Impact on Jupiter

Jay Albert - July, 2009

Around July 19, 2009, Australian amateur astronomer Anthony Wesley observed and photographed a strange dark marking in the south of Jupiter. He put his photo on the web and sent it to various organizations. It was quickly determined to be a “scar” from an asteroid or comet impact. Professional astronomers began pointing their large telescopes (including Hubble) at Jupiter. While the marking is very dark visually, it is very bright in infra-red photographs. The marking can be seen transiting Jupiter’s central meridian two hours and six minutes after the Great Red Spot. At the time I write this, the scar is about the width of the Pacific Ocean.

I checked the GRS transit times on the Sky & Telescope website using the link on our club’s website and found that the impact scar would transit Jupiter’s central meridian at 1:07 EDT. I set up my Celestron NexStar 6” SCT in my driveway. The hazy but steady air gave me a very good view of Jupiter at 214x. It was pretty good at 336x also, but the view was sharper at 214x. The scar shows up in the sketch below as a small black mark centrally located in Jupiter’s south. It is a bit elongated east to west.

The North and South Equatorial Belts are the most prominent features on Jupiter’s disk. The South Equatorial Belt appears double with the southern portion very much wider and darker. The North and South Temperate Belts are also very prominent. The South Tropical Zone was the brightest of the zones and I noted a couple of festoons hanging from the southern edge of the North Equatorial Belt that seemed to enclose a white oval near the following limb.

The impact scar is suspected to possibly be a fragment of comet Shoemaker-Levy 9 which crashed into Jupiter 15 years ago. It is expected to continue to elongate east to west and will eventually dissipate after anywhere from a few weeks to a few months…so check the transit times and go out for a look. There may not be another such event for a very long time.

This article first appeared in the ASPB Newsletter. Be sure you don't miss out on more interesting astronomy news and events. Benefits of membership include a free subscription to our monthly newsletter, Stars and Scopes, as well as discounted subscriptions to Sky and Telescope and Astronomy magazines. Members are also entitled to sign out any of the club's various "loaner" telescopes, eyepieces, and other related equipment. The fees can be submitted in person at the meetings, or if desired, you may mail your check along with a completed membership form to: "ASPB Membership, PO Box 19652, West Palm Beach, Florida 33416. For your convenience, a membership form is included here.   Individual Membership: $20.00 - Family Membership: $25.00 Download Membership Form