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Something slammed into the rings of Saturn and Jupiter

The views expressed are those of the author and are not necessarily those of Scientific American.

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PASADENA—This week I’m here at the annual Division for Planetary Sciences meeting. Much as I enjoy Pasadena, it’s rather a comedown from last year’s meeting place in Puerto Rico. Leave aside the natural attractions: even the freeways in Puerto Rico are in better repair than California’s. Then again, we don’t come here for the earthly sights, but for the celestial ones.

On Tuesday, we heard the latest chapter of a bizarre discovery about the rings of Saturn that I wrote about from Puerto Rico. Last year, Matt Hedman of Cornell University showed conferees pictures of a gentle ripple in Saturn’s rings that stretches for tens of thousands of kilometers. Such a vast and regular disruption means that a fairly dramatic occurrence must have befallen the rings. Something managed to torque the entire ring system or else the giant planet itself lurched; either way, the rings fell out of alignment with the equator of the planet. The giant planet’s gravity tugged on this imbalance and wound it up into a spiraling ripple.

Based on the current spacing of the pattern, Hedman and his colleagues estimated that the initial disruption occurred in the mid-1980s. At a loss to explain what could possibly have torqued an entire ring system, they suggested that Saturn itself shuddered for some unknown and almost unimaginable reason.


Now one of Hedman’s colleagues, Mark Showalter of the SETI Institute, has announced that it has happened again—this time to the rings of Jupiter. In fact, not just once, but twice. Using images taken by the Galileo space probe in October 1996 and June 2000, Showalter has found two overlapping sets of ripples in the main ring of Jupiter. One has a spacing of 600 kilometers and a height of 600 meters, the other a spacing of 2,000 kilometers and a height of 3 kilometers. The first appears to date to early 1990, the second to mid-1994. (The ripples are visible in the alternating pair of images above—they rise above and below the central plane.)    

Those dates ring a very loud bell. The second is when Comet Shoemaker-Levy 9 crashed into Jupiter, and the first is when the comet made an earlier pass by the giant planet. The comet left giant scars in the planet’s atmosphere, but scarcely budged it. It did, though, dribble a trail of fine dust that the gentle pressure of sunlight could then have pushed into the rings. "Over a one-week period in 1994, all this crap hit the ring," Showalter says. The shower of dust would have perturbed the ring and sent the ripples into motion.

If no planetary lurch was needed in this case, then maybe Saturn’s ripple, too, came from a shower of incoming debris. In an accompanying talk, Joe Burns, also at Cornell, described how a comet a kilometer or so in size could break up and rain down on the rings. To create an imbalance, the debris had to have been unevenly distributed; that would have happened if the planet created a rain shadow, blocking debris from reaching one section of rings. Burns estimates that objects of the requisite size should strike both the Jovian and Saturnian rings once a decade on average.

"All of us came in somewhat skeptical," Burns says. But the Jupiter discovery and the dawning implausibility of explaining how an entire planet might abruptly lurch tipped the balance in favor of meteor showers. It’s amazing to think that the rings absorb these blows and yet remain the jewels of the solar system.


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  1. 1. Michael Hanlon 5:33 am 10/8/2010

    Doesn’t it seem strange that not all the rings on both planets got confambulated? If I’d cornered Mr Showalter, I would have pressed for a molecular analysis of the effected rings to see if there was a possibility of a magnetic cause of the noted disturbances. If there was a high iron content in those rings, attributable to their unique original material, I’d expect to see such reactions out in the planets’ magnetospheres. Aren’t explosions a source of magnetic pulsing? Any chance of asking about that Mr. Musser?

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  2. 2. promytius 6:46 am 10/8/2010

    While I find the mystery of the ring changes fascinating, I can’t imagine what literary or reporting significance WHERE you hear this information rises to the level of being important enough to waste on the opening paragraph. Puerto Rico seems to have its own drug-soaked headlines and had no place in the opening of the article. Who cares where you are when you report science news? Unless of course you had entered some parallel universe; that may merit the first paragraph. The condition of the roads in California relate to the rings of Saturn, how?

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  3. 3. JamesDavis 7:57 am 10/8/2010

    I agree with you, ‘promytius". Garbage talk should not hold a place in science. Save that stuff for the bathroom so you can flush it.

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  4. 4. gmusser2 2:21 pm 10/8/2010

    Look, it was just supposed to be a brief, light-hearted aside – this is a blog post, not a scientific paper or even a news story.

