Titan, or Saturn VI, is the largest moon of Saturn and the second largest moon in the solar system, after Jupiter's moon Ganymede.
It is roughly 50% larger than Earth's moon by diameter, and is larger by diameter and mass than all known dwarf planets.
It is also larger by diameter than the planet Mercury, though Mercury is more than twice as massive.
Titan is the only moon in our solar system to have a dense atmosphere.
The atmosphere is 98.4% nitrogen.
Until very recently, this atmosphere inhibited understanding of Titan's surface, but the moon is currently undergoing study by the Cassini-Huygens mission, and new information about it is accumulating.
On July 27, 2006, NASA confirmed the presence of hydrocarbon lakes in Titan's north polar region.
At the surface, Titan's temperature is about 94 K.