History of astronomy 14021 226062433 2008-07-16T17:38:05Z Xn4 1896773 /* Uniting physics and astronomy */ + ref. {{histOfScience}} [[Astronomy]] is the oldest of the [[natural science]]s, dating back to [[ancient history|antiquity]], with its origins in the [[Religion|religious]], [[mythological]], and [[astrological]] practices of [[pre-history]]: vestiges of these are still found in [[astrology]], a discipline long interwoven with public and governmental astronomy, and not completely disentangled from it until a few centuries ago in the [[Western World]] (see [[astrology and astronomy]]). Early astronomy involved observing the regular patterns of the motions of [[visual perception|visible]] [[celestial sphere|celestial]] objects, especially the [[Sun]], [[Moon]], [[star]]s and [[naked eye planets]]. An example of this early astronomy might involve a study of the changing position of the Sun along the horizon or the changing appearances of [[star]]s in the course of the year, which could be used to establish an agricultural or ritual [[Calendar#Pragmatic, theoretical and mixed calendars|calendar]]. In some cultures astronomical data was used for astrological prognostication. Ancient astronomers were able to differentiate between stars and [[planets]], as stars remain relatively fixed over the [[century|centuries]] while planets will move an appreciable amount during a comparatively short time. ==Early history== Early [[culture]]s identified celestial objects with [[mythology|god]]s and [[spiritual being|spirit]]s. They related these objects (and their movements) to phenomena such as [[rain]], [[drought]], [[season]]s, and [[tide]]s. It is generally believed that the first "professional" astronomers were [[priest]]s (such as the [[Magi]]), and that their understanding of the "[[heaven]]s" was seen as "[[divinity|divine]]", hence astronomy's ancient connection to what is now called astrology. Ancient structures with [[Archaeoastronomy#Alignments|astronomical alignments]] (such as [[Stonehenge]]) probably fulfilled both astronomical and [[religion|religious]] [[social function|functions]]. [[Calendar]]s of the world have usually been set by the Sun and Moon (measuring the [[day]], [[month]] and [[year]]), and were of importance to [[agriculture|agricultural]] societies, in which the harvest depended on planting at the correct time of year. The most common [[Gregorian calendar|modern calendar]] is based on the [[Roman calendar]], which divided the year into twelve months of alternating thirty and thirty-one days apiece. In [[46 BC]] [[Julius Caesar]] instigated [[Julian calendar|calendar reform]] and adopted a calendar based upon the [[leap year|365 1/4 day year length]] originally proposed by 4th century BC Greek astronomer [[Callippus]]. The [[Bible]] contains a number of unsophisticated statements on the position of the Earth in the universe and the nature of the stars and planets; see [[Biblical cosmology]]. ==Mesopotamia== {{main|Babylonian astronomy}} {{see|Babylonian astrology|Babylonian calendar}} The origins of [[Western culture|Western]] astronomy can be found in [[Mesopotamia]], the "land between the rivers" [[Tigris]] and [[Euphrates]], where the ancient kingdoms of [[Sumer]], [[Assyria]], and [[Babylonia]] were located. A form of writing known as [[cuneiform]] emerged among the Sumerians around 3500-3000 BC. The Sumerians only practiced a basic form of astronomy, but they had an important influence on the sophisticated astronomy of the Babylonians. Astral theology, which gave planetary gods an important role in [[Mesopotamian mythology]] and [[Mesopotamian religion|religion]], began with the Sumerians. They also used a [[sexagesimal]] (base 60) place-value number system, which simplified the task of recording very large and very small numbers. The modern practice of dividing a circle into 360 [[degree (angle)|degrees]], of 60 minutes each, began with the Sumerians. For more information, see the articles on [[Babylonian numerals]] and [[Babylonian mathematics|mathematics]]. Classical sources frequently use the term [[Chaldeans]] for the astronomers of Mesopotamia, who were, in reality, priest-scribes specializing in [[astrology]] and other forms of [[divination]]. The first evidence of recognition that astronomical phenomena are periodic and of the application of mathematics to their prediction is Babylonian. Tablets dating back to the [[Old Babylonian period]] document the application of mathematics to the variation in the length of daylight over a solar year. Centuries of Babylonian observations of celestial phenomena are recorded in the series of [[cuneiform]] tablets known as the ''Enūma Anu Enlil''. The oldest significant astronomical text that we possess is Tablet 63 of the ''Enūma Anu Enlil'', the Venus tablet of [[Ammi-saduqa]], which lists the first and last visible risings of Venus over a period of about 21 years and is the earliest evidence that the phenomena of a planet were recognized as periodic. The [[MUL.APIN]], contains catalogues of stars and constellations as well as schemes for predicting [[heliacal rising]]s and the settings of the planets, lengths of daylight measured by a [[water-clock]], [[gnomon]], shadows, and [[intercalation]]s. The Babylonian GU text arranges stars in 'strings' that lie along declination circles and thus measure right-ascensions or time-intervals, and also employs the stars of the zenith, which are also separated by given right-ascensional differences.