Titan (astronomy)

In astronomy, largest moon of the planet Saturn, with a diameter of 5,150 km/3,200 mi and a mean distance from Saturn of 1,222,000 km/759,000 mi. It was discovered in 1655 by Dutch mathematician and astronomer Christiaan Huygens, and is the second-largest moon in the Solar System (only Ganymede, of Jupiter, is larger).

Titan is the only moon in the Solar System with a substantial atmosphere (mostly nitrogen), topped with smoggy orange clouds that obscure the surface, which may be covered with liquid ethane lakes. Its surface atmospheric pressure is greater than Earth's. NASA's Cassini space probe reached Saturn in 2004 and its subprobe Huygens landed on Titan in January 2005. It has long been thought that Titan might have lakes or even oceans of liquid methane or ethane, but there is currently no evidence to confirm this, either from the probes or from Earth-based observations.