The expansion of space does not affect gravity or the size of Earth, as gravity and other fundamental forces dominate at smaller scales. Even if space expands within atoms, the effect is negligible compared to the forces that hold atoms and larger objects together. The expansion of the universe is significant only over vast distances, not within bound systems like Earth. Any minuscule expansion within atoms does not lead to them flying apart, as gravity maintains their integrity. Overall, the expansion of space is too small to have any noticeable impact on objects like Earth.