jueves, 17 de junio de 2010
Hubble Finds Jupiter’s Missing Stripe
New Hubble images reveal what happened to one of Jupiter’s main cloud belts: It’s hiding behind ammonia clouds.
“Weather forecast for Jupiter’s Southern Equatorial Belt: cloudy with a chance of ammonia,” planetary scientist Heidi Hammel of the Space Science Institute in Boulder, Colorado said in a press release Wednesday.
The gas giant’s characteristic band of dark clouds started fading late last year and had vanished completely by early May, 2010. Images taken with Hubble’s Wide Field Camera 3 on June 7 — just over three days after an unknown object smacked into the planet — found a layer of white ammonia ice crystal clouds. The ammonia clouds float at a higher altitude than the missing brown clouds, obscuring them from view.
The images show a preview of what’s to come for the dark stripe, too. A chain of dark spots along the boundary of Jupiter’s south tropical zone peek through the white cloud layer as the ammonia thins and dissipates.
“The Hubble images tell us these spots are holes resulting from localized downdrafts. We often see these types of holes when a change is about to occur,” said planetary scientist Amy Simon-Miller of NASA.
The clouds blocking the famous equatorial stripe should clear out similarly in a couple of months, the team predicts.
“The Southern Equatorial Belt last faded in the early 1970s. We haven’t been able to study this phenomenon at this level of detail before,” Simon-Miller added. “The changes of the last few years are adding to an extraordinary database on dramatic cloud changes on Jupiter.”
The images also provided clues to the identity of the mystery object that hit Jupiter on June 3. A lack of dark debris at the impact site, which would have been kicked up by the object exploding beneath the clouds, suggests that the object was relatively small and burned up in Jupiter’s atmosphere like a meteor.
“Hubble was only one of several observatories that looked for signs of Jupiter’s impact scar, with more results on their way,” planetary scientist Leigh Fletcher of the University of Oxford noted on Twitter. “Gemini, Keck, VLT and IRTF were all racing to find signs of the impact within hours of the event taking place.”
Images: 1) NASA, ESA and Z. Levay (STScI), 2) NASA, ESA, UC Berkeley, STScI, Jupiter Impact Science Team.