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Space

Saturn Rings But No Spokes 132

Posted by CmdrTaco from the look-at-the-pretty-pictures-bob dept.
An anonymous reader writes "Scientists continue to ponder why images of Saturn's rings today lack the 'spokes' or dark radial bands radiating outward and first observed on the Voyager flyby. The Boulder-based Cassini Image Team describes 5 visible moons, plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now."
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Saturn Rings But No Spokes More

Saturn Rings But No Spokes

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  • Spokes? (Score:4, Informative)

    by RedCard ( 302122 ) on Sunday February 29, 2004 @11:33AM (#8422859)
    I'm sorry, maybe I'm just an idiot, but I don't really see any of the 'spokes' in the image [nasa.gov] you linked to.

    Could somebody paste a big red arrow on there for the outer-space-cluefully-impared, such as myself?

    Thanks.
    • Same here. All I saw were little roughly circular blotches, but I don't see why those would be called spokes.

    • Re:Spokes? (Score:5, Informative)

      by Queuetue ( 156269 ) <queuetue&gmail,com> on Sunday February 29, 2004 @11:37AM (#8422881) Homepage
      I think they mean the itty-bitty breaks in the rings that you can see if you look very close. (There's one just about in the very center of the image.)

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

        by Kierthos ( 225954 ) on Sunday February 29, 2004 @11:43AM (#8422915) Homepage
        Okay, I was wondering... although it looks like it could easily be something on the lens. Heck, it almost looks like what we call a 'density dot' at work. (Explanation: I work at a copy shop, and when doing colour copies, sometimes the toner will not be applied evenly, leaving small blank or lighter shaded dots in the middle of coloured areas.)

        But it couldn't be a density dot because the imaging would have been sent back from the probe using radio signals, right? It's not like a radio signal gets a bad spot on a belt.... and interference would have produced a much more distorted image....

        Hrm...

        Kierthos
    • Maybe they mean the dark rings.

    • Re:Spokes? (Score:5, Informative)

      by eddie can read ( 631836 ) * on Sunday February 29, 2004 @11:54AM (#8422967)
      Google it.

      Here [ucar.edu]

      Here [the-planet-saturn.com]

      Here [utk.edu] (scroll down to find a movie)

    • Re:Spokes? (Score:3, Informative)

      by Naito ( 667851 )
      the spokes are perpendicular dark bands spanning the ring from the inner ones to the outer ones. the gaps between the rings are divisions, unrelated to the spokes.

    • Re:Spokes? (Score:5, Informative)

      by Anonymous Coward on Sunday February 29, 2004 @12:48PM (#8423266)
      To all,

      I am the leader of the Cassini Imaging Team, and came upon the discussion all of you are having about spokes. The image that you have linked to does not clearly show spokes -- so it's not a good example -- and the caption at JPL is wrong: it was *not* the first time spokes were seen by Voyager. Voyager 1 first saw spokes on approach to Saturn, when the resolution was comparable to what Cassini is seeing now.

      We're not sure if spokes are a seasonal phenomenon, or their visibility is very sensitive to viewing geometry. We will find out though, since Cassini will remain in orbit and make observations for 4+ years.

      So stay tuned.

      - Carolyn Porco
      Cassini Imaging Team
    • All those spokes were made of countless black monoliths that were needed for somethin on Jupiter.
    • Saturn? We never went to Saturn, and we never will!. Those "spokes" are just where one of the NASA/JPL project artisits took their work home, and immediately after supper while the parents were cleaning up, little Johnny and Suzie started clicking on tools in GIMP and pressed the mouse button while sliding it across the desk. Johnny and Suzie were just pretending to be like grown-ups. This is kinda/sorta similar to the conspiracy theories that the USA never went to the Moon.

