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Space Science

Saturn's Rings Formed From Large Moon Destruction 115

Posted by CmdrTaco
from the now-it's-definitely-no-moon dept.
Matt_dk writes "The formation of Saturn's rings has been one of the classical if not eternal questions in astronomy. But one researcher has provided a provocative new theory to answer that question. Robin Canup from the Southwest Research Institute has uncovered evidence that the rings came from a large, Titan-sized moon that was destroyed as it spiraled into a young Saturn."
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Saturn's Rings Formed From Large Moon Destruction

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  • by pezpunk (205653) on Thursday October 07, 2010 @10:45AM (#33824568) Homepage

    sorry.

    • by CheshireCatCO (185193) on Thursday October 07, 2010 @10:48AM (#33824614) Homepage

      No, you're not.

    • by 0racle (667029) on Thursday October 07, 2010 @10:48AM (#33824620)
      Well ... not any more.
      • Re:that's no moon! (Score:5, Informative)

        by mcgrew (92797) * on Thursday October 07, 2010 @11:09AM (#33824872) Homepage Journal

        The rings/moon's firewalled off here, but I found a BBC article [bbc.co.uk] that's not.

        I've wondered for a long time if the asteroid belt was formed by some sort of collision, and thought about writing a science fiction story about an interstellar war between Mars and the no longer existing fifth planet (story would end with Mars losing its atmosphere and Planet Five being blown to bits).

        Astronomers? Is this possible, or likely? I know that's where current theory says our moon came from; a Mars sized object that collided with a young Earth.

        • by EdZ (755139)
          There are quite a few stories based on an extra planet being shattered to form the asteroid belt. I'd mention one of my favourites here, but it would be a huge spoiler.
        • Re: (Score:2, Informative)

          by Duodecimal (938540)
          It'd be a tiny itty bitty planet. All the asteroids together are only 4% of the Moon's mass. http://en.wikipedia.org/wiki/Asteroid_Belt#Formation [wikipedia.org]
          • Re: (Score:3, Informative)

            by Duodecimal (938540)
            I should have read the article further. It's hypothesized that the belt contained as much as an earth-mass of material. But overall, it never coalesced into a planet due to being disturbed by Jupiter's gravity.
          • "It'd be a tiny itty bitty planet. All the asteroids together are only 4% of the Moon's mass."

            Yes, but that's because they are the remainders from the planet. Only 1% of its mass was recaptured after the armaggedon, so the planet was in fact about the size of the Earth.

        • Re:that's no moon! (Score:4, Interesting)

          by interactive_civilian (205158) <mamoru@@@gmail...com> on Thursday October 07, 2010 @12:17PM (#33825832) Homepage Journal

          I am not an astronomer, but it is my understanding (mainly from Carl Sagan's "Pale Blue Dot") that the asteroids are more likely leftovers from the formation of the solar system that, when caught between the gravity of the sun and tidal forces from Jupiter never got the chance to accrete into a planet. So, rather than being a destroyed planet, they are a planet that never was.

          I don't know if there has been any new data to confirm or refute that hypothesis, though.

          • by CorSci81 (1007499)
            I was an astronomer once upon a time. As far as I'm aware this is pretty much still the prevailing theory, with some caveats that Jupiter likely did not form in its present orbit, and in fact the process of clearing out mass from the asteroid belt was partially responsible for putting Jupiter in its present place.
        • by magarity (164372)

          and thought about writing a science fiction story about an interstellar war between Mars and the no longer existing fifth planet

          Good science fiction uses fantastic settings to explore how people interact. If you've got a good story about interesting characters and their struggles with each other and/or their societies, go ahead and write it anyway and take a little artistic license with the settings. But if your story is so dependent on the realism of Mars's relationship to the asteroid belt that

          • by mcgrew (92797) *

            If you've got a good story about interesting characters and their struggles with each other and/or their societies

            Well, that's the hard part and is why you haven't had a chance to read it yet. I haven't figured out why they're at war. The easy part (to me anyway) is writing in such a fashion that it engages the reader; I've been writing stories with practically no story at all, but many folks seem to like them. Of course, the characters and their actions are based on real people so the "interesting characte

          • by Grishnakh (216268)

            That's soft sci-fi you're talking about. Hard sci-fi is much more about real science or future technologies.

