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( Ptolemy)
Claudius Ptolemaeus (Greek ??a?d??? ?t??eµa??? Klaúdios Ptolemaios; after 83 – 161 AD), known in English as Ptolemy, was an ancient mathematician, geographer, astronomer, and astrologer. He lived in Roman Egypt, and was probably born there in a town in the Thebaid called Ptolemais Hermiou; he died in Alexandria in 161 AD.[1] Ptolemy was the author of several scientific treatises, three of which would be of continuing importance to later Islamic and European science. The first is the astronomical treatise now known as the Almagest (in Greek, ? ?e???? S??ta???, "The Great Treatise", originally ?a??µat??? S??ta???, "Mathematical Treatise"). The second is the Geography, which is a thorough discussion of the geographic knowledge of the Greco-Roman world. The third is the astrological treatise known as the Tetrabiblos ("Four books") in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. Beyond his being considered a member of Alexandria's Greek society, few details of Ptolemy's life are known. He wrote in Ancient Greek; some scholars have concluded that Ptolemy was a Greek,[2] [3] and others, a Hellenized Egyptian.[4][3][5][6] He was often known in later Arabic sources as "the Upper Egyptian",[7] suggesting that he may have had origins in southern Egypt.[6] Ptolemy is also known to have used Babylonian astronomical data.[8][9] The Almagest is the only surviving comprehensive ancient treatise on astronomy. Babylonian astronomers had developed arithmetical techniques for calculating astronomical phenomena; Greek astronomers such as Hipparchus had produced geometric models for calculating celestial motions; Ptolemy, however, claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations. Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets.[10] The Almagest also contains a star catalogue, which is an appropriated version of a catalogue created by Hipparchus. Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky (only the sky Hipparchus could see). Through the Middle Ages it was spoken of as the authoritative text on astronomy, with its author becoming an almost mythical figure, called Ptolemy, King of Alexandria.[11] The Almagest was preserved, like most of Classical Greek science, in Arabic manuscripts (hence its familiar name). Because of its reputation, it was widely sought and was translated twice into Latin in the 12th century, once in Sicily and again in Spain.[12] Ptolemy's model, like those of his predecessors, was geocentric and was almost universally accepted until an equally systematic presentation of a heliocentric geometrical model by Nicolaus Copernicus.
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