1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

If a comet kicks the moon out of its orbit and away from earth

  1. Sep 4, 2009 #1
    If a comet kicks the moon, or any celestial object for that matter, out of its orbit and away from the earth, would it alter earth's rotational axis?
  2. jcsd
  3. Sep 4, 2009 #2


    Staff: Mentor

    The earth's axis would become less stable without the moon, but I would think that the bigger problem would be debris from the collision. I mean, that would be an enormous collision. Even the largest comet discovered so far is less than 1/1000 that of the moon.
  4. Sep 5, 2009 #3


    User Avatar
    Gold Member

    As DaleSpam points out, comets aren't large enough.

    let's introduce a foreign body. Let's say a celestial body that was ejected from another solar system happens to fly right through our Solar system. Let's say that celestial body doesn't collide with the Moon, but just grazes it, resulting in a case of gravitational assist. (I'm guessing that a gravitational assist is the most efficient energy transfer. In a collision much of the energy would dissipate.)

    I don't think such a gravitational assist can be vigorous enough to release the Moon from the Earth-Moon system, but it could alter the Moon's orbit significantly.

    There would not be any immediate effect on the Earth's rotational axis. To change the direction of angular momentum of an object a torque must be exerted, and no such torque is present in this scenario

    For a long term effect: the precession of the Earth's axis is due to gravitational interaction with the Sun and the Moon. If the Moon is lifted to a much higher orbit then the gravitaional interaction with the Moon will be weaker, resulting in an overall slower precession than the current precession.

  5. Sep 5, 2009 #4
    I feel earth will start moving towards the sun. because the moon has the influence over the earth gravity. when you say there is no moon it sure alters the sun and earth attractive force also.
  6. Sep 5, 2009 #5


    User Avatar

    Staff: Mentor

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook