Titan (astronomy)

The Cassini and Huygens probes have revealed a geologically young surface on Titan, with few visible impact craters. The features seen so far appear to be formed from dirty water ice overlain mainly by organic (carbon-containing) deposits. The moon’s surface temperature is a frigid -178°C (-289°F). At such temperatures water ice probably plays a role very similar to silicate rocks on Earth and makes up the moon’s crust. The organic deposits form highlands and dunes, and may coat flat plains. In some cases the dunes are as high as 100 m (330 ft) and stretch for as long as 1,500 km (930 mi), running parallel to each other like those in the Sahara desert on Earth.

The terrain is rugged and shows evidence of erosion from methane rain and from liquid seeping from underground. The rocklike ice chunks on the surface, photographed by Huygens, have a rounded shape that could result from their tumbling in flash floods. Scientists have also identified possible cold volcanoes that may spew a mix of ammonia and water ice.

Titan is Saturn’s densest moon. Planetary scientists theorize that Titan has a rocky core about 3,400 km (about 2,100 mi) in diameter, surrounded by ice. Some researchers think an underground ocean of liquid water may surround the ice. Above this possible ocean is the moon’s crust, made of solid ice.