Apollonius of Perga

Apollonius built on what Euclid and Archimedes had started, taking the geometry of conic sections to a peak that wouldn't be surpassed until analytic geometry arrived centuries later. Most of his work beyond geometry — including astronomy — is lost, known only through fragments cited by later writers like Pappus. He proposed that planets moved in eccentric orbits to account for their strange wanderings across the sky, a model that held through the Middle Ages before the Renaissance swept it aside. A crater on the Moon carries his name now.