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Space Science

A Planet That Orbits Its Star the Wrong Way 257

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.'"
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A Planet That Orbits Its Star the Wrong Way

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  • by srothroc ( 733160 ) on Thursday August 13, 2009 @08:17PM (#29060173) Homepage
    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.
  • by DaveAtFraud ( 460127 ) on Thursday August 13, 2009 @08:39PM (#29060363) Homepage Journal

    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.


  • by LordNimon ( 85072 ) on Thursday August 13, 2009 @08:57PM (#29060521)
    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.
  • Re:Odd, then... (Score:2, Insightful)

    by needs2bfree ( 1256494 ) on Thursday August 13, 2009 @08:59PM (#29060541)
    I would think that one side of the star would be blueshifted, the other side redshifted ever so slightly.
    I also wonder if the planet suffers more collisions than it would otherwise.
  • by Anonymous Coward on Thursday August 13, 2009 @09:09PM (#29060611)

    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.

  • by PPH ( 736903 ) on Thursday August 13, 2009 @09:17PM (#29060665)
    Why does everything different have to be labeled 'wrong'?
  • Axial Tilt? (Score:3, Insightful)

    by Ark42 ( 522144 ) <slashdot@@@morpheussoftware...net> on Thursday August 13, 2009 @09:18PM (#29060671) Homepage
    Instead of spinning the "wrong" way, couldn't the planet just have a 180 degree axial tilt, sort of like Uranus has a pretty steep 97 degree tilt. At 180 degrees, it would be right sight up by a different perspective, but spinning the opposite direction as the star.
  • by radtea ( 464814 ) on Thursday August 13, 2009 @09:38PM (#29060815)

    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.

  • by chromas ( 1085949 ) on Thursday August 13, 2009 @09:50PM (#29060921)
    It already hasn't
  • by ChromaticDragon ( 1034458 ) on Thursday August 13, 2009 @10:28PM (#29061171)

    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.

  • by Anonymous Coward on Thursday August 13, 2009 @11:07PM (#29061427)

    Humans were simply not endowed by nature with sufficient imagination to anticipate more than a small fraction of all the crazy shit we've already found.

  • by Fluffeh ( 1273756 ) on Friday August 14, 2009 @12:01AM (#29061765)
    What if the sun was turned on it's axis 180 degrees (turning it upside down). It would appear that the planet is therefore orbiting in the wrong direction.

    Could this perhaps been the effect of another star passing nearby and changing the axis of the star rather than flipping the orbit of the planet?
  • by Gerzel ( 240421 ) * <(moc.liamg) (ta) (terrefyllorb)> on Friday August 14, 2009 @12:48AM (#29062077) Journal

    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.

  • by Deadstick ( 535032 ) on Friday August 14, 2009 @12:49AM (#29062097)
    I remember when the first proof of an extra-solar planet was found, and people were amazed.

    Well, maybe you were amazed. The existence of extra-solar planets has never been in serious doubt; we went a long time without finding any for the simple reason that they are extremely hard to detect. There were many supposed observations that fizzled out in experimental error, and that resulted in a lot of skepticism being attached to further finds. Now that we have the proper measurement techniques, the discoveries are coming at a rate of a dozen or more per year.

    Look at it this way. Suppose you and I are standing on two mountaintops a few miles apart on a dark moonless night. I have a five-cell flashlight and one of those war-surplus searchlights they use to advertise new furniture stores. If I point the flashlight at you and turn it on, you'll see it easily.

    Now suppose I point the searchlight at you and turn it on. Then I turn the flashlight on again -- or maybe I don't. Can you tell whether it's on or not?

    That is approximately the problem involved in finding an extrasolar planet.


  • by AlecC ( 512609 ) <aleccawley@gmail.com> on Friday August 14, 2009 @07:17AM (#29063645)

    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.

  • by megrims ( 839585 ) on Friday August 14, 2009 @07:48AM (#29063795)

    You haven't had too many good discussions with Theologians, have you?

    Theology and science are sibling disciplines, addressing different issues. You find lots of curiosity, reason and doubt in both.

    Seven days, 6k years, etc. aren't theology. I agree entirely with your conclusion there. These kind of small, restrictive ideas come from the same kind of (selective) mindlessness that you can often find in militant atheism.

    I agree with your response to the GP, for the record.

  • by dkleinsc ( 563838 ) on Friday August 14, 2009 @08:43AM (#29064193) Homepage

    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.

    Of course religion doesn't give you a wet ball of mud. It gives you a wet flat plane of mud, with water above it (read Genesis).

  • by flaming error ( 1041742 ) on Friday August 14, 2009 @12:50PM (#29067433) Journal

    Wow, what a free-your-mind moment I had reading that.

    A similar scenario could be that the sun somehow turned upside down. Maybe the sun spins in two dimensions: around the expected axis perpendicular to the orbital plane, and also an axis parallel to the orbital plane.

  • by Anonymous Coward on Friday August 14, 2009 @01:29PM (#29067989)

    Your posts demonstrates no understanding of the reality of human behavior's impact on science's workings and scientists thinking.

    Being trained to do something doesn't mean you can change your nature. Real-world science, and its organizational power structures, exist in no vacuum, and is subject to the trappings of dogma and groupthink due to human nature.

The best book on programming for the layman is "Alice in Wonderland"; but that's because it's the best book on anything for the layman.