system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is it incredible that we only see the same side of our moon or is this common in the universe? Why doesn't it rotate and is there an explanation?
gpt
It's not really incredible.  It's a relatively common situation called "tidal locking".  A bunch of other moons in our solar system work the same way.

Basically the earth pulls on a bulge on the moon slightly stronger which changes it's rotation just slightly over a long time until it matches the orbit and becomes tidally locked.

Pluto and it's moon are actually tidally locked to each other like the moon is towards the earth!