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NASA Space Science

The Return of Saturn's Spokes 125

Posted by CowboyNeal from the wheel-in-the-sky dept.
CheshireCatCO writes "After more than a year in orbit around Saturn, the Cassini spacecraft has finally spotted 'spokes' in the rings. Spokes, large radial structures in the rings, where seen by the Voyager spacecraft and have remained difficult to fully explain. The reappearce of the spokes comes about two years earlier than many models predicted."
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The Return of Saturn's Spokes More

The Return of Saturn's Spokes

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  • Footfall (Score:1, Offtopic)

    by rossdee ( 243626 )
    Is it the Fithp?
    • "Attack of the Inconsistent Slashdot Moderators", coming soon to a funny post near you!

  • What about Scientists? (Score:5, Funny)

    by Anonymous Coward on Thursday September 15, 2005 @08:24PM (#13571907)
    Yeah, but what do models know? A lot of them don't even have degrees.

  • Upon closer examination (Score:5, Funny)

    by Prophetic_Truth ( 822032 ) on Thursday September 15, 2005 @08:24PM (#13571910)
    Astronomers have noticed a giant baseball card embedded in the spokes to make saturn feel like its a real motorcycle.

  • Spokes? (Score:4, Funny)

    by __aaydvd4604 ( 915212 ) on Thursday September 15, 2005 @08:27PM (#13571928)
    Clearly the Saturnians are using space elevators to reach the rings... duh!
    • Look this way please sir...
      (takes out pen shaped flash bulb)
      (flash of light)
      What you saw weren't spokes in the rings of Saturn, they were shadows cast by interstellar monkey spunk.
      Nice meeting you...

  • Saturn's Spokes Explained (Score:5, Funny)

    by Blue-Footed Boobie ( 799209 ) on Thursday September 15, 2005 @08:28PM (#13571941)
    You see, there is a photo dimetric charge built up with the gaseous core surrounding the ferrite sphere that is Saturn's core. Of course, as wel all know, this induces a strong para-helic cohesive bond between the ferro-flux dense matter which is on a cyclic Herbrunger-Feltz Path throughout the rings.

    It is really quite simple.

  • Maybe it's the models that are two years late...

  • Space.com lacking an editor? (Score:1, Insightful)

    by Anonymous Coward
    Saturn's odd ring spokes were photographed during NASA's Voyager mission, which swung passed the planet in the 1980s, and later observed by astronomers using the Hubble Space Telescope.

    What, they don't have an editor? Let's try again:

    Saturn's odd ring spokes were photographed during NASA's Voyager mission in the 1980s, and were later observed by astronomers using the Hubble Space Telescope.
    • The actual text is in a style I see very often in journalism, even when it is generally edited well. Personally, I think the best way to write it would be:

      Saturn's odd ring spokes were photographed during NASA's Voyager mission, which swung passed the planet in the 1980s, and
      were later observed by astronomers using the Hubble Space Telescope.
    • What? Are you suggesting that the Voyager wasn't observed by Hubble?
    • The following:

      Spokes, large radial structures in the rings,

      where seen by the Voyager spacecraft and have remained difficult to fully explain.

      ... should probably be ...

      Spokes, large radial structures in the rings,

      were seen by the Voyager spacecraft and have remained difficult to fully explain.

      But this is /., right? Typos are a form of personal expression, and grammar checking is verboten!

  • Duh! (Score:5, Funny)

    by jav1231 ( 539129 ) on Thursday September 15, 2005 @08:43PM (#13572032)
    Everyone knows that the spokes keep the rings equidistant from the planet while providing lateral stability! Hello!
    • Inertia is a property of matter where objects in motion remain in motion, and objects at rest remain at rest unless acted on by some external force (Newton's First Law). The more mass an object has, the more inertia, and thus, the harder it is to change the speed and direction of it in motion. In the case of rings, we are concerned with how easy it is to make the ring spin faster (or slower) - this is angular momentum. We want to minimize angular momentum so that the rings' responsiveness will be maximiz

  • Impact debris? (Score:2, Interesting)

    by williwilli ( 639147 )
    Isn't the most obvious reason that an asteroid or meteoroid or something similar simply hit the rings and broke apart? Is there some reason why this isn't likely?
    • um... because there is nothing to break...
    • That's pretty much like sugesting that something hit a raindbow and shattered against it - or a cloud. The rings are so diffuse that there realy isn't anything to hit except for a load of dust.

