Founders of Modern Astronomy 1 Founders of Modern Astronomy From Hipparchus to Hawking Subodh Mahanti Vigyan Prasar 2 Contents Foreword Acknowledgements Preface Introduction 1. Hipparchus of Rhodes (ca 190-ca 120 B.C): The Greatest Astronomer of the Antiquity 2. Claudius Ptolemy (ca A.D. 90-168): “The Last of the Great Classical Astronomers” 3. Aryabhata (ca A.D. 476): The Greatest Astronomer of Ancient India 3. Nicolaus Copernicus (1473-1543): Founder of Heliocentric Model of the Solar System 4. Tycho Brahe (1546-1601): The Greatest Observational Astronomer of Pre -telescopic Era 5. Giordano Bruno (1548-1600): The Defiant Scientist 6. Galileo Galilei (1564-1642): Father of Modern Astronomy 7. Johannes Kepler (1571-1630): Founder of Celestial Mechanics 8. Christiaan Huygens (1629-1895): Founder of the Wave Theory of Light 9. Isaac Newton (1642-1727): Founder of Gravitational Theory 10. Edmond Halley (1656-1742): Founder of Modern Cometary Science 11. Frederick William Herschel (1738-1822): Founder of Stellar Astronomy 12. Samanta Chandra Sekhar (1835-1904): India’s Last Noted Siddhantic Astronomer 14. Albert Einstein (1879-1955): Founder of Theory of Relativity 15. Arthur Stanley Eddington (1882-1944): Who Pioneered the Study of Internal Structure of Stars 16. Edwin Powell Hubble (1889-1953); Founder of the Science of Cosmology 17. Meghnad Saha (1894-1956): Pioneer of Astrophysics 18. George Gamow (1904-1968): Scientist and Science Populariser 19. Hans Albrecht Bethe (1906-): Founder of Theory of Energy Production in Stars 20. Subrahmanyan Chandrasekhar (1910-1995: one of the Gretest Astrophysicist of the 20 th Century) 21. Fred Hoyle (1915-): The Most Versatile Astrophysicist of the 20 th Century 22. Martin Ryle (1918-1984): A Pioneer of Radio Astronomy 23.Antony Hewish (1924- ): Discoverer of Pulsars 24. Vainu Bappu (1927- ): The Doyen of Modern Indian Astronomy 25. Arno Allan Penzias (1933-) and Robert Woodrow Wilson (1936 - ): Discoverers of the Cosmic Background Radiation 26. Stephen William Hawking (1942-): Who Predicted that Black Holes Emit Radiation Time-line of Astronomy Glossary Useful Astronomical Facts References Index 3 4 “The history of astronomy is the growth of man’s concept of his world. He always instinctively felt that the heavens above were the so urce and essence of his life in a deeper sense than the earth beneath. Light and warmth come from heaven.” A. Pannekoek in “A History of Astronomy”, 1961 “Astronomy tells us that the universe is v ast and powerful, but it also tells us that we are astonishing creatures. We humans are the parts of the universe that think. The human brain is the most complex piece of matter known, so as you explore the universe, remember that it is your human brain th at is capable of understanding the depth and beauty of the cosmos. To appreciate your role in the beautiful universe, you must learn more than just the facts of astronomy. You must understand what we are and how we know.” Michael A. Seeds in “Foundations of Astronomy”, 2003 5 Preface The roots of any of the main branches of science say astronomy, chemistry, geology, mathematics, medicine, physics and zoology can be traced to the antiquity. Undoubtedly astronomy is the oldest discipline of science. It has taken hundreds of years to shape a scientific discipline. The shaping of a scientific discipline is not the work of one or a few scientists. Thousands of scientists worked tirele ssly for hundreds of years before a particular discipline of science emerged. The early scientists contributed to these fields when the very methodology of modern science called `method of science’ was yet to be even formulated. There was a time when there were no distinct scientific disciplines and a truly learned person knew all the sciences whatever there were to be known. For example, the great Greek philosopher Aristotle, who is generally credited with the demarcation of different scientific disciplines, worked in physics, chemistry, astronomy, biology, geology and so on. Gradually distinct disciplines of science emerged and the scope and content of each discipline expanded enormously. It is also true that in every branch of science the achievements of some scientists stand apart. There are founders, those whose works led to the foundation of a particular discipline. There are scientists whose works brought new insights into a particular field and opened new vistas. Sometimes an individual’s work brought about what Thomas Kuhn called paradigm shift. We find such examples in astronomy as well. The progress of science has been uneven in the sense that there are periods when it has progressed at a very high pace and there are periods when there was hardly any progress or it progressed slowly. This is true for every discipline of science. The different branches of science are not mutually exclusive. The research findings in one