system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we only see one side of the moon?

Why do we only see the same side of the moon from the earth? Is the reason for this random?


EDIT: thanks for the quick replies!
gpt
The Moon is tidally locked, so its orbital period is equal to its rotational period.

Because the Moon has some size, the force of gravity felt by the near side of the Moon is slightly greater than that felt by the far side. This causes the Moon to bulge (with one bulge towards the Earth and another exactly opposite, away from the Earth). If the Moon could deform instantaneously the bulge would always point exactly towards/away the Earth but, since the Moon cannot deform so quickly, if the Moon is not spinning at the same rate it is orbiting then the bulge will get rotated away from that position. This causes torques on the Moon and acts to change the Moon's rotational period to its orbital period.