Astronomers have created the first complete full-color map of the surface of Saturn's largest moon,Titan - a frozen place where liquid methane flows across a windswept landscape, and where scientists have found a surprising variety of Earth-like features.
Scientists at the University of Nantes in France produced the map from images taken by NASA's unmanned Cassini spacecraft, in orbit around Saturn since 2004, during its first 70 flybys of Titan over a six-year period. Cassini's Visual and Infrared Mapping Spectrometer, or VIMS, is able to see through Titan's thick nitrogen-rich atmosphere and methane clouds, and provide a window on its varied landscape.
Astronomers are keenly interested in Titan because of its sand dunes, mountains, valleys and lakes, and its intriguing atmospheric conditions. Titan is a world of hydrocarbons, such as the methane that many researchers believe rains down on its surface, fills its lakes and gathers in its clouds. The new map and animations are expected to advance our understanding of Titan, where the temperature averages a very un-Earth-like minus 180 degrees Celsius.
Cassini was launched in 1997, and is due to make 48 more flybys of Titan before the end of its orbital mission at Saturn in 2017.
The team of astronomers had to make painstaking pixel-by-pixel analyses of each image because Cassini’s six years of observations of Titan were made from different distances, at different times of day, and during different seasons and weather conditions. The tedious process required the cosmic mapmakers to resize the images to the same scale, as well as compensate for differences in illumination and shadow, and screen out atmospheric distortions.
Saturn, with its 60 moons and spectacular rings, is more than 1.2 billion kilometers from the Earth. It is the sixth most-distant planet from the Sun, after Jupiter, Mars, Earth, Venus and Mercury. Beyond Saturn are the ice-giant planets, Uranus and Neptune.