discipline may benefit another discipline. In fact the revolution in astronomy ushered in by Nicolaus Copernicus gave a stimulus to all branches of science and thus emerged the modern science. There are scientists who have made significant contributions to more than one field. Isaac Newton’s contributions to physics are unrivalled but then he also made very significant contributions to mathematics and astronomy. There will be many such examples. As stated above astronomy is one of the oldest sciences. Its origins go back to prehistoric times. It originated much earlier than the ot her branches of science. It had become a highly developed science of its own when systematic study of other branches like physics and chemistry had not yet began. 6 The year 2009 has been declared as the International Year of Astronomy. Vigyan Prasar has planned a number of activities around the year to utilize this unique opportunity for creating an interest in science particularly in astronomy. This book is part of the series of publication brought out by Vigyan Prasar on this occasion. There is no doubt that there cannot be a better occasion than the International Year of Astronomy to remember those who laid its foundation, whose works contributed significantly to its growth or those who pioneered its study in a particular region or country. In fact thi s is also one of the objectives of the International Year of Astronomy. In this book we have included 27 astronomers. The selection may not be perfect. The author would not be surprised if someone argues that some of those included here should not have bee n included and similarly someone may point out the omissions that is those who have not been included. But then any book takes shape based on the understanding and limitation of the resources at the disposal of the author. So is the case here. The introduction presents some glimpses of the history of astronomy. In no way it should be treated as an account connecting all the developments that led to the emergence of modern astronomy. The history of astronomy is rather complex. This section also highlights the most prominent contributions of the astronomers included in the book. The section “Time-line of Astronomy” attempts to list the major events in astronomy. Some of the common concepts and terms in astronomy have been briefly described in the Glossary f or those who have no background in astronomy. The quotations given at the beginning of each biography highlight some salient features of the life and work of the concerned scientist. Some useful information like astronomical constants, the nearest and the brightest stars, the names of the constellations and the planets and principal satellites of the solar system have been added. A list of reference has also been added for the benefit of inquisitive readers. The length of the write-up of a particular astronomer has nothing to do with the significance and volume of his or her work. The most of the biographies are based on the biographies earlier published in “Dream -2047”, Vigyan Prasar’s monthly newsletter-cum-popular science magazine. There are some repetitions and they have been kept for the reader’s benefit. This is because normally it is expected that the book will not be read like a novel from beginning to end. It is quite possible somebody may be interested in some particular biographies. Keeping thi s fact in mind the biographies are not linked. The book is certainly not for those who are well -versed with the development of astronomy. It is meant for general readers having interest in science and students of schools and colleges. To make them famili ar some of the greatest names in the field of modern astronomy and some of whom actually laid 7 its foundation. The aim is to highlight the circumstances in which the astronomers included in this book worked, what inspired them to pursue science, what they thought about science and human society, what are their personal traits worth emulating for the young aspiring scientists and what were their major contributions. The ultimate aim of this book is to enthuse its readers to take an interest in astronomy and thus in science. It is not intended to teach astronomy. Here the author’s may be compared with a persuasive and fairly well informed tourist guide showing historical monuments to visitors. The monuments stand as testimony to intellectual, cultural and architectural heritage of a particular period of human civilisation. The guide moves from place to place and briefs the visitors about the importance of different sites. Often visitors go only for sight seeing and are not much interested for background infor mation. They simply admire and do not pursue further. But sometimes, a particular remark about certain aspect of a monument may ignite the mind of a visitor to marvel at it, to ponder over it and realise the true achievement.