            Not all sci-fi is like Star Trek, with future technologies being reduced to technobabble to serve as a plot device.

            For nontechnical people, soft sci-fi is indeed more "fun to read", so that's why it's more popular and prevalent.

        • I've wondered for a long time if the asteroid belt was formed by some sort of collision, and thought about writing a science fiction story about an interstellar war between Mars and the no longer existing fifth planet (story would end with Mars losing its atmosphere and Planet Five being blown to bits).

          No, it's the rest of Mars, blown off in the War by the planet killer. The strangely-light, oddly-small, iron-rich Mars we see today is just the core of the original planet. Search the belt for artifacts, no

          • by Grishnakh (216268)

            This isn't likely, but perhaps part of one of the two warring planets broke off and collided with early Earth, creating the Moon.

            Also, there already is a Planet Five: it's called Ceres. It's really tiny, though (but still enormous compared to everything else in the Asteroid Belt).

            • Also, there already is a Planet Five: it's called Ceres. It's really tiny, though (but still enormous compared to everything else in the Asteroid Belt).

              Wow, I totally missed that one (only one /. story in '07?). Largely water ice? - Strange that we'd be thinking of going to Mars and not there. I see NASA launched "Dawn" in 2007 to wind up there eventually. An 8-year trip seems uncharacteristically slow - hrm, another site says its ion drive should be able to make the trip in 6 months.

              Thanks for the tip!

    • by precariousgray (1663153) on Thursday October 07, 2010 @11:57AM (#33825558)
      M-O-O-N, that spells rings!
    • by sempir (1916194)
      Course there isn't...everyone knows the ring is made up of lost airline luggage!
    • Does that mean that Saturn is infested with Teddy Bears?

      OH NO! Are Teddy Bears just stuffed baby Wookies from Saturn? The secret space program must be earning money somehow, but what happens if the Zombie virus gets to them? We don't have enough Slim Whitman records to protect us all!

    • Since they're Saturn's rings: "That's no moon... it's a PlayStation!"
  • by CheshireCatCO (185193) on Thursday October 07, 2010 @10:50AM (#33824640) Homepage

    This is a really interesting model and it has a nice ring to it. (And Robin is one of the best researchers I know in this area, so that adds confidence, too.) But can we not use the definite statements in the headlines? This is a model. A good model, to be sure, but just one. I've definitely seen work even recently that makes a comet origin seem plausible, so in the very least, there's a competing model that has to be answered.

    • It's only a model

      They said the same thing about Camelot !

    • by Anonymous Coward on Thursday October 07, 2010 @10:55AM (#33824700)

      It has a nice "ring" to it? Seriously? Be ashamed.

      • I can honestly say that I didn't even spot that pun when I wrote that. When you live with ring-puns every day, you stop noticing accidental ones, I guess.

    • Re: (Score:3, Insightful)

      by Facegarden (967477)

      This is a really interesting model and it has a nice ring to it. (And Robin is one of the best researchers I know in this area, so that adds confidence, too.) But can we not use the definite statements in the headlines? This is a model. A good model, to be sure, but just one. I've definitely seen work even recently that makes a comet origin seem plausible, so in the very least, there's a competing model that has to be answered.

      ALL HEADLINES ARE TRUE.
      -Fantasyland, USA: Today, a top researcher said some headlines might be true, under certain circumstances. This is an amazing find, as previously it was believed that all headlines were complete fabrications, as covered in our story yesterday entitled "ALL HEADLINES FALSE".

    • I know I'm not in the planetary science loop, but I always thought that was the main theory of Saturn's rings.

      • That or comet breakup (or moon breakup due to comet impact... etc). I don't know that either theory is terribly strongly supported, but the origin and age of the rings is all an wide open question, but one that I've never felt (as a ring scientist) was particularly worrisome.

  • Obvious? (Score:3, Insightful)

    by esobofh (138133) <khg@teSTRAWlus.net minus berry> on Thursday October 07, 2010 @10:54AM (#33824682)

    Aren't all rings of this nature formed form orbiting debris - debris caused by collisions? The thought that Jupiter will have rings once the conflicting orbits of it's moons finally cause them to collide is not new.. it's expected and assumed that it will happen..

