Hipparchus

Hipparchus of Nicaea was the greatest astronomer of antiquity, working chiefly on Rhodes in the 2nd century BCE. By comparing his own measurements with older Babylonian and Greek records he discovered the slow precession of the equinoxes, and he founded much of the mathematical machinery — including an early form of trigonometry — that later astronomers relied on.

• Compiled one of the first comprehensive star catalogues
• Discovered the precession of the equinoxes
• Devised the apparent-magnitude scale of stellar brightness

• Precession of the Equinoxesc. 130 BCE

• StudiesThe Milky Way
• Part ofGreek Astronomy
• InfluencedPtolemy
• DiscoveredPrecession of the Equinoxes