Does the Moon rotate?
And if the Moon rotates, why do we alway see the same side – it never seems to change.
Well, the Moon does rotate. In fact, the Moon takes 27.3 days to turn once on its axis. But the Moon also takes 27.3 days to complete one orbit around the Earth. Because the Moon’s rotation time is exactly the same amount of time it takes to complete an orbit, it always presents the same face to the Earth, and one face away (the Dark Side).
Because it only presents one face to the Earth, astronomers say that the Moon is tidally locked to the Earth. Although the Moon looks like a perfectly smooth ball, it has slight differences in the shape of its gravity field. A long time ago, the Moon did rotate. But each time it turned, the Earth’s gravity tugged at it, slowing down its rotation until it only presented one face to the Earth. At that point, the Moon was tidally locked, and from our perspective, it doesn’t seem to rotate.
Many other moons in the Solar System are also tidally locked to their planet. In fact, most of Jupiter’s large moons are tidally locked.
via Universe Today
“What is the Dark Side of the Moon?” Well, of course it’s the award-winning album by Pink Floyd. 😉
And it’s always playing on the Dark Side of the Moon!
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