Ptolemy

Ptolemy, Latin in full Claudius Ptolemaeus  (b. c. ad 100—d. c. 170), an Egyptian  astronomer, mathematician, and geographer of Greek descent who flourished in Alexandria during the 2nd century ad. In several fields his writings represent the culminating achievement of Greco-Roman science, particularly his geocentric (Earth-centred) of theuniverse now known as the Ptolemaic system