Question

Apply Newton’s third law to a falling boulder, identifying the action and reaction forces. If a force is exerted on the earth, why doesn’t it move? Explain.

Answer 1

They are orders of magnitude different in mass. The earth does move, everything with mass exerts "some" gravity. It appears as the earth doesn't move, its just so minutely immeasurable that you can't feel it. The earth is our frame of reference for almost all things in life, it feels still but it obviously moves.