Ptolemy, Claudius (120–170)



  • Egyptian astronomer who developed the theory of deferents and epicycles to explain the apparent movements of the Moon and planets in an Earth-centred universe. His main work on astronomy is now known by its Arabic title of the Almagest, and was the definitive work on western astronomy until the time of Copernicus. Ptolemy also worked on optics and astrology, and has been accused on faking observations on a virtually industrial scale.