Saturn's largest moon is the only planetary satellite in the Solar System with a dense atmosphere.
In the early 1980s, the Voyager 1 and 2 probes took the first close-ups of the permanent orange haze that hides Titan's surface.
In early 2005 the European Huygens probe parachuted through Titan's nitrogen-rich atmosphere and landed on the moon's surface while the Cassini spacecraft studied the moon from orbit. Images and other measurements from the craft show a world with riverbeds, liquid methane lakes and cryovolcanoes (ice volcanoes).
Photo: Titan with Saturn in the background taken by the Cassini probe (NASA/JPL/Space Science Institute)
Titan is the only moon with a dense atmosphere.
Brian Cox describes what rain on Saturn's moon Titan would be like.
Professor Brian Cox explains how Titan's dense atmosphere combined with its weak gravity would mean that a rain storm on this moon of Saturn would be a very unusual experience.
The Cassini probe proves that Titan has lakes.
Professor Brian Cox shows how a picture taken by the Cassini spacecraft proves the existence of lakes of liquid on Titan.
Huygens entered Titan's atmosphere at 20,000mph. The team had just one question: would it survive?
The Huygens probe entered the atmosphere of Titan at 20,000 miles per hour. The scientific team behind it had just one question: would it survive?
Sir Patrick Moore and Chris Lintott discuss lakes found on Saturn's moon.
Sir Patrick Moore and his co-presenter Dr Chris Lintott discuss lakes discovered on the surface of Titan by the Cassini spacecraft.
Saturn's moon intrigues scientists.
The Voyager 1 space probe, launched in 1977, photographed Saturn and its moons. Titan, with its thick, orange atmosphere, frustrated scientists eager to see the moon's surface.
Titan (or Saturn VI) is the largest moon of Saturn. It is the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found.
Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, Titan has a diameter 50% larger than Earth's natural satellite, the Moon, and is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and is larger by volume than the smallest planet, Mercury, although only 40% as massive. Discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn, and the fifth known satellite of another planet.
Titan is primarily composed of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan's surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in Titan's polar regions. The geologically young surface is generally smooth, with few impact craters, although mountains and several possible cryovolcanoes have been found.
The atmosphere of Titan is largely nitrogen; minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. The climate—including wind and rain—creates surface features similar to those of Earth, such as dunes, rivers, lakes, seas (probably of liquid methane and ethane), and deltas, and is dominated by seasonal weather patterns as on Earth. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan's methane cycle is viewed as an analogy to Earth's water cycle, although at a much lower temperature. On June 23, 2014, NASA announced strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn earlier. On July 2, 2014, NASA reported the ocean inside Titan may be "as salty as the Earth's Dead Sea". On September 3, 2014, NASA reported studies suggesting methane rainfall on Titan may interact with a layer of icy materials underground, called an "alkanofer," to produce ethane and propane that may eventually feed into rivers and lakes.