Greek geometer from the southern coast of Turkey who postulated that the planets revolved around the Sun and the Sun revolves around the Earth. Apollonius is believed to be the inventor of the system of epicycles and eccentric circles, used extensively by Hipparchus of Nicaea. He also wrote a monumental treatise on conic sections entitled On Conics. In this treatise, the term ellipse was first used.

Additional biographies: MacTutor (St. Andrews), Bonn, Greek and Roman Science and Technology