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The double bulge!

  1. Mar 2, 2009 #1
    Text books and teacher's often cite different arguements for why there is a tidal bulge on the oposite side of the earth to the sun. What is the correct explanation? Is there any research/calculations to support this?
  2. jcsd
  3. Mar 3, 2009 #2
    The only tidal bulges I'm familiar with are the tidal bulges caused by the moon's gravity while orbiting earth. There is one bulge towards the moon and one on the opposite side of earth. The earth spins faster than the moon's orbital period, so these bulges are dragged along by the earth surface, leading the moon. This slows the spin of the earth, and will continue to do so until it matches the moon's orbital period. The sun will then become the primary body that influences earthly tides. This will take an extremely long time, though.
  4. Mar 3, 2009 #3


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    P.Tryon, there's a discussion of this around here someplace, if you want to do a forums search. Essentially, the inverse square law of gravity is responsible. The moon pulls the ocean that is nearest to it the most, and then the Earth itself a little less, and the opposite ocean least of all.
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