In their orbital ballet, Janus and Epimetheus swap positions every four years - one moon moving closer to Saturn, the other moving farther away. The two recently changed positions (the swap occurring on January 21, 2010). Although the moons appear to be close in the image, they are not. Janus (r.) is 113 miles across and Epimetheus is 72 miles across in this view. In fact, even when they are at their closest, tugging at each other and swapping orbital positions, they are never closer than about 9,000 miles.