Titan (moon)

Titan (/ˈtaɪ.tən/, from Ancient Greek Τῑτάν) 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. It was discovered on March 25, 1655, by the Dutch astronomer Christiaan Huygens, and was the first of Saturn's moons to be discovered.

Titan is the only moon in our solar system to have a dense atmosphere. Until 2004, this atmosphere prevented understanding of Titan's surface, but with the arrival of the Cassini–Huygens mission, new information about it has accumulated, such as the discovery of liquid hydrocarbon lakes near its north pole. These are the only large, stable bodies of surface liquid known to exist anywhere other than Earth.

Titan is never visible to the naked eye, but can be observed through small telescopes (diameter greater than 5 cm) or strong binoculars. It has a maximum magnitude of +7.9, outshone by six asteroids (Vesta, Pallas, Iris, Hebe, Juno, Melpomene) and the dwarf planet Ceres. Titan reaches an angular distance of about 20 Saturn radii from Saturn and subtends a disk 0.8 arcseconds in diameter.