      • Ring Object Size (Score:3, Informative)

        by williwilli ( 639147 )
        While I understand your concept, another poster suggested the rings are made of smoke sized particles. Actually, the particles are sometimes quite large according to this page:

        More recently, astronomers bouncing radar off the rings and analyzing the reflected signal found that ring particles must be from a few centimeters to a few meters across. When the Voyager spacecraft went behind the rings with respect to the Earth, astronomers could measure the particles sizes from how Voyager's radio signal scatt

      • No.
        Some of the rings are diffuse and dusty.
        The A and B rings of Saturn, however, are thick and filled with larger (figure meter-sized) particles. A typical photon doesn't make it through these rings without meeting a particle somewhere, so a meteroid would more likely than not hit something solid.
    • Acutally, small impacts are believed to be involved. But how do you levitate the dust that they kick up over the ring plane?

    • Re:Impact debris? (Score:5, Interesting)

      by Malor ( 3658 ) on Thursday September 15, 2005 @10:01PM (#13572453) Journal
      The rings aren't very solid; most of the material is believed to be ice crystals that are, at most, a few meters in diameter. And despite their apparent solidity from here, they're an awful lot of empty space.

      Chances are pretty good that an asteroid would just sail right through the rings unimpeded. If it did hit something, it wouldn't be stopped. The inertia of the (small) body it hit would almost certainly be completely overcome by the incoming inertia of the asteroid. If it hit hard enough to break the asteroid apart, the result might look something like a shotgun blast, with a spray of asteroid chunks and a tiny bit of ring material continuing roughly along the same path the asteroid had been following. The 'hole' in the rings would almost certainly be filled within hours or days.

      If the asteroid happened to be slow enough to be captured into orbit, and happened to be on the same plane as the rings, it could potentially join the ring system. Over time, it might be torn apart by tidal forces into small chunks and blend in with the rest of the material.

      No matter what, it wouldn't just hit them and explode in place. The rings aren't nearly solid enough for that. It'd be like trying to stop a bullet with a sheet of Saran Wrap, perhaps with rice stuck to it.

      • It'd be like trying to stop a bullet with a sheet of Saran Wrap, perhaps with rice stuck to it.


        That is great sig material.

      • The rings aren't very solid; most of the material is believed to be ice crystals that are, at most, a few meters in diameter. And despite their apparent solidity from here, they're an awful lot of empty space.

        Is it in fact known that there's neither gaseous atmosphere nor fine dusty mist among the rings? If gas were emitted or dust kicked up from some member of the rings, would it necessarily float off? Or might it be held by the combined gravity or electrical charge of the local ring structure? (I'm

        • Actually, dust tends to fall in towards the planet over short timescales due to various forms of drag not felt by the larger particles. (Mostly associated with emission of thermal radiation or the magnetosphere.) Gas would tend to diffuse out the ring plane and probably escape or ionize and become part of the magnetosphere.

          To answer the first question, yeah, we know that there isn't a lot of dust in there. Recent measurements from Cassini show that there just isn't a lot of small stuff around.
    • This is unlikely.

      A large object flying towards Saturn and cutting through the rings might cause this kind of pattern, but the large object wouldn't necessarily break apart. It'd just cause a noticeable displacement in the ring material. It'd probably look like a large hole or gap. But that doesn't account for the rings actually getting brighter at these points, which is probably due to an increase in matter. A small object probably wouldn't cause anything noticeable.

