Figuring out the neighborhood
From the surface of Earth, the sun and moon look to be about the same size. Other planets are tiny specks of light, and everything seemingly spins around us. But that’s not what our solar system is really like. So, how did we find out what was where, and which way things were moving?
Here are a couple of links with some history.
And here’s a page on ways to notice that the Earth is round.