<ref>{{Harvtxt|Pingree|1998}}<br>{{Harvtxt|Rochberg|2004}}<br>{{Harvtxt|Evans|1998}}</ref> A significant increase in the quality and frequency of Babylonian observations appeared during the reign of [[Nabonassar]] (747-733 BC). The systematic records of ominous phenomena in astronomical diaries that began at this time allowed for the discovery of a repeating 18-year cycle of lunar eclipses, for example. The Greek astronomer [[Ptolemy]] later used Nabonassar's reign to fix the beginning of an era, since he felt that the earliest usable observations began at this time. The last stages in the development of Babylonian astronomy took place during the time of the [[Seleucid Empire]] (323-60 BC). In the third century BC, astronomers began to use "goal-year texts" to predict the motions of the planets. These texts compiled records of past observations to find repeating occurrences of ominous phenomena for each planet. About the same time, or shortly afterwards, astronomers created mathematical models that allowed them to predict these phenomena directly, without consulting past records. A notable Babylonian astronomer from this time was [[Seleucus of Seleucia]], who was a supporter of the [[heliocentrism|heliocentric model]]. Babylonian astronomy was the basis for much of what was done in [[Greek astronomy|Greek and Hellenistic astronomy]], in classical [[Indian astronomy]], in Sassanian Iran, in Byzantium, in Syria, in [[Islamic astronomy]], in Central Asia, and in Western Europe.<ref name=dp1998>{{Harvtxt|Pingree|1998}}</ref> ==China== {{Main|Chinese astronomy}} {{see also|Book of Silk|Chinese astrology|Timeline of Chinese astronomy}} The astronomy of [[East Asia]] began in [[China]]. [[Solar term]] was completed in [[Warring States Period]]. The knowledge of Chinese astronomy was introduced into East Asia. Astronomy in China has a long history. Detailed records of astronomical observations were kept from about the 6th century BCE, until the introduction of Western astronomy and the telescope in the 17th century. Chinese astronomers were able to precisely predict [[comets]] and eclipses. Much of early Chinese astronomy was for the purpose of timekeeping. The Chinese used a lunisolar calendar, but because the cycles of the Sun and the Moon are different, astronomers often prepared new calendars and made observations for that purpose. Astrological divination was also an important part of astronomy. Astronomers took careful note of "guest stars" which suddenly appeared among the [[fixed star]]s. They were the first to record a supernova, in the Astrological Annals of the Houhanshu in 185 A.D. Also, the supernova that created the [[Crab Nebula]] in 1054 is an example of a "guest star" observed by Chinese astronomers, although it was not recorded by their European contemporaries. Ancient astronomical records of phenomena like supernovae and comets are sometimes used in modern astronomical studies. The world's first [[star catalogue]] was made by [[Gan De]], a [[:Category:Chinese astronomers|Chinese astronomer]], in [[4th century BC]]. This is an abridged [[Chronology|timeline]] of [[China|Chinese]] records and investigations in [[astronomy]]. * 4000 BCE - Astronomy used to orient houses at Banpo to the constellation Yingshi (part of Pegasus). * 4000 BCE - Astronomical mosaics of the Dragon and Tiger flanked a male burial at Xishuipo, Puyang. * 2300 BCE +/- 250 y - Yaodian (Book of Yao) records astronomical markers for calendrical purposes, using the leading-stars of the four mega-constellations. * 2137 BCE - [[Classic of History]]; records the earliest known [[solar eclipse]] on [[October 22]]. * ca. 2000 BCE - Chinese determine that [[Jupiter]] needs 12 years to complete one revolution of its orbit. * ca. 1400 BCE - Chinese record the regularity of solar and [[lunar eclipse]]s and the earliest known [[Solar prominence]] and two [[nova]]s. * ca. 1200 BCE - Sky divided into twenty eight regions ([[Chinese constellation]]); for recognitions of the stars. * ca. 1100 BCE - First determination of the [[spring equinox]]. * 776 BCE - The earliest reliable record of [[solar eclipse]]. * 613 BCE, July - A [[Comet]], possibly [[Comet Halley]], record in [[Spring and Autumn Annals]]. * 532 BCE - A [[nova]] was recorded in [[Records of the Grand Historian]] and [[Zuo Zhuan]]. * 28 BCE - Chinese history book [[Book of Han]] makes earliest known dated record of [[sunspot]]. * 78-139 CE - The astronomer, mathematician, and inventor [[Zhang Heng]] catalogued some 2500 stars in his lifetime, along with recognizing over 1000 constellations. * 185 CE - The earliest recorded and verifiable supernova of RCW 86 * 687 - Chinese make earliest known record of [[meteor shower]]. * 1054 - On July 4, Chinese astronomers noted the appearance of a ''guest star'', the [[supernova]] now called the [[Crab Nebula]], [[Charles Messier|Messier's]] M1. * 1088 - In his ''[[Dream Pool Essays]]'', the polymath Chinese scientist [[Shen Kuo]] ([[1031]]-[[1095]]) wrote of his findings for the improved meridian measurement between the [[polestar]] and [[true north]], which was an invaluable concept for aiding [[navigation]] by use of the magnetic [[compass]]. Shen Kuo also argued for spherical celestial bodies by using evidence of [[lunar eclipse]] and [[solar eclipse]], which promoted [[spherical earth]] theory and went against [[flat earth]] theory. Along with his colleague [[Wei Pu]], he accurately plotted the orbital paths of the sun, moon, and planets over a five year period, and supported [[retrogradation]]. ==Greece and Hellenistic world== {{Main|Greek astronomy}} The [[Ancient Greeks]] developed astronomy, which they treated as a branch of mathematics, to a highly sophisticated level. The first geometrical, three-dimensional models to explain the apparent motion of the planets were developed in the [[4th century BC]] by [[Eudoxus of Cnidus]] and [[Callippus of Cyzicus]] . Their models were based on nested homocentric spheres centered upon the Earth. Their younger contemporary [[Heraclides Ponticus]] proposed that the Earth rotates around its axis. A different approach to celestial phenomena was taken by natural philosophers such as [[Plato]] and [[Aristotle]]. They were less concerned with developing mathematical predictive models than with developing an explanation of the reasons for the motions of the Cosmos. In his ''Timaeus'' Plato described the universe as a spherical body divided into circles carrying the planets and governed according to harmonic intervals by a world soul.