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Many of the works of Ancient Greek scientists ( Mathematicians , ''' 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 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 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 was strongly influenced by the Chaldea ns. The best documented borrowings are those of Hipparchus (2nd century BCE) and Claudius Ptolemy (2nd century CE). INFLUENCES 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. 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 . 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):
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:
POSSIBLE MEANS OF TRANSMISSION All this knowledge was transferred to the 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 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 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 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 ) the courses of both stars (=Sun and Moon) for 600 years were prophecied 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. REFERENCES
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