PBS
Pbs Learning Media: Galileo: Sun Centered System
In the early 1600s, most people believed that the Sun revolved around a stationary Earth. This video segment adapted from NOVA tells how Galileo proved that the Sun, not Earth, is at the center of our universe.
Wolfram Research
Wolfram Science World: Copernicus, Nicolaus (1473 1543)
A biography of Nicolaus Copernicus and his contribution to science, specifically astronomy.