Galileo Galilei was an Italian genius that is famous for many things, most notably for his contributions to astronomy. He is responsible for discovering Jupiter's four moons, advancing telescope technology and declaring that the Earth revolves around the sun.
Galileo was an astronomer, philosopher, mathematician and engineer. Many of his contributions to the world have been said to have started the scientific revolution. When Galileo declared that the Earth revolved around the sun, he was accused of heresy because this contradicted what was written in the Bible. As a sick old man under arrest, he took back his statement to be allowed to live out his days in Florence.