Saturn has 62 moons formally, the largest of which is Titan. Titan is a really interesting moon for many reasons. Most moons in the solar system don’t come anywhere near the size of our Moon, but Titan does as it has a radius 50% larger than our Moon. This allows Titan to have a substantial atmosphere, which is almost entirely made out of nitrogen (98.4%). This is the only body in the solar system found that so far has a substantial nitrogen atmosphere, other than the Earth (78% nitrogen). What’s also cool about Titan is that there are geological features similar to those on Earth such as beaches (the sand is made out of methane ice crystals!) dunes, seas, rivers and river deltas! All the liquid on the surface of Titan is believed to be liquid methane, which requires very low temperatures to be in this state. Titan is similar to Earth because although it doesn’t have Earth’s water cycle, it has an analogous methane cycle. It’s theorized that not only rain exists on Titan, but lightning as well!
Also, it can be theorized that life exists in the seas of Titan, or in subsurface reservoirs thought to be a mixture of ammonia and water. This hypothesis comes from the fact that the atmosphere of Titan is similar to what scientists think the Earth’s atmosphere was like very early on in it’s evolution. With the chemical compounds as they are now known it is possible for complex molecules to be generated! This is the most interesting thing for me since I would like to get my doctorate in astrobiology sometime in the future. The above picture is an artist’s impression of the surface.