Great ideas. I have some things to say.
- Actual supernovas.
Well I just 3 hours ago posted about that, but here your idea is little different. Have a look: Second bunch of my ideas - #10 by kokokokos - darker background
I like realistic things, but this background is so lovely. I wrote more about it here in 4th point: Bunch of my ideas after longer play - Use for wormholes
@Nikito explained how wormholes wor but I really love the Our Solar System EE. - Planet storms effect
Great idea, but we have lightning already. Maybe only clouds and fog?