<ref>Plato, ''Timaeus,'' 33B-36D</ref> Aristotle, drawing on the mathematical model of Eudoxus, proposed that the universe was made of a complex system of concentric [[Celestial spheres|spheres]], whose circular motions combined to carry the planets around the earth.<ref>Aristotle, ''Metaphysics,'' 1072a18-1074a32</ref> This basic cosmological model prevailed, in various forms, until the Sixteenth century. Greek geometrical astronomy developed away from the model of concentric spheres to employ more complex models in which an [[deferent|eccentric]] circle would carry around a smaller circle, called an [[epicycle]] which in turn carried around a planet. The first such model is attributed to [[Apollonius of Perga]] and further developments in it were carried out in the [[2nd century BC]] by [[Hipparchus|Hipparchus of Nicea]]. Hipparchus made a number of other contributions, including the first measurement of [[precession]] and the compilation of the first star catalog in which he proposed our modern system of [[apparent magnitude]]s. The study of astronomy by the ancient Greeks was not limited to Greece itself but was further developed in the 3rd and 2nd centuries BC, in the Hellenistic states and in particular in Alexandria. However, the work was still done by ethnic Greeks. In the 3rd century BC [[Aristarchus of Samos]] was the first to suggest a [[heliocentric]] system, although only fragmentary descriptions of his idea survive.<ref>Pedersen, ''Early Physics and Astronomy'', pp. 55-6</ref> [[Eratosthenes]], using the angles of shadows created at widely-separated regions, estimated the circumference of the [[Earth]] with great accuracy.<ref>Pedersen, ''Early Physics and Astronomy'', pp. 45-7</ref> The [[Antikythera mechanism]], an [[Ancient Greece|ancient Greek]] device for calculating the movements of planets, dates from about 80 B.C., and was the first ancestor of an astronomical [[computer]]. It was discovered in an ancient shipwreck off the Greek island of [[Antikythera]], between [[Kythera]] and [[Crete]]. The device became famous for its use of a [[differential gear]], previously believed to have been invented in the [[16th century]], and the miniaturization and complexity of its parts, comparable to a clock made in the [[18th century]]. The original mechanism is displayed in the Bronze collection of the [[National Archaeological Museum of Athens]], accompanied by a replica. Depending on the historian's viewpoint, the acme or corruption of physical Greek astronomy is seen with [[Ptolemy|Ptolemy of Alexandria]], who wrote the classic comprehensive presentation of geocentric astronomy, the ''Megale Syntaxis'' (Great Synthesis), better known by its Arabic title ''[[Almagest]]'', which had a lasting effect on astronomy up to the [[Renaissance]]. In his ''Planetary Hypotheses'' Ptolemy ventured into the realm of cosmology, developing a physical model of his geometric system, in a universe many times smaller than the more realistic conception of [[Aristarchus of Samos]] four centuries earlier. ==India== {{Main|Indian astronomy}} {{See|Jyotisha}} Ancient Indian astrology is based upon [[sidereal]] calculations. The sidereal astronomy is based upon the [[stars]] and the sidereal period is the time that it takes the object to make one full [[orbit]] around the [[Sun]], relative to the [[stars]]. It can be traced to the final centuries BC with the [[Vedanga Jyotisha]] attributed to [[Lagadha]], one of the circum-Vedic texts, which describes rules for tracking the motions of the Sun and the Moon for the purposes of ritual. After formation of [[Indo-Greek]] kingdoms, Indian astronomy was influenced by Hellenistic astronomy (adopting the zodiacal signs or ''[[rāśi]]s''). Around [[500]] CE, [[Aryabhata]] presented a mathematical system that took the Earth to spin on its axis and considered the motions of the planets with respect to the Sun. He also made an accurate approximation of the Earth's [[circumference]] and [[diameter]], and also discovered how the [[lunar eclipse]] and [[solar eclipse]] happen. He gives the [[radius]] of the planetary [[orbit]]s in terms of the radius of the Earth/Sun orbit as essentially their periods of rotation around the Sun. He was also the earliest to discover that the orbits of the planets around the Sun are [[ellipse]]s. [http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Aryabhata_I.html] [[Brahmagupta]] (598-668) was the head of the astronomical [[observatory]] at [[Ujjain]] and during his tenure there wrote a text on astronomy, the ''[[Brahmasphutasiddhanta]]'' in [[628]]. He was the earliest to use [[algebra]] to solve astronomical problems. He also developed methods for calculations of the motions and places of various planets, their rising and setting, [[Astronomical conjunction|conjunctions]], and the calculation of eclipses. [[Bhaskara]] (1114-1185) was the head of the astronomical observatory at Ujjain, continuing the mathematical tradition of Brahmagupta. He wrote the ''Siddhantasiromani'' which consists of two parts: ''Goladhyaya'' (sphere) and ''Grahaganita'' (mathematics of the planets). He also calculated the time taken for the Earth to orbit the sun to 9 decimal places. The Buddhist University of [[Nalanda]] at the time offered formal courses in astronomical studies. Other important astronomers from India include [[Madhava of Sangamagrama]], [[Nilakantha Somayaji]] and [[Jyeshtadeva]], who were members of the [[Kerala school of astronomy and mathematics]] from the [[14th century]] to the [[16th century]]. Nilakantha Somayaji, in his ''Aryabhatiyabhasya'', a commentary on Aryabhata's ''Aryabhatiya'', developed his own computational system for a partially [[heliocentrism|heliocentric]] planetary model, in which Mercury, Venus, [[Mars]], [[Jupiter]] and [[Saturn]] orbit the [[Sun]], which in turn orbits the [[Earth]], similar to the [[Tychonic system]] later proposed by [[Tycho Brahe]] in the late 16th century. Nilakantha's system, however, was mathematically more effient than the Tychonic system, due to correctly taking into account the equation of the centre and [[latitude|latitudinal]] motion of Mercury and Venus. Most astronomers of the [[Kerala school of astronomy and mathematics]] who followed him accepted his planetary model.