Titan

Titan is one of Saturn’s moons. It was discovered in 1655 by the Dutch astronomer Christiaan Huygens.

Titan is the largest of Saturn’s moons and the 9th-largest moon in the Solar System. Saturn has 62 moons with confirmed orbits, 53 of which have names. 24 of these are regular satellites that orbit Saturn with only small inclinations to its equatorial plane. 37 of the remaining 38 are irregular satellites that orbit at high inclinations and a much greater distance from Saturn. These are probably minor planets captured by its gravity or debris from them. The final irregular satellite is unclear.

Saturn was the Roman god of agriculture and harvest. His brothers (Titans) and sisters (Titanesses) where used to give names to the planet’s moons. When these names were exhausted, other names were taken from additional characters in Greek or Roman mythology or from the mythologies of other cultures. The irregular satellites are named after figures from Inuit, Gallic and Norse mythology. Titan is the collective term for “elder gods” in Greek mythology. The name was first suggested 1847 by William Herschel’s son John. Titan is also called Saturn VI because it is the fifth moon from the planet.

The composition of Titan may consist of several differentiated layers of rock and ice. There is a rocky centre surrounded layers of different crystal forms of ice. The moon’s core may be molten and hot. It interior may also have a liquid layer of water and ammonia in between some of the ice layers. Titan is the only celestial body in the Solar System, other than Earth, which has both stable liquid accumulations on its surface and a nitrogen-rich atmosphere.

Titan’s atmosphere is mainly nitrogen with minor amounts of methane and ethane. This creates a climate, as on Earth and features such as sand dunes, rivers, lakes and seas (probably liquid methane and ethane), as well as smog. The moon could host some microbial forms of life. Clouds, possibly ethane, have been observed over Titan’s polar regions. Its surface shows many sedimentary and volcanic features that are seen on Earth, such as mountain chains and depositional features. Titan’s volcanoes erupt water and ammonia. There are few impact craters, though the Menvra basin in the western part of Titan is a multiple-impact feature with a diameter of 440 km.

As with most of Saturn’s other moons, Titan rotates synchronously around the planet and keeps the same hemisphere towards Saturn and the same hemisphere facing forward during the orbit. Its atmosphere rotates east to west along with this motion and appears to rotate faster than the moon surface. Titan takes 15.9 Earth days to rotate around Saturn and to complete one spin on its own axis. Along with Saturn and its other satellites, it takes 29.4 Earth years to orbit the sun.

Voyager 1 and Voyager 2 in 1980 and 1981 provided the first unclear images of Titan. The Hubble Space Telescope took infrared images of the moon. The Huygens Probe landed on its surface in 2005 and sent back images of rocks with a resolution of centimetres. The closest Cassini spacecraft flyby was at 880 km in 2010.