On the left we see a rather poor photo of the moon. We always see
the same side of the moon. So, it would seem that the moon does not rotate
(spin on its axis), right? A surprising number of people are very insistent
that the moon does not rotate. Return to my Astronomy/Space pages
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© Copyright 1999, Jim Loy
On the left we see a rather poor photo of the moon. We always see
the same side of the moon. So, it would seem that the moon does not rotate
(spin on its axis), right? A surprising number of people are very insistent
that the moon does not rotate.
A person standing in one spot on the moon would see the
earth in the same part of the sky (directly overhead, for the person in the
diagram on the right), unmoving. But, he/she would see the sun appear to move
around the sky in about 29 earth days. The person would correctly deduce that
the moon has a solar day of about 29 earth days. This person would also see
that the stars appear to move around the sky in about 27 earth days. Again, the
person would correctly deduce that the moon spins on its axis once in about 27
earth days.
The moon definitely rotates. It just doesn't look like it, from where we stand.
The moon rotates at a constant rate. But, it's distance from earth, and speed in its orbit, varies quite a bit. This means that we can see a little ways around the edge of the moon. So, over a period of time, we can see slightly more than 50% of the moon, from earth.
Addendum: In the movie, Crocodile Dundee II, Paul Hogan travels back to Australia. In one scene, they show the moon. And it looks just like the moon looks in America. It should be upside down (South on top).