Thursday, April 2, 2009

Jupiter's stormy Great Red Spot is shrinking -

NASA's Cassini spacecraft photographed Jupiter and its Great Red Spot, seen center near the equator, in 2000.Everything about Jupiter is super-sized, including its colorful, turbulent atmosphere. But there's fresh evidence that one of the planet's most recognizable features, the Great Red Spot, is shrinking.

he spot, which is actually an ancient monster storm that measures about three Earths across, lost 15 percent of its diameter between 1996 and 2006, scientists at the University of California, Berkeley, have found.

It shrank by about 1 kilometer (about 0.6 miles) a day during that time period, said Xylar Asay-Davis, a postdoctoral researcher who was part of the study.

Astronomers have observed for years that the clouds of the Great Red Spot have been waning, but this newest research focused on the motion of the storm -- a much more reliable way to measure its size, Asay-Davis said.

He and fellow Berkeley researchers Philip Marcus, Imke de Pater, Michael Wong and Sushil Shetty developed software that tracked the movement of the spot's cloud patterns over long periods of time.

"It's not just the motion of the spot as a whole object. Within it, it has a very complicated swirl to it -- sort of a thin ring on the outside and then a sort of quiet area in the center -- and that shape of it has been changing over time," Asay-Davis said.

"What we actually look at is where the winds are the strongest in the vortex. It's the ring where they're the strongest, and that ring has been shrinking over time."

via Jupiter's stormy Great Red Spot is shrinking -

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