Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravity between earth and moon

  1. Mar 3, 2005 #1
    If an astronaut is located close to the positional median between the Earth and its moon, will the astronaut float around as if it was not being effected by gravity for the same reason that a person in an elevator in free fall would float around being unable to use a measuring device to calculate gravitational pull?
    Last edited by a moderator: Mar 3, 2005
  2. jcsd
  3. Mar 3, 2005 #2
    I don't think so. What'll happen is the Earth, with it's greater gravity, will pull the astronaut toward Earth. Of course the Moon's gravity will affect the astronaut, but the Moon's gravity isn't strong enough for what you have in mind.

    Anyone else?
  4. Mar 3, 2005 #3


    User Avatar
    Science Advisor

    The "positional median"?? Do you mean halfway between (in which case the earth's gravity would be much greater) or the point at which the earth's gravitational force and the moons are equal?

    If you mean the latter AND assume the astronaut is motionless (momentarily) with respect to the earth and the moon, then there would be no net gravitational force on the astronaut. However, that won't last long since earth and moon are moving relative to one another!
  5. Mar 4, 2005 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    related info...LaGrange Points
    http://www.physics.montana.edu/faculty/cornish/lagrange.html [Broken]
    Last edited by a moderator: May 1, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook