I first heard of this astronomer in a documentary about Astronomy (though I forgot what documentary that is sadly). He is actually a pioneer in his time for his revolutionary ideas, particularly about the idea that the Sun is the center of the Universe, and that the planet Earth, as with other planets, are revolving around it.
Aristarchus of Samos was an ancient Greek astronomer and Mathematician, who presented a model, the very first of its kind, that actually placed the Sun at the center of the known universe with the Earth revolving around it. Born around 310 B.C.E. (or Before Common Era commonly known as B.C.), that is around 2,300 years ago.
His works unfortunately did not survive but his ideas are known from references by Greek mathematician Archimedes, the Greek biographer Plutarch, and the Greek philosopher Sextus Empiricus. His ideas were rejected at that time in favor of the Geocentric model, which explains that the Earth is the center of the Universe and the Sun and all the planets are circling around it. Ptolemy’s calculation based on this theory was used as the basis for this belief for the next 1,500 years until Nicolaus Copernicus re-ignited the interest for the Heliocentric model which is now a known fact today.
Geocentric Model of the Universe
Picture source: http://outreach.atnf.csiro.au/education/senior/cosmicengine/images/cosmoimg/aristarchus.gif