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  5. 5. jack.123 5:23 pm 10/8/2010

    Perhaps comets or asteroids passing through the electromagnetic fields of those planets rather than dust is what caused the ripples.Michael,think maybe we will see the same kind of reaction to our own Van Allen belts when Apophis or other’s make a close pass?Nice to see your back,long time no read.As always you ask great questions.

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  6. 6. robert schmidt 5:27 pm 10/8/2010

    @promytius, when you read someone’s blog you are reading their impressions. Take it or leave it. It is not their responsibility to make life interesting for you. I found your comment to be boring and self centered, does that mean you shouldn’t have written it?

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  7. 7. akmangalick 6:22 pm 10/8/2010

    Observations: Opinions, analysis and arguments….

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  8. 8. ennui 10:38 pm 10/8/2010

    It could have been caused by a space ship, as they are using strong electrostatic fields for propulsion.
    Since nobody saw anything touching and as they are able to bend light, it would be a possibility.

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  9. 9. Michael Hanlon 12:14 am 10/9/2010

    Perhaps it’s like the butterfly effect. A Lepidoptera fluttered its wings in Mozambique and Saturn’s rings commenced to a’jigglin’. Or like Schroediger’s cat, until the twists were observed, all they had was a waltz!

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  10. 10. Michael Hanlon 4:23 am 10/10/2010

    The more I think about it, the more my head hurts. No, really one large magnetic object circling in the rings is eventually going to attract the less magnetic objects to its orbit (well, a summation of forces but the big one wins out) Any comet or asteroid material that gets pulverized in the rings lets its ferrous materials drift to the mag orbit, cleaning the other rings of magnetic material. (That’s why the other rings don’t react to a strong E/M pulse, none of their constituents are magnetic just ice and granite.) Of course there could be two rings that react if the younger or weaker ring hasn’t finished it’s merget attraction mission. Some numbers could help back this theory. One would be any noted differences in the amounts of perturbations at different orbital heights (Inverse square law in action the closer in the more of a reaction) Another would be a measure of arc effected initially. If ten degrees or so were impacted, then that would point to a localized pulse up from the surface below, In the Shoemaker-Levi impacts there should be seen 10 or so ten degree purturbations ringing (like a bell) around that single ring and harmonic resonances and attenuations should be noted. And this needs to be asked (I’m uncertain of the answer) but aren’t Jupiter’s rings inside its magnetosphere (the largest object aside from the sun in our solar system)? Wouldn’t that magnetosphere also help to confine any mag pulses around Jove and accentuate the effect like our Ionisphere does to radio waves here?

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  11. 11. Michael Hanlon 4:34 am 10/10/2010

    And GM, if your itinerary permits, return with a drive through Death Valley/Mojave Desert to Phoenix or Tucson and fly out of there. A couple of hours of the desert sun will only help to make you more assure of your commitment to solar power is a good one. And the landscape is as close to another world as you can find.

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  12. 12. gmusser 10:58 am 10/11/2010

    This isn’t a magnetic effect.

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  13. 13. Michael Hanlon 4:10 am 10/12/2010

    What are you seeing in the attached double image of the ring wobble? Are you seeing the giant inside ring going up and down? Well look at the outside ring, it’s doing it too. Meaning the one ring not acting like the others is the middle one Why isn’t that ring bouncing up and down? Gotsta go back to my original observation Why aren’t all the rings acting the same. I find it difficult to believe that that one narrow middle ring wasn’t effected by cometary dust like the others around it. So maybe magnetics has held that one in place? And a neat photographic trick can be played here where the ring that is bouncing is the one the camera focuses on and it makes the others look like they’re the ones going up and down. Too bad the image is soo poor we cannot lock a distant star in the background in place.

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  14. 14. Michael Hanlon 4:08 am 10/13/2010

    Before I get yumped on, Okay, not faked photos. But, the photos do raise questions. Are we looking at the ’96 or 2000 images here? Are we seeing the 6oo Km by 600 meter wobble or the 2,000Km by 3Km event. Also I’m fairly certain that the Galileo probe didn’t stay in that one spot for 4 years to take comparitive photos so is there any major difference in the two wobbles? Still, why isn’t that one middle ring wobbling too?

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  15. 15. jack.123 8:56 pm 10/25/2010

    Perhaps the composition of individual rings is why some vibrate and others don’t.If you go back to the original story about Saturn’s vibrating rings you will see that I suggested that a impactor was involved,and was criticized for doing so.Looks like maybe I was right after all.

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