Titan is Saturn's largest moon and the second largest in the solar system (after Ganymede of Jupiter). The origins of the name Titan come from ancient Greek. According to sources like NASA, Titan has a lot of conditions that make it similar to Earth.
Titan is the only moon in the solar system with clouds and a dense, planet-like atmosphere. It is surrounded by an orange haze that kept its surface a mystery for Earth´s scientists until the arrival of the Cassini mission.
Titan's atmosphere is active and complex, and it is mainly composed of nitrogen (95 percent) and methane (5 percent). Titan also has a presence of organic molecules that contain carbon and hydrogen, and that often include oxygen and other elements similar to what is found in Earth's atmosphere and that are essential for life. Scientists believe that these conditions are similar to Earth's early years (the main difference is that, because it is closer to the sun, Earth has always been warmer).
Facts About Titan
Titan was first discovered by a Dutch astronomer called Christiaan Huygens in 1655. The Huygens lander probe sent to the moon aboard NASA's Cassini spacecraft by the European Space Agency is named in his honor. Huygens was the first human-built object to land on Titan's surface. [Amazing Photos of Titan]
Orbital Period: 15,945 days.
Diameter: 3,200.051 miles (5,150 kilometers), about half the size of Earth and almost as large as Mars.
Surface Temperature: minus 290 Fahrenheit (minus 179 degrees Celsius), which makes water as hard as rocks and allows methane to be found in its liquid form.
Surface Pressure: Slightly higher than Earth's pressure. Earth's pressure at sea level is one bar while Titan's is 1.6 bars.
Other Titan Facts:
Titan's diameter is 50 percent larger than that of Earth's moon. The moon is larger than the planet Mercury but is half the mass of Mercury.
Titan's upland areas are shorter than Earth's. The largest mountains are only a few hundred yards high.
The moon's mass is mainly composed of water in the form of ice and rocky material.
Titan has no magnetic field.
There is an abundance of methane lakes, which are mainly concentrated near its southern pole.
Large areas of Titan's surface are covered with sand dunes made of hydrocarbon. Dunes on Titan may resemble the ones of the Namibian desert in Africa.
Because methane exists as a liquid, it also evaporates and forms clouds, which occasionally causes methane rain.
Sunlight is quite dim in Titan, and climate is driven mostly by changes in the amount of light that accompanies the seasons.
There is also data that suggests the presence of a liquid ocean beneath the surface, but it is still to be confirmed.
Why Is Titan's Atmosphere So Different From Others?
One of the most intriguing facts about Titan and the one that has actually drawn scientists' attention: its atmosphere.
Titan's atmosphere extends around 370 miles high (about 600 kilometers), which makes it a lot higher than Earth's atmosphere. This is also the main reason why Titan's gravity is extremely low. Because of this high atmosphere, Titan was thought to be the largest moon in the solar system for a long time. It wasn't until 1980 that Voyager was close enough to discover it was actually smaller than Ganymede.
An Unsolved Mystery:
The complex chemistry of the atmosphere is possible because of the presence of methane. Since methane is broken down by sunlight, scientists believe there is another source that replenishes what is lost. They are yet to determine if this is due to volcanic activity.
Cassini Spacecraft at Titan
Cassini is currently in the middle of its Solstice mission at Saturn, the second mission for the spacecraft. The probe's primary mission, called Equinox, was aimed at exploring the Saturnian system and ended in June 2008 after four years orbiting the ringed planet. The spacecraft's mission was then extended, with its current Solstice effort expected to last until 2017, when Saturn's solstice takes place — hence its name.
The Cassini spacecraft launched in 1997 and carried the Huygens probe built by the European Space Agency. Huygens was equipped to study Titan by landing on the Saturn moon and achieved astounding results. [Video: Future Mission to Saturn's Moon Titan]
Cassini arrived in orbit around Saturn in 2004 with the Huygens probe landing via parachute on Jan. 14, 2005. Because of Huygens's observations, Titan became a top priority for scientists. The mission has achieved excellent results, such as taking the highest resolution images ever achieved of this moon´s surface.
During its primary and extended missions, Cassini was able to get fundamental data about Titan's structure and the complex organic chemistry of its atmosphere. It is because of Cassini's findings that scientists suspect the presence of an internal ocean composed of water and ammonia.
The focus of the mission, as it relates to Titan, is to find signs of seasonal changes and volcanic activity.
Possibilities for Life
It is thought that conditions on Titan could become more habitable in the far future. If the sun increases its temperature (6 billion years from now) and becomes a red giant star, Titan's temperature could increase enough for stable oceans to exist on the surface, according to some models. If this happens, conditions in Titan could be similar to Earth's, allowing conditions favorable for some forms of life.
Sources and more reading:
NASA's Cassini Solstice Mission:
Saturn's Moon Titan-Explore the Cosmos, The Planetary Society: http://planetary.org/explore/topics/saturn/titan.htm
European Space Agency's Cassini-Huygens: