A satellite of Saturn, in virtually the same orbit as Epimetheus between the F and G Rings (the tenuous rings outside the A Ring), at a mean distance of 151 450 km; also known as Saturn X. Its mean orbital period is 0.695 days. Janus was discovered in 1966 by the French astronomer Audouin Charles Dollfus (1924–2010). It is an irregular body, 203 × 185 × 153 km in size.
Geology and Earth Sciences
One of the lesser satellites of Saturn, with a radius measuring 99.3 × 95.6 × 75.6 km; mass 0.0198 × 1020 kg; mean density 650 kg/m3; visual albedo 0.8. It was discovered in 1966 by A. Dolfus, Gerard Kuiper, J. Fountain, and S. Larsen.