      Something with a large gravitational pull
      • The spokes aren't a disturbance in the ring material itself. They can't be: the maintain their radial orientation over time. The parts of the rings that are closer to Saturn orbit more rapidly and so the spokes would shear out if they were part of the rings proper.

        In reality, they spokes hover over the rings, probably levitated electrostatically. They hold their orientation because they are tied to the magnetic field of Saturn.
    • No, the most likely reason is we are now to fear the flishithy thuktun.

      I just re-read Footfall by Larry Niven and Jerry Pournelle. Excellent literature.

      • Actually, I've just arrived early.

        • Nice. (I consider myself a Protector, although I've yet to eat Tree-of-Life.)

          • I wouldn't do it. Too much intelligence is a Major Drag.

            You think Niven was just 'poo-poo'ing with that stuff about not having any free will when you're a Protector?

            • Not at all. I've actually been thinking about this a lot lately, and came to the conclusion that "free will" just gives you the ability to choose a solution which is less optimal than the most optimal solution that you know about.

              Which can then be expressed in several ways. On the good, it gives you the ability to "play", to try out many different competing solutions to determine for yourself which is the most optimal, in a certain situation.

              On the bad, it means that a more rigorous decision-making st

  • See Cassini's path (Score:5, Informative)

    by latent_biologist ( 827344 ) on Thursday September 15, 2005 @08:49PM (#13572061)
    "Unlike Voyager or Hubble, Cassini is in a unique position to study ring spoke phenomena at Saturn."

    With Celestia [shatters.net], you can actually follow Cassini's path as it follows Saturn. It really puts the above statement in perspective (plus it makes u feel like an astronaut).
  • Saturn be representin' the second largest plizzy in the sizzolar system, yo.

  • The article mentioned models on the spokes, and spoke a bit on photoelectric effects, but didn't go into much detail to describe just what's going on. Does anybody have some better insight?

    Also, could any of these spokes be created by a large object cutting across the rings on the way to an impact with Saturn? (e.g., a meteor or small comet) I suppose that type of event would be too rare to explain the spokes that have been observed ... -- Paul

    • Re:Cause of the spokes? (Score:5, Informative)

      by CheshireCatCO ( 185193 ) on Thursday September 15, 2005 @10:26PM (#13572607) Homepage
      In a word, no.
      The spokes must be tied to the magnetic field of Saturn. This explains why the stay at the same magnetic longitude of the planet and why they don't wind up as the inner parts of the rings orbit the planet faster. So they're not disturbances in the ring particles themselves, since the ring particles are too massive to really feel the magnetic field.

      However, if you levitated dust over the rings, that would do the trick. The problem is how to levitate the dust. It turns out that you can develop a negative potential on the rings (I think it's negative... I forget, to be honest) which can repel the dust and cause it to hover. So under the right conditions, if dust were kicked up by a small collision in ther rings (say a meteroid collision), it can float over the rings and spread radially, making a spoke.

      Or so we think...
      • Thank you! Very intersting, and a helpful explanation, that. Much appreciated. -- Paul

      • The wikipedia article [wikipedia.org] says that the spokes are viewed in the B ring. Here [nasa.gov] says that the B inner edge has a density of 20 - 100 gm/cm2. So my question is, could the ring's ice particles be ionized by collissional processes, like the ice particles in a cumulonimbus clouds?

        Another question... which travels faster around saturn, the spokes or the ring's particles?

        And thanks for your informative post, glad to see anything different than +5 Funnies...

        • Most of the ice particles are pretty big, so while ionization of them through collisions could occur, it's not likely to affect them much. (It's like shuffling your feet on the carpet: you can give yourself a good shock, but you aren't going to stick to the walls due to the excess charge.) What you're really after is forming a plasma around the particles. That could happen through particle bombardment in the magnetosphere or through photo-ionization. We suspect the latter for various reasons. (And I'm

  • magnetic fields (Score:2, Interesting)

    by Kev_Stewart ( 737140 )
    Could the magnetic fields be seasonal? I'm no expert but might that explain why they seem to appear and disappar periodically?
    • The spokes do appear to be tied to the seasons on Saturn. (Which has a much longer year, of course.)

