Nicolaus Copernicus was a Polish scientist who is credited with the early 16th-century discovery that the sun is the center of the universe and that Earth and several other planets orbit it. Copernicus' discovery, which subsequent astronomers expanded on, has become known as the heliocentric solar system.
Copernicus' theory was a drastic adjustment to the previous geocentric model, which suggested that the sun and all other planets and stars orbited the Earth. The astronomer also proposed theories on the motion of different planets and stars. He published his findings, which were all based on his naked eye observations, in 1514.