Why are the moon’s period of rotation and revolution identical?

You know, I’ve wondered this myself, but never seen an explanation until now, courtesy of Scientific American:

The moon keeps the same face pointing towards the Earth because its rate of spin is tidally locked so that it is synchronized with its rate of revolution (the time needed to complete one orbit). In other words, the moon rotates exactly once every time it circles the Earth.  The same forces that create tides in the Earth’s oceans (from the gravitational pull of the moon and, to a lesser extent, the sun) also act on the solid body of the moon.


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