<ref name=Joseph408>George G. Joseph (2000), ''The Crest of the Peacock: Non-European Roots of Mathematics'', 2nd edition, p. 408, Penguin Books, London, ISBN 0691006598</ref><ref>K. Ramasubramanian, M. D. Srinivas, M. S. Sriram (1994). "Modification of the earlier Indian planetary theory by the Kerala astronomers (c. 1500 AD) and the implied heliocentric picture of planetary motion", ''[[Current Science]]'' '''66''', p. 784-790.</ref> ==Mesoamerica== {{Main|Maya calendar|Aztec calendar}} [[Maya civilization|Maya]] astronomical [[Maya codices|codices]] include detailed tables for calculating [[Lunar phases|phases of the Moon]], the recurrence of eclipses, and the appearance and disappearance of [[Venus]] as morning and [[Venus#Observation|evening star]]. The Maya based their [[Maya calendar|calendrics]] in the carefully calculated cycles of the [[Pleiades]], the [[Sun]], the [[Moon]], [[Venus]], [[Jupiter]], [[Saturn]], [[Mars]], and also they had a precise description of the eclipses as depicted in the [[Dresden Codex]], as well as the ecliptic or zodiac, and the [[Milky Way]] was crucial in their Cosmology. (Source:[http://www.authenticmaya.com/maya_astronomy.htm Maya Astronomy]). A number of important Maya structures are believed to have been oriented toward the extreme risings and settings of Venus. To the ancient Maya, Venus was the patron of war and many recorded battles are believed to have been timed to the motions of this planet. [[Mars]] is also mentioned in preserved astronomical codices and early [[Maya mythology|mythology]].<ref>A. F. Aveni, ''Skywatchers of Ancient Mexico,'' (Austin: Univ. of Texas Pr., 1980), pp. 173-99.</ref> Although the [[Maya calendar]] was not tied to the Sun, [[John E. Teeple|John Teeple]] has proposed that the Maya calculated the [[tropical year|solar year]] to somewhat greater accuracy than the [[Gregorian calendar]].<ref>A. F. Aveni, ''Skywatchers of Ancient Mexico,'' (Austin: Univ. of Texas Pr., 1980), pp. 170-3.</ref> Both astronomy and an intricate numerological scheme for the measurement of time were vitally important components of [[Maya civilization#Religion|Maya religion]]. ==Islamic astronomy== {{Main|Islamic astronomy}} {{See|Maragheh observatory|Istanbul observatory of al-Din}} The Arabic world under [[Islam]] had become highly cultured, and many important works of knowledge from [[Greek astronomy]] and [[Indian astronomy]] were translated into Arabic, used and stored in libraries throughout the area. The late [[9th century]] [[Persian people|Persian]] astronomer [[al-Farghani]] wrote extensively on the motion of celestial bodies. His work was translated into Latin during the [[Latin translations of the 12th century]]. In the late [[10th century]], a huge observatory was built near [[Tehran]], [[Iran]], by the astronomer al-Khujandi who observed a series of [[Meridian (astronomy)|meridian]] [[Astronomical transit|transits]] of the Sun, which allowed him to calculate the [[Axial tilt|obliquity of the ecliptic]], also known as the tilt of the Earth's axis relative to the Sun. In Persia, [[Omar Khayyám]] compiled many tables and performed a reformation of the [[calendar]] that was more accurate than the [[Julian Calendar|Julian]] and came close to the [[Gregorian calendar|Gregorian]]. An amazing feat was his calculation of the year to be 365.24219858156 days long, which is accurate to the 6th decimal place. In the 10th century, [[Abd al-Rahman al-Sufi]] (Azophi) carried out observations on the [[star]]s and described their [[position]]s, [[apparent magnitude|magnitude]]s, brightness, and [[colour]] and drawings for each constellation in his ''[[Book of Fixed Stars]]''. He also gave the first descriptions and pictures of "A Little Cloud" now known as the [[Andromeda Galaxy]]. He mentions it as lying before the mouth of a Big Fish, an Arabic [[constellation]]. This "cloud" was apparently commonly known to the [[Isfahan (city)|Isfahan]] astronomers, very probably before [[905]] AD.<ref name="NSOG">{{cite book |last= Kepple |first= George Robert |coauthors= Glen W. Sanner |title= The Night Sky Observer's Guide, Volume 1 |publisher= Willmann-Bell, Inc. |year= 1998 |id= ISBN 0-943396-58-1 |pages=18 }}</ref> The first recorded mention of the [[Large Magellanic Cloud]] was also given by al-Sufi.