DOCSLIB.ORG

47940 CH01 0001.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
47940 CH01 0001.Pdf © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION PE1 © JonesThe & Bartlett Quest Learning, LLC Ahead © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION1 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEO ORN THE DISTRIBUTION NIGHT OF MARCH 23, 1993, amateur astronomerNOT David FOR Levy SALE photographed OR DISTRIBUTION part of Comet Shoemaker-Levy 9 the sky near the planet Jupiter. His friends, fellow astronomers Carolyn Shoemaker was broken by Jupiter’s and her husband Eugene Shoemaker, spotted something unusual in the picture: a gravitational forces into comet that had broken up into about 20 pieces. The comet became known officially as more than 20 fragments (bottom photo), all follow- Comet Shoemaker-Levy 9 (the ninth comet discovered by these three sky-watchers) ing the same path toward and unofficially© Jonesas the “string & Bartlett of pearls” Learning, comet. LLC © Jonesa &collision Bartlett with Jupiter. Learning, LLC When astronomersNOT FOR announced SALE OR the DISTRIBUTION news of the comet on June 1, 1993, theyNOT had FORCourtesy SALE of Hubble OR DISTRIBUTIONSpace traced its path closely enough to tell that it had come under the influence of Jupiter’s Telescope Comet Team powerful gravitational field. They had deduced that the comet was pulled apart by and NASA. This photo of Jupiter’s gravity in July of 1992. They predicted that the comet would crash into Jupiter (top photo) shows Jupiter on or about July 25, 1994. the impact spots left by © JonesBy October& Bartlett 1993, Learning, astronomers LLC had refined their predictions.© Jones The comet & Bartlettwas Learning,some of the fragments.LLC Courtesy of STScI/NASA. NOTthen FOR stretched SALE out OR over DISTRIBUTION a distance of 3 million kilometers (1.8NOT million FOR miles) SALE in orbit OR DISTRIBUTION around Jupiter. The first piece was predicted to hit Jupiter at 4:01 PM (Eastern day- light savings time in the United States) on July 16, and the last piece was predicted to hit at 4:00 AM on July 22, 1994; however, nobody knew whether the impacts would be big or small or even observable by telescopes on Earth. © Jones & Bartlett ByLearning, the time of LLC the predicted impacts, the entire© Jones world & was Bartlett watching, Learning, linked to- LLC NOT FOR SALEgether OR DISTRIBUTION by the Internet and the television. The NOTHubble FOR Space SALETelescope OR was DISTRIBUTIONtrained on 1 © Jones & Bartlett Learning,4TH LLC. NOTPAGES FOR SALE OR DISTRIBUTION. 2 CHAPTER 1 The Quest Ahead Jupiter, as was the Galileo space probe then approaching the Jupiter system, as well as most © Jones & Bartlett Learning,major LLC observatories around the world© Jones and untold & Bartlett numbers Learning, of amateur LLCtelescopes. It has been NOT FOR SALE OR DISTRIBUTIONsaid that more telescopes were aimedNOT at FORthe same SALE spot—Jupiter—than OR DISTRIBUTION ever before or since, and the viewers were not disappointed. Fragment A of the comet hit Jupiter at 4:11 PM Eastern daylight time, only 10 minutes off the prediction made 10 months earlier. Traveling at 60 kilometers/second (130,000 miles/ hour),© Jones each &fragment Bartlett created Learning, a fireball LLC in Jupiter’s upper atmosphere© Jones reaching & up Bartlett as high asLearning, LLC 3000 kilometers (1900 miles) and leaving darkened areas in the atmosphere as wide across as theNOT diameter FOR ofSALE the Earth. OR ScientistsDISTRIBUTION estimated that some of the largerNOT impacts, FOR causedSALE by OR frag DISTRIBUTION- u Six million megatons is about ments about 3 kilometers across, released energy equivalent to 6 million megatons of TNT. 600 times the estimated arsenal (The largest nuclear bomb ever detonated produced a blast equivalent to about 5 megatons.) of the world. The event made front-page headlines around the world, featuring photographs of fireballs © Jones & Bartlettand dark Learning,impact spots LLCacross the giant planet. © Jones & Bartlett Learning, LLC How were astronomers able to predict the time of impact with such accuracy? What did NOT FOR SALEthey learnOR DISTRIBUTIONfrom observing the aftereffects of this stupendousNOT FOR collision? SALE ORMany DISTRIBUTION scientists believe that a similar collision with an asteroid occurred on Earth 65 million years ago, heralding the end of the age of dinosaurs. Since seeing the visible proof of such collisions on Jupiter, many people worry about the chances of further catastrophes on our own planet. Astronomers say © Jones & Bartlett Learning,that the LLC chances of such an event© happening Jones & here Bartlett are roughly Learning, once in 300,000LLC years, but how can they make such a prediction? NOT FOR SALE OR DISTRIBUTIONYou will learn the answers to NOTsome ofFOR these SALE questions OR in DISTRIBUTION this book. You will find that although collisions of comets and planets are very rare in our immediate neighborhood of space, the vast regions of the universe show tremendous activity. Stars are born in dense clouds of gas while other stars explode, spewing forth gas back into space. Galaxies collide over© Jones periods & of Bartlett millions of Learning, years, hurtling LLC stars around at fantastic ©speeds. Jones The & universe Bartlett is Learning, LLC a wild and fabulous showcase, and we will see some of its highlights, looking out from our quietNOT corner FOR called SALE Earth. