The solar system is a happening place this week! I just learned of a major storm in Saturn's northern hemisphere, being monitored by the usual band of talented amateurs. See this site for a list of recent images. Chris Go's site has a particularly nice image.

John

That's a big 'un! Is Cassini in any kind of a position (both orbitally & in terms of planning flexibility) to snap a few close-ups?

Of course it is in a position, but always remember, Cassini observations are planned months in advance and changes in the observation plan almost never happen (trust me, we tried). Near the end of Rev142, there are a couple of quick imaging opportunities with the WAC but nothing extensive. The storm should be visible during the December 24 observation. The next orbit, Rev143 has many more Saturn observations, so hopefully the storm will stick around till then.

I hate to ask this question, but I'm really curious. If Cassini had a scan platform, would on-demand retargeting be a lot more feasible? I'm thinking, yes, we'd simply be trading off imaging vs. imaging, not imaging vs. the whole suite. But I don't know enough about the sequencing. Would a spacecraft with a scan platform have a separate sequence for the scan platform that could be modified by itself?

Maybe Hubble Space Telescope can snap some nice image of this BIG NEW STORM.
Does any member of UMSF knows somebody in Space Telescope Science Institute (STScI)?

It would certainly be simpler, but nothing in spacecraft operations is simple. There would still be numerous issues to be resolved- what pre-planned observations would be displaced, where would the data be put and when would they be downloaded, thermal implications of the new scan platform orientation would have to be checked, and new command sequences would have to be developed and tested. The Mars Rovers are always responding to new information on ~24 hour timescales, but they and their operations are designed from the ground up to be able to do that. Orbital missions are never that flexible.

John

This seems to be a re-occurring phenomenon on Saturn - remember the large equatorial outbreak of 1990?

http://hubblesite.org/newscenter/archive/r...s/1991/1991/04/

Of course, English actor and comedian Will Hay is famous for (probably) being the first astronomer to observe one of these white spots, back in 1933:

http://en.wikipedia.org/wiki/Will_Hay#Private_life

Nice shot of Saturn storm taken by Cassini (props to VP): http://saturn.jpl.nasa.gov/multimedia/imag...5/W00065990.jpg

Using the Solar System calculator to get the actual time of observation (caption indicated 1.323 M km away) sets it at 12/22/2010 23:40 UTC. This observation seemed like it would be nicely centered on Saturn's sunlight hemisphere and thus nicely visible from Earth.

Using a rotation rate of 10:47 h for Saturn, and propagating forward, here is an EXCEL table observation times where the storm should be centered on Saturn's visible disk on Earth. (Times are UTC and EST). Saturn rises around 3 AM and is better viewed closer to morning as it rises higher in the pre-dawn sky. I put "XXX" for view times where the storm is likely to be best. (Hopefully I got all the calculations right):

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Right, I'm off to eat my Christmas dinner...

Thanks for the picture and... MERRY CHRISTMAS!
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1. Wow. Look at that churned atmosphere! Remarkable.

2. Dude, Santa is like totally ripping that peak! Merry Christmas, all.

Wow. It looks a *little* bit like Karman vortex street. I wonder what its 'downwind' of

P

Images from December 24 are hitting the ground and the pages for them are on the JPL raw images page:

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=230977

Enjoy!

Even more dramatic in the BL1 filter:

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=230973

Fascinating...

Not really my planet, but I've had a go, just messing about really..

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My quick version using CB2/GRN/BL1:

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EDIT: Ugh, that'll teach me to do color composites on a laptop screen... Image replaced with an improved version. I didn't want to use CB2 as full resolution luminance as the storm contrast is quite different from the visible channels, especially in the tail. Too bad it wasn't the GRN that was full res.

Spectacular!!!

I wonder if that thing is lighting up Saturn's magnetosphere as well...looks like it'd be a major lightning generator.

Here's my take on the storm. Looks pretty massive. Used MT2, GRN, BL1 filters for color and the CB2 filter for luminance to maintain definition.


Edit: Whoops, I posted the wrong file. Fixed it with the version that doesn't look so crummy in the darks. I'll work on a better version in a bit.

It's interesting to see how "untidy" it is compared to say the GRS on Jupiter. Very nice pictures though.

Yeah, that was one 'badass' big pigeon!

Next year I'll buy it a present.

It's interesting to check earlier Cassini images to see if there are any images showing how this new feature formed. I imagine it might have started as a small, bright spot.

