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The first trigonometric table was apparently compiled by Hipparchus, who is consequently now known as "the father of trigonometry".įurther information: Babylonian astronomyĮarlier Greek astronomers and mathematicians were influenced by Babylonian astronomy to some extent, for instance the period relations of the Metonic cycle and Saros cycle may have come from Babylonian sources (see " Babylonian astronomical diaries"). 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. Hipparchus also made a list of his major works that apparently mentioned about fourteen books, but which is only known from references by later authors. This is a highly critical commentary in the form of two books on a popular poem by Aratus based on the work by Eudoxus. Although a contemporary of Hipparchus', Seleucus of Seleucia, remained a proponent of the heliocentric model, Hipparchus' rejection of heliocentrism was supported by ideas from Aristotle and remained dominant for nearly 2000 years until Copernican heliocentrism turned the tide of the debate. Hipparchus was amongst 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. Most of what is known about Hipparchus comes from Strabo's Geography and Pliny's Natural History in the first century Ptolemy's second-century Almagest and additional references to him in the fourth century by Pappus and Theon of Alexandria in their commentaries on the Almagest. Although he wrote at least fourteen books, only his commentary on the popular astronomical poem by Aratus was preserved by later copyists. Relatively little of Hipparchus's direct work survives into modern times. In the second and third centuries, coins were made in his honour in Bithynia that bear his name and show him with a globe. He is believed to have died on the island of Rhodes, where he seems to have spent most of his later life. Hipparchus obtained information from Alexandria as well as Babylon, but it is not known when or if he visited these places. Hipparchus must have lived some time after 127 BC because he analyzed and published his observations from that year. 190 BC) was calculated by Delambre based on clues in his work. The exact dates of his life are not known, but Ptolemy attributes astronomical observations to him in the period from 147 to 127 BC, and some of these are stated as made in Rhodes earlier observations since 162 BC might also have been made by him. Hipparchus was born in Nicaea (Greek Νίκαια), in Bithynia.
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