Press cutting: 'Proof' of methane lakes on Titan

Radar images reveal dark, smooth patches that range in size from three to 70km across (two to 44 miles). …

The researchers tell the journal 'Nature' that everything about the patches points to them being pools of liquid.

"They look very similar to lakes on Earth," explained Dr Ellen Stofan [UCL Earth Sciences], a Cassini radar team member. …

"They have channels feeding into them just like you have rivers feeding into lakes on the Earth. Their shapes, their shore-lines, all of those geologic aspects are actually very familiar."…

With temperatures on the Saturnian satellite rarely venturing above -179C (-290F), it has long been hypothesised that abundant volumes of methane should pool on the surface into lakes, and even large seas.

But evidence for current bodies of liquid material on the surface has until now been sparse and equivocal. …

The latest data was obtained last July, when the probe made its most northern radar pass of Titan to date.

The spacecraft imaged a narrow strip about 250km wide and over 1,000km long. It was found to contain more than 75 lakes. …

Some of the liquid would be expected to rain out of the sky, some could have welled up from below the surface.

"The methane-ethane would become transparent, the way water is on Earth; it would be behaving like water, the lakes could have small waves on the surfaces," speculated Dr Stofan. …

On Earth, the cycling of water between the atmosphere, the land and oceans is known as the hydrological cycle. Titan would appear to be the only other place in the Solar System to have a similar, active fluid cycle. Scientists have already dubbed it the "methane-ologic cycle". …

BBC News Online