Jupiter, and the Moon

A large impact mark on Jupiter’s south polar region captured on Monday by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii.


40 years ago yesterday, men walked on the moon. Mission to the Moon











One of several images of the impact mark on Jupiter — the dark spot at the upper right of this photograph — taken by the man who discovered it.




July 21, 2009, 8:59 am
Amateur Finds New Earth-Sized Blot on Jupiter
By Robert Mackey
NASA/JPL, via Associated Press A large impact mark on Jupiter’s south polar region captured on Monday by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii.

NASA has confirmed the discovery of a new hole the size of the Earth in Jupiter’s atmosphere, apparently showing that the planet was hit by something large in recent days. The impact mark was first spotted on Monday morning by an amateur astronomer in Australia, who then drew the attention of scientists at NASA’s Jet Propulsion Laboratory to the dark mark on Jupiter’s south polar region.

The apparent impact comes almost exactly 15 years after a comet named Shoemaker-Levy 9 struck Jupiter, “sending up blazing fireballs and churning the Jovian atmosphere into dark storms, one of them as large as Earth,” as The New York Times reported on July 19, 1994.

Images of the impact mark, as seen through a NASA telescope in Hawaii, were posted on the space agency’s Web site on Monday with this explanation:

Following up on a tip by an amateur astronomer, Anthony Wesley of Australia, that a new dark “scar” had suddenly appeared on Jupiter, this morning between 3 and 9 a.m. PDT (6 a.m. and noon EDT) scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., using NASA’s Infrared Telescope Facility at the summit of Mauna Kea, Hawaii, gathered evidence indicating an impact.

New infrared images show the likely impact point was near the south polar region, with a visibly dark “scar” and bright upwelling particles in the upper atmosphere detected in near-infrared wavelengths.

Glenn Orton, a scientist at the Jet Propulsion Laboratory, said “It could be the impact of a comet, but we don’t know for sure yet.”

Mr. Orton told New Scientist magazine that the planet could have been hit by a block of ice or a comet that was too faint for astronomers to detect before the impact. Leigh Fletcher, an astronomer at the Jet Propulsion Lab told the magazine the impact scar “is about the size of the Earth.”

In Australia, the Sydney Morning Herald reported that the amateur astronomer, Anthony Wesley, a 44-year-old computer programmer from a village north of Canberra, made the discovery “using his backyard 14.5-inch reflecting telescope.” The Herald explained: “Wesley, who has been keen on astronomy since he was a child, said telescopes and other astronomy equipment were so inexpensive now that the hobby had become a viable pastime for just about anybody. His own equipment cost about $10,000.”

Mr. Wesley recorded the discovery of the impact mark, and posted several of the first images he took of it, in an observation report he posted online:
Anthony Wesley One of several images of the impact mark on Jupiter — the dark spot at the upper right of this photograph — taken by the man who discovered it.

I came back to the scope at about 12:40am I noticed a dark spot rotating into view in Jupiters south polar region started to get curious. When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I thought likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions improved I suddenly realised that it wasn’t just dark, it was black in all channels, meaning it was truly a black spot.

My next thought was that it must be either a dark moon (like Callisto) or a moon shadow, but it was in the wrong place and the wrong size. Also I’d noticed it was moving too slow to be a moon or shadow. As far as I could see it was rotating in sync with a nearby white oval storm that I was very familiar with - this could only mean that the back feature was at the cloud level and not a projected shadow from a moon. I started to get excited.

It took another 15 minutes to really believe that I was seeing something new - I’d imaged that exact region only 2 days earlier and checking back to that image showed no sign of any anomalous black spot.

Now I was caught between a rock and a hard place - I wanted to keep imaging but also I was aware of the importance of alerting others to this possible new event. Could it actually be an impact mark on Jupiter? I had no real idea, and the odds on that happening were so small as to be laughable, but I was really struggling to see any other possibility given the location of the mark. If it really was an impact mark then I had to start telling people, and quickly.

The Guardian reports that Mr. Wesley, who “spends about 20 hours a week on his passion of watching and photographing Jupiter,” almost missed making the discovery because he interrupted his work late on Sunday night to watch sports on television. Mr. Wesley told The Guardian:

I was imaging Jupiter until about midnight and seriously thought about packing up and going back to the house to watch the golf and the cricket. In the end I decided to just take a break and I went back to the house to watch Tom Watson almost make history.

I came back down half an hour later and I could see this black mark had turned into view.

In another interview, Mr. Wesley told the Sydney Morning Herald that spotting the impact mark on Jupiter made him glad the huge planet is in Earth’s neighborhood: “If anything like that had hit the Earth it would have been curtains for us, so we can feel very happy that Jupiter is doing its vacuum-cleaner job and hoovering up all these large pieces before they come for us.”