Your Cassini awesomeness for today

By Phil Plait | October 13, 2008 5:10 pm


Cassini view of a vortex at Saturn’s south pole

If you’re asking yourself, "What the frak is that?" then join the club. I kinda sorta understand what’s going on, but the details! Yikes!*

What you’re looking at is an incredibly detailed image of Saturn’s south pole (with ten times better resolution than any image taken before), taken by the Cassini spacecraft. It was taken from an angle, but then mathematically "deprojected" to make it look like you are hovering over the pole and looking down.

Previous images showed some sort of weird rotating vortex at the pole. It was thought that the edges were clouds at high altitude (40 – 70 km (25 – 45 miles) above the inner deck) surrounding a region of clear air. But this image shows the central air isn’t clear at all; there are clouds in it, forming a loose inner ring. They are convection clouds; something like cumulonimbus clouds on Earth.

Convection is when hot air rises and cold air sinks. This can happen in cells, self-contained regions in the atmosphere. This occurs pretty much whenever you have a temperature gradient vertically; that is, when it’s hot underneath something cold. Saturn’s interior is hot, so the air rises, gets up to some altitude, cools, and sinks.

In fact, the entire gigantic vortex — it’s 4000 km (2500 miles) across, folks — is a convection feature. The relatively clear center indicates this is warm air, which makes it similar to the eye of a hurricane on Earth. However, on Earth, convection doesn’t occur in the eye, leaving it clear and free of clouds. But the clouds in the middle of this Saturnian region indicate convection is happening on smaller scales there too… meaning the analog of this region to a hurricane only goes so far.

Saturn’s a mess.

Some of the inner clouds are "S"-shaped. They get that way due to Saturn’s rotation making them spin (I’ve seen demos of liquids in spinning bowls that look exactly like this). At the upper left of the inner ring you can see one cloud that looks like an oval; that’s actually the eye of a smaller hurricane-like structure. Its rising air has cleared through Saturn’s haze layer, allowing us to see the circular structure.

The power for all this comes from the heat deep inside Saturn, aided by its rapid 10-hour rotation. Saturn is much larger than Earth, so its rapid rotation means things are spinning around there quickly. Even at Saturn’s poles, unlike Earth’s, there’s enough rotational momentum to keep hurricanes circulating.

So there’s a basic understanding of some of what’s going on in this image, but the details — what’s powering the smaller convection cells; why is one big enough to punch through the lower atmosphere, what’s the chemical composition of these features, how long do they last, how old is this whole vortex thingy — are still head-scratchers.

I imagine images like this will keep planetary atmospheric scientists gleefully arguing with each other for years. That’s one thing I kinda miss about not doing research: the debating over what the heck we’re seeing. When Hubble images would come in, we’d all gather around someone’s computer screen and point and talk and conjecture and speculate, and generally have a blast. It was only later, when we had to dig in and do the dirty work that we started to get our real answers. Sometimes you can see what’s going on just by looking at a picture, and other times — like with this shot of Saturn — it shows us that there’s a lot left to figure out.

*Note: I am trying to puzzle this out after examining the picture and reading the Cassini website. This is all pretty odd stuff, so any mistakes stated here are mine, and not from the Cassini website.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (52)

  1. JoeSmithCA

    Wait, no its [x][quantity][currency] (wasted,ill-spent) by a [country][space agency]in a [name or type of conspiracy]. The image is actually done by [select from below]:

    1. A child using black and white ink [reference to smiley face like image].
    2. Peace loving aliens sending us an image of happiness [reference to smiley face like image].
    3. [Other, insert as needed. Cite reasons with anecdotal and/or unverifiable evidence]

  2. JKH

    KEWL! Thanks BA. Your non-political (ahem!… excuse me) posts are awesome. Just awesome.

  3. Personally, I like the political posts and the science posts. That thing looks like an ultrasound… but of what?! lol

  4. Not BA Phil

    If you look hard enough, and squint, then smoke something and poke yourself in the eye, I think you can make out Jesus somewhere in there, or Mary, or maybe Darwin. Damn paradolia not working right.

  5. I guessed immediately what it was. It was still unexpectedly bizarre though. Wonderful stuff! Hooray for all our space probes, and the Web – together they are changing people’s lives.

  6. Pfui. I think it’s an femto scan of a quantum bowling ball in the gutter at The Pauli Lanes.

  7. “Even at Saturn’s poles, unlike Earth’s, there’s enough rotational momentum to keep hurricanes circulating.”

    The lack of Coriolis forces is not what disallows hurricanes at the Earth’s poles. Rather, it is the low surface temperatures, which impedes convection.

    If you heated the Arctic ocean up to 30 degrees C (86F), it would produce cyclonic storms just fine.

    Saturn’s atmosphere is heated internally, instead of by the sun, so hot poles are not a problem.

  8. Crux Australis

    Jewel; like JoeSmith says, it’s an ultrasound of a smiley face!

  9. firemancarl

    Awesome, just 100% made of awesome.

  10. Maura

    Looks like a BSG special effect.

  11. Saturn is, BY FAR, the coolest planet in our Solar System.

    There. I said it.

