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Astro*Dictionary by Michael Erlewine





1 article for "Hipparchus"

Hipparchus [Astro*Index]

Greek astrologer and astronomer (BC190-120). Born at Nicaea (now Iznik, Turkey) and may have been educated at Alexandria, but he did not work there; he established his observatory at Rhodes, an island in southeastern part of the Aegean. He invented many instruments used in naked-eye astronomy for the following 1700 years. He is credited with the discovery of the precession of the equinoxes (BC134), although this motion was known to the Babylonian astronomers Niburiannu and Kidinnu, whose solar and lunar tables were sent from Babylon to Greece. He determined the Moon's parallax (and, thus, the Earth-Moon distance), cataloged over a thousand stars, and introducted the concept of the Eccentric, Deferent, and Epicycle to model planetary motions (which provided a basis for Ptolemy's work). He rejected the heliocentric cosmology of Aristarchus in favor of a geocentric one.

See also:
♦ Aristotle ♦ Callisthenes


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