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 FOR JANUS|
|Mass (kg)||2.01e + 18|
|Mass (Earth = 1)||3.3635e - 07|
|Radius (km)||98 x 96 x 75|
|Radius (Earth = 1)||1.5365e - 02|
|Mean Density (g/cm3)||0.67|
|Mean Distance from Saturn (km)||151,472|
|ORBITAL DATA FOR JANUS|
|Rotational period (days)||0.6945|
|Orbital period (days)||0.6945|
|Mean orbital velocity (km/s)||15.87|
|Orbital inclination (degrees)||0.14|