Forgot your password?
typodupeerror
Moon Space Science

Earth May Once Have Had Multiple Moons 186

Posted by kdawson
from the many-moons-ago dept.
fyc writes "A new study from NASA's Ames Research Center has suggested that the collision of Earth and a Mars-sized object that created the Moon may also have resulted in the creation of tiny moonlets on Earth's Lagrangian points. 'Once captured, the Trojan satellites likely remained in their orbits for up to 100 million years, Lissauer and co-author John Chambers of the Carnegie Institution of Washington say. Then, gravitational tugs from the planets would have triggered changes in the Earth's orbit, ultimately causing the moons to become unmoored and drift away or crash into the Moon or Earth.'" The longest-lasting of such Trojans could have persisted for a billion years. They would have been a few tens of kilometers in diameter and would have appeared in the sky like bright stars.
This discussion has been archived. No new comments can be posted.

Earth May Once Have Had Multiple Moons

Comments Filter:
  • by Hal_Porter (817932) on Wednesday May 07, 2008 @04:49AM (#23321862)
    In Star Wars when Luke looks up at the sky and sees several moons I always wondered.

    But this is scientific proof that the Gospels according to George Lucas are the truth.
  • by Anonymous Coward
    there. stupid joke out of the way.

    continue.
  • by Viol8 (599362) on Wednesday May 07, 2008 @05:00AM (#23321886)
    ... was one of those old moonlets paying its last visit to earth. If it had left a Langraigian point it could still have orbited very near earth for a long long time until one small nudge put it on the trajectory for that fateful day.
    • by Viper Daimao (911947) on Wednesday May 07, 2008 @07:28AM (#23322588) Journal
      if that were the case, there wouldn't be a k/t boundary layer would there?
      • by MBGMorden (803437) on Wednesday May 07, 2008 @08:23AM (#23323020)
        Quite true. Any "moonlet" if it had been created by the Earth/Thea collision would have bee composed of roughly the same thing as Earth is. The highly increased iridium is a signature of an asteroid and not a terrestrial rock.
      • by d3ac0n (715594)
        Why do you say that?

        Nothing to say that these "moonlets" weren't made of the same stuff of the KT boundary. I forget the name of the particular rare mineral/ore/whatever that defines the KT boundary, but is there a large amount of it on the moon? If there is, wouldn't it then stand to reason that these moonlets would have been made of similar materials? And if they were made of similar materials, would it not then be possible for one of them to have caused the impact event that created the KT boundary?

        Of
        • by d3ac0n (715594)
          Aaand MBGMorden appears to have answered my question for me. Never mind then. :)
        • by RockDoctor (15477)

          I forget the name of the particular rare mineral/ore/whatever that defines the KT boundary, but is there a large amount of it on the moon?

          In a number of globally-scattered locations, there is a narrow peak of concentration of iridium (element, atomic number 77, a platinum group metal) which is approximately coincident with the Cretaceous-Tertiary boundary. However this does not DEFINE the position of the "K/T boundary" - that is done by fossil content, and more specifically by the lowest position of certain

    • Would it be moving quickly enough to have the kinetic energy required to do the kind of damage that was done? Given that it was stationary, it wouldn't be hitting earth at more then terminal velocity, right?
      • by Lijemo (740145)

        Would it be moving quickly enough to have the kinetic energy required to do the kind of damage that was done? Given that it was stationary, it wouldn't be hitting earth at more then terminal velocity, right?

        The key question is "stationary with regard to what?".

        In the case of the Lagrangian points, the answer is "stationary in regard to the Earth/Moon System", NOT "stationary in regard to a point on the Earth's surface".

        (Also, "just terminal velocity" with regard to the distance of either a Lagrangian point or a geosynchronous orbit would still be nothing to sneeze at, and given the "tens of kilometers across", the force of impact would be far from trivial.)

  • Not far fetched. (Score:5, Interesting)

    by Auckerman (223266) on Wednesday May 07, 2008 @05:05AM (#23321898)
    Doesn't sound too far fetched since Earth has Cruithne [wikipedia.org] sharing it's orbit, which in it's own way is a "second moon". On a functional level, not that different from what they are suggesting. I would even take it step futher, there's no reason to even believe any specific natural satellite of Earth originated from our planet or it's creation.
    • Re:Not far fetched. (Score:5, Informative)

      by mpe (36238) on Wednesday May 07, 2008 @06:09AM (#23322162)
      Doesn't sound too far fetched since Earth has Cruithne sharing it's orbit, which in it's own way is a "second moon".

