In his book On the Revolutions of the Heavenly Spheres, Copernicus argued that the sun, not the Earth, was the center of the universe, that the planets (including the Earth) moved around the sun, and that Earth rotates on its axis (which explained why the Sun and other stars seemed to be moving). He got his ideas from Cicero, Plutarch, Heraclides, Ecphantus, and Philolaus. He mentioned that “certain others were of this opinion [that the Earth moves around the sun].” (Spielvogel 480) Copernicus’ new ideas were significant and controversial since before he published his book, the vast majority of the Europeans believed in the geocentric universe. Copernicus’ ideas led some people to question their beliefs in the geocentric universe and humanity’s