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Nothing is rich but the inex- Astronomy is the oldest of the sciences, but it is still changing rapidly today. It is a study haustible wealth of nature. rich in interesting personalities and exciting discoveries. Its long history and recent advances She shows us only surfaces, but make it an excellent example of the progressive nature of science. she is a million fathoms deep. Science is fundamentally a quest for understanding, and in the case of astronomy, the —Ralph ©Waldo Jones Emerson & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC subject of the quest is the entire universe. The study of astronomy covers the full range of NOT FOR SALEmatter OR from DISTRIBUTION smallest to largest. On the small end, NOTit includes FOR atoms SALE and OR their DISTRIBUTION internal work- ings, for astronomers need to know about the nuclear reactions that make stars shine; star A self-luminous celestial this knowledge one day may lead to peaceful applications of thermonuclear reactions. object. Astronomers also study Earth’s neighbors, the planets, and in doing so help us solve problems right here on Earth. For example, a study of weather patterns on Venus and Jupiter has ad- © Jones & Bartlett Learning,vanced LLC our understanding of weather© Jones on Earth. & Bartlett In addition, Learning, studying Mars LLC and Venus helps NOT FOR SALE OR DISTRIBUTIONus understand the past and futureNOT of our FOR own planet.SALE InformationOR DISTRIBUTION we collected using un- u Planets shine by reflected manned spacecraft and Earth-based telescopes has revolutionized our understanding of how sunlight, but stars have an our solar system formed billions of years ago and has evolved since then. In particular, our internal source of energy for their neighborhood was and, to a lesser extent, still is a shooting gallery; we can see the scars of light. We discuss this source collisions on the surfaces of Mercury, the Moon, and other planetary satellites. Understanding the© Jonescomposition & Bartlett of the objects Learning, in our vicinity LLC may one day prove extremely© Jones valuable & Bartlett in our Learning, LLC (nuclear fusion) in our studies of NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the Sun. efforts to find additional sources of materials for our own survival. The apparent weight- lessness and very low density of space may one day lead to the manufacture of exceptional substances. In some cases, astronomy’s results are more trivial but nevertheless practical: materials developed for the Apollo missions to the Moon are now used in tennis rackets. Astronomers also study the largest groupings of billions of stars, and they ask big ques- © Jones & Bartletttions, the Learning, answers to whichLLC tell us something about© Jonesourselves, & bothBartlett as individuals Learning, and asLLC a NOT FOR SALEspecies. OR Our DISTRIBUTION studies of stars and nebulae help us betterNOT understand FOR SALE the ORnatural DISTRIBUTION cycle of the nebula (plural nebulae) An formation of a star, its evolution, its death, and the recycling of some of its material into a interstellar region of dust and/ new star. or gas. Our studies of galaxies help us better understand the creation and evolution of our universe. Studying astronomy causes us to change our basic outlook as we better appreci- © Jonesgalaxy & A Bartlettgroup of gravitationally Learning, LLC © Jones & Bartlett Learning, LLC bound stars, ranging from a billion ate where humans fit into the magnificent universe. Our species and our planet seem to be NOT FORto perhaps SALE a thousand OR billion stars.DISTRIBUTIONdwarfed by the immensity of the cosmos.NOT FOR In a sense,SALE astronomy OR DISTRIBUTION teaches humility. © Jones & Bartlett Learning,4TH LLC. NOTPAGES FOR SALE OR DISTRIBUTION. 1-1 The View from Earth 3 At the same time, one marvels that humans have been able to learn so much about the © Jones universe& Bartlett in which Learning, we live LLCand that such tiny beings are© ableJones to comprehend & Bartlett the Learning, huge, com -LLC NOT FORplex SALE universe.
