1564-1642
Referred to as the "father of modern astronomy, physics, and science," Galileo didn't invent the telescope, but was the first to use it well. By making improvements to existing technology, he discovered Jupiter's four largest moons, which helped him verify a Sun-centered model for the solar system (which defied the Church's belief that Earth was at the center of it all). He was also the first to spot Saturn's rings.