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A Planet That Orbits Its Star the Wrong Way

Smivs writes "BBC News is reporting that astronomers have discovered the first planet that orbits in the opposite direction to the spin of its star. Planets form out of the same swirling gas cloud that creates a star, so they are expected to orbit in the same direction that the star rotates. The new planet is thought to have been flung into its 'retrograde' orbit by a close encounter with either another planet or with a passing star. The work has been submitted to the Astrophysical Journal for publication. Co-author Coel Hellier, from Keele University in Staffordshire, UK, said planets with retrograde orbits were thought to be rare. 'With everything [in the star system] swirling around the same way and the star spinning the same way, you have to do quite a lot to it to make it go in the opposite direction.' Professor Hellier said a near-collision was probably responsible for this planet's unusual orbit. 'If you have a near-collision, then you'll have a large gravitational slingshot from that interaction,' he explained. 'This is the likeliest explanation. But it might be possible you can do it by gradually perturbing the orbit through the influence of a second planet. So far, we haven't found any evidence of a second planet there.'"

27 of 257 comments (clear)

  1. Why do they blame the planet? by flaming+error · · Score: 5, Interesting

    Maybe the sun reversed its spin.

    1. Re:Why do they blame the planet? by srothroc · · Score: 4, Insightful

      The way I read it is that the GP is not saying that the star CAUSED the retrograde orbit -- he's asking why everyone's asking how the PLANET's orbit changed rather than asking why the star's spin changed. For a car analogy.. it's like asking why the car pissed off the dog that's chasing it rather than why the dog is chasing the car.

    2. Re:Why do they blame the planet? by davester666 · · Score: 5, Funny

      Sun's don't go both ways. They're all either straight or gay.

      --
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    3. Re:Why do they blame the planet? by ChromaticDragon · · Score: 4, Insightful

      Depends on what gets perturbed, I guess.

      Try not to think just in two dimensions. Imagine the orbit as a very large ring. Instead of thinking of it shrinking, imagine the ring pivoting out of the usual orbital plane. Imagine this ring slowly rotating. Eventually, it'll settle back to the plane yet the planet will be orbiting backwards relative the the original and the star's rotation.

    4. Re:Why do they blame the planet? by BluBrick · · Score: 4, Funny

      Sun's don't go both ways. They're all either straight or gay.

      Maybe, but who's to say it can't be turned? It's orbital ring got invaded by a foreign object. Maybe this particular sun, you know, liked the experience?

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    5. Re:Why do they blame the planet? by Gerzel · · Score: 5, Insightful

      You have little understanding of how science works and how scientists actually think. If you want to talk about cherished theories that can't be changed talk to creationists and theologians. If you want to talk about theories that explain and simulate the universe that are regularly changed, usually but not always gradually, learn the scientific method and about science.

      I have been trained as a physicist and a scientist and the first lessons they begin teaching(besides calculus and the other basic courses) are that science is the process of curiosity, reason and doubt. It is a collaborative effort that is larger than any single person and it is a slow struggle where answering one question means opening up many many more. It is the process of expanding the universe by exploring the world around us and seeing how big, vast and wonderful our lives and this world really are.

      Religion too often gives us the like of seven days, 6000 years and a wet ball of mud to live on, with harps and clouds if you've been good afterward. Its comforting but it is small.

    6. Re:Why do they blame the planet? by AlecC · · Score: 4, Insightful

      The "dust cloud" theory only states that the majority of planets should rotate with their sun. There are a number of known mechanisms, some discusses in TFA, which can produce retrograde motion. We have several moons in the solar system showing retrograde motion. So this does absolutely nothing to disturb current theories of planet formation - you would have to find dozens of these to do that. It just appears that, in this case, one of several interesting events must have happened, and it might be worth looking for evidence of such an event. For example, if it were a near collision, it would be worth backtracking the paths of nearby stars to see if they were candidates for this decision.