Load more

Recommended publications
  • Interstellar Na I Absorption Towards Stars in the Region of the IRAS Vela Shell 1 3 M
    4. Towards the Galactic Rotation Observatory and is now permanently in­ the rotation curve from 12 kpc to 15 kpc Curve Beyond 12 kpc with stalled at the 1.93-m telescope of the and answer the question: ELODIE Haute-Provence Observatory. This in­ "Does the dip of the rotation curve at strument possesses an automatic re­ 11 kpc exist and does the rotation curve A good knowledge of the outer rota­ duction programme called INTER­ determined from cepheids follow the tion curve is interesting since it reflects TACOS running on a SUN SPARC sta­ gas rotation curve?" the mass distribution of the Galaxy, and tion to achieve on-line data reductions The answer will give an important clue since it permits the kinematic distance and cross-correlations in order to get about the reality of a local non-axi­ determination of young disk objects. the radial velocity of the target stars symmetric motions and will permit to The rotation curve between 12 and minutes after the observation. The investigate a possible systematic error 16 kpc is not clearly defined by the ob­ cross-correlation algorithm used to find in the gas or cepheids distance scale servations as can be seen on Figure 3. the radial velocity of stars mimics the (due for instance to metal deficiency). Both the gas data and the cepheid data CORAVEl process, using a numerical clearly indicate a rotation velocity de­ mask instead of a physical one (for any References crease from RG) to R= 12 kpc, but then details, see Dubath et al. 1992).
    [Show full text]
  • Azimuth and Altitude – Earth Based – Latitude and Longitude – Celestial
    Basics of Celestial Navigation - stars • Coordinate systems – Observer based – azimuth and altitude – Earth based – latitude and longitude – Celestial – declination and right ascension (or sidereal hour angle) • Relationship among three – star pillars • Motions of the stars in the sky • Major star groupings Comments on coordinate systems • All three are basically ways of describing locations on a sphere – inherently two dimensional – Requires two parameters (e.g. latitude and longitude) • Reality – three dimensionality – Height of observer – Oblateness of earth, mountains – Stars at different distances (parallax) • What you see in the sky depends on – Date of year – Time – Latitude – Longitude – Which is how we can use the stars to navigate!! Altitude-Azimuth coordinate system Based on what an observer sees in the sky. Zenith = point directly above the observer (90o) Nadir = point directly below the observer (-90o) – can’t be seen Horizon = plane (0o) Altitude = angle above the horizon to an object (star, sun, etc) (range = 0o to 90o) Azimuth = angle from true north (clockwise) to the perpendicular arc from star to horizon (range = 0o to 360o) Note: lines of azimuth converge at zenith The arc in the sky from azimuth of 0o to 180o is called the local meridian Point of view of the observer Latitude Latitude – angle from the equator (0o) north (positive) or south (negative) to a point on the earth – (range = 90o = north pole to – 90o = south pole). 1 minute of latitude is always = 1 nautical mile (1.151 statute miles) Note: It’s more common to express Latitude as 26oS or 42oN Longitude Longitude = angle from the prime meridian (=0o) parallel to the equator to a point on earth (range = -180o to 0 to +180o) East of PM = positive, West of PM is negative.
