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Lagrange points

  1. Mar 4, 2006 #1
    Hey a friend asked me for help on his physics homework, and I found this place and was wondering if you guys could help me out.

  2. jcsd
  3. Mar 4, 2006 #2


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    Google for Hill Sphere. Wikipedia has a good site. The Hill Sphere will give you the distance to the L1 and L2 points.

    L3 is in Earth's orbit, on the opposite side of the Sun, so it is exactly 2 AU away.

    L4 and L5 are 60 degrees ahead of and behind the Earth. The Earth, Sun, and L4 form an equilateral triangle, as do the Earth, Sun, and L5. So the Earth L5 distance is 1 AU. The Earth L4 distance is 1 AU. The Sun is also 1 AU from both these points.

    Actually, one mass doesn't need to be smaller than the other two, at least for the L4 & L5. And I suspect the other 3 L points as well. The two orbiting masses combined need to be at most ~1/25 the mass of the large object. It's possible for an Earth-mass planet to be in Earth's L4 or L5 point.

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