Evening in space is an interesting concept.

The only thing that bothers me is the broken horizon lights.

I think you should do something differently with the beam, say, dithering, so that it doesn't look so jagged with the color changes. I do like your style, though, especially the lighting effect you pulled off on the astronaut.

Something that looks jagged, too, is the little bump on the background lines. It's turning out pretty good!

32 colors

64 colors is too much. That gradient looks impressive, but it's kinda cheating.