
In 1992, shortly after launch, the Jupiter-bound Galileo probe took photographs of the moon as it flew past.
I've been asked on a number of occasions recently why the moon always
seems to show us the same face -- the lunar nearside. I'm not sure why
there's the sudden interest, but it's a very good and valid question,
especially as tonight (March 27) is a full moon.
Look at the moon at any time and -- aside from the constantly
changing phases that are caused by changing relative positions of the
Earth, the moon and sun -- it does indeed show us the same face,
constantly.
Perhaps surprisingly, it's 'non-rotation' (from our
perspective) comes from its interaction with the Earth.
Both the Earth and moon are big lumps of rock with the moon in
orbit around the Earth or, more precisely, both objects in orbit around
their common center of gravity -- known as the 'barycenter.' It just
happens that this point lies very close to the center of our planet, so
to all intents the moon orbits us.
For the rest of the story: http://news.discovery.com/space/astronomy/why-doesnt-moon-spin-tides-locked-130327.htm#mkcpgn=rssnws1
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