Saturn's moon Titan has 100-m deep methane lakes, finds Nasa

Washington DC: Saturn's largest moon Titan has small liquid lakes that run more than 100 metres deep, perched atop hills and filled with methane, scientists have found using data from NASA's Cassini spacecraft.

The findings, published in the journal Nature Astronomy, are the first confirmation of just how deep some of Titan's lakes are (more than 300 feet, or 100 meters) and of their composition.

They provide new information about the way liquid methane rains on, evaporates from and seeps into Titan -- the only planetary body in our solar system other than Earth known to have stable liquid on its surface.

Scientists have known that Titan's hydrologic cycle works similarly to Earth's -- with one major difference. Instead of water evaporating from seas, forming clouds and rain, Titan does it all with methane and ethane.

We tend to think of these hydrocarbons as a gas on Earth, unless they're pressurised in a tank. However, Titan is so cold that they behave as liquids, like gasoline at room temperature on our planet.

Scientists have known that the much larger northern seas are filled with methane, but finding the smaller northern lakes filled mostly with methane was a surprise.

Previously, Cassini data measured Ontario Lacus, the only major lake in Titan's southern hemisphere. There they found a roughly equal mix of methane and ethane. Ethane is slightly heavier than methane, with more carbon and hydrogen atoms in its makeup. "Every time we make discoveries on Titan, Titan becomes more and more mysterious," said Marco Mastrogiuseppe, Cassini radar scientist at California Institute of Technology in the US.