I'm trying to get my head around GR. As I understand it, any frame of reference is as valid as any other for modeling the universe. Therefore, it is valid to use a non-rotating Earth as a frame of reference, and try to model the movement that is seen from this frame. But if that is true, I would view the Sun as rotating around the Earth once a day. That would that mean that the Sun would be moving at approximately 11,000 Km/s if you do the math. That doesn't seem very reasonable, but even worse is if you start thinking about stars that are further away. If you calculate their speed, they must be moving faster than the speed of light, in order to orbit the Earth in a single day. How can this be possible? Can anyone please explain how to resolve this?