Unfortunately there do not seem to be many images of Saturns this month but I found these images from December 5:

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=230356
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=230355

A small, bright spot appears in both of the images so it is real. It's located at approximately the 'correct' latitude but I don't know if this is the same feature - this could be determined if I knew the subspacecraft longitude.

I'm aware it's very difficult to change observations that were planned months in advance but this is a *really* interesting event. Hopefully there are enough Saturn observations planned for the next rev. I remember some quick changes to Galileo's observations in response to unexpected events, e.g. the loss of the E16 Europa imaging (some of the originally planned E16 observations were incorparated into the E17 observations) but I imagine the Cassini obervation sequences must be far more complex than Galileo's.

Yes, that's the same storm, right about the time the RPWS first detected lightning from it.

There are many more Saturn observations during the next orbit, but I have no idea yet on whether they will show the storm, if it is still around.

Heres a bit clearer version of the storm. False color with stacked images and some noise suppression. Filters, MT2, GRN, BL1, CB2(lum) again.
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Wow

So are we seeing high cold[er] cloud tops punching though the normal aerosol/haze layer here?

P

So it would seem.

Question to anyone knowledgeable: Is the storm drifting within the larger atmosphere like the GRS, or is it fixed in longitude? Reason I ask is that it looks very much like a plume of sorts in this image, with the prevailing winds peeling off material from the top of the emission.

Would be interesting indeed if this is a manifestation of some sort of surface disturbance (whatever the word "surface" might mean on Saturn, if anything...)

Anyone noticed the moon shadow? Not nearly as impressive as the storm but still moderately noteworthy.

Yep, that's Dione's shadow.

From what I've read, it is drifting about 2-2.5 degrees to the west (the head of the storm I mean) each day. So the System III longitude increases by that amount each day.

Ground based image (Celestron C14 I assume): http://www.flickr.com/photos/31167687@N02/5299087913/

Thanks, VP, and wow, Mike! The sheer scale of that thing is just jaw-dropping in this view!

Holy Moly! One of the images/events of the year - and right at the 11th hour too.

Ground based obs are going to produce some spectacular movies as they track the evolution of this baby...

P

Well hot diggity-dawg, that EXCEL file posted above worked!!! One of our local amateur astronomers used it to image Saturn and snagged two timepoints:

http://www.raleighastro.org/gallery/main.php?g2_itemId=4342

Hi folks! This is my first post to this board. I happen to be fascinated with violent weather on other planets-in particular, thunderstorms. I'm wondering if this is what this particular storm is-one massive thunderhead or a series of them bunched in some sort of titanic squall line. I note that similar massive thunderheads had appeared on Jupiter, supposedly towering 100 miles above the surrounding clouds. Those storms were also very rare. I hope that Cassini can do radio readings to check for lightning bolts. If there are lightning bolts in this storm, it wouldn't surprise me if some of them were strong enough to incinerate a city! Flying alongside this beast would be a truly terrifying and awe-inspiring experience.

Another thought would be to photograph this storm when it's on Saturn's night side to check for lightning flashes.

It's too bad we can't do some sort of 3-D representation of this storm, so we could check out is vertical structure.

A quick animation from the Flickr photos Juramike linked to (greyscale in order that the GIF not be banded or dithered):
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Here is my new and improved EXCEL spreadsheet for predicting Saturn storm visibility from Earth. It is based on ground-based observations and starts from Dec 10 and projects forward to Jan 24, 2011. (It correlates to images already acquired between Dec 10 and Dec. 27th.)

Assuming a "System II" cloud rotation rate of 10 h 39 min, the storm is tracking westwards 3 min every Saturn rotation. Effectively the storm is rotating around Saturn every 10 h 42 min as viewed from Earth.

The best views will be about 30 minutes or so before the storm is at dead center on Saturn's disk.

Enjoy!

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Saturn in MethanoVision, using RGB[CB2, MT2, CB2xInvert(BL1)] from the December 24th observation:

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Neat dark ring around the storm (downwelling, so more methane absorbance?) and some detail of a bright upwelling in the storm center itself.

Hmmm...





Coincidence?

Here is an animated sequence showing storm evolution from ground-based observations from December 14th to December 30, 2010:
http://www.flickr.com/photos/31678681@N07/5309489179/

See also:
Link to Trevor Barry's website here: http://trevsastronomy.webs.com/apps/photos...albumid=8090267
Link to Anthony Wesley's website here: http://www.acquerra.com.au/astro/

From Rev143 Looking Ahead Cassini should get some more images of the storm between now and Jan 20.

