Hipparchus

Hipparchus, the first systematic astronomer on record, was born at Nicea, in Bithynia, and flourished between 160 and 125 B.C. Of his personal history nothing is known except that he observed at Rhodes. The only authority we have regarding his researches is the Syntaxis of Ptolemy; from it we learn that Hipparchus discovered the precession of the equinoxes and the eccentricity of the sun's path, determined the length of the solar year and the distances of the sun and moon respectively from the earth, invented the planisphere, drew up a catalogue of 1080 stars, and fixed the geographical position of places on the earth by giving their longitude and latitude. All that we have of his works is a commentary to the poetical description of the stars by Aratus, published in Patavins's Uranologia (1630). See Delambre's Histoire de l'Astronomie Ancienne (Paris, 1817).