<ref name="obspm">{{cite web | title=Observatoire de Paris (Abd-al-Rahman Al Sufi) | url=http://messier.obspm.fr/xtra/Bios/alsufi.html | accessdate=2007-04-19 }}</ref><ref name="obspm2">{{cite web | title=Observatoire de Paris (LMC) | url=http://messier.obspm.fr/xtra/ngc/lmc.html | accessdate=2007-04-19 }}</ref> In 1006, [[Ali ibn Ridwan]] observed [[SN 1006]], the brightest [[supernova]] in recorded history, and left a detailed description of the temporary star. Other Muslim advances in astronomy included the construction of the first [[observatory]] as a [[research institute]] in [[Baghdad]] during the reign of [[Caliph]] [[al-Ma'mun]],<ref>{{cite book |last=Nas |first=Peter J |authorlink= |coauthors= |editor= |others= |title=Urban Symbolism |origdate= |origyear= |origmonth= |url= |format= |accessdate= |accessyear= |accessmonth= |edition= |series= |date= |year=1993 |month= |publisher=Brill Academic Publishers |location= |language= |isbn=9-0040-9855-0 |oclc= |doi= |id= |pages=350 |chapter= |chapterurl= |quote= }}</ref> the collection and correction of previous astronomical data, resolving significant problems in the [[Geocentric model|Ptolemaic model]], the development of the universal latitude-independent [[astrolabe]] by [[Arzachel]],<ref>{{cite book |last=Krebs |first=Robert E. |title=Groundbreaking Scientific Experiments, Inventions, and Discoveries of the Middle Ages and the Renaissance |year=2004 |publisher=Greenwood Press |isbn=0-3133-2433-6 |pages=196}}</ref> the invention of numerous other astronomical instruments, the beginning of [[astrophysics]] and [[celestial mechanics]] after [[Ja'far Muhammad ibn Mūsā ibn Shākir]] theorized that the [[Astronomical object|heavenly bodies]] and [[celestial sphere]]s were subject to the same [[physical law]]s as [[Earth]],<ref>[[George Saliba]] (1994). "Early Arabic Critique of Ptolemaic Cosmology: A Ninth-Century Text on the Motion of the Celestial Spheres", ''Journal for the History of Astronomy'' '''25''', p. 115-141 [116].</ref> the first elaborate [[experiment]]s related to astronomical phenomena and the first [[semantic]] distinction between astronomy and [[astrology]] by [[Abū al-Rayhān al-Bīrūnī]],<ref>S. Pines (September 1964). "The Semantic Distinction between the Terms Astronomy and Astrology according to al-Biruni", ''Isis'' '''55''' (3), p. 343-349.</ref> introduction of exacting [[empirical]] observations and [[experiment]]al techniques,<ref>Toby Huff, ''The Rise of Early Modern Science'', p. 326. [[Cambridge University Press]], ISBN 0521529948.</ref> and the introduction of empirical testing by [[Ibn al-Shatir]], who produced the first model of [[Moon|lunar]] motion which matched physical observations.<ref>Y. M. Faruqi (2006). "Contributions of Islamic scholars to the scientific enterprise", ''International Education Journal'' '''7''' (4), p. 395-396.</ref> The [[Earth's rotation]] and [[heliocentrism]] were also discussed by several Muslim astronomers, such as [[Biruni]], [[Al-Sijzi]] and [[Qutb al-Din al-Shirazi]],<ref>Seyyed [[Hossein Nasr]] (1964), ''An Introduction to Islamic Cosmological Doctrines,'' (Cambridge: Belknap Press of the Harvard University Press), p. 135-136</ref> while the first empirical [[observation]]al evidence of the Earth's rotation was given by [[Nasīr al-Dīn al-Tūsī]] and [[Ali al-Qushji]], and [[al-Birjandi]] developed an early hypothesis on "circular [[inertia]]."<ref name=Ragep>F. Jamil Ragep (2001), "Tusi and Copernicus: The Earth's Motion in Context", ''Science in Context'' '''14''' (1-2), p. 145–163. [[Cambridge University Press]].</ref> [[Natural philosophy]] was also separated from astronomy by [[Alhazen]], Ibn al-Shatir,<ref>Roshdi Rashed (2007). "The Celestial Kinematics of Ibn al-Haytham", ''Arabic Sciences and Philosophy'' '''17''', p. 7-55. [[Cambridge University Press]].</ref> and al-Qushji.<ref name=Ragep/> It is known that the [[Copernican heliocentrism|Copernican heliocentric model]] in [[Nicolaus Copernicus]]' ''[[De revolutionibus]]'' was adapted from the [[geocentric model]] of [[Ibn al-Shatir]] and the [[Maragheh observatory|Maragha school]] (including the [[Tusi-couple]]) in a heliocentric context,<ref>[[George Saliba]] (1999). [http://www.columbia.edu/~gas1/project/visions/case1/sci.1.html Whose Science is Arabic Science in Renaissance Europe?] [[Columbia University]]. <br> The relationship between Copernicus and the Maragha school is detailed in Toby Huff, ''The Rise of Early Modern Science'', [[Cambridge University Press]].</ref> and that his arguments for the Earth's rotation were similar to those of Nasīr al-Dīn al-Tūsī and Ali al-Qushji.<ref name=Ragep/> Some have referred to the achievements of the Maragha school as a "Maragha Revolution", "Maragha School Revolution", or "Scientific Revolution before the Renaissance".<ref>[[George Saliba]] (1994), ''A History of Arabic Astronomy: Planetary Theories During the Golden Age of Islam'', p. 245, 250, 256-257. [[New York University Press]], ISBN 0814780237.</ref> ==Medieval Western Europe== {{see|Science in Medieval Western Europe}} After the significant contributions of Greek scholars to the development of astronomy, it entered a relatively static era in Western Europe from the Roman era through the Twelfth century. This lack of progress has led some astronomers to assert that nothing happened in Western European astronomy during the Middle Ages.<ref>Henry Smith Williams, ''The Great Astronomers'' (New York: Simon and Schuster, 1930), pp. 99-102 describes "the record of astronomical progress" from the Council of Nicea (325 AD) to the time of Copernicus (1543 AD) on four blank pages.</ref> Recent investigations, however, have revealed a more complex picture of the study and teaching of astronomy in the period from the Fourth to the Sixteenth centuries.<ref>Stephen C. McCluskey, ''Astronomies and Cultures in Early Medieval Europe'', (Cambridge: Cambridge University Press, 1999) ISBN 0-521-77852-2.</ref> [[Western Europe]] entered the Middle Ages with great difficulties that affected the continent's intellectual production. The advanced astronomical treatises of [[classical antiquity]] were written in [[Greek language|Greek]], and with the decline of knowledge of that language, only simplified summaries and practical texts were available for study. The most influential writers to pass on this ancient tradition in [[Latin]] were [[Macrobius]], [[Pliny]], [[Martianus Capella]], and [[Calcidius]].<ref>Bruce S. Eastwood, ''Ordering the Heavens: Roman Astronomy and Cosmology in the Carolingian Renaissance'', (Leiden: Brill, 2007) ISBN 979-90-04-16186-3.