Jupiter Impact Revisited

Jay Albert - September, 2009

Around July 19, 2009, Australian amateur astronomer Anthony Wesley observed and photographed a strange dark marking in the south of Jupiter.  Professional astronomers quickly determined that this was an impact scar which was in the same general area as the impact of comet Shoemaker-Levy 9 some 15 years before.  Readers of Stars & Scopes may recall the article in the August issue about my first sighting and drawing of this impact scar on July 24th.  At that time, it was about the width of the Pacific Ocean.  I spotted the scar again (with some difficulty) on the night of August 19th after I checked the GRS transit times on the Sky & Telescope website using the link on our club’s website.  The impacting object is still unknown.

I set up my Celestron NexStar 6” SCT in my driveway.  The sky was mostly clear with 4th magnitude stars visible and the hot, humid and still air provided good 7/10 seeing.  I observed at 214x with a W8 yellow filter to help steady the image and improve contrast.  The scar shows up in the sketch below as a very elongated E-W grey mark located in Jupiter’s south south temperate belt (SSTB) a bit past Jupiter’s central meridian.  When I drew it, I wasn’t sure if it was just a darkening of the SSTB or truly the impact scar because it was much lighter, fainter and more strung out than when I saw it on July 24th.  A photograph of Jupiter taken the night of August 19th and posted on Spaceweather.com confirmed that the object was the dissipating impact scar.  As an added bonus that night, I was able to observe Ganymede and Europa close together on the preceding (P) side of Jupiter with Europa’s shadow just below the north equatorial belt and Io close on the following side after it had just emerged from behind Jupiter.



The impact scar is expected to continue to stretch out and dissipate until it vanishes altogether.  I suspect a larger scope will now be required to view the impact scar and it may disappear within the next few to several weeks, so hurry up if you want to catch it.

Jay Albert 09/04/2009