Astronomical theory

The Greeks pioneered enormous developments in astronomical theory. Aristotle disproved Anaximander’s theory that the Earth floats freely and without support; Pythagoras was probably the first man to ‘know’ (if without proof) that the world was one of the planets, and round. This theory, first put forward it seems by Philolaus of Thebes at the end of the 5th century BC, was based on intuition rather than on reason, but the guess was an important one. It was clear by this time, too — at least to some astronomers — that the Sun was much larger than the Earth, and therefore probably the latter was not the centre of the universe. And by 230 BC, Aristarchus of Samos, centuries before Copernicus, argued that the Earth and all the planets revolved in circles round the Sun, the Earth turning on its axis once in twenty-four hours. But the time was against him, and only his colleague Seleucus accepted his theory, which otherwise sank like a stone — although Copernicus was heartened, pursuing it in his own age, to find evidence of an ancient conviction of the hypothesis.