</ref> In the Sixth Century Bishop [[Gregory of Tours]] noted that he had learned his astronomy from reading Martianus Capella, and went on to employ this rudimentary astronomy to describe a method by which monks could determine the time of prayer at night by watching the stars.<ref>Stephen C. McCluskey, ''Astronomies and Cultures in Early Medieval Europe'', (Cambridge: Cambridge University Press, 1999), pp. 101-110 ISBN 0-521-77852-2.</ref> In the Seventh Century the English monk [[Bede of Jarrow]] published an influential text, [[De temporum ratione|On the Reckoning of Time]], providing churchmen with the practical astronomical knowledge needed to compute the proper date of [[Easter]] using a procedure called ''[[computus]]''. This text remained an important element of the education of Clergy from the Seventh Century until well after the rise of the [[Medieval university#Origins|Universities]] in the [[Renaissance of the 12th century|Twelfth Century]].<ref>Faith Wallis, ed. and trans., ''Bede: The Reckoning of Time'', (Liverpool: Liverpool University Press, 2004), pp. xviii-xxxiv ISBN 0-85323-693-3</ref> The range of surviving ancient Roman writings on astronomy and the teachings of Bede and his followers began to be studied in earnest during the [[Carolingian Renaissance|revival of learning]] sponsored by the emperor [[Charlemagne]].<ref>Stephen C. McCluskey, ''Astronomies and Cultures in Early Medieval Europe'', (Cambridge: Cambridge University Press, 1999), pp. 131-164 ISBN 0-521-77852-2.</ref> By the Ninth Century rudimentary techniques for calculating the position of the planets were circulating in Western Europe; medieval scholars recognized their technical flaws, but texts describing these techniques continued to be copied, reflecting an interest in the motions of the planets and in their astrological significance.<ref>David Juste, "Neither Observation nor Astronomical Tables: An Alternative Way of Computing the Planetary Longitudes in the Early Western Middle Ages," pp. 181-222 in Charles Burnett, Jan P. Hogendijk, Kim Plofker, and Michio Yano, ''Studies in the Exact Sciences in Honour of David Pingree'', (Leiden: Brill, 2004)</ref> Building on this astronomical background, in the Tenth Century European scholars such as [[Gerbert of Aurillac]] began to travel to the Spain and Sicily to seek out learning which they had heard existed in the Arabic-speaking world. There they first encountered various practical astronomical techniques concerning the calendar and timekeeping, most notably those dealing with the [[astrolabe]]. Soon scholars such as [[Hermann of Reichenau]] were writing texts in Latin on the uses and construction of the astrolabe and others, such as [[Walcher of Malvern]], were using the astrolabe to observe the time of eclipses in order to test the validity of computistical tables.<ref>Stephen C. McCluskey, ''Astronomies and Cultures in Early Medieval Europe'', (Cambridge: Cambridge University Press, 1999), pp. 171-187 ISBN 0-521-77852-2.</ref> By the Twelfth century, scholars were traveling to Spain and Sicily to seek out more advanced astronomical and astrological texts, which they [[Latin translations of the 12th century|translated into Latin]] from Arabic and Greek to further enrich the astronomical knowledge of Western Europe. The arrival of these new texts coincided with the rise of the universities in medieval Europe, in which they soon found a home.<ref>Stephen C. McCluskey, ''Astronomies and Cultures in Early Medieval Europe'', (Cambridge: Cambridge University Press, 1999), pp. 188-192 ISBN 0-521-77852-2.</ref> Reflecting the introduction of astronomy into the universities, [[Johannes de Sacrobosco|John of Sacrobosco]] wrote a series of influential introductory astronomy textbooks: the [[De sphaera mundi|Sphere]], a Computus, a text on the [[Quadrant (instrument)|Quadrant]], and another on Calculation.<ref>Olaf Pedersen, "In Quest of Sacrobosco", ''Journal for the History of Astronomy'', 16(1985): 175-221</ref> In the [[14th century]], [[Nicole Oresme]], later bishop of Liseux, showed that neither the scriptural texts nor the physical arguments advanced against the movement of the Earth were demonstrative and adduced the argument of simplicity for the theory that the earth moves, and ''not'' the heavens. However, he concluded "everyone maintains, and I think myself, that the heavens do move and not the earth: For God hath established the world which shall not be moved."<ref>Nicole Oresme, ''Le Livre du ciel et du monde'', xxv, ed. A. D. Menut and A. J. Denomy, trans. A. D. Menut, (Madison: Univ. of Wisconsin Pr., 1968), quotation at pp. 536-7.</ref> In the [[15th century]], cardinal [[Nicholas of Cusa]] suggested in some of his scientific writings that the Earth revolved around the Sun, and that each star is itself a distant sun. He was not, however, describing a scientifically verifiable theory of the universe. == Copernican revolution == [[Image:galileo.arp.300pix.jpg|thumb|left|200px|Galileo Galilei (1564-1642) crafted his own telescope and discovered that our Moon had craters, that Jupiter had moons, that the Sun had spots, and that Venus had phases like our Moon.]] The [[renaissance]] came to astronomy with the work of [[Nicolaus Copernicus]], who proposed a [[heliocentric]] system, in which the planets revolved around the Sun and not the Earth. His ''[[De revolutionibus]]'' provided a full mathematical discussion of his system, using the geometrical techniques that had been traditional in astronomy since before the time of [[Ptolemy]]. His work was later defended, expanded upon and modified by [[Galileo Galilei]] and [[Johannes Kepler]]. Galileo was among the first to use a [[Refracting telescope|telescope]] to observe the sky, and after constructing a 20x [[refractor telescope]] he discovered the four largest [[Galilean moon|moon]]s of [[Jupiter (planet)|Jupiter]] in [[1610]]. This was the first observation of satellites orbiting another planet. He also found that our Moon