Nicolaus Copernicus (1473–1543) has, by tradition, taken all the credit for establishing the fact of the Earth’s orbit around the sun. Before the publication of his thesis On the Revolutions of the Heavenly Spheres in 1543, and for some time after that, it was generally assumed that the Earth stood still at the centre of a planetary system with the sun, the stars and quite a few of the known planets circling around it. We talk of this change in perception as the ‘Copernican Revolution’ and of the heliocentric principle as ‘Copernicanism’ but, in point of fact, Copernicus was by no means the first to come up with a heliocentric schema. Around 250 BC, according to Archimedes, a philosopher called Aristarchus claimed that ‘the fixed stars and the sun remain unmoved, that the earth revolves about the sun in the circumference of a circle, the sun lying in the middle of the orbit’. Dava Sobel writes that Copernicus ‘had no idea that Aristarchus of Samos had proposed much the same thing in the third century B.C.’ and that he ‘knew nothing of the Earth-moving plan of Aristarchus which had not yet been reported to Latin audiences’.