A distant space probe has found giant seas of liquid methane on Saturn’s biggest moon. Titan, which is half as big again as our own Moon, was already known to have rivers and a lake district.

Now Nasa’s Cassini spacecraft has found oceans as big as some seas on Earth in Titan’s high northern latitudes.

Cassini’s radar instrument peered through the moon’s orange, hazy atmosphere to see several very dark features near Titan’s north pole.

They are much larger than any similar features seen before, with the largest measuring at least 39,000 square miles.

Dr Jonathan Lunine, of the University of Arizona, said: “We’ve long hypothesised about oceans on Titan. Now we have a first indication of seas that dwarf the lakes seen previously.”

Scientists say the seas’ shape and dark appearance point to them being filled with liquids, believed to be a combination of methane and ethane, given the abundance of those gases in Titan’s atmosphere.

One large, irregular, dark feature stretches for more than 620 miles in the image, down to 55 degrees north latitude, making it only slightly smaller than Earth’s Caspian Sea. Nasa are now planning to take another close look at the area when Cassini, which is orbiting Saturn, flies close in May.

UK space scientist Professor John Zarnecki believes aquatic aliens could be swimming in Titan’s seas. Professor Zarnecki, of the Open University, led the team that landed Cassini’s piggyback probe Huygens probe on the slushy surface of Titan last year. Photo: Nasa/JPL.

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