Distance from Saturn: 1.2 million km (760,000 mi)
Orbital period: 16 days
Surface pressure: 147 kPa (Earth: 101 kPa at sea level)
Note: These numbers have all been rounded off.
Saturn's moon Titan is the second biggest moon in the Solar System.
Jupiter's moon Ganymede is a bit larger than Titan, and they're both bigger than the planet Mercury. Saturn has over sixty moons. If you added up the masses of all these moons, 96% of the mass would belong to Titan.
Dutch astronomer Christiaan Huygens discovered Titan in 1655.
Huygens landed on Titan 350 years after the moon's discovery that was Huygens the European Space Agency (ESA) probe! NASA's Cassini spacecraft took it to Saturn. They named the spacecraft after Jean Dominique Cassini. He was an Italian-French astronomer who observed Saturn in the 17th century, and discovered four of its moons.
Scientists think that Titan is a lot like Earth.
In some ways it's similar to the Earth we know, but it's really very different today. The scientists are thinking of a very cold version of ancient Earth before life began.
Titan is layered like a planet.
Small bodies, like moons and asteroids, don't show much layering. This means that they're pretty much the same all the way through. But Earth, for example, has a solid iron center surrounded by liquid iron, a mantle, and on the outside, a solid rocky crust. Titan also has a number of layers, including a liquid water ocean under the surface.
Titan and Earth are the only Solar System bodies that we know have an atmosphere of mainly nitrogen.
Earth's atmosphere is about 78% nitrogen and 21% oxygen. Titan's is over 95% nitrogen, and the rest is methane and other hydrocarbons. (Hydrocarbons are substances made of carbon and hydrogen.) Titan is the only moon with a thick atmosphere. It's even thicker than Earth's atmosphere that's why its surface pressure is over one and a half times what we're used to.
Titan's atmosphere contains a thick smog.
We think the smog in Los Angeles or Beijing is bad, but that's nothing compared to Titan's smog. It's so thick that we can't see Titan's surface. Cassini has instruments that can see through the smog, and has used radar to map Titan's surface. Between the smog and its greater distance from the Sun, you wouldn't get a tan on Titan. Daylight on Earth is a thousand times brighter.
Earth and Saturn are the only two objects in the Solar System that we know have bodies of liquid on the surface.
On Earth the liquid is water. On Titan it's liquid methane mixed with other hydrocarbons. Titan has lakes and seas, but the seas aren't as big as those on Earth. Methane is what natural gas is made of, so with the methane seas and atmosphere, you might worry about Titan catching fire. But remember burning needs oxygen and Titan doesn't have it.
Titan's surface temperature is -178 C (-289 F).
Even if you live in Canada, Scandinavia or Siberia, you would find Titan extremely cold. When the temperature is that low, water freezes into an ice as hard as rock. The rocks and pebbles in the pictures Huygens took are frozen water.
Titan has mountains, hills and sand dunes.
Overall Titan is rather flat. Unlike some of the Martian mountains, those on Titan aren't very high. There are dunes that look very much like dune fields on Earth. But the sand isn't like sand on Earth - we don't actually know what it's made of.
Titan may have volcanoes.
Many people think that Titan has volcanoes, and there are structures that could be volcanoes. These would be cryovolcanoes which erupt water instead of lava. Such eruptions have been seen on Jupiter's moon Europa, Neptune's Triton and Saturn's Enceladus. Unfortunately, we can't see Titan's surface.
There are images related to this article at Saturn's Moons.