Babylonian astronomy 4536514 225181244 2008-07-12T09:15:51Z 81.208.13.171 '''Babylonian astronomy''' refers to the [[astronomy|astronomical]] theories and methods that were developed in ancient [[Mesopotamia]], the "land between the rivers" [[Tigris]] and [[Euphrates]] (modern southern [[Iraq]]), where the ancient kingdoms of [[Sumer]], [[Akkad]], [[Babylonia]] and [[Chaldea]] were located. Babylonian astronomy was the basis for much of the astronomical traditions that later developed in [[Greek astronomy|Greek and Hellenistic astronomy]], in classical [[Indian astronomy]], in [[Sassanid Empire|Sassanid]], [[Byzantine Empire|Byzantine]] and [[History of Syria|Syrian]] astronomy, in medieval [[Islamic astronomy]], and in [[Western Europe]]an astronomy.<ref name=dp1998>{{Harvtxt|Pingree|1998}}</ref> The origins of [[Western culture|Western]] astronomy can be found in Mesopotamia. 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 degrees, of 60 minutes each, began with the Sumerians. For more information, see the articles on [[Babylonian numerals]] and [[Babylonian mathematics|mathematics]]. During the 8th and 7th centuries BC, Babylonian astronomers developed a new [[Empiricism|empirical]] approach to astronomy. They began studying [[philosophy]] dealing with the ideal nature of the [[universe]] and began employing an [[Consistency proof|internal logic]] within their predictive planetary systems. This was an important contribution to astronomy and the [[philosophy of science]], and some scholars have thus referred to this new approach as the first '''scientific revolution'''.<ref>D. Brown (2000), ''Mesopotamian Planetary Astronomy-Astrology '', Styx Publications, ISBN 9056930362.</ref> This new approach to astronomy was adopted and further developed in Greek and Hellenistic astronomy. Classical [[Greek language|Greek]] and [[Latin]] 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]]. ==Old Babylonian astronomy== Old Babylonian astronomy refers to the astronomy that was practiced during and after the [[First Babylonian Dynasty]] and before the [[Neo-Babylonian Empire]]. The Babylonians were the first to recognize that astronomical phenomena are periodic and apply mathematics to their predictions. Tablets dating back to the [[First Babylonian Dynasty|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 ''[[Enûma Anu Enlil]]'' — the oldest significant astronomical text that we possess is Tablet 63 of the ''Enûma Anu Enlil '', the [[Venus tablet of Ammisaduqa]], which lists the first and last visible risings of Venus over a period of about 21 years. It is the earliest evidence that planetary phenomena were recognized as periodic. The [[MUL.APIN]], contains catalogues of stars and constellations as well as schemes for predicting [[heliacal rising]]s and settings of the planets, and lengths of daylight as 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> There are dozens of cuneiform Mesopotamian texts with real observations of eclipses, mainly from Babylonia. ==Neo-Babylonian astronomy== Neo-Babylonian astronomy refers to the astronomy developed by [[Chaldea]]n astronomers during the [[Neo-Babylonian Empire|Neo-Babylonian]], [[Seleucid Empire|Seleucid]] and [[Parthia]]n periods of Mesopotamian history. A significant increase in the quality and frequency of Babylonian observations appeared during the reign of [[Nabonassar]] (747-733 BC), who founded the [[Neo-Babylonian Empire]]. 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 [[Ancient Egypt|Egyptian]] 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. ===Empirical astronomy=== Most of the Chaldean astronomers were concerned exclusively with [[Ephemeris|ephemerides]], and not with theory. The predictive Babylonian planetary models were usually strictly [[Empiricism|empirical]] and [[arithmetic]]al, and usually did not involve [[geometry]], [[cosmology]] or speculative [[philosophy]] like that of the later [[Greek astronomy|Hellenistic models]],<ref>[[George Sarton]] (1955). "Chaldaean Astronomy of the Last Three Centuries B. C.", ''Journal of the American Oriental Society'' '''75''' (3), p. 166-173 [169-170].</ref> though the Babylonian astronomers were concerned with philosophy dealing with the ideal nature of the early [[universe]].<ref>D. Brown (2000), ''Mesopotamian Planetary Astronomy-Astrology '', Styx Publications, ISBN 9056930362.