Claudius Ptolemy

Ptolemy was an Egyptian astronomer, mathematician, and geographer of Greek descent who flourished in Alexandria during the 2nd century. In several fields his writings represent the culminating achievement of Greco-Roman science, particularly his geocentric model of the universe now known as the Ptolemaic system. His first major astronomical work, the Almagest, was completed about 150 ce and contains reports of astronomical observations that Ptolemy had made over the preceding quarter of a century.