  12. It looks like there are white cloudy things lurking beneath … creepy.

  13. Yoeman

    Do I see a bit of a hexagonal outline in there? I’ve seen that from the North Pole shots, but not on the South before, it appeared pretty much circular to me.
    What an awesome picture, I wish I could live another 200 years, if only to be able to see what wonderful things we will be discovering along the way.

  14. > liquids in spinning bowls

    I was gonna say, looks a bit like somebody stirring their cafe con leche.

  15. I’m waiting for the pictures of Rukhs flying around the Saturnian atmosphere. – g^2

    Key Phrases: “Saturn Rukh” “Robert L. Forward”

  16. IVAN3MAN

    “Air”, Dr. Plait? According to Wikipedia: “Air is that part of the Earth’s atmosphere that humans [and animals] breathe and as such one of the four classical elements.”

    According to the Oxford English Dictionary: air noun 1 The invisible gaseous substance surrounding the Earth, a mixture mainly of oxygen and nitrogen. 2 The open space above the surface of the Earth. 3 Before another noun indicating the use of aircraft: air travel. 4 The Earth’s atmosphere as a medium for transmitting radio waves. 5 One of the four elements (air, earth, fire, and water) in ancient and medieval philosophy and in astrology. 6 Music a tune or short melodious composition. 7 (an air of) An impression of. 8 (airs) An affected and condescending manner.

  17. Whoa, that is a cool picture. And like Jewel, I do like Dr Plait’s political posts, although they really depress me. We let people that have such a tenuous understanding of science run this planet. :(

  18. Phil does not need me to come to his defense, but methinks it is IVAN3MAN who is putting on airs, as Dr. Plait has repeatedly mentioned that he uses terms colloquially to better connect with a broader audience. . . – g^2

  19. themadlolscientist

    @ IVAN3MAN: Picky, picky, picky………………….. :-)

  20. Pop

    Do I understand that you said convection happens “only” in the eyewall of a hurricane? If this be the case, you may have mispoke (wrote). It is my impression that convection occurs with the clouds making up the most of the visible body of a hurricane. Anytime you get cumbulonimbus clouds it’s because there is convection. Or have I misunderstood the mechanics of thunderstorm formation? And when these clouds are over an ocean the possibility of a low pressure area forming in connection with coriolis effect then aids “central convection” developing. Convection occurs from start to finish in earth-bound hurricanes across the body, not just eyewall. But, I repeat myself. OK, I’m wearing my asbestos underwear, flame-on you sundery readers.

  21. rayceeya

    Oh Cassini, how much I love thee.

    To think that you’re little nuclear powered heart caused so much trouble a decade ago when you were launched.

    And yet who can put value to the knowledge you and you’re little friend Huygens have brought to us here on Earth.

  22. IVAN3MAN

    @ themadlolscientist

    It’s Dr. Phil Plait’s fault — he keeps posting political issues which have put me in a bad mood! :mad:

  23. Lab Lemming: I fiddled with that line quite a bit. I didn’t want to misuse terms, and the warm air “powers” the hurricane itself, but the rotation is mostly due to Coriolis forces. I wound up leaving it like that to avoid going into unnecessary detail. It’s Hobson’s choice in a blog, I know.

    Pop: I meant to say that convection happens in the eyewall and not the eye itself. Yeah, I could have been clearer. I’ll fix that now.

    Ivan: Feh. :)

  24. The two cents from Seattle say – that’s clearly a latte!

  25. Robster

    “If you heated the Arctic ocean up to 30 degrees C (86F), it would produce cyclonic storms just fine.”

    So that’s what, in 40 years? Unless we all stop driving our SUVs.

  26. Naomi

    I will never stop appreciating Cassini’s habit of making me go, “Coooooool.”

  27. Phil, the rotation is caused by the change in velocity with latitude, which increases towards the poles. So if you can get a storm to spiral at 15 degrees N, you can easily get it to spin at 90N.

    Lack of rotation is why hurricanes don’t form closer to the equator than 10 degrees. But for a storm of a given size, there’s more differential rotation at the pole than close to the equator.

  28. Undermentals

    What you call an “eye of a smaller hurricane-like structure” is clearly and obviously an Orb. Unmistakable evidence of ghosts on Saturn. Ah, but I suppose you are in denial and will try to explain it away with some highfalutin scientific gobbledygook.

  29. Bein'Silly


    The hippies are right y’all the cosmos is … like … pyschedelic! :-D

    Oh & awesome, awesome, awesome! 8)

    Thanks BA for making me feel I’m drunker than I am! ;-) :-)

  30. StevoR

    Naomi said on Oct. 14th, 2008 at 2:45 am :

    “I will never stop appreciating Cassini’s habit of making me go, “Coooooool.””

    Agreed & same here.

    The south pole of Saturn (actually both poles ) is very cool indeed – and not just in temperature terms either! ;-) 8)

  31. Bein'Silly

    Tman Says:October 13th, 2008 at 7:35 pm

    “Saturn is, BY FAR, the coolest planet in our Solar System. There. I said it.”

