Urania Observatory 162 Vogel, Hermann 234 Wisconsin, University of 103 Uranus 1–3, 151, 158–159, Voskhod project 191–192 Wittenberg, University of 60 204 Vostok project 191, 268 Wolf, Johann Rudolf 257 Urban VIII (pope) 125 Vulcan 204, 256 Wolf, Maximilian 281–282 Urey, Harold Clayton Wolff, Christian 51 273–275, 274 Wollaston, William H. 120 Urey-Miller experiment W Woltosz, Walt 147 273–275 women in astronomy and Utrecht, University of 180 Wallace, William 264 space science Wallenstein, Albrecht von Burbidge 68–71 183–184 Cannon 74–76 V Ward, Effie 138 Fleming 117–118 Warner, H. H. 35 Herschel 150–153 Valz Prize 174 Washington University Leavitt 200–201 Van Allen, Abigail 276 88–89 Somerville 263–265 Van Allen, James Alfred Watson, James 129 Tereshkova 268 276–279, 278 Watson, William 158 Wooley, Richard van der Riet Vanderbilt University 37 Watson Gold Medal, 105 Vanguard project 64, 277 National Academy of Wooster College 87 Venus 7 Sciences 83, 134, 182, 263 Worcester Polytechnic Verein für Raumschiffahrt Wellesley College 75, 118 Institute 136 (VFR) 62, 108, 169–170, Wells, H. G. 62, 134 worm holes 147, 149 223–224 Westminster Abbey 5, 156 Würzberg, University of Verne, Jules 62, 134, 221 Wexler, Marcus 252 86–87 Vesta 224 Wheeler, John 149 Victoria (asteroid) 133 white dwarves 7, 47, 80, 84, Victoria Gold Medal, Royal 118, 248 X Geographical Society 265 Wickham, Lillian 6 Victoria (queen of Great Wigner, Eugene 96 X-ray astronomy 129–132, Britain, empress of India) Wigner, Margit 96 244, 246 5, 172, 174, 208 Wilde, Jane 147, 150 X-rays 87–89, 161 322 A to Z of Scientists in Space and Astronomy

Y ylem 10, 128 Zurich, University of Young, Thomas 20 111–112 Yale University 226 Zurich Polytechnic Institute year length 30, 38–39, 42, 241 111 Yegorov, Boris 191 Z Zwicky, Fritz 31–32, 49, Yerevan State University 16 283–285, 284 Yerkes, Charles Tyson 141 Zarqali, Abu Ishaq Ibrahim Yerkes Observatory 6, 36–37, Ibm Yahya al- 8 68, 70, 81, 84–85, 141–142, Zhang Sui 146 170, 193 Zöllner, Karl Friedrich 21–22