      In all seriousness though I
    • The article mentioned dark spokes, but linked to a photo with practically no spokes visible. However, those that are visible are bright spokes, as is mentioned in the photo's caption. The person in charge of finding appropriate photos for the article failed to grasp that the spokes were either dark or bright depending on viewing angle, and so inadvertantly linked to bright spokes instead of the proper dark. Since the spokes are so hard to see in the photo that was chosen, it is quite possible the person
    • I can't see them either, and I'm enormously grateful to eddie-can-read for posting links to better pictures (below), and to the representative of the Cassini Imaging Team for confirming that it's not a good picture.

      As a very, very amateur backyard astronomer, I find that one of the most difficult problems I have in showing non-astronomical friends anything in my telescope, is that very few people will tell you what they are seeing or will say "I can't see it." My telescope is a Cassegrainian, meaning out-o
    • There are no spokes in that picture.

      Here's a decent picture of spokes: http://voyager.jpl.nasa.gov/image/images/saturn/8 b g.jpg

      On this occasion, I do know what I'm talking about. I am a co-investigator on the Voyager mission. Do not cause this you to believe that I always know what I'm talking about, though. Especially in /. posts.

      (And, in case anyone cares, the most-commonly-accepted theory of the cause of spokes is that they are caused by dust particles that electrostatically elevated slightl

  • But I don't see the "spokes" in the Voyager images everyone is talking about. I'm looking for dark lines extending from the center of the rings outward, like the spokes on a bicycle wheel, but I don't see any. Can someone explain for me in some detail what the spokes look like?

  • Obligatory APOD reference (Score:5, Informative)

    by rodney dill ( 631059 ) on Sunday February 29, 2004 @11:35AM (#8422872) Journal
    There were no real current Astonomy Picture of the Day [nasa.gov] references so I linked to a search on Saturn. This gives quite a few different views of Saturn and some other related material as well.

  • When I'm not kicking ass, I'm studying saturn (Score:5, Informative)

    by H4x0r Jim Duggan ( 757476 ) on Sunday February 29, 2004 @11:35AM (#8422873) Homepage Journal
    By the way, next summer NASA's Cassini spacecraft, launched in 1997, is scheduled to go into orbit around Saturn and its moons for about four years.

    The piggybacking Huygens probe is scheduled to go into the hazy Titan atmosphere and land on the moon's surface (if all goes well). The Huygens probe is geared primarily towards sampling atmosphere. The probe is equipped to take measurements and record images for up to 30 minutes on the surface. But the probe has no legs, so when it sets down on Titan's surface its orientation will be random. And its landing may not be by a site bearing organics.

  • Well, duh, haven't you read Niven? (Score:5, Funny)

    by Mukaikubo ( 724906 ) <gtg430b.prism@gatech@edu> on Sunday February 29, 2004 @11:36AM (#8422878) Journal
    Obviously the Fithp has already left Saturn and is headed to Earth.

    Time to start studying those old Orion plans...

    • Re:Well, duh, haven't you read Niven? (Score:5, Informative)

      by Chairboy ( 88841 ) on Sunday February 29, 2004 @11:48AM (#8422933) Homepage
      Why was this modded offtopic? I'm guessing the moderator didn't recognize what he was talking about. I was actually looking to see if there was a Fithp post before I posted.

      Background, in the Niven book 'Footfall', the first indications they see of the incoming alien invasion is weird, spoke-like distortions in the rings of Saturn.

      • Re:Well, duh, haven't you read Niven? (Score:5, Interesting)

        by shadowbearer ( 554144 ) on Sunday February 29, 2004 @03:14PM (#8424073) Homepage Journal
        Actually I believe it was the intertwined out rings that they saw ("two earthworms mating") when the reporter Roger and a couple other characters were at JPL viewing the Voyager images. The two narrow rings were being roiled by the Message Bearer's drive, but of course we didn't know that at the time :)
        The same chapter does refer to the spokes, but (pulls out copy to check) Yup, in the Prologue: "Outside the broad main ring system, a narrower ring still roiled from the wake of Message Bearer's drive". The first indication that *Earth* had of the oncoming ship was when they detected it, however; nobody could explain the rings.

        I thought it was a neat way to refer to the Voyager images...

