Because our Earth is in a system called Solar System. I don’t think the answer would be simple as that. Why the Earth could not be the center? Actually it could. As we learn in physic, all motions are relative, like we feel we are still on the Earth, but we actually spin and orbit the Sun. Moreover, we orbit the Sun, in another words that the Sun also orbits us. This doesn’t conflict with motion relative law. But why we are not saying the Sun is orbiting Earth?     Continue Reading