The idea that the Sun is at the centre of the Solar System seems to fly in the face of the ‘obvious’ fact that it moves across the sky, along with all the other planets. Combine that with religious doctrine about the Earth being the focus of everything, and it’s small wonder that the so-called ‘heliocentric theory’ only became established in the 16th Century.
Credit for that goes to the Polish astronomer Nicolaus Copernicus, whose treatise On The Revolutions Of The Heavenly Spheres (1543) argued that the Sun’s motion was the result of the Earth spinning on its axis. Even so, Copernicus kept the ancient notion of the Solar System being made up of concentric spheres, within which the planets moved on gear-like ‘epicycles’.
Nor was Copernicus the first person to put the Sun at the centre of it all. Around 1,800 years earlier, the Greek astronomer Aristarchus of Samos had also proposed the same idea. In common with some earlier scholars, he argued that the Earth rotated on its axis, but he also realised that this raised the possibility that the Sun’s apparent movement across the sky might be an illusion. Unfortunately for Aristarchus, he was so far ahead of his time he was unable to provide any clinching evidence.