Lunar Laser Ranging Experiment - Results

Results

Some of the findings of this long-term experiment are:

  • The Moon is spiraling away from Earth at a rate of 3.8 cm per year. This rate has been described as anomalously high.
  • The Moon probably has a liquid core of about 20% of the Moon's radius.
  • The universal force of gravity is very stable. The experiments have put an upper limit on the change in Newton's gravitational constant G of less than 1 part in 1011 since 1969.
  • The likelihood of any "Nordtvedt effect" (a composition-dependent differential acceleration of the Moon and Earth towards the Sun) has been ruled out to high precision, strongly supporting the validity of the Strong Equivalence Principle.
  • Einstein's theory of gravity (the general theory of relativity) predicts the Moon's orbit to within the accuracy of the laser ranging measurements.

The presence of reflectors on the Moon has been used to rebut claims that the Apollo landings were faked. For example, the APOLLO Collaboration photon pulse return graph, shown here, has a pattern consistent with a retroreflector array near a known landing site.

Read more about this topic:  Lunar Laser Ranging Experiment

Famous quotes containing the word results:

    Being a parent is unlike any previous job—the results of any one action are not clearly visible for a long time, if at all.
    —Anonymous Mother. As quoted in Between Generations by Ellen Galinsky, ch. 2 (1981)

    I have no doubt that it was a principle they fought for, as much as our ancestors, and not to avoid a three-penny tax on their tea; and the results of this battle will be as important and memorable to those whom it concerns as those of the battle of Bunker Hill, at least.
    Henry David Thoreau (1817–1862)

    Nothing is as difficult as to achieve results in this world if one is filled full of great tolerance and the milk of human kindness. The person who achieves must generally be a one-ideaed individual, concentrated entirely on that one idea, and ruthless in his aspect toward other men and other ideas.
    Corinne Roosevelt Robinson (1861–1933)