    I don't think this is new "science".. seems obvious.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Jupiter already has rings.

      http://en.wikipedia.org/wiki/Rings_of_Jupiter [wikipedia.org]

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

      by Chemicles (771024) on Thursday October 07, 2010 @11:08AM (#33824854)
      I think the article's content is more along the lines of "this new theory explains how Saturn's rings were formed, with their particular composition, while also explaining the other nearly-pure ice moons in the vicinity". The theory in the article is a little more comprehensive than "Saturn's rings were caused by a collision" (even though the summary was lacking information and seemed to imply that... go figure).
    • Re: (Score:1, Insightful)

      by Anonymous Coward

      It is fortunate that scientists do not simply stop thinking about or discussing problems as soon as somebody conjectures an answer.

    • Re:Obvious? (Score:4, Insightful)

      by mea37 (1201159) on Thursday October 07, 2010 @01:21PM (#33826732)

      Really? Not new science because it seems obvious? Because after all, everything that seems obvoius turns out to be scientifically correct, right?

      For example, to move from point A to point B, an object must move through all the points in between. Oh, except that's not true on a quantum scale.

      And if you're on a train that's moving at speed X, and you walk toward the front of the train at speed Y, then you're speed is X+Y. Except if the velocities are large, that will yield a measurable error.

      And a little closer to home here, we "knew" for quite some time that 9 objects were unique in the solar system. To many people this was so obvious that they won't accept it as wrong, even though we've since figured out that one of them wasn't like the others, and was more like a vast number of other objects.

      What we 'know' about planets' ring systems is speculation - a suitable answer to give an elementary school student who asks, so long as you preface it with "we think that this is the explanation".

      A new model is new science. It refines the hypothesis well beyond "debris caused by collisions". That it confirms, rather than refutes, the suitability of the (refined) hypothesis doesn't make it any less new.

      • Rings are made from Debirs - Obvious

        Rings formed from something larger breaking up - Always been a possibility

        Rings formed from Ice moon breaking up, and this is how Ice moons formed - this is the new bit ...

        The definition of Planet was vague at best and is now properly defined .... but this has nothing to do with science it's just human categories
        Nothing happened to Pluto when we decided to not call it a planet anymore ....

        Knowing how the rings formed (if it can be proved this is how they did form) will ma

    • by arisvega (1414195)

      Aren't all rings of this nature formed form orbiting debris - debris caused by collisions?

      Possibly yes, but that is not a scientific explanation; with that attitude, everything is formed by collapsing and colliding- astrophysics' goal is also to quantify; why this kind of rings and not some other? Why not similar ones to every planet? What are the initial conditions that lead to the development of Saturn's rings?

      The thought that Jupiter will have rings once the conflicting orbits of it's moons finally cause them to collide is not new.. it's expected and assumed that it will happen..

      Here is a hypothesis with a counterintuitive ring to it; there are many stable orbital configurations where orbiters need not align themselves with the body that they are orbiting- in en

  • I read a while ago that the same happened with the Earth's moon, or the Moon. The same side of the moon is always facing the Earth, because it bounced off of the Earth. It's also moving away from the Earth, for the same reason. The theory was the object that crashed into the Earth was about the size of Mars; that object is now the Moon.
    • by mcgrew (92797) * on Thursday October 07, 2010 @11:33AM (#33825206) Homepage Journal

      Not exactly. It was a Mars sized object, and the collision completely demolished it. For a while, the earth had a ring formed from the collision. The ring eventually coalesced to form the moon.

      The collision caused the earth's rotation. Ar one time a day on earth lasted three hours. The farther the moon gets from the earth, the more the earth's rotation slows.

      I wonder what the sky would have looked like then? The moon would have been HUGE, tides would have been tremendous.

      • by CheshireCatCO (185193) on Thursday October 07, 2010 @12:04PM (#33825670) Homepage

        The collision caused the earth's rotation. Ar one time a day on earth lasted three hours. The farther the moon gets from the earth, the more the earth's rotation slows.

