Thank you!! Yes, it's one sun, but I confess, I used another trick. With the sun and the environment light the parts in the shadow were very dark. Probably physically correct, but I decided to take the artistic freedom to place an invisible large sphere which is slightly selfilluminated with a blueish color to make the dark parts a little brighter. The earth itself didn't reflect enough light.
As I said, I rendered the parts separately, so I only used this trick for the ships.
