hipparchus

noun

1. died 514 b.c., tyrant of Athens 527–514.
2. c190–c125 b.c., Greek astronomer.

noun

1. 2nd century bc, Greek astronomer. He discovered the precession of the equinoxes, calculated the length of the solar year, and developed trigonometry
2. died 514 bc, tyrant of Athens (527–514)

noun

1. a large crater in the SW quadrant of the moon, about 130 kilometres in diameter

1. Greek astronomer who mapped the positions of about 850 stars in the earliest known star chart (129 bce). His observations of the heavens formed the basis of Ptolemy’s Earth-centered model of the universe. He was also a pioneer of trigonometry.