        I think you're confusing two things, here. The collision did almost surely affect the Earth-Moon system's total angular momentum, but the early spin rate and the gradual slowing of the Earth isn't due to the collision (except indirectly), but due to tides transferring angular momentum from Earth to the Moon.

        We really don't know Earth's initial spin state since there's no way to find that in any sort of record. (At least none I can think of. It just doesn't leave much of a mark.)

    • by MozeeToby (1163751) on Thursday October 07, 2010 @11:37AM (#33825284)

      We always see the same side of the moon because of tidal locking [wikipedia.org]. It doesn't have anything to do with how the moon formed except in that the impact hypothesis puts the new moon close enough to the Earth that it became tidally locked fairly quickly, but that isn't unique to the impact hypothesis. In very basic terms it works like this:

      1) Tides cause bulges on one or both bodies
      2) The material that the bodies are made of resists that bulge so the bulge is never precisely where it it 'should' be gravitationally speaking. If the body rotates slower than it revolves the bulge will be behind, faster than it revolves and the bulge will be ahead. Let's say the bulge is ahead in this example.
      3) The orbiting body (relative to the tidal bulge) is slightly more attracted to the bulge, since it is slightly closer than the rest of the planet. Since the bulge is ahead this pulls the bulge back (causing the bulging body to slow its rotational speed) and pulls the orbiting body as a whole forward (causing it to increase it's revolution speed).

      In the Earth/Moon system, this has locked the moon's rotation rate to it's revolution rate. The same isn't (yet) true for the earth, if you stand on the moon you will see all sides of the Earth. However, that is very, very slowly changing. Each trip around the planet, the moon steals some of the Earth's rotational energy and turns it into orbital energy, raising the orbit of the moon a tiny bit and lengthening the day a tiny bit.

      • by Tablizer (95088)

        Each trip around the planet, the moon steals some of the Earth's rotational energy and turns it into orbital energy, raising the orbit of the moon a tiny bit and lengthening the [earth] day a tiny bit.

        Damn moon! Makes us have to update our Java clock drivers all the time. Nuke the moon!
               

    • "The same side of the moon is always facing the Earth, because it bounced off of the Earth."

      Actually nearly all significant moons have one side always facing the bodies they orbit. It's not because of collision, it's because of tidal locking.

      http://en.wikipedia.org/wiki/Tidal_locking [wikipedia.org]
  • Wrong (Score:5, Funny)

    by bperkins (12056) on Thursday October 07, 2010 @11:16AM (#33824960) Homepage Journal

    God liked it, so he put a ring on it.

  • ACC was right! (Score:5, Interesting)

    by cvd6262 (180823) on Thursday October 07, 2010 @11:23AM (#33825044)

    In 2001, ACC pointed out the odd coincidence between the ring of Saturn being only 4 million years old, and the time when the Monolith appeared on Earth. Hmmmmmm.

    BTW - The book has the large monolith at Saturn, not Jupiter. Kubrick was worried about the FX it would take to portray the rings on film, so they changed it to Jupiter.

    • Very interesting coincidence. And, if some day a researcher discover that mankind has begun four million years ago, Clarke will smile above us.
  • New? (Score:3, Interesting)

    by MaWeiTao (908546) on Thursday October 07, 2010 @11:24AM (#33825064)

    Is this really a new theory? Or is this a new interpretation of an existing theory.

    I recently read 2001, finally, and I'm fairly certain Arthur C. Clarke mentions Saturn's rings having been formed due to the destruction of a moon. He's not a scientist, but I'm fairly certain he got the idea from scientific circles.

    • Re: (Score:1, Insightful)

      by Anonymous Coward

      No, it's not new, it's more complete. But I suppose it would be so much simpler to tell who wins the science game if people just stopped asking questions when somebody else said "FURST! LOL"

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      He's not a scientist, but I'm fairly certain he got the idea from scientific circles.

      You should probably read more about Clarke or possibly redefine your idea of what a scientist is.

    • I read the theory in a child's field guide to astronomy in the early 70s. I have an old Time Life book that talks about how if the Moon ever spiraled in it might break up and form a ring.

      Oh what am I doing... Wikipedia! I choose you!

      Zap!

