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Origin of Orbital Precession

  1. Nov 13, 2014 #1
    If we had a literal two body system (point masses M and m), with one orbiting the other according to Newton's Law of gravitation, would there be orbital precession? Or would they map out the same ellipse each time?
     
  2. jcsd
  3. Nov 13, 2014 #2

    A.T.

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    No
     
  4. Nov 13, 2014 #3
    Perfect A.T. Thank you! That is what I thought, but running a simulation I wrote, there appeared to be precession. I thought that it was an artifact, but wanted to be sure.
     
  5. Nov 13, 2014 #4
    numerical simulations can be unstable - you accumulate errors over time. You should check that the total energy of the system remains constant in your simulations.

    Note that any kind of perturbations which deviate from a 1/r potential will lead to precession.
     
  6. Nov 14, 2014 #5

    DrDu

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    There would be no orbital precession. The deeper reason is the hamiltonian of the system having a dynamical symmetry so that the direction of the axis of the ellipsis is a constant of motion, the Runge Lenz vector.
    http://en.wikipedia.org/wiki/Laplace–Runge–Lenz_vector
     
  7. Nov 14, 2014 #6
    I was somewhat surprised that the simulation would lead to precession, though. I would have expected the orbit to wobble, but it the type of error introduced in these simulations tend to always go the same way...
     
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