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Updated: July 8th, 2008 05:26 PM CDT

Cassini Reveals Titan's Earth-Like Xanadu Region

via PRNewswire

WASHINGTON, July 19 /PRNewswire/ -- Radar images, from a strip more than 2,796 miles long, show Xanadu is surrounded by darker terrain, reminiscent of a free-standing landmass. At the region's western edge, dark sand dunes give way to land cut by river networks, hills and valleys. These narrow river networks flow onto darker areas, which may be lakes. A crater formed by the impact of an asteroid or by water volcanism is also visible. More channels snake through the eastern part of Xanadu, ending on a dark plain where dunes, abundant elsewhere, seem absent. Appalachian-sized mountains crisscross the region.

"We could only speculate about the nature of this mysterious bright country, too far from us for details to be revealed by Earth-based and space-based telescopes. Now, under Cassini's powerful radar eyes, facts are replacing speculation," said Jonathan Lunine, Cassini interdisciplinary scientist at the University of Arizona, Tucson . "Surprisingly, this cold, faraway region has geological features remarkably like Earth."

Titan is a place of twilight, dimmed by a haze of hydrocarbons surrounding it. Cassini's radar instrument can see through the haze by bouncing radio signals off the surface and timing their return. In the radar images bright regions indicate rough or scattering material, while a dark region might besmoother or more absorbing material, possibly liquid.

Xanadu was first discovered by NASA's Hubble Space Telescope in 1994 as a striking bright spot seen in infrared imaging. When Cassini's radar system viewed Xanadu on April 30, 2006 , it found a surface modified by winds, rain, and the flow of liquids. At Titan's frigid temperatures, the liquid cannot be water; it is almost certainly methane or ethane.

"Although Titan gets far less sunlight and is much smaller and colder than Earth, Xanadu is no longer just a mere bright spot, but a land where rivers flow down to a sunless sea," Lunine said.

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