In the sixteenth century, Nicolas Copernicus revived an idea originating with early Greek philosophers that the Sun, instead of the Earth, resided at the center of the solar system. Subsequent observations by Galileo and others validated the Copernican, or heliocentric, view (for a brief introduction to the conflict between Galileo and the Roman Catholic Church, look here.) In the early 1920s, Harlow Shapley correctly argued that the sun did not reside at the center of the Milky Way Galaxy (MWG). Shortly afterward, Edwin Hubble demonstrated that other galaxies similar to the Milky Way existed and that the MWG did not reside at the center of the universe.