Titan ‘like a second Earth’

Giant moon Titan has a landscape startlingly like the Earth’s, scientists have revealed.

Titan – the only moon with a dense atmosphere – has mountains, valleys and sand dunes plus flowing rivers. The river channels run into dark areas that may be lakes, according to the latest radar pictures taken by Nasa’s Cassini spaceprobe of a bright “continent” the size of Australia called Xanadu.

Experts say the surface features have clearly been shaped by winds and rain just like those of our own planet. The discovery will fascinate space scientists because some believe that Titan – the biggest moon orbiting the ringed planet Saturn – is the best place to look for life in the solar system.

Cassini found that dark dunes on Xanadu’s western edge give way to rivers, hills and valleys. A crater caused by an asteroid impact was also spotted. To the east of Xanadu, more dunes are crisscrossed by Appalachian sized mountains. A crucial difference between Earth and Titan is that the surface liquid on Saturn’s moon cannot be water. Instead it is believed to be methane or ethane.

UK scientists have taken a close interest in Titan which is 3,200 miles in diameter. Professor John Zarnecki, of the Open University, led the team that successfully landed a European Space Agency probe called Huygens onto its slushy surface last year. The probe, which had been carried the 2.5 billion miles to the Saturn system aboard Cassini, detected organic chemicals that are the building blocks of life, including nitrogen and methane, as it parachuted to a soft landing.

Nasa scientist Dr Jonathan Lunine, of the University of Arizona, said: “Surprisingly, this cold, faraway region has geological features remarkably like Earth. Although Titan gets far less sunlight and is much smaller and colder than Earth, Xanadu is a land where rivers flow down to a sunless sea.”

Commenting on the latest results, obtained as the probe flew past Titan on April 30, radar scientist Steve Wall said: “This land is heavily tortured, convoluted and filled with hills and mountains. “There appear to be faults, deeply cut channels and valleys. Also, it appears to be the only vast area not covered by organic dirt. Xanadu has been washed clean. What is left underneath looks like very porous water ice, maybe filled with caverns.”

Wall, of Nasa’s Jet Propulsion Laboratory in Pasadena, California, added: “If it hadn’t been for the Cassini radar, we would have missed all of this. We have a newly discovered continent to explore.”

Cassini will tackle another close look at Titan tomorrow, exploring the high northern latitudes of the moon. In the next two years the orbiter will fly by Titan 29 times.

The picture shows a section of the radar image, revealing rivers flowing across Xanadu.

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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