Simplification: Galileo Galilei and Johannes Kepler, two other scientists, helped to prove that Copernicus's idea was right. <SEP> They looked at how the moons of some planets moved in the sky, and they used this to prove Copernicus right.
Nearly a century later, Galileo Galilei, an Italian scientist, and Johannes Kepler, a German scientist, studied how the moons of some planets moved in the sky, and used their observations to validate Copernicus's thinking.