Dark impact mark in Jupiters south polar region 19 July

[davegrennan]

Indeed ... but given that the impact mark is so large, by comparison with SL9 we're talking about a 1 Km +, possibly 2 Km diameter object; I think a "fresh" comet would have some sort of tail if it were out by Jupiter and should have been detected long since. Don't forget that, the more we look at even small asteroids, the more we find have small satellites.

The news media seem to be studiously avoiding reporting this event, not even a whisper on e.g. the science page on the BBC News site.
 

I would not be surprised one little bit if even a comet of this size went undetected.  For lots of reasons.  It is likely to be a fresh 'first timer' and may well have come from jupiter's blind side.  A 1-2k object at Jupiter's distance would be in the mag +20 range. Also I wouldn't expect too much of a tail out by Jupiter.  Also surveys would tend to avoid searching the area immediately around Jupiter meaning that the only chance for it to be detected was when it was not in the Jupiter zone and hence even further away and fainter.

I see what you mean about the news media, I suspect this is due in part to all of the unknowns which still exist.  I also heard that JPL are aware that some of us are unhappy that Anthony's part in all of this was understated by them.

[brianb]

I see what you mean about the news media, I suspect this is due in part to all of the unknowns which still exist.

Doesn't usually stop them speculating, or even trying to manufacture stories out of thin air. I suspect the problem is they can't cover it because they haven't got 150 reporters with satellite video phones in the disaster area.

As for the nature of the object, if the subsidiary scars are shown to be genuine, I think this adds weight to the asteroid theory. An incoming comet would be in one piece, we rarely see "multiple comets", and Jupiter's gravity wouldn't have had time to rip up a directly incoming object enough to make sufficient difference to the impact point. SL9 was only in widely seperated pieces because of its previous close encounter with Jupiter, when it was perturbed into its impacting trajectory. Anyhow I guess we'll never know, unless pre-impact images of the object do come to light, and maybe not even then. Finally the distinction between comets and some types of asteroid is rather wooly anyway!

[davegrennan]

The asteroid theory has one BIG problem.  The area around Jupiter is notably devoid of asteroids because the 'big guy' has already swept them all up or ejected them to the langragian points as trojans. Don't forget that SL9 was broken on its first pass of Jupiter.  Given this there is no reason to beleive that if this indeed was a comet it was also broken on its first pass (which may or may not have also been its last).  The other piece of evidence supporting a soft body impact event is the secondary scarring which indicate substantial fallback.  A harder body would have punched much deeper and would have resulted in a more defined scar with far less secondary scarring.

Also it is almost certain that any asteroid with satellites which got this close to jupiter would have had to have made relatively close passes previously.  This would almost certainly result in the asteroid and any potential moons parting company at that stage (again tidal forces).

[brianb]

Also it is almost certain that any asteroid with satellites which got this close to jupiter would have had to have made relatively close passes previously.  This would almost certainly result in the asteroid and any potential moons parting company at that stage (again tidal forces).

Yes, that's a good point!

[martinastro]

Dave, thanks for the latest information and for sharing your wonderful memory with me about seeing the SL-9 impact scars and meeting Gene...what an experience that must have been, a real dream come true!. Observing the eyes on Jupiter must be at the top of your all time favourite list along with your asteroid discoveries.

Back in 94 I knew nothing about Astronomy although I did have a growing interest in it at the time. I recall beeing fascinated by the SL-9 impact and its build-up, and fondly recall watching programmes showing Gene, Caroline, and David on TV and getting excited by the developments. I didn't know back then that these same people would later be so inspirational to me. I didn't have a scope back then nor did I know that they could be seen in a back yard scope so I never got to see that event. I have read plenty of detailed books on that impact since though.

I agree with your theory. I believe it most definitely is a comet which hit Jupiter.  It probably hit the far side of the planet as it approached from the outer solar system then rotated into view, the probability of a comet is higher in that region of the solar system. Just goes to show how systematic observation and imaging of the solar system (and beyond) by amateurs can still make phenomenal discoveries!. I agree also that the role of Anthony Wesley's discovery has been played down in a big way, with the attention in turn given to NASA and JPL and their instruments which is unfair. However, it's good to see that SW today has made sure Anthony got the credit he deserves.