    [Show full text]
  • Astronomical Coordinate Systems
    Appendix 1 Astronomical Coordinate Systems A basic requirement for studying the heavens is being able to determine where in the sky things are located. To specify sky positions, astronomers have developed several coordinate systems. Each sys- tem uses a coordinate grid projected on the celestial sphere, which is similar to the geographic coor- dinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth’s equator). Each coordinate system is named for its choice of fundamental plane. The Equatorial Coordinate System The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the most closely related to the geographic coordinate system because they use the same funda- mental plane and poles. The projection of the Earth’s equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles onto the celestial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate sys- tems: the geographic system is fixed to the Earth and rotates as the Earth does. The Equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but it’s really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec. for short). It measures the angle of an object above or below the celestial equator.
    [Show full text]
  • Arxiv:1709.07265V1 [Astro-Ph.SR] 21 Sep 2017 an Der Sternwarte 16, 14482 Potsdam, Germany E-Mail: [email protected] 2 Smitha Subramanian Et Al
    Noname manuscript No. (will be inserted by the editor) Young and Intermediate-age Distance Indicators Smitha Subramanian · Massimo Marengo · Anupam Bhardwaj · Yang Huang · Laura Inno · Akiharu Nakagawa · Jesper Storm Received: date / Accepted: date Abstract Distance measurements beyond geometrical and semi-geometrical meth- ods, rely mainly on standard candles. As the name suggests, these objects have known luminosities by virtue of their intrinsic proprieties and play a major role in our understanding of modern cosmology. The main caveats associated with standard candles are their absolute calibration, contamination of the sample from other sources and systematic uncertainties. The absolute calibration mainly de- S. Subramanian Kavli Institute for Astronomy and Astrophysics Peking University, Beijing, China E-mail: [email protected] M. Marengo Iowa State University Department of Physics and Astronomy, Ames, IA, USA E-mail: [email protected] A. Bhardwaj European Southern Observatory 85748, Garching, Germany E-mail: [email protected] Yang Huang Department of Astronomy, Kavli Institute for Astronomy & Astrophysics, Peking University, Beijing, China E-mail: [email protected] L. Inno Max-Planck-Institut f¨urAstronomy 69117, Heidelberg, Germany E-mail: [email protected] A. Nakagawa Kagoshima University, Faculty of Science Korimoto 1-1-35, Kagoshima 890-0065, Japan E-mail: [email protected] J. Storm Leibniz-Institut f¨urAstrophysik Potsdam (AIP) arXiv:1709.07265v1 [astro-ph.SR] 21 Sep 2017 An der Sternwarte 16, 14482 Potsdam, Germany E-mail: [email protected] 2 Smitha Subramanian et al. pends on their chemical composition and age. To understand the impact of these effects on the distance scale, it is essential to develop methods based on differ- ent sample of standard candles.
