Calisto has been bombarded a lot by meteorites, and has a very thick crust of ice and dust covering it. Unlike most moons, Titan has an atmosphere. The second largest moon in the solar system has an atmosphere mostly of nitrogen, a little bit of methane, and possibly some argon as well. It is likely that Titan is covered by continents and ethane-rich oceans. It was probably blown apart and then it came back together due to gravity, which gave it this strange topography.
Triton has an extremely thin atmosphere made predominantly of nitrogen.
Gas jets from inside the moon have been seen, although their origin is unclear. There also exist frozen lakes of water ice on the moon's surface. It may have been gravitationally captured by Neptune. Photos of planets and moons from NASA JPL, courtesy California Institute of Technology, Copyright 1995 except Venus, from the Nine Planets by Bill Arnett, taken by Galileo. Back to the NSRT Reference page Created by Marta Lewandowska , June 1999.