Comment by accidentallfact
7 hours ago
The thing that made him question geocentrism was that Venus quite visibly orbits the Sun.
It has always been known that the tides are caused by the Moon. The hard part is to predict the tides in detail, as they depend on the geography as well. Some of the first computers were invented to predict the tides.
Galileo not only actively rejected lunar explanations for the tides, but felt that they were driven purely by the kinetic motion of the Earth - rotation about its own axis + revolution around the Sun. He dismissed the concept of invisible action at a distance -- Newton would be born in the same year that Galileo would die. You can read more about Galileo and his views on the tides here. [1] He felt that this was his most compelling argument for heliocentricism.
[1] - https://galileo.library.rice.edu/sci/observations/tides.html
> Venus quite visibly orbits the Sun
https://en.wikipedia.org/wiki/Tychonic_system
Was already a thing, though.