Putting one layer over another

I’m just fooling around a bit. I’m creating a scene with 5 different layers. The stars, the clouds, the atmosphere, the moon, and a building. When I render them, they’re all kind of just mashed on top of everything but obviously, I want the moon to appear on top of the stars and the clouds on top of the moon etc. How can I do this? Attached is a picture of the current result and the current blender file.

Sky1.blend (5.8 MB)

looks quite helpful.

Unfortunately, now the environment is transparent. I need the environment to fill in the background.

My way round this is to have a layer for “sky” set to one sample with an output for sky. I’ll look up my exact node setup when I get home.

I did what the video told me to do and then got rid of the transparency and rendered the environment separate from the rest. It was kind of an odd move but it worked.