    [Show full text]
  • Arxiv:1708.07700V3 [Physics.Ed-Ph] 31 Aug 2017 Zon to the South
    AstroEDU manuscript no. astroedu1645 c AstroEDU 2017 September 1, 2017 Navigation in the Ancient Mediterranean and Beyond M. Nielbock Haus der Astronomie, Campus MPIA, Königstuhl 17, D-69117 Heidelberg, Germany e-mail: [email protected] Received August 8, 2016; accepted March 2, 2017 ABSTRACT This lesson unit has been developed within the framework the EU Space Awareness project. It provides an insight into the history and navigational methods of the Bronze Age Mediterranean peoples. The students explore the link between exciting history and astronomical knowledge. Besides an overview of ancient seafaring in the Mediterranean, the students explore in two hands-on activities early navigational skills using the stars and constellations and their apparent nightly movement across the sky. In the course of the activities, they become familiar with the stellar constellations and how they are distributed across the northern and southern sky. Key words. navigation, astronomy, ancient history, Bronze Age, geography, stars, Polaris, North Star, latitude, meridian, pole height, circumpolar, celestial navigation, Mediterranean 1. Background information the celestial poles. Archaeological evidence from prehistoric eras like burials and the orientation of buildings demonstrates that the 1.1. Cardinal directions cardinal directions were common knowledge in a multitude of The cardinal directions are defined by astronomical processes cultures already many millennia ago. Therefore, it is obvious that like diurnal and annual apparent movements of the Sun and the they were applied to early navigation. The magnetic compass was apparent movements of the stars. In ancient and prehistoric times, unknown in Europe until the 13th century CE (Lane 1963). the sky certainly had a different significance than today.
    [Show full text]
  • Three Proposed B-Associations in the Vicinity of Zeta Puppis
    THREE PROPOSED B-ASSOCIATIONS IN THE VICINITY OF ZETA PUPPIS Edward K. L. Upton University of California, Los Angeles Los Angeles, California 90024 'It has recently been suggested by Brandt et al. (1971) that some of the bright B stars within 40 of y Velorum may comprise a physical association. This suggestion coincides with the conclusions of Robert Altizer and myself from an unpublished study of the distribution of B stars in this part of the Milky Way. Our study tends to confirm the reality of the association around y Vel. It also indi- cates the existence of one or two additional associations of B stars in neighboring regions, and gives some indication of the ages of all three groups. We were interested not so much in stars associated with y Vel or the pulsar PSR 0833-45, as in those which might be associated with 5 Puppis. An 05 star so close to the Sun (about 400 parsecs if M v = - 6), and without any obvious cluster or association as its place of origin, presents a strong challenge to the idea that all stars are formed in clusters or associations. The magnitude of the challenge was not entirely clear to begin with, for although no nearby OB- associations had been recognized in the Vela-Puppis area, it was by no means evident that no such association existed. A map of B stars in this area (e.g.: Becvar's Atlas Australis) shows plenty of candidates for any number of associa- tions. The problem is to separate out those with distances near 400 parsecs, and to locate the high-density regions at that distance.
    [Show full text]
  • How Astronomical Objects Are Named
    How Astronomical Objects Are Named Jeanne E. Bishop Westlake Schools Planetarium 24525 Hilliard Road Westlake, Ohio 44145 U.S.A. bishop{at}@wlake.org Sept 2004 Introduction “What, I wonder, would the science of astrono- use of the sky by the societies of At the 1988 meeting in Rich- my be like, if we could not properly discrimi- the people that developed them. However, these different systems mond, Virginia, the Inter- nate among the stars themselves. Without the national Planetarium Society are beyond the scope of this arti- (IPS) released a statement ex- use of unique names, all observatories, both cle; the discussion will be limited plaining and opposing the sell- ancient and modern, would be useful to to the system of constellations ing of star names by private nobody, and the books describing these things used currently by astronomers in business groups. In this state- all countries. As we shall see, the ment I reviewed the official would seem to us to be more like enigmas history of the official constella- methods by which stars are rather than descriptions and explanations.” tions includes contributions and named. Later, at the IPS Exec- – Johannes Hevelius, 1611-1687 innovations of people from utive Council Meeting in 2000, many cultures and countries. there was a positive response to The IAU recognizes 88 constel- the suggestion that as continuing Chair of with the name registered in an ‘important’ lations, all originating in ancient times or the Committee for Astronomical Accuracy, I book “… is a scam. Astronomers don’t recog- during the European age of exploration and prepare a reference article that describes not nize those names.
