The Sun and the Moon set astronomy back thousands of years.
As the only two things in the heavens that the ancients could look at and see any detail whatsoever, the fact that the Sun is a brilliant, featureless disk, and the fact that the Moon is a featureful but unchanging disk, kept Ptolemy and the rest of those guys in the dark. It was obvious to everyone that these things up in the sky were two dimensional. They were not spheres, they were heavenly stamps.
This is my example: if the Moon had rotated as it revolved about us, so that it showed a different face, gradually, every night, then it would have been obvious that it was a big ball out there. It is a stupendous coincidence of natural law that it shows us one unchanging surface. This stupendous coincidence allowed people to assume that it was not spherical. And if the Moon wasn’t a sphere, why think that anything else up there was? And if nothing else up there was spherical, why believe that the Earth was round?
There was no obvious reason to think that. It took many different people many lifetimes to convince everyone else that their subtle reasoning that the Earth is a ball, surrounded by other balls, was correct.
I tire myself out right now, just thinking about the inherent difficulty in trying to convince the hoi polloi of thousands of years ago that the earth is round, given the Sun and the Moon.