Discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan is the biggest of the 31 known moons orbiting Saturn. It is a cold world enclosed by a thick, hazy atmosphere impenetrable by telescopes and cameras.
With an equatorial radius of 2,575 kilometers (1,600 miles), Titan is the second largest moon in our solar system. It's bigger than our own moon and even the planet Mercury. Only Jupiter's moon Ganymede is larger than Titan, with a diameter barely 112 kilometers (62 miles) greater.
The temperature at Titan's surface is about minus 178°C (minus 289°F).
Titan orbits Saturn at a distance of about 1.2 million kilometers (745,000 miles), taking almost 16 days to complete a full orbit - 15.94 days to be exact.
Titan is of great interest to scientists because it is the only moon in the solar system known to have clouds and a mysterious, thick, planet-like atmosphere. In 1980, NASA's Voyager 1 spacecraft tried to take close up images of the natural features of Titan's landscape but was unable to penetrate the thick clouds. Instead, the images showed only slight color and brightness variations in the atmosphere. Titan's atmospheric pressure is about 60 percent greater than Earth's - roughly the same pressure found at the bottom of a swimming pool.
