Lunar Orbital Distance Change
Name: Chuck P.
How much is the average distance between Earth and the
moon changing with time? Is the moon getting closer or more distant from
During the Apollo mission, Neil Armstrong placed a series of what are
essentially mirrors on the surface of the moon. Earth scientists could
then bounce a laser off these reflectors and by analyzing the time it
takes for the light to come back (accounting for such things as atmosphere
and so on) precise data could be made about the moon's distance, it's spin
rate, and how fast it is receding from the Earth. Currently it is receding
at about 1.5inches per year.
Btw, the fact that the moon is receding (instead of being pulled in by
Earth's gravity) is a strong suggestion that the moon was created during a
Greg (Roberto Gregorius)
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Update: June 2012