What is Hipparchus?
'''Hipparchus''' (greek {{polytonic|Ἵππαρχος}}; ca. [[190 BC]] – ca. [[120 BC]]) was a [[Ancient Greece|Greek]] [[astronomer]], [[geographer]], and [[mathematician]]. He lived in the [[Hellenistic]] period. He was born in [[Nicaea]] (now [[Iznik]], [[Turkey]]), and probably died on the island of [[Rhodes]]. He worked as an astronomer at least from [[147 BC]] to [[127 BC]]. Hipparchus is considered the greatest ancient astronomical observer. Some people see him as the greatest overall astronomer of [[classical antiquity|antiquity]]. Hipparchus was the first Greek whose quantitative and accurate models for the motion of the [[Sun]] and [[Moon]] survive. To do this, he used the observations and perhaps the mathematical techniques accumulated over centuries by the [[Chaldea]]ns from [[Babylonia]]. He had a [[trigonometry|trigonometric]] table. It looks like he solved some problems of [[Polar coordinate system|spherical trigonometry]] with the table. With his solar and lunar theories and his trigonometry, he was perhaps the first to develop a reliable method to predict [[solar eclipse]]s. His other well-known achievements include the discovery of [[precession]], and the compilation of the Hipparchus Catalog, the first comprehensive [[star catalog]] of the western world. He might also have invented the [[astrolabe]], and the [[armillary sphere]] which first appeared during his century and which he used in making the star catalog. It would be three centuries before [[Ptolemy|Claudius Ptolemaeus]]' synthesis of astronomy would make the work of Hipparchus obsolete; it is heavily dependent on it in many areas. Craters on the Moon and on Mars are named for Hipparchus, as are an asteroid and the [[Hipparcos]] satellite. {{Authority control}} [[Category:190 BC births]] [[Category:2nd-century BC deaths]] [[Category:Ancient Greek astronomers]] [[Category:Greek geographers]] {{bio-stub}}