Aristarchus of Samos

310 - 230 BC, was an ancient Greek astronomer and mathematician.

He was the first to present a model that placed the Sun at the center of the known universe. This kind of model is known as a heliocentric model. The Earth would revolve around the Sun once a year, and rotate about its axis once a day. 

He suspected that the stars were other bodies like the Sun, farther away from Earth.