A near-infrared color mosaic captured by NASA’s Cassini spacecraft shows sunlight glinting off Titan’s north polar seas. Image: NASA/JPL-Caltech/University of Arizona/University of Idaho
Earth and Saturn’s large moon Titan are the only bodies in the solar system where stable liquids are known to exist on the surface. But on Titan, the largest moon in the solar system and the only one with a thick atmosphere, the liquids are ultra-cold methane and ethane, filling large, low-elevation seas in the eastern side of the moon and small but surprisingly deep lakes or pools on the western side.
During its final flyby of Titan in 2017, NASA’s Cassini spacecraft used its cloud-penetrating radar to study those frigid lakes, finding them to be more than 100 metres (300 feet) deep and filled with pure methane, not a mixture of methane and ethane as seen elsewhere.
Just as intriguing, Cassini confirmed the relatively small lakes, tens of kilometres across, are well above sea level on the western side of the moon, etched into mesas or buttes rising hundreds of metres above the surrounding landscape.
The observations indicate the lakes may have formed when surrounding ice and organic compounds chemically dissolved and collapsed. Similar lakes on ...