Galileo Galilei was a highly prolific thinker and inventor who lived during the 16th and 17th centuries. He made several important contributions to the fields of philosophy, astronomy, physics, mathematics and cosmology. One of his accomplishments was discovering Jupiter's four largest moons through his improved telescope.
Discovering Jupiter's moons made Galileo famous, causing the Medici family to propel him to a position of prestige and power. Galileo used his new authority to proclaim his own theories about the solar system and universe, many of which contradicted existing theories that had been established by the Greek philosopher Aristotle. Galileo's theories were not welcomed by the Church, and he was sentenced to house arrest on suspicion of heresy.