" ISS begins its observations for Rev143 and the new year on January 2 as it performs astrometric observations of Saturn's small, inner moons. During this observation, the camera system will image Polydeuces, Telesto, Pallene, Prometheus, Anthe, and Atlas. Shortly before, the wide-angle camera (WAC) will image Saturn. The large, bright storm that formed in December 2010 in the North Temperate Zone of Saturn should be visible during this observation (though slightly farther to the west than shown in the graphic at right as the storm is slowly drifting to the west by 2.5 degrees per day with respect to the IAU longitude system for Saturn). ISS will take a similar observation on January 6, when the narrow-angle camera (NAC) will observe Prometheus, Anthe, Atlas, Methone, Calypso, Pallene, and Polydeuces. The Saturn WAC images should show the western end of the large northern storm."

There will be other images of Saturn on the 10^th and 15^th, but the storm will not be imaged unless it has expanded significantly.

Blink animation of Dec 24 and Jan 2 in MethanoVision. The new spot to the E looks "fresher" (more white = less methane absorbance = higher cloudtops). This suggests a hot spot plume from a deeper atmospheric layer and the older storm lobes being carried westward?

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[Animated GIF: click to animate]

The MethanoVision Jan 2 image can be seen here: http://www.flickr.com/photos/31678681@N07/...in/photostream/

Ah! Finally, someone gets it.
I am part of the tactical uplink operations and engineering team for the Rovers, and I'm glad to see that it's understood how different these things can be!
Based on the little I know about Cassini (I've never been acquainted with its sequencing process either, other than its pointing design and control suite for attitude constraints), I would guess that having a scan platform has just as many pros as cons. The pros would obviously include increased science -- you no longer have to move the whole spacecraft -- and maybe reduced usage of the reaction wheels. Would be tough to say without a high-fidelity analysis there. The cons would be adding more analyses and sequence flight rule checks for the operations team, and wear and tear for the engineering team.
No such thing as a free lunch.
In any case... pretty pics!

New set down.

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[first edit] Can someone explain how to get the image reduced? I thought that happened automatically. I simply inserted address of this image with the insert image button.

[second edit] Image now correctly posted. Thanks ugordan, uploading as attachment works (The attachment function is somewhat counter intuitive as after you UPLOAD, you still have to go into the Manage drop down box and hit +). Thanks also centsworth_II, however, that thread was locked so I couldn't open/edit my old post to see what I had done. I post pictures so infrequently that I forget what I did previously by the time I post again--or maybe I post regularly, but my memory is so poor that I don't remember that either.

You can't. If it's an inline image like that, it will be automatically reduced if it exceeds a certain size. It's best to either just post a link to it or upload the image as an attachment - saves bandwidth when viewing the thread and automatically produces a thumbnail image.

It looks like you did it here. I guess that's the only way to post a small image that can then be enlarged by the viewer.

Blink animation of Cassini views of the big storm on Saturn Dec 24 - Jan 2 - Jan 6:

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[animated GIF: click to animate]

Beautiful, Mike; thanks!

Morphologically, this storm seems very similar in many ways to the 'curdled' features often seen trailing behind the GRS, although considerably larger. I find that striking; is it possibly significant?

Additional images from Rev 143.
http://saturn.jpl.nasa.gov/multimedia/imag...5/W00066331.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...5/W00066332.jpg

Have we seen those ripples extending up toward the equator before?

There's some beautiful belt detail in the last batch of raws. It is starting to look more like Jupiter.
Gotta figure a creative way to use the MT3, MT2, and CB2 combo set.

Straightforward combo of HiPassMT2 RGB[MT3,MT2,CB2]. Some channel mixing between the methane transmission layers and a gentle contrast enhancement:
Blue is deep atmosphere (much methane absorbtion), white is upper levels (light reflected before methane can get absorbed) .

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Amazing detail in this! The bright upwelling at the upper left of the image seems to have a dark spot in MT2 and MT3 images (eyewall??). Immediately to the SW of the upwelling is a deep blue vortex of descending air. Cloud patterns around this spot show a counterclockwise pattern.

And a shockwave can be seen trailing from the W edge of the storm down through the southern belt almost to northern edge of the the Equatorial belt.

That's really nice Mike - quite some detail there, and yes, you can clearly see the shockwave propagating back from the storm's leading edge.

Awesome.

Another shot of the storm on Saturn. Better view around the main "spot":

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Taken from 1,000,000 km on January 12, 2011.