Hubble: Jupiter 'Flash' Caused by Meteor, Not Fireball : Big Pic

June 16, 2010 -- With the help of the Hubble Space Telescope, astronomers have been able to take a closer look at the location of the June 3 "flash" spotted by Australian amateur astronomer Anthony Wesley. The flash was thought to have been caused by a sizable comet or asteroid slamming into the gas giant's atmosphere, generating a huge fireball.

Although the assumption was that something hit Jupiter, astronomers couldn't see any sign of impact after the fact. Using the sheer power of Hubble, which zoomed in on the location of the flash three days later, astronomers hoped to shed some light on the phenomenon. So, what did Hubble see?

Well, nothing. But that's not the end of the story.

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After being hit in the past, Jupiter's atmosphere has always formed a "bruise" around the impact site. This bruising occurs when a large object falls deep into the atmosphere, exploding within the clouds where the atmospheric pressure is high, blasting charred fragments back into space. These fragments fall back down, producing dark rings around the impact site.

The 1994 Shoemaker-Levy 9 comet impact left a series of huge charred scars in Jupiter's atmosphere, and last year's suspected asteroid impact bruise (also discovered by Wesley) left a Pacific Ocean-sized scar. This is the reason why astronomers expectantly stared through their telescope lenses after June 3; there simply had to be some evidence in the Jovian clouds of the strike.

Actually, the fact that Hubble has confirmed there is no impact bruise tells us a lot about the thing that caused the fireworks nearly two weeks ago.

Although other theories have been floating around as to the origin of the flash, an impact remains the most likely explanation. But this impact was caused by an object that was too small to penetrate deep into the clouds. It burned up as a bright meteor high in the atmosphere. Any trace of the meteor vaporized, it was simply too small to slam into Jupiter's clouds, generate a fireball and create an impact bruise.

In addition to the "what shot Jupiter?" detective work, Hubble also investigated the mysterious disappearance of the planet's Southern Equatorial Belt (SEB). It was thought that a sudden atmospheric shift had occurred, causing a band of ammonia clouds to rise above the SEB, obscuring it from view. Hubble has revealed that this is the most likely explanation.

"Weather forecast for Jupiter’s Southern Equatorial Belt: cloudy with a chance of ammonia," said Heidi Hammel of the Space Science Institute in Boulder, Colorado.

Great work Hubble, two Jupiter mysteries solved in one go!

--Ian O'Neill, Discovery News

Image: Hubble's view of the "flash" location (NASA/ESA Hubble Space Telescope)