      Except that this object isn't sharing the Earth's obit at all. It's in a solar orbit which is similar to the Earth's. In order to call something a "moon" of the Earth it would need to be orbiting the Earth.
      • by thewiz (24994)

        Except that this object isn't sharing the Earth's obit at all.


        Actually, it's a newspaper policy that there's only one obit per customer.
    • Re:Not far fetched. (Score:5, Interesting)

      by 4D6963 (933028) on Wednesday May 07, 2008 @07:19AM (#23322546)

      Earth has Cruithne sharing it's orbit, which in it's own way is a "second moon"

      If it's not permanently orbiting within the Earth's Hill sphere [wikipedia.org], it's no moon.

      On a side not, since these moons were originally at Lagrangian points, it makes me wonder whether or not some of them could evolve into having a horseshoe orbit with the Earth. Actually a mission to one of these asteroids when they get about 1.5 Gm from Earth would be interesting and pretty easy as they would be close to Earth and moving pretty slowly. I guess you could look them up closer to find out if they share material in common with the Moon or anything.

  • That's no moon (Score:5, Insightful)

    by sporkme (983186) * on Wednesday May 07, 2008 @05:06AM (#23321902) Homepage
    IANAP, but this seems to illustrate a physical possibility, not evidence of past existence. The existence of the moon demands answers, which have been delivered ad nauseum, but this seems to be a bit of "well enough" not being left alone as I see it. TFA:

    "The giant impact that likely led to the formation of the Moon launched a lot of material into Earth orbit, and some could well have been caught in the Lagrangian points,"
    The possibility of existence does not necessitate existence, but it apparently necessitates a Slashdot headline.
    The real headline seems to be:
    Post-collision debris from Lunar creation might have persisted a little bit longer than originally thought in these crazy gravitational slots, but no evidence is available to back up this theory, and it sure would be neat-o."
    Yay.
    • by IkeTo (27776)
      > Post-collision debris from Lunar creation might have persisted a little bit longer than originally thought in these crazy gravitational slots, but no evidence is available to back up this theory, and it sure would be neat-o."

      Reading the abstract of the article actually led me to think the opposite: "The L4 and L5 positions are a little less stable than previously thought, so the non-existence of objects in those locations nowadays cannot be used to demostrate the lack of such objects in the past." IAN
    • Re: (Score:3, Insightful)

      by khallow (566160)
      Ok, so what's your problem? Constructing a testable hypothesis is one of the key steps of the scientific method. Further, the article mentions two different models that lead to the same conclusion. That is sufficient evidence to generate a hypothesis.
      • Could have happened is certainly a hypothesis but yet it is not testable, therefore it lacks any scientific value. I don't have any problem with people suggesting possibilities of how things occured, but saying "it could have happened, it is the most likely to have happened, therefore it must have happened" is not science at all, it's fiction.
        • by khallow (566160)
          There are some ways to test this. The key as I see it, is either to find collision remnants from a sizeable object that has a composition similar to the Moon and impact energy consistent with a drop from L4/L5. Or an actual asteroid somewhere in the Solar System (almost surely an Earth crossing asteroid) that is chemically similar to the Moon, an age consistent with the formation of the Moon, and has energy consistent with a similar object at L4/L5. The most likely place to look would be the Moon since it k
  • by pbhj (607776) on Wednesday May 07, 2008 @05:08AM (#23321908) Homepage Journal

    fyc writes "A new study .. has suggested .. may also have .. likely remained .. would have .. could have .. They would have .. and would have appeared in the sky like bright stars.
    So it's a first hypothesis, now find some evidence.

    Meanwhile a new study by me has suggested that reading Slashdot stops time and may also make you hyper-intelligent. Slashdotters would have bigger brains that could be farmed in the future to feed entire villages. Villagers would crack open the skulls with sharp metal straws which would be used to drink the brains out. A strong light then placed in the skull cavity would then shine in the night like bright stars.
  • by Anonymous Coward on Wednesday May 07, 2008 @05:20AM (#23321970)
    before the man in the moon ate it all millions of years ago. The smell of cheese may have lingered for several centuries after that.
  • Moonlets? (Score:5, Funny)

    by moosesocks (264553) on Wednesday May 07, 2008 @05:20AM (#23321974) Homepage
    Although "Moonlets" is a cute, fuzzy term, I would have much preferred if they'd called them 'mooninites'
  • by OpenSourced (323149) on Wednesday May 07, 2008 @05:23AM (#23321988) Journal
    would have appeared in the sky like bright stars.

