tags: science rhodes astrolabe astronomy greece

Hipparchus (Greek; ca. 190 BC ca. 120 BC) was a Greek astronomer,
geographer, and mathematician of the Hellenistic period.

Hipparchus was born in Nicaea (now Iznik, Turkey), and probably died
on the island of Rhodes. He is known to have been a working astronomer
at least from 147 BC to 127 BC. Hipparchus is considered the greatest
ancient astronomical observer and, by some, the greatest overall
astronomer of antiquity. He was the first Greek whose quantitative and
accurate models for the motion of the Sun and Moon survive. For this
he certainly made use of the observations and perhaps the mathematical
techniques accumulated over centuries by the Chaldeans from Babylonia.
He possessed a trigonometric table, and appears to have solved some
problems of spherical trigonometry. With his solar and lunar theories
and his trigonometry, he may have been the first to develop a reliable
method to predict solar eclipses. His other reputed achievements
include the discovery of precession, the compilation of the first
comprehensive star catalog of the western world, and possibly the
invention of the astrolabe, also of the armillary sphere which first
appeared during his century and was used by him during the creation of
much of the star catalogue. It would be three centuries before
Claudius Ptolemaeus' synthesis of astronomy would supersede the work
of Hipparchus; it is heavily dependent on it in many areas.