Moons of Jupiter

Jupiter has 53 named moons and another 26 awaiting official names.

The most massive of the moons are the four Galilean moons: Io, Europa, Ganymede, and Callisto, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun.

This debunked the religious dogma at the time that all objects rotate around the earth.

It helped newton with his theory around gravity and how the solar system was structured to rotate around the sun. 

Notice the moon IO transiting the surface of Jupiter, with Europa further out.