    Appeared to whom?

    • by PJ The Womble (963477) on Wednesday May 07, 2008 @05:56AM (#23322110)
      Having once played a gig to an audience of zero, I can't agree with your logic here. "Appear" doesn't have to be "to" anyone, sadly! At least the moons got to come back the next night. I didn't.
    • Just ask Tom Cruise. It was the Xenu!
    • Re: (Score:2, Funny)

      by mcamino (970752)
      I think Cher and Milton Berle were dating at that time.
    • Traveling to the past, of course.
    • Re: (Score:3, Informative)

      by Chris Burke (6130)
      would have appeared in the sky like bright stars.

      Appeared to whom?


      Nobody. One of the first things you learn in astronomy (observation, not education) is how to distinguish between a star and a planet or moon. It's easy: stars twinkle, big balls of rock or gas don't. Next time you're out at night, try to find Venus (it's the brightest object after the moon and sun), and compare it to any bright stars in the sky like Polaris. Venus will look very static, like it's just a dot of paint on the sky. Long bef
    • by danzona (779560)
      John McCain!

      I'll be here all week, try the broccoli.
  • by Lord Graga (696091) on Wednesday May 07, 2008 @05:33AM (#23322022)
    I did a math project in university on lagrangian points and read what I could find on the net - as far as I remember, there is a similar theory that our moon was formed in one of the Earth's lagrangian points, and grew bigger with asteroid crashes (or something similar), until it grew so big that the lagrangian points couldn't hold it any more, and it flew into orbit with earth. Anyhow, this is purely speculation, but if you look closely enough into our universe, you might be able to find places where this is happening right now.
    • Re: (Score:2, Informative)

      by bearbones (532127)

      insightful?

      lagrangian points require two bodies

      what was the second body creating the points while the moon was being formed?

    • > it grew so big that the lagrangian points couldn't hold it any more, and it flew into orbit with earth.

      These days they have scientific theories about the orbits of planets and nobody talks about planets flying around any more.

  • by sithkhan (536425) <sithkhan@gmail.com> on Wednesday May 07, 2008 @05:47AM (#23322080)
    Let me see if I have this straight - Pluto is NOT a planet, because it falls beneath some arbitrary threshold for 'planet', but ANY object orbiting a planet is automagically a moon?

    I have no problem with the theory, but if objects 'tens of kilometers' across are moons, then Pluto is surely a planet.

    And don't call me Shirley.
    • Mod Parent Clueless (Score:5, Informative)

      by Anonymous Coward on Wednesday May 07, 2008 @06:28AM (#23322256)
      Dude, there are hundreds, if not thousands of Pluto sized planetoids. Pluto was discovered first of those objects, and mistakenly thought to be very unique.

      Planets are the huge and few main satellites of the sun. It's a category defined entirely by scarcity. There are only 8. Not 8000. Pluto can't be a planet and the hundreds or thousands of larger objects not be, but the fact that there were thousands of similar objects wasn't discovered until after Pluto was added to the planet list. It's just an act of intellectual honesty to note that Pluto is only unique historically for being seen early. But now we know: It's not a major satellite sufficient to be in the planet category. You call this arbitrary, but it's as unarbitrary as anything could be.

      What the hell does this have to do with how big a moon is? Any object orbiting a planet is automatically a satellite, any satellite that is naturally occurring is automatically a moon (by some definitions, anyway). Perhaps you should invest in a good dictionary. They are free on the internet.

      Thank goodness we don't have to rely on your inane concepts of 'fairness' in celestial bodies for our language needs.
      • by khallow (566160)

        While I agree that the original post was clueless, the current definition of planet isn't useful scientifically. In addition to being ill-defined, it doesn't extend naturally to other star systems in two critical ways. First, it can only be used in mature single star systems like the Solar System where no perturbation of planets is possible. Second, it requires considerable effort to prove the object is "clearing" its neighborhood, whatever that means. Try doing that for a star system so far away that you c

        • by Lijemo (740145)

          At the very least, "clearing it's neighborhood" should have a more precise meaning, such as: Clearing a ring equivalent to X times it's own diameter of all objects Y% of it's own size or mass. Without some kind of clarification, any dust in a planet's orbital trail could be interpreted to mean the planet hasn't "cleared it's neighborhood".

