Galileo Galilei was an Italian astronomer, physicist and engineer who played a major role in the scientific revolution. Through his telescope observations, he discovered that the moon was not smooth but had mountains and craters, and that Jupiter had moons orbiting it. His observations supported the heliocentric model of the solar system and contradicted the geocentric model advocated by the Catholic Church. Despite his scientific contributions, Galileo was eventually tried by the Inquisition and forced to recant his heliocentric views.