The Greco-Egyptian scientist who perfected the system of equants, deferents, and epicycles for explaining planetary motion was Claudius Ptolemy. Ptolemy was a prominent astronomer and mathematician who lived in Alexandria, Egypt, during the 2nd century CE. He is best known for his work "Almagest," which presented a comprehensive model of the universe based on the geocentric theory, where Earth is at the center and planets orbit around it in complex paths involving epicycles and deferents.
