|revolution (rěv'ə-l'shən) Pronunciation Key
Our Living Language : In everyday speech revolution and rotation are often used as synonyms, but in science they are not synonyms and have distinct meanings. The difference between the two terms lies in the location of the central axis that the object turns about. If the axis is outside the body itself—that is, if the object is orbiting about another object—then one complete orbit is called a revolution. But if the object is turning about an axis that passes through itself, then one complete cycle is called a rotation. This difference is often summed up in the statement "Earth rotates on its axis and revolves around the Sun."