      This is not a "the current rules are broken" announcement, but a "hey, something interesting" announcement.

      --
      Consciousness is an illusion caused by an excess of self consciousness.
  2. Maybe its in the southern hemisphere of that star? by randy+of+the+redwood · · Score: 5, Funny

    Doesn't everything rotate backwards if its from down under?

    --
    The sun is the same in a relative way, but you are shorter of breath and one day closer to death
  3. Poor Planet by russlar · · Score: 5, Funny

    All the other planets keep pointing and saying "You're doing it wrong!"

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    1. Re:Poor Planet by Normal+Dan · · Score: 5, Funny

      It's different. Let's destroy it.

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  4. Re:I'm no astrophysicist... by Anonymous Coward · · Score: 5, Funny

    A rouge planet

    What does Mars have to do with this?

  5. "But it might be possible... by msauve · · Score: 4, Interesting

    "...you can do it by gradually perturbing the orbit through the influence of a second planet" claims the article.

    But, if it were to happen slowly, doesn't that imply that at some point it has a minimal orbital speed (if that's the correct term), and would fall right in? Seems to me that if it reversed direction, it must have been a relatively quick event. Unless, perhaps, the planet ends up being sent away from the star, and is then recaptured in a retrograde orbit. But, that's still not a "gradual perturbation."

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    1. Re:"But it might be possible... by DaveAtFraud · · Score: 5, Insightful

      Er, no. The idea is that the inclination of the orbit keeps getting larger until the planet is orbiting "backwards." The planet doesn't stop and reverse its orbit.

      Cheers,
      Dave

      --
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      Ben
    2. Re:"But it might be possible... by FooAtWFU · · Score: 5, Informative

      No. Here's the ASCII art.

      <--O--<

      ^
      -
        O
         -
          ^

         ^
         -
         O
         -
         ^

           ^
          -
         O
        -
      ^

      >--O-->

      --
      The World Wide Web is dying. Soon, we shall have only the Internet.
    3. Re:"But it might be possible... by gehrehmee · · Score: 4, Interesting

      In this case, it's really the angle of the orbit that would be perturbed. Eventually it would be orbiting above and below the north and south poles of the star, and then perturbed even further until it was rotating the wrong direction. In that sense, it's actually orbiting in the correct direction, just offset 180degrees.

      A similar explanation is often used to describe the fact that Uranus rotates clockwise, whereas all the other planets in our solar system rotate counter-clockwise. (Note, rotation != revolution. Rotation == spin, revolution = orbit). Effectively, virtually all the angular momentum of any given solar system is in the same direction. The odd object's motion may be twisted into appearing the wrong way by some dramatic celestial event.

      --
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    4. Re:"But it might be possible... by Anonymous Coward · · Score: 5, Insightful

      To put this in analogy form:
      Picture someone making a pizza, when they spin it and throw it up in the air it lands spinning the same way. But if the pizza flips over in mid-air the rotation will be reversed when it lands but it didn't have to stop and reverse direction to do it.

      Oh, and somehow a car is involved.

  6. Re:Losing it's luster by colonelxc · · Score: 4, Informative

    They're already working on that; I read something recently about a probe that they're testing on Earth right now (it's in space, looking at Earth as a control).

    I think you mean the LCROSS Spacecraft

  7. Opposite spin by StartCom · · Score: 5, Informative

    Well, in our solar system at least one planet is spinning the other way around: http://wiki.answers.com/Q/Why_does_venus_spin_the_other_way It's not quite the same like orbiting into the opposite direction, but the Venus apparently received a nudge or two as well in order to spin the other way around. Such accidents appear to happen.

  8. were thought to be rare? by LordNimon · · Score: 4, Insightful

    planets with retrograde orbits were thought to be rare

    Since this is the only one that's been found, I'd say that planets with retrograde orbits are still thought to be rare.

