Portrait of Nicholas Copernicus Image courtesy of SPL/Photo Researchers

Nicholas Copernicus was a Polish astronomer who lived between 1473-1543. Before his time, people believed in the Ptolemaic model of the solar system, which maintained that the Earth was the center of the universe.

Copernicus changed this belief when he introduced the heliocentric model, centered around the sun. He claimed that all the planets, including Earth, moved in orbits around the sun, and showed how this new system could accurately calculate the positions of the planets.