very odd lighting in my scene

I have setup a single directional light for a sun, a planet and two moons. The lighting works perfectly for the planet, but it's acting very strange for the moons. Here is a screenshot : alt text

The lighting for the Earth is perfect, but the moon seems to have the complete opposite (shadow on completely wrong side).

I have the 2nd moon (not shown in the image) set to orbit and rotate, but the moon in the shot is not moving (thought maybe that was causing the odd light effects for some reason).

Is light being reflected off the planet or something?

I'd bet on a bad texture for normal maps.

Also, in your screen from comment it looks like the moon is not being lighted at all. Did you put the right shader on it?