        SB

      • Well, duh, if you'd checked, you'd see it was a collaberation between Larry Niven and Jerry Pournelle. [jerrypournelle.com] If you're going to make a reference, at least get it right.

    • Re:Well, duh, haven't you read Niven? (Score:4, Informative)

      by Mad Man ( 166674 ) on Sunday February 29, 2004 @01:28PM (#8423498)
      re: Well, duh, haven't you read Niven? [slashdot.org]

      Time to start studying those old Orion plans...


      ...which can be found at http://www.up-ship.com/apr/michael.htm [up-ship.com]


      Aerospace Imagineering Presents:

      MICHAEL

      from FOOTFALL by Larry Niven & Jerry Pournelle

      Science Fiction author Larry Niven needs no introduction. In his stories and collaborations, he has created some of the most imaginative and advanced spacecraft concepts ever conceived. Aldo Spadoni is an aerospace engineer and conceptual designer, specializing in the realistic design and visualization of future technology. Larry and Aldo have been collaborating to visually bring to life these wonderful spacecraft and other advanced technological concepts, as described in Larry's stories. The detailed designs are being developed by Aldo using aerospace industry systems engineering principles

      MICHAEL is an example of this endeavor. FOOTFALL by Larry Niven & Jerry Pournelle is a classic story of alien invasion. The invading Fithp force the human race into a condition of servile surrender. In secrecy, humanity builds a battleship named MICHAEL, a nuclear powered mountain of steel to rise up into space and do battle with the aliens on their own turf. MICHAEL is based on the nuclear pulse propulsion concept developed under Project ORION (1958 - 1965).

      Aldo Spadoni is President of Aerospace Imagineering , a consulting firm specializing in advanced technology conceptual design and visualization for the aerospace, publishing, television, and motion picture industries. For more information about the Niven Project, please contact us at aldo@alum.mit.edu.

      All imagery is copyrighted (C) 2001 by Aerospace Imagineering and Aldo Spadoni. All rights reserved.

  • Magnetic field not coherent? (Score:5, Informative)

    by Saltation ( 756369 ) <saltation_signups.nospammail@net> on Sunday February 29, 2004 @11:37AM (#8422884) Homepage
    The "spokes" are odd disruptions in the rings caused by Saturn's magnetic field rotating through them. They show up as dark patches radiating directly away from Saturn or occasionally arching, and they travel like a wave around Saturn in time with its rotation. It was this timing/speed that tipped astronomers off as to what was causing them, incidentally.

    So if the spokes aren't visible now, maybe Saturn's magnetic field is fluctuating/less coherent than normal. It's a gas giant so its field could be less stable than the denser planets. There may be some low-level eg mid-atmosphere storm disrupting the normal field-generating circulations.

    Just a thought. IANAA

    cheers, Sal

    --
    Sal

    Writings: saltation.blogspot.com [blogspot.com]
    Wravings: go-blog-go.blogspot.com [blogspot.com]

    • Re:Magnetic field not coherent? (Score:5, Funny)

      by Waffle Iron ( 339739 ) on Sunday February 29, 2004 @12:05PM (#8423026)
      So if the spokes aren't visible now, maybe Saturn's magnetic field is fluctuating/less coherent than normal.

      The Saturnians have taken notice that this vessel is on a trajectory to permanently enter their planetary system, with the apparent further intention of penetrating one of their moons. They have therefore diverted the entire force of the giant planet's magnetic field into charging the energy banks of their weapons systems. If the spacecraft does not alter its course soon, they will no recourse but to unleash a devestating counterattack on the inner planet that initiated hostilities.

      • The Saturnians have taken notice that this vessel is on a trajectory to permanently enter their planetary system [...] If the spacecraft does not alter its course soon, [...]

        Or maybe if the spokes aren't visible, it's because someone nicked the Saturnians' bike.