    --
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    1. Re:were thought to be rare? by radtea · · Score: 4, Insightful

      There have only been a few hundred extra-solar planets found, so finding one that has a retrograde orbit is surprising if they were thought to be much less probable than 0.5% or so.

      It all depends on the meaning of "rare", which is one of those innumerate words we ought to be doing without.

      --
      Blasphemy is a human right. Blasphemophobia kills.
  9. Re:Losing it's luster by Dragonslicer · · Score: 4, Informative

    However, we're still unable to detect Earth-size planets in other star systems, as most of the planets we've detected are Jupiter-sized or more, but they are detecting progressively smaller planets.

    You're a bit behind on that. Planets that are well within one order of magnitude of the size of Earth have been discovered. This one may be less than twice the size of Earth.

  10. Re:I'm no astrophysicist... by Slammer64 · · Score: 4, Informative

    It's rogue dammit, ROGUE!

  11. Re:Losing it's luster by Anonymous Coward · · Score: 5, Interesting

    I was looking at the stars one evening and the thought occurred to me that every star harbors a hideous mess; an immense collection of orbiting debris ranging from bloated gas giants with dozens of exotic moons to mangled chunks of gold weighing billions of tons. Those nice neat little points of light are actually solar systems, every bit as rich and complex as our own. Life, at least in primitive forms, is probably a common afterthought.

    Think about the planet you're on now. Everything beyond iron is the shrapnel of stellar detonations coalesced and melted into a ball of metal orbiting the sun. Staggering quantities of baryons mushed together in weird configurations, colliding, erupting and aging for billions of years. Somewhere there is a near perfect sphere of nickel weighing five Earths and orbiting a black hole. It will be destroyed next week when it collides with and vanishes forever into the guts of an 9 billion year old brown dwarf. It will have never been observed by anything more sentient than a dusty comet.

    When you really think about it the universe is creepy.

    Extrasolar astronomy requires extraordinary equipment. We need to build more of it and figure out what the universe looks like below cosmological scales because we haven't got the first clue what's really out there. Humans were simply not endowed by nature with sufficient imagination to anticipate more than a small fraction of all the crazy shit we're going to find.

  12. You are going to Kill Someone...... by jameskojiro · · Score: 4, Funny

    This evokes that scene from "Trains Planes and Automobiles"......

    --
    Tsukasa: All I really want, is to be left alone...
  13. Re:Not the first by icegreentea · · Score: 4, Informative

    Venus SPINS opposite of the rest of planets. It orbits in the same direction. Uranus' axis of rotation is rotated 90 degrees, so it lies nearly in the solar plane. But it orbits like the rest of the planets. Pluto has a retarded orbit (no, that's not a scientific term), but its still going in the same direction. You mixed up orbit and rotation.

  14. Re:Losing it's luster by Fluffeh · · Score: 4, Informative

    why do you slashfucks keep using this order of magnitude shit even when it doesn't apply? do you really think it makes you look smart? orders of magnitude are used in a very specific fashion that even a 2nd grader can understand but you guys keep throwing it out there like it's a generalization. it's fucking not.

    What's wrong with what he said? He said planets within an order of magnitude have been found. That means planets up to ten times as massive as the earth or as small as on tenth of the earth. He then points to an example where the planet is estimated to be half the size of earth.

    Maybe you should brush up on simple 2nd grade mathematics principles before taking a pitchfork out and lighting that flaming brand?

    As for a generalization, it can very well be one. It compares like objects within a scale that doesn't require any other measurements. You can say that one object is 2 magnitudes bigger than another if it is 100 times the size. You don't need to measure either object in any units.

    So either get used to us "slashfucks" using scientifically agreed to and mathematically correct statements even if you don't understand them, or well, feel free to go find a site more suited to your level. Perhaps something with lolcatz or photos and a rating system?

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  15. Re:I'm no astrophysicist... by geekgirlandrea · · Score: 4, Funny

    What happens if it goes to plaid, though?