solar system with constraints

Hi everyone
I want to animate the orbit of the earth and the orbit of the moon. I used constraints so I only rotate one empty in the center along z and the rest rotates automatically. The problem is when I rotate the empty in the center over 180° the moon jumps on the other side of the earth.
Does anyone know how to fix this problem?

here is the .blend file:
moon.blend (1.55 MB)

Thanks for your help!