This lesson re-derives Newton’s result, that if the force of gravity decreases like the square of the distance from the center of attraction, the same force that causes objects on the Earth’s surface to fall can also be responsible for the motion of the Moon. The student will learn how Newton tied together the gravity observed on Earth and the motion of the Moon and to appreciate the philosophical implication of Newton’s calculation that all parts of the universe seem to obey the same laws of nature.