eli5: If every frame of reference is valid, why do people say the earth spins around the sun instead of the opposite, wouldn’t both views be equally valid?

Question

eli5: If every frame of reference is valid, why do people say the earth spins around the sun instead of the opposite, wouldn’t both views be equally valid?

In: Physics

Answer 1

Not entirely. If you are looking at the Earth and only the Earth, sure. But when you add any other planet in our solar system – the sun becomes the central entity that the Earth and that other planet both revolve around.

So if your reference is *only* the Earth and the Sun, sure, that can be a valid viewpoint. As soon as you add other planetary objects it becomes invalid.