Discovered by Dutch astronomer Christiaan Huygens in 1655, Titan is Saturn's largest moon, and the second largest moon in the Solar System, after Jupiter's moon Ganymede.
Although a moon, Titan is in fact larger than Mercury and Pluto.
Titan has a planet-like atmosphere which is denser even than that of Earth. The atmospheric pressure at Titan’s surface is about 1.6 bars, or 60% greater then Earth’s. This makes Titan unique among all the other moons of our Solar System.
Titan’s atmosphere is composed primarily of nitrogen, organic compounds, such as methane, and traces of argon and ammonia. Sunlight reacting with methane in Titan's atmosphere creates other hydrocarbons: ethane, acetylene, ethylene, and (when combined with nitrogen) hydrogen cyanide. These hydrocarbons in Titan’s atmosphere create a thick, orange haze.
Titan’s surface temperature is -179°C (or -290°F). Due to the moon's cold climate, methane, ethane and other hydrocarbons are in liquid form. In fact, these organic compounds rain down on the moon's surface, forming rivers which in turn pool into lakes. The two largest lakes have been named respectively Kraken Mare and Ligeia Mare, and are larger than Lake Superior in North America.
Among the Solar System's moons, Titan is significant to astrobiologists because its environment, although harsh, may have the necessary conditions to harbour life.
Video link: Saturn's Moon Titan
Diameter: 5,151 km, or approx. 3,201 miles
Distance from Saturn: 1,221,870 km, or 759,233 miles
Distance from Sun: 1,427,000,000 km, or 886,694,990 miles (9.54 AU)
Orbital period: 15.95 days
Rotational period: 15.95 days
Titan passing in front of Saturn
False colour image of Ligeia Mare in Titan's northern hemisphere