</ref> Contributions made by the Chaldean astronomers during this period include the discovery of [[eclipse cycle]]s and [[saros cycle]]s, and many accurate astronomical observations. Chaldean astronomers known to have followed this model include [[Naburimannu]] (fl. 6th-3rd century BC), [[Kidinnu]] (d. 330 BC), [[Berossus]] (3rd century BC), and [[Sudines]] (fl. 240 BC). They are known to have had a significant influence on the [[Greek astronomy|Greek astronomer]] [[Hipparchus]] and the [[Ancient Egypt|Egyptian]] astronomer [[Ptolemy]], as well as other [[Hellenistic civilization|Hellenistic]] astronomers. ===Heliocentric astronomy=== {{main|Seleucus of Seleucia}} The only [[Chaldea]]n astronomer known to have supported a [[heliocentrism|heliocentric]] model of planetary motion was [[Seleucus of Seleucia]] (b. [[190 BC]]).<ref>[[Otto E. Neugebauer]] (1945). "The History of Ancient Astronomy Problems and Methods", ''Journal of Near Eastern Studies'' '''4''' (1), p. 1-38.</ref><ref>[[George Sarton]] (1955). "Chaldaean Astronomy of the Last Three Centuries B. C.", ''Journal of the American Oriental Society'' '''75''' (3), p. 166-173 [169].</ref><ref>William P. D. Wightman (1951, 1953), ''The Growth of Scientific Ideas'', Yale University Press p.38.</ref> Seleucus is known from the writings of [[Plutarch]]. He supported the heliocentric theory where the [[Earth's rotation|Earth rotated]] around its own axis which in turn revolved around the [[Sun]]. According to [[Plutarch]], Seleucus even proved the heliocentric system, but it is not known what arguments he used. According to [[Lucio Russo]], his arguments were probably related to the phenomenon of [[tide]]s.<ref>[[Lucio Russo]], ''Flussi e riflussi'', Feltrinelli, Milano, 2003, ISBN 88-07-10349-4.</ref> Seleucus correctly theorized that [[tide]]s were caused by the [[Moon]], although he believed that the interaction was mediated by the [[Earth's atmosphere]]. He noted that the tides varied in time and strength in different parts of the world. According to [[Strabo]] (1.1.9), Seleucus was the first to state that the [[tide]]s are due to the attraction of the Moon, and that the height of the tides depends on the Moon's position relative to the Sun.<ref>[[Bartel Leendert van der Waerden]] (1987). "The Heliocentric System in Greek, Persian and Hindu Astronomy", ''Annals of the New York Academy of Sciences'' '''500''' (1), 525–545 [527].</ref> According to [[Bartel Leendert van der Waerden]], Seleucus may have proved the heliocentric theory by determining the constants of a [[geometry|geometric]] model for the heliocentric theory and by developing methods to compute planetary positions using this model. He may have used [[trigonometry|trigonometric]] methods that were available in his time, as he was a contemporary of [[Hipparchus]].<ref>[[Bartel Leendert van der Waerden]] (1987). "The Heliocentric System in Greek, Persian and Hindu Astronomy", ''Annals of the New York Academy of Sciences'' '''500''' (1), 525–545 [527-529].</ref> ==Babylonian influence on Hellenistic astronomy== Many of the works of ancient [[Ancient Greece|Greek]] and [[Hellenistic civilization|Hellenistic]] writers (including [[Greek mathematics|mathematicians]], [[Greek astronomy|astronomers]], and [[geographers]]) have been preserved up to the present time, or some aspects of their work and thought are still known through later references. However, achievements in these fields by earlier [[ancient Near East]]ern civilizations, notably those in [[Babylonia]], were forgotten for a long time. Since the discovery of key archaeological sites in the 19th century, many [[cuneiform script|cuneiform]] writings on [[clay tablet]]s have been found, some of them related to [[astronomy]]. Most known astronomical tablets have been described by Abraham Sachs and later published by [[Otto Neugebauer]] in the ''Astronomical Cuneiform Texts'' (''ACT''). Since the rediscovery of the Babylonian civilization, it has become apparent that [[Greek astronomy|Hellenistic astronomy]] was strongly influenced by the [[Chaldea]]ns. The best documented borrowings are those of [[Hipparchus]] (2nd century BCE) and Claudius [[Ptolemy]] (2nd century CE). ===Early influence=== Many scholars agree that the [[Metonic cycle]] is likely to have been learned by the Greeks from Babylonian scribes. [[Meton of Athens]], a Greek astronomer of the 5th century BCE, developed a [[lunisolar calendar]] based on the fact that 19 solar years is about equal to 235 lunar months, a period relation already known to the Babylonians. In the fourth century, [[Eudoxus of Cnidus]] wrote a book on the [[fixed star]]s. His descriptions of many constellations, especially the twelve signs of the [[zodiac]], are suspiciously similar to Babylonian originals. The following century [[Aristarchus of Samos]] used an eclipse cycle of Babylonian origin called the [[Saros cycle]] to determine the year length. However, all these examples of early influence must be inferred and the chain of transmission is not known. ===Influence on Hipparchus and Ptolemy=== In 1900, Franz Xaver Kugler demonstrated that Ptolemy had stated in his ''[[Almagest]]'' IV.2 that Hipparchus improved the values for the Moon's periods known to him from "even more ancient astronomers" by comparing eclipse observations made earlier by "the Chaldeans", and by himself. However Kugler found that the periods that Ptolemy attributes to Hipparchus had already been used in Babylonian [[ephemerides]], specifically the collection of texts nowadays called "System B" (sometimes attributed to [[Kidinnu]]). Apparently Hipparchus only confirmed the validity of the periods he learned from the Chaldeans by his newer observations. Later Greek knowledge of this specific Babylonian theory is confirmed by second-century papyrus, which contains 32 lines of a single column of calculations for the Moon using this same "System B", but written in Greek on papyrus rather than in cuneiform on clay tablets.<ref>Asger Aaboe, ''Episodes from the Early History of Astronomy'', New York: Springer, 2001), pp. 62-5; Alexander Jones, "The Adaptation of Babylonian Methods in Greek Numerical Astronomy," in ''The Scientific Enterprise in Antiquity and the Middle Ages'', p. 99</ref> It is clear that Hipparchus (and Ptolemy after him) had an essentially complete list of eclipse observations covering many centuries. Most likely these had been compiled from the "diary" tablets: these are clay tablets recording all relevant observations that the Chaldeans routinely made. Preserved examples date from [[652 BC]] to [[130|AD 130]], but probably the records went back as far as the reign of the Babylonian king [[Nabonassar]]: Ptolemy starts his chronology with the first day in the Egyptian calendar of the first year of Nabonassar, i.e., 26 February, [[747 BC]]. This raw material by itself must have been hard to use, and no doubt the Chaldeans themselves compiled extracts of e.g., all observed eclipses (some tablets with a list of all eclipses in a period of time covering a [[saros]] have been found). This allowed them to recognise periodic recurrences of events. Among others they used in System B (cf. ''Almagest'' IV.2): * 223 ([[synodic]]) months = 239 returns in anomaly ([[anomalistic month]]) = 242 returns in latitude ([[draconic month]]). This is now known as the [[saros]] period which is very useful for predicting [[eclipse]]s. * 251 (synodic) months = 269 returns in anomaly * 5458 (synodic) months = 5923 returns in latitude * 1 [[synodic month]] = 29;31:50:08:20 days (sexagesimal; 29.53059413... days in decimals = 29&nbsp;days 12&nbsp;hours 44&nbsp;min 3⅓&nbsp;s) The Babylonians expressed all periods in synodic [[month]]s, probably because they used a [[lunisolar calendar]]. Various relations with yearly phenomena led to different values for the length of the year. Similarly various relations between the periods of the [[planet]]s were known. The relations that Ptolemy attributes to Hipparchus in ''Almagest'' IX.3 had all already been used in predictions found on Babylonian clay tablets. Other traces of Babylonian practice in Hipparchus' work are: * first Greek known to divide the circle in 360 [[degree (angle)|degrees]] of 60 [[arc minute]]s. * first consistent use of the [[sexagesimal]] number system. * the use of the unit ''pechus'' ("cubit") of about 2° or 2½°. * use of a short period of 248 days = 9 anomalistic months. ===Means of transmission=== All this knowledge was transferred to the [[Greeks]] probably shortly after the conquest by [[Alexander the Great]] ([[331 BC]]). According to the late classical philosopher [[Simplicius of Cilicia|Simplicius]] (early [[6th century AD]]), Alexander ordered the translation of the historical astronomical records under supervision of his chronicler [[Callisthenes|Callisthenes of Olynthus]], who sent it to his uncle [[Aristotle]]. It is worth mentioning here that although Simplicius is a very late source, his account may be reliable. He spent some time in exile at the [[Sassanid]] (Persian) court, and may have accessed sources otherwise lost in the West. It is striking that he mentions the title ''tèresis'' (Greek: guard) which is an odd name for a historical work, but is in fact an adequate translation of the Babylonian title ''massartu'' meaning "guarding" but also "observing". Anyway, Aristotle's pupil [[Callippus|Callippus of Cyzicus]] introduced his 76-year cycle, which improved upon the 19-year [[Metonic cycle]], about that time. He had the first year of his first cycle start at the summer solstice of [[28 June]] [[330 BC]] ([[Julian calendar|Julian]] [[proleptic]] date), but later he seems to have counted lunar months from the first month after Alexander's decisive battle at [[Gaugamela]] in fall [[331 BC]]. So