The discovery of gravitation by Sir Isaac Newton, due to his observation of the falling apple, explained the movements of planets and satellites not only in our solar system but also in other systems as well. It explained why the Earth and other planets where spherical or nearly spherical in shape.
If two electrons are separated by a small distance there is a gravitational force of attraction and an electrostatic force of repulsion between them. Since the gravitational force of attraction is much weaker the force of repulsion, the latter predominates. Thus, gravitational force is a weak force but exists over large distances.
