Catherine M. Andronik 
Copernicus [PDF ebook] 
Genius of Modern Astronomy

Copernicus worked with primitive scientific instruments to prove that Earth revolved around the sun. The idea of Earth circling the sun is universally accepted today, but this was not always the case. Centuries ago, it was widely believed that the earth stood still and the sun moved. At first, Copernicus was denounced and ridiculed for this belief. Later, scientists with more advanced instruments proved that Earth did indeed revolve around the sun. Many of our modern advances in science would not have been possible without the heliocentric theory of Copernicus.