Nicolaus Copernicus was honored recently when Google recognized the 450th anniversary of the scientists's birth with a Google Doodle. The Christian Science Monitor followed with a article which looks at the career of the Polish astronomer.
Copernicus' book, On the Revolutions of the Heavenly Spheres, was published in 1543, disputing the Earth-centered theories of Aristotle.
From the article:
Copernicus's alternative system proposed that the Earth was a planet, and that all planets moved in perfect circles around the sun, which was close to the center of the universe. The Earth also rotates daily, which accounts for the apparent motion of the sun. He correctly noted that the apparent loop-de-loop of the other planets occurs when our planet overtakes another one on its trip around the sun.