Nothing. Movement is relative, based on your chosen point of origin.
But, I guess your question was, how did we learn about the structure of the solar system, planets and orbits and all...
By observing the planets, you can map out their path, and you can see that they are not orbiting earth. The only sensible explanation is that all the planets, including Earth, must be orbiting the Sun.
Kepler then further observed that the orbits are elliptical, and then postulated Kepler's laws (that planets orbit the sun in an ellipse, with the sun in one of the focuses).
But, I guess your question was, how did we learn about the structure of the solar system, planets and orbits and all...
By observing the planets, you can map out their path, and you can see that they are not orbiting earth. The only sensible explanation is that all the planets, including Earth, must be orbiting the Sun.
Kepler then further observed that the orbits are elliptical, and then postulated Kepler's laws (that planets orbit the sun in an ellipse, with the sun in one of the focuses).