        This could also explain the posited incoherence:- rage-choked fist-waving Saturnian hordes milling backwards and forwards under the constant swirling clouds, roaring "Give us back our blurry bike!" at the intruder spacecraft above desperately

  • They're not taking the pictures the same way... (Score:5, Informative)

    by bc90021 ( 43730 ) * <bc90021&bc90021,net> on Sunday February 29, 2004 @11:39AM (#8422896) Homepage
    From the second link:

    In order to bring out the very faint detail in the B-ring, the image was specially processed for the spokes and thus does not show the true relative brightness of the other rings.


    Perhaps the spokes don't show up because they're not applying those same techniques? I certainly don't see any mention of those techniques in the article in the first link.
    • Or maybe someone is just covering their tracks:

      "Canals? No canals to see here. Just move along..."

      "Oops, they saw the pyramids. Quick, hit their probes with the disrupter beam until we get them smoothed over."

      "What? They got photos of our rotating homing beacon around Saturn? Dummkopfs! Turn it off next time they get close, you knuckleheads!"

      "And next time, don't drain the energy out of their landers at the same time! [mumble...buy them books, send them to school, and they eat the teacher...grumble.]

  • visual astronomers... (Score:4, Informative)

    by OneOver137 ( 674481 ) on Sunday February 29, 2004 @12:01PM (#8423004) Journal
    have been seeing spokes in the rings for quite some time using ground-based telescopes of various sizes. This may be one of those features, like the canals on Mars, that shows up because the eye-brain software processes images differently than the spacecraft ccd-computer does. An article in Sky & Telescope discovered they could reproduce the canal effects using the techniques of registration (stacking), and various applications of wavelets and other processing methods. They concluded our eye-brain mechanism does something similiar in real time at the eyepiece during moments of steady seeing conditions, causing dark lines to be seen where a smoother color gradient actually exists.
    • have been seeing spokes in the rings for quite some time using ground-based telescopes of various sizes. This may be one of those features, like the canals on Mars, that shows up because the eye-brain software processes images differently than the spacecraft ccd-computer does.

      No, the Voyager probe(s) clearly photographed them.

      • Re:visual astronomers... (Score:5, Informative)

        by Tablizer ( 95088 ) on Sunday February 29, 2004 @12:27PM (#8423147) Journal
        Here is a link to Voyager spoke images

        Single Image [nasa.gov]

        Gallary [nasa.gov]
        • The Voyager images may be correct, but I'm playing skeptic until Cassini shows the same thing. Like I said in my original post, if image processing algorithms can show canals on mars, what makes you think Voyager's pictures are correct? If Cassini shows nothing, what does that prove? What about Hubble? I've said this above, but I'll say it again. If there is good corroboration between ground-based and space-based imaging, the image processing algorithms are normalized, and planetary geophysicists have a be
          • if image processing algorithms can show canals on mars, what makes you think Voyager's pictures are correct?

            IIRC, they have followed some bands moving around the rings. An image-processing artifact is not likely to fit the changing orientation of a feature moving around the visual curve of the rings. It would have to "interpret" the image to do that. In other words, it would have to know what it actually represents, such as know it is an oblique view of a ringed disk rather than a rubber band.

            And, I d

    • Re:visual astronomers... (Score:5, Insightful)

      by Iron Sun ( 227218 ) on Sunday February 29, 2004 @12:29PM (#8423158)

      But the spokes were first observed with the CCDs on Voyager. Also, no astronomer actually looks through an eyepiece any more, its all CCDs or other detectors. All of the ground-based spoke observations (could you provide a source for such images?) are thus not going to be subject to the Percival Lowell wishful thinking effect.

      It's more likely to be due, as other posters have suggested, to be due to variations in Saturn's magnetic field. It would seem that Cassini is already producing interesting science before it goes into Saturnian orbit.

      • Re:visual astronomers... (Score:4, Insightful)

        by OneOver137 ( 674481 ) on Sunday February 29, 2004 @01:12PM (#8423416) Journal
        Also, no astronomer actually looks through an eyepiece any more, its all CCDs or other detectors.

        True, the pros don't have much eyepiece time, but many amateurs still do, and these spokes still show up.