had [[Impact crater|craters]] and observed (and correctly explained) [[sunspots]]. Galileo noted that Venus exhibited a full set of [[Phases of Venus|phases]] resembling [[lunar phase]]s. Galileo argued that these observations supported the Copernican system and were, to some extent, incompatible with the favored model of the Earth at the center of the universe. == Uniting physics and astronomy == [[Image:Table of Astronomy, Cyclopaedia, Volume 1, p 164.jpg|thumb|right|250px|Table of astronomy, from the 1728 ''[[Cyclopaedia]]'']] Although the motions of celestial bodies had been qualitatively explained in physical terms since Aristotle introduced celestial movers in his [[Metaphysics (Aristotle)|Metaphysics]] and a fifth element in his [[On the Heavens]], [[Johannes Kepler]] was the first to attempt to derive mathematical predictions of celestial motions from assumed physical causes.<ref>Bruce Stephenson, ''Kepler's physical astronomy,'' (New York: Springer, 1987), pp. 67-75.</ref><ref>"[Kepler's] revolutionary role lay in his succesful attempt to solve the problem of uniting astronomy and natural philosophy which had been sought for two thousand years." P. 484 in Wilbur Applebaum, [http://adsabs.harvard.edu/abs/1996HisSc..34..451A "Keplerian Astronomy after Kepler: Researches and Problems,"] ''History of Science'', 34 (1996): 451-504.</ref> Combining his physical insights with the unprecedentedly accurate naked-eye observations made by [[Tycho Brahe]],<ref>"We have found Tycho's mature planetary observations to be consistently accurate to within about 1'." P. 30, n. 2 in Owen Gingerich and James R. Voelkel, [http://adsabs.harvard.edu/abs/1998JHA....29....1G "Tycho Brahe's Copernican Campaign,"] ''Journal for the History of Astronomy,'' 29(1998): 2-34</ref><ref>The average error of Tycho's stellar observations, as recorded in his observational logs, varied from 32.3" to 48.8" for different instruments. Table 4 in Walter G. Wesley, [http://adsabs.harvard.edu/abs/1978JHA.....9...42W "The Accuracy of Tycho Brahe's Instruments,"] ''Journal for the History of Astronomy,'' 9(1978): 42-53.</ref><ref>An error of as much as 3' was introduced into some of the stellar positions published in Tycho's star catalog due to Tycho's application of an erroneous ancient value of parallax and his neglect of refraction. See Dennis Rawlins, "Tycho's 1004 Star Catalog", [http://www.dioi.org/vols/w30.pdf DIO 3] (1993), p. 20.</ref> Kepler discovered the three [[Kepler's laws of planetary motion|laws of planetary motion]] that now carry his name.<ref>[[John Holmes (schoolmaster)|Holmes, John]], ''Astronomy Ancient and Modern'' (1751)</ref> [[Isaac Newton]] developed further ties between physics and astronomy through his [[Gravitation#Newton's theory of gravitation|law of universal gravitation]]. Realising that the same force that attracted objects to the surface of the Earth held the moon in orbit around the Earth, Newton was able to explain - in one theoretical framework - all known gravitational phenomena. In his [[Philosophiae Naturalis Principia Mathematica]], he derived [[Kepler's laws of planetary motion|Kepler's laws]] from [[first principles]]. Newton's theoretical developments lay many of the foundations of [[modern physics]]. == Modern astronomy == At the end of the 19th century it was discovered that, when decomposing the light from the Sun, a multitude of [[spectral line]]s were observed (regions where there was less or no light). Experiments with hot gases showed that the same lines could be observed in the spectra of gases, specific lines corresponding to unique elements. It was proved that the [[chemical element]]s found in the Sun (chiefly [[hydrogen]] and [[helium]]) were also found on Earth. During the 20th century [[spectrometry]] (the study of these lines) advanced, especially because of the advent of [[quantum physics]], that was necessary to understand the observations. Although in previous centuries noted astronomers were exclusively male, at the turn of the 20th century women began to play a role in the great discoveries. In this period prior to modern computers, women at the [[United States Naval Observatory]] (USNO), [[Harvard University]], and other astronomy research institutions often served as human "computers," who performed the tedious calculations while scientists performed research requiring more background knowledge. [http://maia.usno.navy.mil/women_history/history.html] A number of discoveries in this period were originally noted by the women "computers" and reported to their supervisors. For example, [[Henrietta Swan Leavitt]] discovered the [[cepheid variable]] star period-luminosity relation, [[Annie Jump Cannon]] organized the stellar [[stellar classification|spectral types]] according to stellar temperature, and [[Maria Mitchell]] discovered a comet using a telescope. (See [http://www.astrosociety.org/education/resources/womenast_bib.html] for more women astronomers.) Some of these women received little or no recognition during their lives due to their lower professional standing in the field of astronomy. And although their discoveries are taught in classrooms around the world, few students of astronomy can attribute the works to their authors. == Cosmology and the expansion of the universe == {{Main|Physical cosmology#History of physical cosmology}} Most of our current knowledge was gained during the 20th century. With the help of the use of [[photography]], fainter objects were observed. Our sun was found to be part of a [[galaxy]] made up of more than 10<sup>10</sup> stars (10 billion stars). The existence of other galaxies, one of the matters of ''[[the great debate]]'', was settled by [[Edwin Hubble]], who identified the [[Andromeda Galaxy|Andromeda nebula]] as a different galaxy, and many others at large distances and receding, moving away from our