I like the rough brush strokes! :)
Maybe you could try to avoid real black, give it a hint of color I think would give it more depth?

Thanks!
What do you mean?

I mean this black can be more interesting if it has some color in it a hint of light to suggest depth .. a blue/cyaan undertone would add some ambience.. Instead of painting it flat black, I'd try a dark blue and add darker green but I would avoid black.

Ok, I just made one with your suggestion, is that what you meant?

yes ! :) But lets be aware that space photography has that specific impenetrable strong deep black, so it might just work for this theme and yes this means I'm contradicting myself :D