The castle is lit from its right, not the right of the picture. The light from the right is coming from reflection off the asteroid (toning that down some). Also, with no atmosphere, the left side of the castle (from the castle's perspective) is completely away from the sun. The sun is also well above the local horizon (check the orientation of the train's shadow compared to its location).
I've done some re-tiling and editing of the asteroid map and added some debris. I've also change the position of the sun to throw some shadows. Keep in mind that the location of the castle was chosen (by me) due to it's relative flatness, so the sun has to be really low to see shadows. It's back in the renderer, so, I should have a rough WIP in a few minutes.
ETA 2: Hit enter too quick. Those fireflys will work out over time.
ETA:
I've done some re-tiling and editing of the asteroid map and added some debris. I've also change the position of the sun to throw some shadows. Keep in mind that the location of the castle was chosen (by me) due to it's relative flatness, so the sun has to be really low to see shadows. It's back in the renderer, so, I should have a rough WIP in a few minutes.
ETA 2: Hit enter too quick. Those fireflys will work out over time.
ETA: