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Just a little question on orbits.

  1. Dec 11, 2006 #1
    Hi all,

    Why is it that the planets in our solar system seem to orbit relatively in the same plane? ( or is it a misconception ?)

    Why can't our planets orbit like this :

    http://www.steve.gb.com/images/science/planetary.png" [Broken]

    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Dec 11, 2006 #2


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    Because of the initial conditions under which the solar system was formed. The planets accreted from a rotating disk of dust and gas. This is also why they all orbit in the same direction.
  4. Dec 11, 2006 #3
    So it is not possible to have planets orbiting in such a fashion as shown in the picture i linked?
  5. Dec 11, 2006 #4


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    I cannot access the picture you've linked to, so I can't see it.


    It IS theoretically possible, it just doesn't happen very much, and is unstable, so doesn't last very long, so even more rare to see.

    Thing is, the system still starts off as a disc. It can't start off with planets going every which way - for several reasons. One: if an object were way off in a polar orbit it, could never accrete mass - it would never grow. Two: these orbits are very unstable. The overwhelming mass from the accretion disc will either draw it in to the plane or will cause it to plunge into the star.

    What can happen though is, a planet can get knocked out of its orbit by another object - either a close pass or collision, and finds itself in an eccentric orbit. Pluto is 17 degrees off the orbital plane.

    But you won't get a system with full-sized planets orbiting in multiple planes in the same system, no.
  6. Dec 11, 2006 #5
    hmm....... thx for the help
  7. Dec 11, 2006 #6


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    I'd still like to see that pic if you get it working.
  8. Dec 12, 2006 #7
    i don't have a problem accessing the picture actually. Anyway it is just a structure of an atom. (the conventional one, with electrons orbiting in dif. planes. Trying the illustrate my point with the structure of an atom.)
  9. Dec 12, 2006 #8


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    The error message is 403 (Forbidden), so since you posted it, it's not too surprising you can access it. Try submitting it as an attachment.
  10. Dec 12, 2006 #9
    Doesn't venus orbit the opposite direction.... or is that the rotation of it's axis?
  11. Dec 12, 2006 #10


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    Just to add to DaveC426913's explanation...
    The original cloud of material was not a disk, but as it collapsed, it spun faster and material was spread out in a plane perpendicular to the axis of rotation (conservation of angular momentum)...thus forming the protoplanetary disk which aggregated (gravitationally) into the planets all orbiting the central sun in the same direction (since the whole disk was rotating that way to begin with).

    It's rotation (on its axis) is retrograde (opposite direction of its orbit). Not sure why...perhaps a large-scale collosion early in its formational history?

    Note that electrons don't actually orbit that way (see quantum mechanics).
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