    [Show full text]
  • The Long-Period Galactic Cepheid RS Puppis-I. a Geometric Distance from Its Light Echoes
    Astronomy & Astrophysics manuscript no. ms8961 c ESO 2018 October 24, 2018 The long-period Galactic Cepheid RS Puppis I. A geometric distance from its light echoes⋆ P. Kervella1, A. M´erand2, L. Szabados3, P. Fouqu´e4, D. Bersier5, E. Pompei6, and G. Perrin1 1 LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Universit´eParis Diderot, 5 Place Jules Janssen, F-92195 Meudon, France 2 Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3965, Atlanta, Georgia 30302-3965, USA 3 Konkoly Observatory, H-1525 Budapest XII, P. O. Box 67, Hungary 4 Observatoire Midi-Pyr´en´ees, Laboratoire d’Astrophysique, CNRS UMR 5572, Universit´ePaul Sabatier - Toulouse 3, 14 avenue Edouard Belin, F-31400 Toulouse, France 5 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, CH411LD, United Kingdom 6 European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19, Chile Received ; Accepted ABSTRACT Context. The bright southern Cepheid RS Pup is surrounded by a circumstellar nebula reflecting the light from the central star. The propagation of the light variations from the Cepheid inside the dusty nebula creates spectacular light echoes that can be observed up to large distances from the star itself. This phenomenon is currently unique in this class of stars. Aims. For this relatively distant star, the trigonometric parallax available from Hipparcos has a low accuracy. A careful observation of the light echoes has the potential to provide a very accurate, geometric distance to RS Pup. Methods. We obtained a series of CCD images of RS Pup with the NTT/EMMI instrument covering the variation period of the star (P = 41.4 d), allowing us to track the progression of the light wavefronts over the nebular features surrounding the star.
    [Show full text]
  • Estrellas Variables Y Su Estudio En El Observatorio Nacional Argentino
    ESTRELLAS VARIABLES Y SU ESTUDIO EN EL [1] OBSERVATORIO NACIONAL ARGENTINO Santiago Paolantonio [email protected] www.historiadelaastronomia.wordpress.com El conocimiento de que determinadas estrellas cambian su brillo, algunas periódicamente otras irregularmente, se remonta a fines del siglo XVI. La cantidad de estos singulares astros conocidos a comienzos de los 1800 era de solo 16, situación que comenzó a revertirse a partir de ese momento en la medida que los astrónomos empezaron a prestarles progresivamente mayor atención, lo que se ve reflejado en el creciente número de estrellas variables identificadas. Friedrich Argelander, en el Anuario para 1844 de H. C. Schumacher, escribe "Invitación a los amigos de la astronomía", en el cual propone diversos trabajos con los que aficionados a la astronomía podían contribuir a esta ciencia, entre ellos, la observación de estrellas variables. En este texto incluye el nombre de 18 de estos objetos, todos visibles a simple vista y solo tres pertenecientes al cielo austral (Argelander, 1844; 214). Una década más tarde, Norman R. Pogson, asistente del Radcliffe Observatory de la Universidad de Oxford, lista 53 variables con sus correspondientes magnitudes máximas, mínimas y períodos, 13 de las cuales tienen declinación negativa (Johnson, 1856; 281-282). En 1865 aparece en la revista alemana Astronomische Nachrichten, un catálogo de 123 estrellas variables, recopiladas por el aficionado británico George W. Chambers, 35 ubicadas al sur del ecuador celeste (Chambers, 1865). Ese mismo año, Eduard Schönfeld, discípulo de Argelander, publica una lista con 113 estrellas (Pickering, 1903). Es en esta época que comienza el estudio sistemático de las variaciones de luz de estas estrellas.
