Landscape lighting


Hoping for a bit of help with a lighting problem on this image. So far I have a sun of to the left and a spotlight on the right hand side close to the rocks. What I am trying to do is have the right hand side of the planets in shadow, the dark side, and I can do this if I turn the spot right down but this then leaves the foreground very dark. So I’m wondering if there’s a way to have the spotlight only effect the rocks, sea and sky but not the planets.
Thanks for any help with this.

I’ve worked it out now, different layers and the light set to only effect that layer.