Figure 6-31Motion of Earth–Moon System (a) The paths of Earth and the Moon as their barycenter follows an elliptical orbit around the Sun. (b) Analogously, this time-lapse image shows a pair of different-mass disks connected by a piece of wood sliding across a table. Note that the center of mass of this collection of objects moves in a straight line, while its other parts follow curved paths. As with the Earth–Moon system, the center of mass is closer to the more massive disk than to the less massive one.