    Er .. actually no you wrote it.
    Unless you were speaking aloud as you typed. ;-)

    OH & the coldest planet is actually Pluto .. Neptune Sedna! ;-)

    Coldest? Coolest? Same diff?

  32. Bein'Silly

    Ooops! Sorry folks – will everything now be in italics on the rest of this thread ..?

  33. Bein'Silly
  34. Jim Shaver

    I agree with Yoeman, in that I see a hexagonal shape in the perimeter of the vortex. In fact, I’m surprised — no, shocked — that the BA did not mention that feature. What on Saturn could create such a giant hexagon!? I hope Phil has an idea or will speculate.


  35. SLC

    Another spectacular photo from Cassini, which space mission has contributed more scientific information then all the manned space flights put together. Just think of how much could be accomplished if the manned space program were deemphasized and the funds freed up spent on missions such as these. This argument has been well made by Bob Park and Steven Weinberg but, of course, these follows don’t know what they are talking about.

  36. Hiya SLC, I’m starting to think you’re just having a laugh. Or are you really just a nasty troll? Three things. Whatever, false dichotomy and no they don’t. But before I go on I’ll save time by just posting a link to what I said last time…

    ..and then to save more time the post that answered your inevitable response…

  37. u….HHHH… What picture are we talking about? I’ve refreshed three times and I’m getting bupkis.

  38. Y’know, SLC, you keep saying the same thing –literally– over and over again, and I suspect you haven’t read anything I’ve written to the contrary. You should try actually adding value to the conversation.

    And you may want to research what you’re saying first, because you’re wrong. NASA absolutely will not slow down with manned spaceflight, and is doing what it can to help both manned and unmanned exploration. I’d love to see more money spent on unmanned, but without manned exploration NASA won’t be able to do unmanned. It’s that simple.

    And yes, both Park and Weinberg are wrong on this.

  39. SLC

    Re Shane

    Mr. Shane apparently has a reading comprehension problem. As I have made is abundantly clear, I am all in favor of unmanned space exploration and believe that the money currently being wasted on manned space activities should be reprogrammed to scientific missions such as Cassini. This is also the position of Profs. Park and Weinberg. Is Mr. Shane claiming that Nobel Prize winning Steven Weinberg is opposed to scientific research”

    Re Phil Plait

    And you may want to research what you’re saying first, because you’re wrong. NASA absolutely will not slow down with manned spaceflight, and is doing what it can to help both manned and unmanned exploration.

    Dr. Plait responds with an arrogant statement that NASA will continue on its present course, full speed ahead and damn the consequences. I notice that he fails to respond to my claim that the scientific discoveries made so far by the Cassini mission alone exceed those of the entire manned space program up to the present moment. And by the way, I have read everything Dr. Plait has written on the subject. I just happen to be more convinced by the argument of Bob Park and Steven Weinberg, whose accomplishments and expertise in scientific research are at least equal to his own.

    I’d love to see more money spent on unmanned, but without manned exploration NASA won’t be able to do unmanned. It’s that simple.

    On what basis does Dr. Plait make such a statement?

  40. Grand Lunar


    I figured this involved one of the giants. If I didn’t know this came from Cassini, I’d have guessed this as a Jovian storm.

  41. It’s obviously the black hole created when the Saturnians turned on their own LHC…

    Or, for those of you who see the hex – it’s the negative of this.

  42. GQ

    This is an incredible image. And a great blog entry. I heart this site…. :o-)

  43. StevoR

    The Bad Astronomer asked :

    “You should try actually adding value to the conversation.”

    Well I’m sure we all *try * but we don’t always succeed -I know that from personal experience! Sorry folks!

    Hmm .. Does this add any value to the conversation .. ?

    Ah well, I’m trying .. some would say * very * trying at times. But hey I’m human like us all! (Or are we?)

    Just remember :
    To err is human,
    To really foul things up requires a computer! ;-)

  44. Curious

    buffalodavid Said on October 14th, 2008 at 10:29 am :

    “u….HHHH… What picture are we talking about? I’ve refreshed three times and I’m getting bupkis.”

    Bupkis??? What’s that mean? Never heard that one before ..

  45. Monolith Spotter

    Robbie Taylor Said October 14th, 2008 at 4:07 pm :

    “It’s obviously the black hole created when the Saturnians turned on their own LHC…”

    Hang on a minute; is that a strange black monolith lurking in the Saturnean clouds!?

    Hmm.. in the original ‘Space Odyssey : 2001′ the stargate monolith was originally located on Japetus (the moon which we now call Iapetus) in the Sauturnian system…

    So has it gone down and is now doing to Saturn what it does to Jove in ‘Space Odyssey 2010′ … is Saturn about to become a star?! ;-) 8)


    PS. I’m guessing not really but fun idea anyhow! Scary tothink we’re now somuchclsoer to 2010 than 2001 … How time flies.

  46. Joker

    Saturn? Nah!

    That’s just a pool of dirty water (or is it black coffee with a tiny spludge of cream?) going down the drain & they’re fakin’ it all! ;-)

    (Runs for cover, shouting : “Joking, jokin’ ppl!” ;-)

  47. Hello. First of all nice blog. Thanks a lot for making this public. I love telekinesis.


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