Jupiter

Months passed, and his telescopes improved. On January 7, 1610, he turned his 30 power telescope towards Jupiter, and found three small, bright stars near the planet. One was off to the west, the other two were to the east, all three in a straight line. The following evening, Galileo once again took a look at Jupiter, and found that all three of the stars were now west of the planet, still in a straight line.

Observations over the following weeks lead Galileo to the inescapable conclusion that these small stars were actually small satellites that were rotating about Jupiter. If there were satellites that didnt move around the Earth, wasnt it possible that the Earth was not the center of the universe? Couldnt the Copernican idea of the Sun at the center of the solar system be correct.