Aristarchus of Samos (310-230 BC)
Aristarchus of Samos was an ancient Greek astronomer and mathematician who presented the first known model that placed the Sun at the center of the known universe with the Earth revolving around it. He belonged to the so-called Pythagorean school of thought, which sought to understand the universe in terms of geometrical and arithmetical relationships.
Aristarchus' only surviving text is his “Treatise on the Sizes and Distances of the Sun and Moon.” However, largely through the writings of Archimedes (287–212 BC) and Plutarch, Aristarchus is known to have the first proponent of the heliocentric hypothesis, an astronomical model in which the Earth and planets revolve around the Sun at the center of the Universe, and the earth rotates daily on its axis. Aristarchus argued that the lack of observed annual parallax in the fixed stars could be explained, within his heliocentric model, by assuming that the distance to the fixed stars is very much larger than the size of the Earth's orbit. The very same argument was to be made by Nicholas Copernicus, seventeen centuries later.
Heath, T. 1913, Aristarchus of Samos. The ancient Copernicus,Oxford: Clarendon Press [1997 reprint].
Porter, R. (ed.) 1994, The biographical dictionary of scientists,Oxford University Press