Janus 

Janus is the sixth satellite of Saturn and was discovered by Audouin Dollfus in 1966. The moon has an irregular shape of 196x192x150 kilometers (122x119x93 miles) in iameter and has thousands of craters that dot the surface. This indicates that the surface must be at least several billion years old and that Janus is one of the oldest moons of Saturn. Janus also has very few linear features.

Janus is in the same orbit of Epimetheus and thus share the orbit of 151,472 (94,125 miles) from the center of Saturn. They are separated by a short distance of 50 kilometers (31 miles) and undergo an interesting process when they encounter one another at close range. Once every four years, the two moons exchange momentum and as a result, one moon is flung inward while the other outward. Thus they actually swap orbits! It is thought that these two satellites were once from a large parent.

Physical Data Key Mass Mass Mass Mass compared to that of Earth. Radius Radius Radius Radius compared to that of Earth. Mean Density Average Density. Distance Distance to the planet's center. Magnitude The brightness of a star or object.

Orbital Data Key Rotational Period Number of days to make one complete rotation. Orbital Period Number of days to obital the planet. Mean Orbital Velocity Average obital speed. Orbital Eccentricity Eccentricity. Orbital Inclination The tilt of the moon or planet. Escape Escape Velocity. Albedo Visual geometric albedo.