      The field, however, is not. The field can't go away and come back that quickly and there's nothing that I can think of that would cause it to since it's generated in the interior of the planet where it's hard to come up with a way for a seasonal influence.
    • I guess that's the question. If not the magnetic field, or some element of gravity that we haven't modeled yet... what about the general clockwork of the rings?

      Presumably, for millions of years this material has been circling Saturn. Long enough for matter of certain sizes and densities to fall into a regular pattern. It could simply be that on occasion certain elements "line up" for a period of time as they get into synchronous orbits.

      Of course if this were the case you'd expect spokes to appear and disapp
  • I predict the next discovery to be made regarding the spokes will be the clothes pins and baseball cards.
  • Are these funny things not just artifacts from the digital image processing?

    • Re:Artifacts? (Score:4, Informative)

      by CheshireCatCO ( 185193 ) on Thursday September 15, 2005 @11:15PM (#13572850) Homepage
      There's nothing that we do that would lead to radial features. Especially across multiple images at consistent magnetic longitudes. Also, these have been seen by at least three or four cameras, now. So it's hard to imagine these being artifacts.

      (In fact, the images on the space.com site might even be the raw images.)
      • Possibly a form of electromagnetic 'shadow' cast by an unseen object or force. Like the radiation belts that cause the aurora in the northern sky? Maybe Saturn's radiation or electromagnetic belts bend gravity and create lenses that, in-turn, cast shadows on the rings.

        my 5-second theory.

        Brad

  • Ye of little faith. Pastafarians have the answer. (Score:4, Funny)

    by ScentCone ( 795499 ) on Thursday September 15, 2005 @10:47PM (#13572718)
    Clearly the Flying Spaghetti Monster has put planet-sized representations of His Noodly Appendages into orbit around Saturn to show us his majestic power.
  • large radial structures in the rings, where seen by the Voyager spacecraft and have remained difficult to fully explain.

    Difficult to explain? clearly the RIAA heard that if you played the rings of saturn backwards on a record player you would hear some copyrighted music, so the dissapearing sections of the ring were clearly removed by cease and desit orders sent by RIAA lawyers to saturn.

  • Spoke mechanism (Score:3, Informative)

    by Anonymous Coward on Thursday September 15, 2005 @11:04PM (#13572801)
    The theory I heard is that the ring particles pick up a charge from being bombarded by particles trapped in the radiation belts. When a meteoroid plows through them, it breaks small, dust-like particles off. Being light and charged, these particles are picked up by the rotating magnetic field and circle the planet as a radial spoke. As the charge leaks off of the dust, the dust particles go into normal orbits with the ones farther in orbiting faster, so the spoke spreads out into a wedge and then dissipates.
    • That doesn't really cover the seasonal nature of the spokes. (Or should I say "the apparent seasonal nature"?) It's likely that sunlight is involved in that case. It probably comes in through photo-ionization, which generates the same sort of plasma.
  • where you can find LARGE wallpaper sized (1400w or bigger) pictures of the planets and stars?
    I miss The Science Channel so much. It's the only thing worth watching but you have to get the $55 a month top level tier to get it. That's a lot of money for a single channel. ALL the other channels are trash.
    • You can find quite a few large images from nasa's photojournal web site. I don't have the link in front of me (since I'm at work), but if you go to nasa.gov or jpl.nasa.gov they usually link to it (as I'm sure google will). You can also look for the press area as they tend to have the huge hi-res versions for printing, typically being 3000+ by 2500+, and you can resize it to what you want with the gimp or photoshop or whatever. (unless you can run that res...)
  • "Spokes, large radial structures in the rings, where seen by the..."

    Achtung! That should be a were.

  • It looks more like a ring [akamaitech.net] than a spoke.

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