Hipparchus (160-125 BC)

A Greek astronomer who carried out his observations at Rhodes. He discovered the precession of the equinoxes and the eccentricity of the sun's path, determined the length of the solar year, estimated the distances of the sun and moon from the earth, drew up a catalogue of 1080 stars, fixed the geographical position of places by latitude and longitude, and invented trigonometry.

He is believed to have introduced the plane angle unit of the degree and the first trigonometric tables.

See also: Degree, Earth, Moon, Sun.

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Subjects: Famous Scientists & Engineers