All planetary systems have this point, called a barycenter, where their mass is perfectly balanced. For some systems — like Pluto and its moon, Charon — the barycenter is outside the planet. The moon orbits Earth — right? The answer is actually a little more complicated than that. The moon is circling a point about 3,000 miles from our planet's center, just below its surface. Earth is wobbling around that point, too, making its own circles. That spot is the Earth-moon system's center of mass, known as the barycenter. It's the point of an object (or system of them) at which it can be balanced perfectly, with the mass distributed evenly on all sides.