Callippus may have obtained his data from Babylonian sources and his calendar may have been anticipated by Kidinnu. Also it is known that the Babylonian priest known as [[Berossus]] wrote around [[281 BC]] a book in [[Greek language|Greek]] on the (rather mythological) history of Babylonia, the ''Babyloniaca'', for the new ruler [[Antiochus I]]; it is said that later he founded a school of [[astrology]] on the Greek island of [[Kos]]. Another candidate for teaching the Greeks about Babylonian [[astronomy]]/[[astrology]] was [[Sudines]] who was at the court of [[Attalus I|Attalus I Soter]] late in the [[3rd century BC]]. In any case, the translation of the astronomical records required profound knowledge of the [[cuneiform script]], the language, and the procedures, so it seems likely that it was done by some unidentified Chaldeans. Now, the Babylonians dated their observations in their lunisolar calendar, in which months and years have varying lengths (29 or 30 days; 12 or 13 months respectively). At the time they did not use a regular calendar (such as based on the [[Metonic cycle]] like they did later), but started a new month based on observations of the [[New Moon]]. This made it very tedious to compute the time interval between events. What Hipparchus may have done is transform these records to the [[Egyptian calendar]], which uses a fixed year of always 365 days (consisting of 12 months of 30 days and 5 extra days): this makes computing time intervals much easier. Ptolemy dated all observations in this calendar. He also writes that "All that he (=Hipparchus) did was to make a compilation of the planetary observations arranged in a more useful way" (''Almagest'' IX.2). Pliny states (''Naturalis Historia'' II.IX(53)) on eclipse predictions: "After their time (=[[Thales]]) the courses of both stars (=Sun and Moon) for 600 years were prophesied by Hipparchus, ...". This seems to imply that Hipparchus predicted eclipses for a period of 600 years, but considering the enormous amount of computation required, this is very unlikely. Rather, Hipparchus would have made a list of all eclipses from Nabonasser's time to his own. ==Later astronomy in Mesopotamia== ===Sassanid astronomy=== The capital of the [[Sassanid Empire]], the city of [[Ctesiphon]], was founded in Mesopotamia. Astronomy was studied by [[Persian people|Persians]] and Babylonians in Ctesiphon and in the [[Academy of Gundishapur]] in [[Persian Empire|Persia]]. Most of the astronomical texts during the Sassanid period were written in the [[Middle Persian]] language. The ''[[Zij|Zij al-Shah]]'', a collection of astronomical tables compiled in Persia and Mesopotamia over two centuries, was the most famous astronomical text from the Sassanid period, and was later translated into [[Arabic language|Arabic]]. ===Islamic astronomy=== {{main|Islamic astronomy}} After the [[Islamic conquest of Persia]], the province of Mesopotamia came to be known as [[Iraq]] in the [[Arabic language]]. During the [[Abbasid]] period of Mesopotamian history, [[Baghdad]] was the capital of the [[Arab Empire]], and for centuries, remained the centre of astronomical activity throughout the [[Islamic Golden Age|Islamic world]]. Astronomy was also studied in [[Basra]] and other Iraqi cities. During the Islamic period, Arabic was adopted as the language of scholarship, and Iraq continued to make numerous contributions to the field of astronomy, up until the [[Battle of Baghdad (1258)|sack of Baghdad]] in 1258. ==See also== {{Astronomy portal}} {{ANE portal}} *[[Babylonian astrology]] *[[Babylonian calendar]] *[[Babylonian mathematics]] *[[History of astronomy#Mesopotamia|History of astronomy]] (Section on Mesopotamia) ==Notes== {{reflist}} ==References== * Aaboe, Asger. ''Episodes from the Early History of Astronomy''. New York: Springer, 2001. ISBN 0-387-95136-9 * Jones, Alexander. "The Adaptation of Babylonian Methods in Greek Numerical Astronomy." ''Isis'', 82(1991): 441-453; reprinted in Michael Shank, ed. ''The Scientific Enterprise in Antiquity and the Middle Ages''. Chicago: Univ. of Chicago Pr., 2000. ISBN 0-226-74951-7 * Kugler, F. X. ''Die Babylonische Mondrechnung'' ("The Babylonian lunar computation.") Freiburg im Breisgau, 1900. * [[Neugebauer]], Otto. ''Astronomical Cuneiform Texts''. 3 volumes. London:1956; 2nd edition, New York: Springer, 1983. (Commonly abbreviated as ''ACT''). * Toomer, G. J. "Hipparchus and Babylonian Astronomy." In ''A Scientific Humanist: Studies in Memory of Abraham Sachs'', ed. Erle Leichty, Maria deJ. Ellis, and Pamela Gerardi, pp. 353-362. Philadelphia: Occasional Publications of the Samuel Noah Kramer Fund 9, 1988. [[Category:Babylonian astronomy| ]] [[it:Astronomia babilonese]]