Why have the media not picked up on this?...I don't know but it's a shame that they haven't. It's got to be one of the biggest news items on the net now within the astro community.

I spent pretty much the entire night observing Jupiter at high mag to help train my eye for spotting delicate features on the planet's disk which was successful despite the poor seeing. The planet danced and quivered all night and as it drifted across the field it felt like watching it slowly sink through the Ocean, viewed from underneath, due to the mositure in the atmosphere and the effects of the jet stream nearby. Hoping to make  a visual on this impact soon. Good luck all.

[martinastro]

I thought this message on the comet mailing list was interesting...

There is one thing I would like to add. Maybe the impacts are not over with. It took several days for all of SL-9's pieces to strike Jupiter in 1994. What if the object that struck a couple of days ago was a fragment
of another shattered comet? It seems likely that SL-9 shattered during its close approach to Jupiter in 1992. Following its 1993 discovery, we watched as the comet's components drifted away from each other, so that it took six days for all 21 pieces to ultimately strike the planet. Now what if a comet had been shattered by Jupiter several years ago, instead of only two? Instead of hours between impacts, maybe it could be days. Obviously, if the components drift too far apart, other perturbations will divert the components into more distinct orbits, instead of all following in the same orbit.

Anyway, some food for thought.

[brianb]

What if the object that struck a couple of days ago was a fragment
of another shattered comet?

If so then lots of "fresh" icy surfaces would have been exposed, so that even if the comet had been "dead" before being ripped up it should have become quite active - that's how SL9 was discovered.

I've seen a suggestion that the "Bird strike object" might have been a fragment of SL9 that somehow missed in 1994, but this was based on the coincidence of date by the Earth calendar & doesn't seem to have any dynamical justification.

Of course we simply DONT KNOW what the "Bird strike object" was, whether it was single or disrupted recently or long ago, without some pre-discovery images. It is of course worth keeping an eye on Jupiter just incase something else does hit.

[martinastro]

(Above) The scar from the probably impact appeared July 19 in Jupiter's southern hemisphere, and has grown to a size greater than the extent of the Pacific Ocean. This infrared image taken with Keck II on July 20 shows the new
feature observed on Jupiter and its relative size compared to Earth.

Jupiter pummeled, leaving bruise the size of the Pacific Ocean. BERKELEY - Something slammed into Jupiter in the last few days, creating a dark bruise about the size of the Pacific Ocean. The bruise was noticed by an amateur astronomer on Sunday, July 19. University of California, Berkeley, astronomer Paul Kalas took advantage of
previously scheduled observing time on the Keck II telescope in Hawaii to image the blemish in the early morning hours of Monday, July 20. The near-infrared image showed a bright spot in Jupiter's southern hemisphere, where the impact had propelled reflective particles high into the relatively clear stratosphere. In visible light, the bruise appears dark against the bright surface of Jupiter.

The observation made with the Keck II telescope marks only the second time astronomers have seen the results of an impact on the planet. The first collision occurred exactly 15 years ago, between July 16 and 22, 1994, when more than 20 fragments of comet Shoemaker-Levy 9 collided with Jupiter. The Shoemaker-Levy 9 (SL9) impact events were well-studied by astronomers, including several from UC Berkeley, and many theories were subsequently developed based on the observations.

"Now we have a chance to test these ideas on a brand new impact event," said Kalas, who observed the aftermath of the new impact with the help of Michael Fitzgerald of Lawrence Livermore National Lab and UCLA. The astronomers decided to observe Jupiter after hearing that Australian amateur astronomer Anthony Wesley had discovered the planet's new scar. They read about it on the blog of UC Berkeley and SETI Institute astronomer
Franck Marchis (http://www.cosmicdiary.org/blogs/nasa/franck_marchis/). Kalas, who is in Greece, consulted intensely with Fitzgerald and Marchis on how best to observe the feature. Fitzgerald then performed the observations with the help of Keck Observatory astronomer Al Conrad.

"The analysis of the shape and brightness of the feature will help in determining the energy and the origin of the impactor," said Marchis. "We don't see other bright features along the same latitude, so this was most likely the result of a single asteroid, not a chain of fragments like for SL9." "The fact that (the feature) shows up so clearly means that it's associated with high-altitude aerosols, as seen in the Shoemaker-Levy impacts," said James Graham of UC Berkeley, who assisted with the new observations as well as with observations taken during the SL9 event in 1994.

