Scientists have wondered whether some unseen process replenishes the lakes of liquid methane on Titan, Saturn's biggest moon. A newly found lake suggests intriguing possibilities.
ESA/NASA/JPL/University of Arizona/USGS
Data from the Cassini spacecraft currently touring the Saturn system have already revealed lakes at Titan's poles, fed by summertime methane rain. But Cassini's radar found nothing similar at lower latitudes, and climate models have suggested that long-lived lakes might be impossible there.
Now, the discovery of the large, shallow lake in the moon's tropics may offer scientists clues about the processes driving a moon that has fascinating similarities to Earth before life emerged.
If the finding is confirmed by additional observations, it could imply the existence of significant subsurface methane deposits feeding the tropical lake. Or perhaps the moon recycles methane, with the liquid in polar lakes migrating underground back to the tropics, where it wells up again in lakes.
Whatever the cause, the discovery could have important implications for understanding how Titan maintains a methane cycle that is strikingly similar to the water cycle on Earth – with methane evaporating as gas, falling as rain, and gathering in lakes.
The report in Thursday's issue of the journal Nature represents a "significant discovery," says Tapio Schneider, a scientist at the California Institute of Technology who models planetary climates, including the moon Titan's.