Copernicus, for one, was a Renaissance-era astronomer and mathematician who is best known for his heliocentric model of the universe. He proposed that the Sun, not the Earth, was the center of the universe, and that the planets revolved around it. His work revolutionized astronomy and paved the way for modern science. He was also a STARGAZER, which is someone who observes stars and other celestial bodies. Additionally, he discovered a CRATER on the Moon which is now named after him.