When I was a kid I had a physics teacher who tried to get us excited with this theory. His argument was that the moon is

1. Perfectly spherical

2. Locked with one side that always faces Earth

3. Placed at such a distance that it appears exactly the same size as our sun in the sky.

I doubt that he truly believed it, I think he just wanted to make the subject more interesting for kids, but I've always been fascinated by astronomy, and the idea that things aren't what they seem is always cool.