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Name: John
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 7/24/2003
Question:
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!

Replies:
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.

Tim Mooney


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