        All of the ground-based spoke observations (could you provide a source for such images?) are thus not going to be subject to the Percival Lowell wishful thinking effect.

        I cannot provide linkage at this time, but google on sci.astro.amateur, and check out some books in the library. I'm not saying this effect isn't real, I'm just playing the skeptic given the history of the Martian canali. Just because one ccd detector-software combo sees something, doesn't mean they all will or can.

        • Re:visual astronomers... (Score:4, Informative)

          by Iron Sun ( 227218 ) on Sunday February 29, 2004 @02:29PM (#8423801)

          True, the pros don't have much eyepiece time, but many amateurs still do, and these spokes still show up.

          Once again, I'd like to see a source for this assertion. You make it sound like they are seen all the time.

          I cannot provide linkage at this time, but google on sci.astro.amateur, and check out some books in the library.

          Gee, Yogi, I hadn't thought of that :-P. I googled with about a half dozen different word combos and came up with one reference to not seeing them. The wording of the Astrobiology article seems to imply that there had been no observations between Voyager and the present, but the fact they are surprised about their current no-show seems to indicate that they weren't expecting to with ground based equipment. You seem very certain, could you give me any pointers to the source of your certainty about these multiple and yet possibly illusory ground based amateur observations?

          I'm just playing the skeptic given the history of the Martian canali.

          From which example we can cast into doubt any observation of dark lines. It's fallacious reasoning: the dark line 'canals' were the result of an optical illusion, there were reports of dark line spokes by obviously illusion-susceptible ground based observers, ergo they are an illusion and so the Voyager CCD images are wrong.

          Just because one ccd detector-software combo sees something, doesn't mean they all will or can.

          The spokes were observed by both Voyagers on both the lit and unlit side of Saturn under a wide range of lighting conditions. It seems a rather specific and yet widely reproducible imaging anomaly. Do you question any of Voyager's other observations, or is it just because these are the dreaded dark lines?

      • Also, no astronomer actually looks through an eyepiece any more

        I do... I'm an amateur astronomer...

      • Re:visual astronomers... (Score:3, Informative)

        by aiabx ( 36440 )
        According to Timothy Ferris in Seeing in the Dark , the spokes were first observed visually by Stephen O'Meara, an exceptionally acute observer, and then confirmed by Voyager.
        -aiabx
  • The Boulder-based Cassini Image Team describes 5 visible moons, plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now.

    It's nice to know that if man ever lands on Titan, there won't be any problem with heating our homes :-)
    • Does Bush know about this? We could be invad^W er, liber^W um, landing sooner than you think!
    • if man ever lands on Titan, there won't be any problem with heating

      Yes, there will be: there's no oxygen.

      Think about it: there can't be free oxygen and lots of hydrocarbons in any atmosphere at the same time, at least not for long. First flash of lightning, and - BOOOOM!

  • Huh? (Score:3, Funny)

    by Anonymous Coward on Sunday February 29, 2004 @12:13PM (#8423066)
    Saturn rang? And no one spoke with it? Geez, maybe it woulda told us everything.

  • Maybe a decent sized object passed through the rings, disturbed them and left.

    Either that or some stoned punk aliens were waving their hands in front of the Voyager cameras just to screw with us.

  • Additional APOD with reference to Spokes (Score:5, Informative)

    by rodney dill ( 631059 ) on Sunday February 29, 2004 @12:37PM (#8423193) Journal
    In all the APOD [nasa.gov] picture of Saturn I found a reference to Spokes [mira.org] and a picture that contains them.

  • I remember when... (Score:5, Informative)

    by rotenberry ( 3487 ) on Sunday February 29, 2004 @12:48PM (#8423269)
    I was a young engineer at JPL when Voyager 2 encountered Saturn, and I remember when the first photos of the spokes in the rings were displayed in real time on the monitors in the cafeteria. The work on other projects had pretty much ground to a halt while everyone watched the data come in.

