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Hipparchus of Nicaea (; (ギリシア語:Ἵππαρχος, ''Hipparkhos''); ), was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry but is most famous for his incidental discovery of precession of the equinoxes.〔G J Toomer's chapter "Ptolemy and his Greek Predecessors" in "Astronomy before the Telescope", British Museum Press, 1996, p. 81.〕 Hipparchus was born in Nicaea, Bithynia (now Iznik, Turkey), and probably died on the island of Rhodes. He is known to have been a working astronomer at least from 162 to 127 . Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and other people from Mesopotamia. He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses. His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first comprehensive star catalog of the western world, and possibly the invention of the astrolabe, also of the armillary sphere, which he used during the creation of much of the star catalogue. It would be three centuries before Claudius Ptolemaeus' synthesis of astronomy would supersede the work of Hipparchus. ==Life and work== Relatively little of Hipparchus's direct work survives into modern times. Although he wrote at least fourteen books, only his commentary on the popular astronomical poem by Aratus was preserved by later copyists. Most of what is known about Hipparchus comes from Strabo's ''Geography'' and Pliny's ''Natural History'' in the 1st century; Ptolemy's 2nd-century ''Almagest''; and additional references to him in the 4th century by Pappus of Alexandria and Theon of Alexandria in their commentaries on the ''Almagest''.〔For general information on Hipparchus see the following biographical articles: G. J. Toomer, "Hipparchus" (1978); and A. Jones, "Hipparchus."〕 There is a strong tradition that Hipparchus was born in Nicaea (Greek ''Νίκαια''), in the ancient district of Bithynia (modern-day Iznik in province Bursa), in what today is the country Turkey. The exact dates of his life are not known, but Ptolemy attributes to him astronomical observations in the period from 147–127 , and some of these are stated as made in Rhodes; earlier observations since 162 might also have been made by him. His birth date ( ) was calculated by Delambre based on clues in his work. Hipparchus must have lived some time after 127 because he analyzed and published his observations from that year. Hipparchus obtained information from Alexandria as well as Babylon, but it is not known when or if he visited these places. He is believed to have died on the island of Rhodes, where he seems to have spent most of his later life. It is not known what Hipparchus's economic means were nor how he supported his scientific activities. His appearance is likewise unknown: there are no contemporary portraits. In the 2nd and 3rd centuries coins were made in his honour in Bithynia that bear his name and show him with a globe; this supports the tradition that he was born there. Hipparchus is thought to be the first to calculate a heliocentric system, but he abandoned his work because the calculations showed the orbits were not perfectly circular as believed to be mandatory by the science of the time. As an astronomer of antiquity his influence, supported by ideas from Aristotle, held sway for nearly 2000 years, until the heliocentric model of Copernicus. Hipparchus's only preserved work is ''Τῶν Ἀράτου καὶ Εὐδόξου φαινομένων ἐξήγησις'' ("Commentary on the Phaenomena of Eudoxus and Aratus"). This is a highly critical commentary in the form of two books on a popular poem by Aratus based on the work by Eudoxus.〔Modern edition: Karl Manitius (''In Arati et Eudoxi Phaenomena'', Leipzig, 1894).〕 Hipparchus also made a list of his major works, which apparently mentioned about fourteen books, but which is only known from references by later authors. His famous star catalog was incorporated into the one by Ptolemy, and may be almost perfectly reconstructed by subtraction of two and two thirds degrees from the longitudes of Ptolemy's stars. The first trigonometric table was apparently compiled by Hipparchus, who is now consequently known as "the father of trigonometry". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hipparchus」の詳細全文を読む スポンサード リンク
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