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Mercredi, 09 Février 2011 20:55

Jupiter's Moon Helps Peek Below Planet's Belt

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Jupiter's Moon Helps Peek Below Planet's Belt

Astronomers have a new view of the chaos brewing beneath Jupiter’s cloud belt, thanks to some help from its icy moon Europa.

This new image, captured Nov. 30, 2010 with the 10-meter Keck II telescope in Hawaii, shows heat escaping from Jupiter’s interior, giving astronomers a peek into the roiling turmoil inside Jupiter’s missing red stripe.

The image shows Jupiter at four wavelengths of infrared light, which is beyond the range that human eyes can see. Three of those wavelengths show reflected sunlight. But one wavelength, 5 micrometers, can sense breaks in the cloud cover.

Jupiter’s famous red stripe mysteriously faded in late 2009 and vanished altogether by May, 2010. Observations with Hubble and other telescopes showed that the ruddy band was hiding beneath a layer of high, bright clouds made from icy ammonia crystals.

Last November, bits of the red band started coming back.

Astronomers wanted to use Keck’s thermal-sensing eyes to peel back the cloud layers. To get sharp pictures of the sky, Keck shines a laser on the sky to create a fake star and uses it to cancel out the blurring effects of the Earth’s atmosphere.

But Jupiter is so bright, it outshines the laser star. Astronomers needed another tiny light source right next to Jupiter to guide the telescope’s atmosphere-canceling system.

Jupiter’s icy moon Europa turned up at just the right moment.

“Because Jupiter is close to Europa in the sky, it will be experiencing similar distortions,” said astronomer Mike Wong of the University of California at Berkeley, who helped make the observations. “So if we can measure Europa’s distortions, those same distortions can be corrected for Jupiter.”

The resulting images show that the return of Jupiter’s cloud belt is happening at different speeds in each layer of the gas giant’s atmosphere.

“This shows us some of the 3D structure of what’s going on,” Wong told Wired.com. “Without the 5 micron observations, we wouldn’t know that the changes we’re seeing are isolated to individual cloud layers.”

Images: Mike Wong, Franck Marchis & W.M. Keck Observatory

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