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On Titan, it drizzles methane

Times Staff Writer

The rain on Titan falls mainly in the foothills.

One important difference between the Earth and Saturn’s giant moon is that Titan’s rain is made of methane, not water.

Otherwise, according to a team of scientists from UC Berkeley, the weather pattern on Titan might make an Englishman feel right at home.

“Widespread and persistent drizzle” falls on Titan, said Mate Adamkovics, a Berkeley research astronomer. A lot of the methane rain is concentrated in the hills of the moon’s large continent, Xanadu, according to the scientists, who published their findings Friday in the journal Science.

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The discovery, revealed in near-infrared images from Hawaii’s W.M. Keck Telescope and Chile’s Very Large Telescope, may solve one of the lingering mysteries associated with Saturn’s bizarre satellite.

NASA’s Cassini spacecraft, which is orbiting Saturn and its moons, found evidence of what appear to be methane lakes and rivers. Other spacecraft found methane, ethane and other smoglike compounds in the toxic atmosphere.

Until now, however, scientists were unsure how the methane got from the ground to the sky and vice versa. Although rain was the obvious candidate, no one had been able to actually see it raining. Titan is about 1 billion miles from Earth, so charting the local weather is a challenge.

The two telescopes snapped images of the moon as the morning sun caught its leading edge, revealing a thick methane cloud bank and a steady drizzle.

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The drizzle appears to dissipate after about 10:30 a.m. Titan time, the research team said. Because Titan rotates so slowly, the morning sprinkle lasts about three Earth days, conditions that might test the hardiest Brit.

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john.johnson@latimes.com


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