Saturday, July 3, 2010

Meteor to blame for Jupiter flash

An impact on Jupiter that was captured on camera by amateur astronomers Anthony Wesley and Christopher Go was apparently nothing more than a giant meteor, according to the latest Hubble Space Telescope observations of the gas giant.

The Wide Field Camera 3�s image of Jupiter, the south equatorial belt absent. There�s no sign that any impact or explosion has taken place. Image: NASA/ESA/Z Levay (STScI).

The flash of light was seen independently by Wesley and Go on 3 June at 20:31 UT (see our earlier report). Four days later Hubble turned its powerful Wide Field Camera 3 on Jupiter, imaging the planet with its south equatorial belt uncharacteristically missing after it faded several months ago when high-level ammonia clouds obscured the darker belt. However, there was no sign of a black soot cloud typical of previous impacts into Jupiter in 1994) and 2009).

“The cloud tops and the impact site would have appeared dark in ultraviolet and visible images due to debris from an explosion,” says Heidi Hammel of the Space Science Institute in the United States, who participated in the Hubble observations. “We can see no feature that has those distinguishing characteristics in the known vicinity of the impact, suggesting there was no major explosion and no fireball.”

So what was it? Likely it was a giant meteor that burned up above the cloud deck, and was only a fraction of the size of the impactors that have been seen to strike Jupiter in the past. As the meteor streaked into Jupiter’s upper atmosphere, it generated a shock wave in the atmosphere that heated the object to extremely high temperatures, and as it vapourised it left a glowing trail of hot gas that was visible as the two-second long flash detected by Anthony Wesley and Chris Go. Because the flash was so brief it could easily have been missed, meaning it is possible that such meteors occur every few weeks but we don’t see them.

A shooting star seen from a distance of 770 million kilometres – amazing!

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