I am literally amazed at the fact that our Moon rotates in synchrony with its
revolution around Earth! Such that we observe essentially the same "face" at all times. What
is the probability of this phenomenon? Is it common for any celestial body in rotation/revolution
to have this "almost exact" synchrony? As we postulate the probability of additional "life
systems" in the universe, this relationship between Earth and her Moon seems to be
inappropriately taken for granted!
It is not a coincidence or an accident. When something as large as the moon revolves while in
orbit, a lot of energy is lost to internal friction, and the loss comes out of the moon's energy
of revolution. The reason energy is lost to internal friction is pretty simple: the part of the
moon nearest us would not stay in the same orbit as the rest of it if it were not attached. The
result is a tidal force that stretches and squashes the moon as it revolves. Because the moon
is not perfectly elastic, the stretching and squashing causes energy of revolution to be
converted into heat.
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Update: June 2012