The moon has a permanent dark side.
Don’t Believe That!
The “dark side of the moon” should more accurately be called the “far side of the moon.” Even though it looks frozen in place, the moon actually rotates, and it completes one rotation for every revolution it makes around the Earth. Therefore, one side is always facing away from us. But this side is not “dark” – it receives just as much sunlight as the side we can view.
When there is a full moon, the area facing Earth is fully illuminated. As the moon passes through its various phases and that side becomes less illuminated, the far side is actually receiving more light. Therefore, only during a full moon is the other side completely dark.
The phrase “dark side of the moon” originally meant “unknown,” because it couldn’t (yet) be viewed, not dark as in the absence of light (for example, Africa was once referred to as the Dark Continent when it was mostly unexplored).
Bonus Fact: Because the moon follows a non-circular (elliptical) orbit around Earth, greater than 50% of its surface is visible at one time or another (59%, to be exact).