galaxy. [[Physical cosmology]], a discipline that has a large intersection with astronomy, made huge advances during the 20th century, with the model of the hot [[big bang]] heavily supported by the evidence provided by astronomy and physics, such as the [[redshift]]s of very distant galaxies and radio sources, the [[cosmic microwave background radiation]], [[Hubble's law]] and [[big bang nucleosynthesis|cosmological abundances of elements]]. == New windows into the Cosmos open == Late in the 19th century, scientists began discovering forms of light which were invisible to the naked eye: [[X-Ray]]s, [[gamma ray]]s, [[radio wave]]s, [[microwave]]s, [[ultraviolet radiation]], and [[infrared radiation]]. This had a major impact on astronomy, spawning the fields of [[infrared astronomy]], [[radio astronomy]], [[x-ray astronomy]] and finally [[gamma-ray astronomy]]. With the advent of [[spectroscopy]] it was proved that other stars were similar to our own sun, but with a range of [[temperature]]s, [[mass]]es and sizes. The existence of our [[galaxy]], the [[Milky Way]], as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the [[universe]] seen in the recession of most galaxies from us. ==Notes== <!--See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref(erences/)> tags--> {{reflist|2}} ==See also== * [[Archaeoastronomy]] * [[History of astrology]] * [[History of astronomical interferometry]] * [[History of supernova observation]] * [[List of Astronomical Instrument Makers]] * [[List of Observatories]] * [[History of telescopes]] * [[Hebrew astronomy]] ==Historians of astronomy== * Scholars Past. [http://adsabs.harvard.edu/abs/1984QJRAS..25..373 Willy Hartner], [[Otto Neugebauer]], [[B. L. van der Waerden]] * Scholars Present. [http://punsterproductions.com/~sciencehistory Stephen G. Brush], [http://history.nasa.gov Stephen J. Dick], [[Owen Gingerich]], [http://adlerplanetarium.org/research/history/staff.shtml Bruce Stephenson], [https://blackhole.aas.org/had/doggett/2004doggett2hoskin.html Michael Hoskin], [http://www.chass.utoronto.ca/~ajones/index.html Alexander R. Jones], [http://adsabs.harvard.edu/abs/1995gha..book.....T Curtis A. Wilson] * Astronomer-historians. [[Delambre|J. B. J. Delambre]], [[J. L. E. Dreyer]], [[Donald Osterbrock]], [[Carl Sagan]], [[F. Richard Stephenson]] ==References== * Aaboe, Asger. ''Episodes from the Early History of Astronomy''. Springer-Verlag 2001 ISBN 0-387-95136-9 * Aveni, Anthony F. ''Skywatchers of Ancient Mexico''. University of Texas Press 1980 ISBN 0-292-77557-1 * [[J. L. E. Dreyer|Dreyer, J. L. E.]] ''History of Astronomy from Thales to Kepler'', 2nd edition. Dover Publications 1953 (revised reprint of ''History of the Planetary Systems from Thales to Kepler'', 1906) * Eastwood, Bruce. ''The Revival of Planetary Astronomy in Carolingian and Post-Carolingian Europe'', Variorum Collected Studies Series CS 279 Ashgate 2002 ISBN 0-86078-868-7 * {{Citation | last=Evans | first=James | author-link= | year=1998 | title=The History and Practice of Ancient Astronomy | publisher=Oxford University Press | isbn =0195095391}}. * Antoine Gautier, ''L'âge d'or de l'astronomie ottomane'', in L'Astronomie, (Monthly magazine created by [[Camille Flammarion]] in 1882), December 2005, volume 119. * Hodson, F. R. (ed.). ''The Place of Astronomy in the Ancient World'': A Joint Symposium of the Royal Society and the British Academy. Oxford University Press, 1974 ISBN 0-19-725944-8 * Hoskin, Michael. ''The History of Astronomy: A Very Short Introduction''. Oxford University Press. ISBN 0-19-280306-9 * McCluskey, Stephen C. ''Astronomies and Cultures in Early Medieval Europe''. Cambridge University Press 1998 ISBN 0-521-77852-2 * [[Otto E. Neugebauer|Neugebauer, Otto]]. ''The Exact Sciences in Antiquity'', 2nd edition. Dover Publications 1969 * [[Anton Pannekoek|Pannekoek, Anton]]. ''A History of Astronomy''. Dover Publications 1989 * Pedersen, Olaf. ''Early Physics and Astronomy: A Historical Introduction'', revised edition. Cambridge University Press 1993 ISBN 0-521-40899-7 * {{Citation | last=Pingree | first=David | author-link=David Pingree | year=1998 | contribution=Legacies in Astronomy and Celestial Omens | editor-last=Dalley | editor-first=Stephanie | editor-link= | title=The Legacy of Mesopotamia | publisher=Oxford University Press | pages=pp. 125 – 137 | isbn =0198149468}}. * {{Citation | last=Rochberg | first=Francesca | author-link= | year=2004 | title=The Heavenly Writing: Divination, Horoscopy, and Astronomy in Mesopotamian Culture | publisher=Cambridge University Press}}. * Stephenson, Bruce. ''Kepler's Physical Astronomy'', Studies in the History of Mathematics and Physical Sciences, 13. New York: Springer, 1987 ISBN 0-387-96541-6 * Walker, Christopher (ed.). ''Astronomy before the telescope''. British Museum Press 1996 ISBN 0-7141-1746-3 ==Refereed Journals== * [http://www.dioi.org DIO: The International Journal of Scientific History] * [http://www.shpltd.co.uk/jha.html Journal for the History of Astronomy] * [http://www.jcu.edu.au/school/mathphys/astronomy/jah2/index.shtml Journal of Astronomical History and Heritage] ==External links== * [http://www.astro.uni-bonn.de/~pbrosche/ Astronomiae Historia / History of Astronomy] at the Astronomical Institutes of Bonn University. * [http://www.le.ac.uk/has/c41/ Commission 41 (History of Astronomy)] of the [[International Astronomical Union]] (IAU) * [http://www.shastro.org.uk Society for the History of Astronomy] * [http://www.authenticmaya.com/maya_astronomy.htm Mayan Astronomy] * [http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/home.html Caelum Antiquum]: Ancient Astronomy and Astrology at [[LacusCurtius]] * [http://www.giovannipastore.it/CALCOLATORE%20DI%20ANTIKYTHERA.htm The Antikythera Calculator (Italian and English versions) - Ing. 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