Astronomy

The above picture is a new radar image from Cassini spacecraft, comprised from seven fly-bys on Saturn’s largest moon, Titan, over the last year and a half. This picture shows a north pole pitted with giant lakes and seas, at least one of them larger than Lake Superior in the USA, the largest freshwater lake on Earth. It has been said as the best views of the hydrocarbon lakes and seas on Saturn’s moon Titan that ever taken.

Approximately 60% of Titan’s north polar region, above 60° north, has been mapped by Cassini’s radar instrument. About 14% of the mapped region is covered by what scientists interpret as liquid hydrocarbon lakes.

Lakes and seas are very common at the high northern latitudes of Titan, which is in winter now. Scientists say as it rains methane and ethane there, these liquids are collected on the surface, filling the lakes and seas. Those lakes and seas then carve meandering rivers and channels on the moon’s surface. Now Cassini is moving into unknown territory, down to the south pole of Titan.

Scientists are making progress in understanding how the lakes may have formed. On Earth, lakes fill low spots or are created when the local topography intersects a groundwater table. Scientists think that the depressions containing the lakes on Titan may have been formed by volcanism or by a type of erosion (called karstic) of the surface, leaving a depression where liquids can accumulate. This type of lake is also common on Earth.

According to Alex Hayes, a graduate student who studies Cassini radar data at the California Institute of Technology in the USA, the lakes their observed on Titan appear to be in varying states of fullness, suggesting their involvement in a complex hydrologic system akin to Earth’s water cycle. This makes Titan unique among the extra-terrestrial bodies in our solar system.

Image credit: ESA

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