Mike Wong, a UC Berkeley researcher currently on leave at the Space Telescope Science Institute in Baltimore, used the observations to calculate that the scar is near the southern pole of Jupiter (305 W, 57 S in planetographic coordinates) and that the impact covers a 190-million-square-kilometer area as big as the Pacific Ocean. Because of the complex shape of the explosion, it is possible that tidal effects fragmented the impactor - a comet or asteroid - shortly before it collided with the planet. The impact fell on the 15th anniversary of the SL9 impacts, but the coincidences do not end there. Kalas' original plan was to search for a previously detected, Jupiter-like planet around the star Fomalhaut. The star is located roughly 25 light years from Earth in the direction of the constellation Piscis Austrinus. Kalas showed previously that the planet, dubbed Fomalhaut b, is bright, and one explanation for that brightness is that it is suffering impacts just like Jupiter, he said.

Later this week, astronomers from UC Berkeley and around the world plan to conduct high-resolution visible and ultraviolet observations of the impact site using the Hubble Space Telescope's brand new Wide Field Camera 3.
Ground-based facilities including the W. M. Keck telescope will also use adaptive optics to obtain much sharper infrared images of the impact's aftermath. But the Keck images reported here will provide a crucial baseline for measuring the spread of impact-related material, Wong said. No other method exists to directly track the winds at these rarified levels of Jupiter's atmosphere. One of those planning to observe Jupiter with Keck is UC Berkeley astronomer Imke de Pater, who was one of the leaders of the campus's SL9 observations of Jupiter in 1994. Working with Conrad and Wong, she plans to observe Jupiter on July 24 using a laser guide star with adaptive optics, analogous to observations conducted in July 2006 and May 2008. More information: Keck Observatory press release, http://keckobservatory.org/index.php/news/jupiters_adds_a_feature/...Article by Robert Sanders from Media Relations, University of California-Berkeley.

[martinastro]

Impressive results Dennis, thanks very much for sharing those with us.

I observed the impact scar visually last night...amazing!.

[martinastro]

Cheers Dennis, it was an 8.5" F/7 reflector.

[martinastro]

''Back in July of 1994 I recall the excitement in the media and within the Astronomical world about comet Shoemaker-Levy 9 which was about to slam into mighty planet Jupiter, it was a monumental event which deeply captivated me at the time. Back then I had a growing interest in Astronomy, however I knew absolutely nothing about the subject, nor did I even know that Jupiter was visible in the sky. I vividly recall the exciting television programmes showing the latest images of the impacts and the live reactions from Scientists all over the world. Among these were the comet's discoverers, David Levy, Gene and Caroline Shoemaker. Many observers the world over marveled at those huge impact bruises on the planet's atmosphere - it was the sight of all sights, a violent and rare event of epic proportions which I never got to see. It was said to have been a once in a life time event and unlikely to be seen by human eyes again. Several years later I got into visual Astronomy in a big way. Comets became my passion, and for me there was nothing more sublime than a great comet in the night sky, in my opinion they are the finest transit event in the heavens. My interest in comets naturally led me into the field of comet impacts on Earth and the search for new visitors, a passion which many amateurs take up, often obsessively, in the quest for making a discovery of their own. During my research it was only a matter of time before the names of David Levy and the Shoemakers arrived back in my life again. They quickly became a source of inspiration to me. Naturally one cannot read these names before the name of Shoemaker-Levy 9 quickly appears. I began to read everything I could about this comet impact, buying books, magazines, documentaries, and listening to radio programmes to learn as much as I could about that incredible event. In truth I was envious of all those amateur observers who seen the impact scars through their telescopes, and as a comet lover I felt that I had missed out, and statistically it should never happen again my life time.

