system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How did Galileo observe that Earth revolves around the Sun? Can an average person today convince themselves of that fact with some basic observations and math?

i.e. without any equipment that is super fancy.
gpt
He didn't. He observed that Jupiter's moons revolved around Jupiter. The previous position supported by the Church was that the Earth was the center of the Universe, and that everything outside it revolved around us. The demonstration that, at least, the four moons he could observe did _not_ revolve around Earth was the final blow to that model. It had already been suggested, long before Galileo, that the planets went around the sun.