          Or perhaps they do have a more precise definition, and it's just not included in the press releases? If that's the case, they should include it-- the definition would so

      • Re: (Score:3, Insightful)

        No, it's completely arbitrary. Why must the planet classification be reserved for only a few satellites? Is it so first graders can memorize all the planets or is there a real reason to make this such an exclusive "club"? I agree with the post above me, there's no reason there shouldn't be hundreds if not thousands of planets.

        Perhaps we should only consider elements up to Iron as atoms, everything else after Iron is just too big to be an atom. It doesn't change the fact that they're still there, but the "a
    • Re: (Score:3, Interesting)

      by mdwh2 (535323)
      Let me see if I have this straight - Pluto is NOT a planet, because it falls beneath some arbitrary threshold for 'planet', but ANY object orbiting a planet is automagically a moon?

      Apparentely so - the 63 Moons of Jupiter [wikipedia.org] include the 1 km in diameter 2003 J 9 [wikipedia.org].

      I find it odd that people can't cope with there being hundreds of planets, and need some arbitrary distinction between "planet" and "natural satellite of the Sun", but 240 moons in the solar system is considered fine.

      It's also strange that a body orbi
      • Given that it's astronomy, I don't think they're really being consistent with the term "dwarf". A dwarf star is still a star, but a dwarf planet is not a planet.

        I actually accept the arguments that Pluto isn't a planet. The problem is that defining a planet is a tough thing, and the oddity I noted above seems to be part of an odd compromise that shouldn't have been made.
    • Re: (Score:3, Insightful)

      by ChrisA90278 (905188)
      Pluto is not a plent because plaets are defined as soething which "dominates" the area in which it orbits. Pluto does not do this. It shares it's space with many, many "peers"

      Mars is a planet because it is by a huge margin the biggest thing in that part of the solar system. The same can not be said of Pluto.

      A "mmon" is simply any natural object capured in orbit around a planet.
  • by hyades1 (1149581) <hyades1@hotmail.com> on Wednesday May 07, 2008 @06:29AM (#23322264)

    This "many moons" phenomenon was occasionally seen at my university quite some time in the past. The moons appeared as pale, bifurcated disks in the darkness around the president's residence, often after the end of final exams.

  • I think the author may have been the victim of a multiple moon drive by - front and rear passenger seat. Thus the earth has more than one moon - at least according to the author.
  • But Earth DOES have a 2nd moon. It is called Anoolios, a dark fragment and has already been documented from Persian folk history.
    Just because NASA can't find it, doesn't mean that it doesn't exist!
  • Why not smaller later impacts? The big one would probably have liquified (basalt flows) the entire surfaces. Smaller, later impacts from trojans could have formed larger features (lunar maria) or fissured eather's supercontinents.

    A good time was not had by all :)

  • by line-bundle (235965) on Wednesday May 07, 2008 @08:37AM (#23323174) Homepage Journal
    Cheddar, Gouda, Parmesan etc..

    The swiss got to the other moons before NASA and mined them clean.

    I stand by my theory.
  • by KlomDark (6370) on Wednesday May 07, 2008 @08:46AM (#23323252) Homepage Journal
    They discovered Cruithne [messagebase.net], orbiting the Earth in a weird 770 year orbit, back around 1999.
  • by WheresMyDingo (659258) on Wednesday May 07, 2008 @09:16AM (#23323536)
    234) When traveling back in time to when the Earth had many moons, using the phrase "not in many moons" to describe the passage of time will only get you blank stares and instantly label you as an outsider (assuming you've managed to blend in with the local environment otherwise).
  • Actually there were uncountable numbers of "moons" right after the impact. These were really to small be even be called "moons" it was more like a cloud or a dense set of rings. Much of the young Earth was vaporized. Then over time this vapor and dust condensed into biger clumps and these into bigger ones unitl now there are just two clumps left The earth and it's present moon.

    I think what this article adds is detail about that period when there were only a few clumps.

    I think logically we knew that if th

3500 Calories = 1 Food Pound

Working...