Ethane cloud seen on Titan

Scientists believe flakes of ethane "snow" or drops of ethane "rain" may be falling from the cloud into lakes of liquid methane.

Before the mission, researchers expected to find the moon awash with oceans of liquid ethane.

But so far, the evidence for them has been scarce, suggesting the ethane may be tied up as ice at Titan's poles.

"We think that ethane is raining or, if temperatures are cool enough, snowing on the north pole right now," said planetary scientist Dr Caitlin Griffith, from the University of Arizona in Tucson, US.

"When the seasons switch, we expect ethane to condense at the south pole during its winter.