An UnSUNg Hero of Astronomy

Yes, when it comes to theories of Heliocentricity, namely those which placed the sun at the centre of the solar system and which we now know to be the case, a Greek got there first. Copernicus revived the theory. In the fourth century BCE, Aristarchus of Samos came to the conclusion that it was more plausible that the earth orbited the sun. His theory was based on his attempts to measure the sun’s distance from the earth by observing the time differences between the different stages of the moon, also using his geometrical knowledge. His investigations led him to believe that the sun must be several times larger than the earth, and, therefore, the smaller body was more likely to orbit the larger one. Between Aristarchus and Copernicus came Claudius Ptolemy’s work ‘On the movements of the Heavenly Spheres’, which claimed to prove the earth was at the centre of the universe (geocentricity). Despite Aristcarchus’ and Copernicus’ theories, the theory had to wait for Kepler and Galileo for acceptance.