Picture of Hipparchus Courtesy of Corbis-Bettmann

Hipparchus was a Greek astronomer who lived between 190-120 B.C. He created the first accurate star map and kept a catalogue of over 850 stars with their relative brightnesses. He also developed the system of epicycles (where everything in space moved in perfect circles) for the planets that both agreed with observation, and preserved the Earth-centered universe of Aristotle.

Hipparchus compiled a table of chord lengths, similar to modern trigonometry tables, and is considered the founder of trigonometry, a branch of mathematics which studies the angles of sides of triangles.