Jupiter's Impact

On 19th July, amongst all the Apollo 11 anniversary celebrations, amateur astronomer Anthony Wesley from Murrumbateman, Australia imaged a dark patch in the atmosphere of Jupiter. On Twitter there was discussion as to whether this might be the impact site of a small comet or asteroid or simply Jovian weather.

Within a couple of days, astronomers using the NASA Infrared Telescope Facility, on the summit of Mauna Kea, had taken infrared images which provided good evidence towards the impact hypothesis. On Wednesday, Gemini North imaged the 'glowing bruise' in the mid-infrared showing that the spot was much warmer than its surroundings in the upper atmosphere.

Jupiter impact site
Closeup view of the new dark spot on Jupiter taken with Hubbles Wide Field Camera 3 on 23 July 2009. CREDIT: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colorado) and the Jupiter Comet Impact Team
By Thursday, the Hubble Space Telescope had interrupted the checkout and calibration period following the recent upgrade to image it with WFPC3 in visible light. The Hubble image shows the dark mark which is described as being twice the length of Europe. The Hubble press release estimates the impact object to be "at least twice the size of several football fields" (whether soccer or American football probably doesn't matter). All this comes almost exactly 15 years after Comet Shoemaker-Levy 9 crashed spectacularly into Jupiter. In that case we had great images showing the string of pearls of the broken-up comet approaching Jupiter. I wonder if someone has unknowingly imaged this impactor before it hit. If you've imaged Jupiter recently it may be worth checking.

What has been particularly exciting about this week is what it shows us about the astronomical community. The word amateur is often used to mean 'in-expert' by people in the media but in astronomy it retains its Latin (and French) roots meaning "lover of" or "enthusiastic pursuer of an objective".

Amateur astronomers can often have very impressive telescopes and, perhaps more importantly, time to watch the sky to catch sudden events. The discovery of new comets, new supernovae, and outbursts of variable stars still rely on the patience and dedication of amateurs around the world. The second remarkable aspect of astronomy is the way the astronomical community will then pursue a discovery with everything from backyard telescopes to large professional instruments. Even the Hubble Space Telescope can be used to chase up your discovery. You don't get that in many other fields of endeavour.

Congratulations to Anthony Wesley for his discovery and if you have a reasonably sized telescope you might want to try observing the impact site yourself. Keep watching the skies.

Posted in astro blog by Stuart on Saturday 25th Jul 2009 (12:43 BST) | Permalink
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