What is tidal locking between Moon and Earth? Does moon not rotate on its axis?
In: Physics
The gravity of earth doesn’t just keep our feet on the ground, it also keeps the moon in its orbit. However, because the far side of the moon is a little further away than the near side, the near side experiences a tiny little bit more gravity from earth. It’s not much, but it causes the moon to bulge a tiny little bit. And because earth pulls slightly stronger at the bulge than the rest of the moon, over millions of years this caused the moon to rotate at the exact speed that keeps the near side pointing towards earth. This is the same effect that causes ebb and flow here on earth.
The moon used to spin relative to the Earth. However, the Earth exerts significant tidal forces on the moon. That is, since the Earth is very big and pretty close by, it pulls on the near side of the moon much harder than the far side.
As the moon tried to continue to spin, it was constantly slowed down by the Earth, effectively, tugging on one end of it. Eventually, all of the rotational motion of the moon relative to the Earth was lost and the same side of the moon always faces the Earth.
The moon rotates at the same speed it rotates the earth so we only see one side of the moon
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