2nd century Greek astronomer, geographer and mathematician

Hipparchus of Nicaea (c. 190 – c. 120 BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry but is most famous for his incidental discovery of precession of the equinoxes.

A portrait of Hipparchus of Nicaea from "The School of Athens" by Raphael.


  • I have composed a book on the length of the year in which I show that the tropical year contains 365 days plus a fraction of a day which is not exactly 1/4 days as the mathematicians-astronomers suppose, but which is less than 1/4 by about 1/300.

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