    [Show full text]
  • Almanacco Astronomico 2002 – Introduzione
    Almanacco Astronomico per l’anno 2002 Sergio Alessandrelli C.C.C.D.S. - Hipparcos La Luna – Principali formazioni geologiche Almanacco Astronomico per l’anno 2002 A tutti gli amici astrofili… 1 Almanacco Astronomico 2002 – Introduzione Introduzione all’Almanacco Astronomico 2002 Il presente Almanacco Astronomico è stato realizzato utilizzando comuni programmi di calcolo astronomico facilmente reperibili sul mercato del software, ovvero scaricabili gratuitamente tramite Internet. La precisione nei calcoli è quindi quella tipica per questo tipo di software, ossia sufficiente per gli usi dell’astrofilo medio. Tutti gli eventi sono stati calcolati per le coordinate di Roma (Lat. 41° 52’ 48” N, Long. 12° 30’ 00” E) e gli orari espressi (tranne laddove altrimenti specificato) in tempo universale. 2 Almanacco Astronomico 2002 – Calendario del 2002 Calendario del 2002 January February March Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa 1 2 3 4 5 1 2 1 2 6 7 8 9 10 11 12 3 4 5 6 7 8 9 3 4 5 6 7 8 9 13 14 15 16 17 18 19 10 11 12 13 14 15 16 10 11 12 13 14 15 16 20 21 22 23 24 25 26 17 18 19 20 21 22 23 17 18 19 20 21 22 23 27 28 29 30 31 24 25 26 27 28 24 25 26 27 28 29 30 31 April May June Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 1 2 3 4 1 7 8 9 10 11 12 13 5 6 7 8 9 10 11 2 3 4 5 6 7 8 14 15 16 17 18 19 20 12 13 14 15 16 17 18 9 10 11 12 13 14 15 21 22 23 24 25 26 27 19 20 21 22 23 24 25 16 17 18 19 20 21 22 28 29 30 26 27 28 29 30 31 23 24 25 26 27 28 29 30 July August September Su Mo Tu We
    [Show full text]
  • Spitzer Space Telescope Observations Reveal Expansion Rate of the Universe
    Spitzer space telescope observations reveal expansion rate of the Universe By Brian Dodson October 17, 2012 The Spitzer space telescope has peered through dust and gas to establish a new value for the Hubble Constant (Image: NASA) The size and age of our Universe is not only a critically important issue in cosmology, but is also among the most controversial and delicate of the cosmological questions. Infrared observations made using NASA's Spitzer Space Telescope have now given us the most precise estimate yet of the rate at which our Universe is expanding. The key was not the discovery of a new method for measuring distance. Rather, astronomers discovered how to measure brightness more accurately. The new value for the Hubble constant, good to within three percent, is 74.3 kilometers per second per megaparsec (km/s/Mpc). Portal of Tunisia: www.chercheinfo.com Page 1 Portal of Tunisia: www.chercheinfo.com Page 2 Portal of Tunisia: www.chercheinfo.com Page 3 Portal of Tunisia: www.chercheinfo.com Page 4 The redshift of galaxies was discovered by Vesto Slipher of the Lowell Observatory (Flagstaff, Arizona, USA) in 1912. He first measured the spectrum of M31 (the Andromeda galaxy), discovering that it wasapproaching our galaxy. However, his later spectral measurements of roughly 15 galaxies established that most galaxies were receding, and some at considerable velocity. Redshifts measured for a series of galaxies located at increasing distances (Photo: NASA) About 15 years later at the Mount Wilson observatory in California, Edwin Hubble had invented a number of ways to determine distance to nearby galaxies, and thought to correlate these distances with galactic redshifts measured by Slipher and others.
    [Show full text]
  • Advancing Astronomy in the Coming Decade: Opportunities and Challenges
    Advancing Astronomy in the Coming Decade: Opportunities and Challenges Report of the National Science Foundation Division of Astronomical Sciences Portfolio Review Committee August 14, 2012 2 Table of Contents Table of Contents..............................................................................................................................2 Executive Summary.........................................................................................................................5 1 Introduction ................................................................................................................................9 2 Statement of Principles ....................................................................................................... 13 3 Budget Overview and Projections..................................................................................15 3.1 New Worlds, New Horizons Recommendations..............................................20 3.2 Budget forecasts ............................................................................................................21 3.3 Projecting the Status Quo ..........................................................................................23 4 Community Input...................................................................................................................27 5 New Worlds, New Horizons and Technical Capabilities......................................... 29 5.1 Cosmology and Fundamental Physics.................................................................
    [Show full text]