    Of course, the real time data had no captions, no explanations of what we were seeing, so we had all sorts of guesses - density waves, camera artifact, etc. Once it was apparent that the waves were holding together as the rings rotated and were not being sheared apart, it was clear they were not due to any gravitational effect. Since they moved with the rotation of the planet, the accepted explanation is the magnetic field of Saturn causing the charged dust in the rings to concentrate into visible spokes. As I understand it, the spokes are not a wave phenomenon at all.

  • In light of the recent discovery of hydrocarbons on Titan, U.S. president George Bush said the following:
    {squints}"We will take immediate {pauses} military action to protect US interests in Titan. We will then make sure that the titanics [people of titan] have democratic elections as soon as possible.
    • Heh heh, the probe landing on Titan is European... I'm sure it won't find any hydro-carbons... the US won't hear of any being found at any rate... :o)

      I'm just kidding around. Some folks are way too uptight. Modding down the parent post? Come on, it's funny and had to be said!

  • Could be a particle rotation thing (Score:3, Interesting)

    by d00ber ( 707098 ) on Sunday February 29, 2004 @01:19PM (#8423455) Journal
    I was wondering if the planetoid and particles could be doing the wave.

    Generally these things are oblong rather than spherical. Maybe there is some gravitational coupling between the particle shape and Saturn and/or the other neighboring particles.

    The particle could be spinning along their axes perpendiculr to the ring and along the line from the center of Saturn to the particle.

    When the particles long axes are aligned perpendicular to the plane of the ring they would look one way (reflect less light perpendicular to the plane of the ring). Then when they rotate with the long axis in the plane of the ring they reflect more light perpendicular to the plane of the ring - they look brighter.

    Admitttedly the dipole interaction would be pretty small. But this would allow for no spokes in the sense of ripples in the particle density but still allow us to "see" the spokes.

  • Yes, but... (Score:4, Funny)

    by Guppy06 ( 410832 ) on Sunday February 29, 2004 @03:13PM (#8424071)
    When will Cassini photograph the monolith on Iapetus.

  • This is obvious (Score:3, Funny)

    by Anonymous Coward on Sunday February 29, 2004 @03:32PM (#8424168)
    The people who faked the images from the Voyager group are not the same people faking the pictures now. Probably all went out with the budget cuts in the early 90's.

    "dammit, we forgot the spokes. Quick, get that guy that colours the martian sky blue to add some in to the new pictures".

  • Hydrocarbons (Score:2, Informative)

    by Guppy06 ( 410832 )
    "plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now."

    All Iraq-related kidding aside, I find this interesting. Saturn is too far out for modern solar energy solutions to be viable, we still haven't figured out the whole fusion thing and hydrogen doesn't like to be cracked out of water. On the other hand, hydrocarbons want to be broken down and we know all about harnessing the energy of that reaction

  • Well, it *was* from *Voyager*... (Score:2, Funny)

    by Anonymous Coward
    Why are there spokes in the Voyager images but not from Cassini? Because Janeway was a nutcase and mismanaged just about every aspect of her mission!

    Anyone who trusts Voyager's telemetry with her in command over even the comparatively primitive computer and sensors Cassini uses is an idiot!
  • Saturn rang but no-one spoke?
  • Does anybody know where I could find a bigger version of the drawing of what it would look like when Huygens decends into Titan's atmosphere. I think it's a really neat picture. Heres a link so that you know what drawing I am referring to http://www.astrobio.net/articles/images/huygens_ed l.jpg
  • Everyone who's read Footfall knows that the spokes were caused by the exhaust wake of the fithp ship on its way to Earth.
  • and stuck them into Uranus.

    Would you like a goatse.cx link with that?
  • On most of the pictures [astrobio.net] that have been released of saturn, it looks like the picture has been flip-flopped horizontally (the left-side is on the right and right-side is on the left). At least to me that is.
    When viewed from above, planets orbit counter-clockwise. Cassini's tragectory also follows the planets counter-clockwise orbits.When Cassini approaches Saturn, it will be coming in from behind the planet, it is trying to catch up to it. This means the Sun will be on the left side of the picture, and t

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