Greek astronomer who discovered the precession of the equinoxes, developed the techniques of trigonometry, and catalogued the positions of 850 stars in the earliest known star chart.
Greek astronomer who mapped the positions of about 850 stars in the earliest known star chart (129 bce ). His observations of the heavens formed the basis of Ptolemy's Earth-centered model of the universe. He was also a pioneer of trigonometry.
It is an extraordinary fact that, if ostracism was introduced in 598 B.C. for the purpose of expelling Hipparchus it was not till twenty years later that he was condemned.
The following is a list of persons who suffered ostracism: - Hipparchus (488); Megacles (487), Xanthippus (485), Aristides (483), Themistocles (471?); Cimon (461?) Thucydides, son of Melesias (444), Damon, Hyperbolus (417) and possibly Cleisthenes himself (q.v.).
The problem of determining an orbit may be regarded as coeval with Hipparchus, who, it is supposed, found the moving positions of the apogee and perigee of the moon's orbit.