What does the moon have in common with a compass needle?

Answer 1

Both can be used for telling where North, south, east and west lie.

Takes some practice with the moon though, and doesn't work at midnight on a full moon. :)

The curved side ( as in the natural part circle curve) always points to where the sun is, even when you can't see the sun, so knowing the time, as in before or after midnight, you can work out whether the curve is pointing East or West, then North and South by deduction.

Answer 2

The moon's gravity controls the tide. During the night it will be high tide. During the day it will be low tide.