      Theory first proposed by Édouard Roche in the 19th century, hence we have the "Roche limit" for moons not breaking apart.

    • Re: (Score:3, Informative)

      by SnarfQuest (469614)

      He's not a scientist, but I'm fairly certain he got the idea from scientific circles.

      Actually, he is a Scientist. Has many published ideas. Geostationary satellites is one of his ideas. Just because you write Science Fiction doesn't cause them to throw you out of the guild.

    • by ivoras (455934)
      Clarke not a scientist? Since when? He might not have had a PhD title (which is only that - a title) but other than that trivial detail he's practically a text-book model of a fine scientist. He is one of *the* role models for the job.

      It's like saying Carl Sagan wasn't a scientist! In fact, Clarke and Sagan had very similar fields of interest and work.

    • by CorSci81 (1007499)
      Tidal destruction of a moon isn't exactly a new theory to explain the rings. Previous iterations just had trouble explaining the composition of the ring material, hence comets were a more favorable model. What Robin has done here is show how you can tidally destroy a moon and get the right ring composition. I'm not entirely surprised to see this coming from her, she previously did the same with Earth's moon-forming collision.
  • That's no moon! (Score:1, Redundant)

    by DarthVain (724186)

    Well not anymore anyway... :)

  • You guys obviously haven't been watching your documentaries. I remember well that episode from Captain Future in the 70's where they state that Saturn's rings are the result of the destruction of the Katein. This is why Captain Future travels back in time to have the people of the Katein build one of their moons into a spaceship to travel to their old holy planet.

    Sheesh. Kids these days.

  • pics or it didn't happen...
  • video? (Score:4, Funny)

    by billmarrs (97555) * on Thursday October 07, 2010 @12:05PM (#33825678) Homepage

    I will believe this when I see the CGI video of a moon exploding as it spirals into Saturn.

  • ... one of Mars' moons? I remember reading somewhere that one of them will either crash into Mars or be disintegrated into a ring in a few million years because it's orbit is shrinking slowly as time goes on.

  • The Death Star was found hanging out at the scene right before the moon's destruction. Apparently, several witnesses testified that a dark-colored moon was in the area acting suspiciously. An old man was quoted as saying 'That's no moon!' but was apparently ignored. More news at 11.
  • by Anonymous Coward

    And this is news? This must have happened millions of years ago!

  • That's no Moon it is the debris of an space station from long ago.

  • it would be cooler to have a ring than a moon, but that would probably screw up the tides.

  • John Varley covered how the rings were created in his Gaean series of books (Titan, Wizard, Demon). The constructs would collapse moons to gather the materials they needed to form their habitats.

  • Titan is such an interesting moon. Too bad its possible twin is lost. It may have been even more interesting than Titan because being closer to Saturn means that it would likely have had many tidal-friction-induced volcanoes that spew water, methane, etc. Think of Io with a real atmosphere and more water. (Well, maybe Io once did have more water. It may have all been boiled away by tidal volcanoes.)

  • by Xerxes314 (585536) <clebsch_gordan@yahoo.com> on Thursday October 07, 2010 @03:46PM (#33828630)

    Well, I read all the comments so far and nobody has discussed the actual new parts of the model. The novelty is that the destroyed moon is assumed to be differentiated (The heavy metal and rock fall to the core and the light ices stay on the surface.) and Saturn was in its very early stages, when it was hot and its atmosphere greatly distended. This means that as the moon spirals in toward Saturn, its icy mantle gets stripped off by tidal forces first. That makes a vast disk of icy material from which the inner icy moons and the ring system are formed. Since the denser rocky material at the core of the moon is less affected by tidal forces, it impacts the extended atmosphere of Saturn and gets swallowed up before it has a chance to contribute to the disk. This explains the composition of the rings and moons better than previous models.

    The point is not that it was a moon. There was no collision. Takeaway point if tl;dr:

    The rings were formed by tidal disruption of a moon with an icy mantle and a rocky core.

  • I went looking for Saturns Moon, and all I could find was Uranus.
  • If he has had facts, fine. But if not... Well, personally I have assumed for years that the rings came from a broken moon or similar object. The main reason for that is that nothing else makes any sense.

    So yah ;)

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