Two pairs of moons make a rare joint appearance in this amazing space wallpaper. The F ring's shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring (the thin faint ring furthest from Saturn). Meanwhile, farther from Saturn the co-orbital moons Janus (near the bottom) and Epimetheus (about a third of the way down from the top) also are captured. Prometheus (53 miles, or 86 kilometers across) and Pandora (50 miles, or 81 kilometers across) sculpt the F ring through their gravitational influences. Janus (111 miles, or 179 kilometers across) and Epimetheus (70 miles, or 113 kilometers across) are famous for their orbital dance, swapping places about every four years. This view looks toward the sunlit side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Oct. 11, 2013.
(Image: © NASA/JPL-Caltech/Space Science Institute)