EARTH'S AND MOON'S CENTER OF GRAVITY - Though we often say that the Moon orbits our Earth, it is more accurate to say that both actually orbit their common center of mass—a point known as the "Earth-Moon barycenter." Here http://www.SkyMarvels.com (formerly celestia4all.com) uses the incredible, free astronomy-simulation software "CELESTIA" to show you this concept. At http://www.SkyMarvels.com you can journey EVERY DAY through our wondrous Solar System and the Universe. MAY YOUR JOURNEYS BE JOYOUS!