"If the Sun were magically replaced with a giant rock that had precisely the same mass, Earth’s orbit would not change. Explain why not."

Question

I'm a little confused as to how to answer this. Is it because Earth doesn't orbit the exact center of the sun. Instead, both Earth and the Sun orbit their common center of mass. Therefore, if this new giant rock, has the same mass, it wouldn't make a difference to Earth's orbit.
Thanks

Answer 1

Earth's orbit would not change. The two masses remain the same, and that is what the causes the graivty which maintains orbit.