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Thread: Planetary orbits

  1. #1

    Planetary orbits

    Hi I was wondering, in every model and graphic of our solar system the planets all seem to orbit the sun on the same plane... Is this the case with every solar system, or is it possible that we could find a system where the planets not only orbit the sun along the y axis but also along the z axis? (making the orbits look something like a gyroscope?)

    Best regards
    Craig Garcia
    Calgary, Alberta

  2. #2
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    It should be possible if some planets were captured objects; if the planets in question are sufficiently small in mass and far enough away from eachother.

  3. #3
    I feel it would be extremely unlikely, the planets evolve from disc of proto-matter which are integral to the production of the planets.

    However should a foreign object from beyond the system be captured by the system it may be possible.

    The planetary object Pluto is not on the planetary plane so can be speculated to be from extra solar area (possibly the Oort cloud)


  4. #4
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    All planets orbit in the same plane because of the way star systems form (accretion disks). Orbits in other planes may occur, but only if a body has been knocked out of its original position or if a foreign body is captured by the star.

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    Heres's an exoplanet in a so-called oddball orbit;
    http://www.universetoday.com/2009/06...oddball-orbit/

    some planets are even stranger, and orbit the opposite way to the way its sun rotates
    http://www.universetoday.com/2009/08...the-wrong-way/

    so yes, exceptions can occur, and since we have only looked at less than 400 systems so far, the oddballs may be reasonably common.

  6. #6
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    Quote Originally Posted by eburacum45
    so yes, exceptions can occur, and since we have only looked at less than 400 systems so far, the oddballs may be reasonably common.
    But to clarify, you're not saying that the odd-ball orbits evolved 'naturally', as opposed to resulting from a disturbance, right?

  7. #7
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    Quote Originally Posted by DrWho View Post
    All planets orbit in the same plane because of the way star systems form (accretion disks). Orbits in other planes may occur, but only if a body has been knocked out of its original position or if a foreign body is captured by the star.
    Yes. It doesn't hurt to note that the planets all orbit in the same direction, too.
    We know time flies, we just can't see its wings.

  8. #8
    Also it's worth noting that at least one protoplanetary system, IRAS 16293-2422, is known to have counter-rotating disks (Remijan & Hollis 2006).

  9. #9
    Nature doesn't like orbits with inclinations of around 90 degrees. The Kozai Mechanism will quickly (in astronomical terms) destroy such orbits. It doesn't mean such objects can't exist. But they're going to be short-lived, so there certainly won't be many of them. I think we know of a few asteroids in our solar system that have nearly-polar orbits around the Sun.

    The Kozai Mechanism causes orbits with high inclinations to go through a periodic exchange between inclination and eccentricity. So over time, a highly inclined orbit becomes a highly eccentric orbit, where it crosses the orbits of other objects, or impacts its parent object.

    The outer moons of Jupiter orbit in lots of seemingly random directions. But there are none with an inclination of more than 60 degrees. Higher orbits would periodically gain enough eccentricity to pass within the orbits of the Galilean moons. If Earth's moon were magically given a polar orbit at its current distance, it would crash to Earth within a decade.

  10. #10
    The Kozai mechanism requires a third body, however, like in the case of the HD 80606 system (binary system).

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    Quote Originally Posted by DrWho View Post
    But to clarify, you're not saying that the odd-ball orbits evolved 'naturally', as opposed to resulting from a disturbance, right?
    I'm not entirely sure what you are asking, Doctor. If there was a disturbance in these systems, as seems likely, I'm 99% sure that it was a natural one.

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    Quote Originally Posted by Hungry4info View Post
    Also it's worth noting that at least one protoplanetary system, IRAS 16293-2422, is known to have counter-rotating disks (Remijan & Hollis 2006).
    Remarkable.
    Here's a short page about it with a graphic
    http://jumk.de/astronomie/exoplanets...293-2422.shtml

    This protoplanetary disk could result in retrograde and prograde planets in the same system.
    I wonder how long that would be stable...

  13. #13
    Quote Originally Posted by eburacum45 View Post
    I wonder how long that would be stable...
    Actually longer than it would if both orbits were prograde. The reason is that the planets spend less time near each other since their relative velocities are increased. Thus, the planet's don't have as much time to toy with the others orbits.

    Here's an interesting paper on the topic.

    On fitting planetary systems in counter-revolving configurations
    http://arxiv.org/abs/0908.1292

  14. #14
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    Interesting; thanks!
    So a counter-rotating system might be formed either by planet-planet scattering, or through the capture of free-floating planets, according to that paper? It doesn't mention the possibility of a counter-rotating protoplanetary disk, unless I missed it.

    But such a counter-rotating system would be most stable if the planets are co-planar, unless I'm reading it wrongly.

    This does open the possibility to occasional cataclysmic collisions, here and there in the universe. Such collisions would be very energetic events.

  15. #15
    Quote Originally Posted by max8166 View Post
    The planetary object Pluto is not on the planetary plane so can be speculated to be from extra solar area (possibly the Oort cloud)

    Here's a vertical-flip animation that might make it clearer (29.4 MB):
    http://s3.amazonaws.com/arklyffe/outerflip.mp4

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