Nicolaus Copernicus proposed the heliocentric model in his work published in 1543, according to NASA Earth Observatory. While the theory of the sun being central was correct, the model in its entirety held many inaccuracies. Because the heliocentric model was initially pieced together without a telescope, all observations had to be made with the naked eye and simple instruments. The positions of planets were predicted largely by observing their position and size against the stars.

Source: Space.com