Galileo Galilei was a physicist and astronomer whose genius lay in his application of the telescope to the heavens. In his 1610 book 'Sidereus Nuncius' (Starry Messenger), he revealed that the Moon had mountains and craters, and that Jupiter was orbited by four moons. These observations directly contradicted the Church-approved Aristotelian view that the heavens were perfect and unchanging. Galileo’s support for the heliocentric (Sun-centered) model led to his persecution by the Inquisition. He also conducted experiments on motion, demonstrating that all objects fall at the same rate regardless of mass (ignoring air resistance), a direct challenge to ancient physics.