What evidence did Galileo use to defend the Heliocentric Theory?
He did not have as much evidence as what people give him credit for. He based his “proof” on the idea that the other system (geocentric) could not explain some of his observations: 1) satellites in orbit around Jupiter (he called them planets as they were wandering celestial bodies = ‘aster planetes’ in Greek; the concept of satellites did not exist yet); Say what you want, this certainly does not prove that things orbit the Sun. It could have been great evidence if he had wanted to prove that Jupiter was the centre… 2) Venus and Mercury showed crescent phases at some point in their orbit. This would be impossible if Venus and Mercury were orbiting Earth. Alas, other astronomers were already using a “mixed system” with Venus and Mercury going around the Sun, with the Sun going around Earth. Therefore, the mixed system explained the phases of Venus and Mercury just as easily. His lack of solid proofs is part of the reason why he got into so much trouble. If he had had solid proof, the
