Hipparchus (CA. 190-CA. 120 BC)

Hipparchus (born in Nicaea) was a Greek geographer and cartographer who was also considered to be one of the greatest astronomers of ancient times. Even though almost all his writings have been lost, his theories have been handed down by Ptolemy and Pliny the Elder.

Hipparchus thought that astronomical observations and methods were fundamental for geographic studies. He was also critical of his predecessor Eratosthenes and argued that the geographer of Cyrene developed his theories without the support of mathematical calculations. His attention also focused on the use of instruments such as the diopter (which measures the angles of light), which enabled him to estimate the size of the sun and the moon and their distance from Earth. Through the use of a gnomon (part of ...