Hey vambam, thanks so much for the feedback! <3
When I did this illustration, I was thinking like this: "let's make the redish thing the main light source. let's say all the objects are closer to that and that's why they get light from it and not from the other light sources, even tho they look closer. The other light sources look closer because they are bigger, but, in fact, they are far away (they are just really big). That;s why there is light on top right and top left of the planets. I hope this makes sense.
About the bounce light. I did the "rim light" on the bottom of things, because I was thinking of some other light source that's not in the illustration; something far away, not shown in the piece. And I used that idea to make the shape stand out easier. It was more for the style. If I wouldn't have done that, it would have looked kinda boring. I hope this makes sense too.
Much love! <3