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Love numbers

  1. Jan 19, 2004 #1


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    The Moon's surface, pulled by the Sun and Earth, may bulge out and dip in as much as 10 centimeters (almost four inches) over 27 days. Love numbers show how elastic the Moon is, giving clues to the material under the surface. The newly calculated Love numbers support the idea, first suggested by Apollo program scientists, that a partially melted zone lies above the core.
    an ofshoot of the LUNAR LASER RANGING experiment.
    i have never given a thought as to the moons geology
    so i am suprised at this finding.
  2. jcsd
  3. Jan 19, 2004 #2


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    the tidal-bulge-massage that satellites get is good to know about
    and most dramatically illustrated by photographs of Jupiter's
    nearest large moon Io

    Do you know about this already? I dont want to repeat already known stuff. Io would be frozen solid if it were not for love numbers or elasticity that make it susceptible to massage by Jupiter and the other large Jovian moons.

    the massage keeps deforming Io and making it bulge slightly by changing amounts and this HEATS IT UP
    and is the reason that instead of being frozen solid it has
    molten sulfur and volcanos belching gas and sending loads of crud up into the sky---the eruptions have been actually photographed

    -----footnote not for people who know it already------

    so an isolated thing under its own gravity wants to be spherical

    but it if is in the neighborhood of another massive thing it wants to be ovoid or oblong with two bulges towards and away from the massive object (like the earth's ocean bulges towards and away fromt he moon and hightide comes twice a day)

    ok so what if there are two massive objects. how can it bulge towards both of them. so there is a kind of massage going on as the directions and angles between the two attractors change. with a specially strong effect when they get aligned and reinforce each other

    this tidal business heats all the main Jovian moons to some extent so that Europa for example has liquid water under the ice (and Sir Arthur Clark imagined a sea-monster living in the Europa under-ice ocean just to make the point especially clear, as I recall----the impulse to depict seamonsters in unexplored oceans has been with us for centuries and Sir Arthur gave in to a common map-makers urge)

    Someday people will take submarines into the Europa sub-ice ocean and it will be the massage by Jupiter and the other Jovian moons that is keeping that ocean liquid instead of frozen solid.

    Never heard of love numbers but guess they are just measures of elasticity in various dimensions
    Last edited: Jan 19, 2004
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