Gravity is the force of attraction between all objects. Gravity keeps the Earth and Moon in their orbits. Isaac Newton was one of the first scientists to explore the idea of gravity. He understood that the Moon can only circle the Earth because some force is pulling the Moon toward Earth's center. Otherwise, the Moon would continue moving in a straight line off into space. Newton also came to understand that the same force that keeps the Moon in its orbit is the same force that causes objects on Earth to fall to the ground