15 years later is has happened again!. When I first heard the news about Anthony Wesley's discovery of an impact scar on Jupiter I couldn't believe my luck. This was unbelievable, a comet has yet again struck Jupiter, this has got to be one of the biggest astronomical events since 94. This was an opportunity not to be missed so I made it my goal to see this impact for myself. Thanks to Dave Grennan I acquired a list of the transit times of the impact scar so it was just a matter of time to catch it in the act. This is not as easy as it sounds because one needs a clear sky with Jupiter at a reasonable altitude, and besides, due to the planet's rapid 10 hour rotation there was only a slight window period when the impact would be visible on the planet at night from Ireland. The best time to see the scar would be when it was located on the centre line of the planet, in other words, on Jupiter's meridian. The first meridian crossings were clouded out for me which was disappointing, however I used the time wisely on other clear nights when the impact was not visible. Jupiter is my favourite planet in the solar system, I cut my first 'sky teeth' on this planet and it was with it that I had learned to observe fine detail through a telescope. There was a time when I knew it intimately. Over the years my observing interests evolved and I found myself being drawn to wide field low power comet observation, so I had neglected Jupiter. With this in mind I decided to begin a relentless observing programme since news of the discovery was announced. I spent hours on every clear night observing the planet in order to train my eye to detect delicate detail at the limit of vision. It was time and effort very well spent.

The next transit crossing was on the morning of the 25th at 02.07. I had the 8.5" F/7 reflector set-up hours earlier so it would cool down to the outside temp and reduce internal thermals within the tube which could hamper observation. I began my search for the impact at 01.00. I switched between two old eyepieces, a 12mm and 9.7mm, which offered a narrow FOV and a poor view. In fact, the eyepieces have become tarnished over the years which was a major handicap. It was however a glorious dark clear night without a cloud in the sky. Jupiter was a brilliant object low in the E within the stars of Capricornus. The view through the scope was not encouraging due to very poor seeing conditions. All I could see where the two Eq cloud belts and nothing else. I stuck with it and never took my eyes from the eyepiece. Gradually, min by min, Jupiter climbed higher into the sky and eventually the rotating Earth threw the planet into a favourable position at a decent elevation. Now I was getting periods of good seeing which produced brief but spectacular views of the planet's belts, zones, festoons, and the four Jovian Moons which where set in pairs on either side of the planet. With averted vision I got blurred glimpses of the impact. At the start it was unimpressive and very difficult to see, however as the atmosphere steadied further I got a rich train of perfect views of the scar which completely blew me away. The impact was dead centre on the meridian and seemed bold and alien as it begged for attention from the south polar region. I seen it as a large well-defined dark smudge, clearly the darkest feature on the planet. With relaxed breathing techniques I oxygenated my blood which improved my vision and by doing this I could see not only a splotch but a striking elongated feature extending from the central area to the E side of the FOV. I checked my watch, it was 02.07 on the dot. I was utterly amazed by the scene, it was breathtaking to see a comet impact scar on another planet...the sight of all sights!. I looked up from the eyepiece and was amazed by a phenomenal black sky with glowing Milky Way crossing the zenith and down into the rich star fields in Sagittarius and Scutum. Behind me to the N was a glorious low level Noctilucent Cloud Display which was beyond words, the skyline was glowing intense yellow-gold which cast shadows. The NLCs looked like a volcanic eruption or impact event itself had occurred on Earth further N. What an incredible soal-satisfying experience. Now as I write this I can see those glimpses of the impact scar in my mind's eye, these will be memories which I will cherish forever!''

[brianb]

Great report Martin ... I tried to "spot the spot" but the seeing was too poor for me. Tried to image as well without success....

Well done Dennis, you should be really proud of those images!

[martinastro]

Thanks very much Brian, I wanted to give the personal touch since it was such a special observation to me. That's another box ticked off the list, a box which I never thought would be ticked in my life time. Nature sure is unpredictable.

Good luck for the next transit, hopefully the seeing will be better for visual observation and imaging.

Cheers.

[martinastro]

Made a second visual observation of the Jovian impact scar last night when it was on the meridian at 03.45. Despite the poor seeing I could make out its very dark colour and irregular shape which looked elongated in a horizontal direction. Four of the brightest Moons where on view aligned in pairs on either side of the planet along with a bright field star to the SW of the high power FOV. Quite a treat!. Used 8.5" F/7 reflector with 9.7mm eyepiece.

[markt]

Anybody got a list of transit times for the impact region for august?

Cheers, Mark