In Conjunction

Realistic it may not be, but I like this presentation of overly large overly close planets and moons - something so grand it is almost frightening somehow. The only thing I would criticise is the foreground which seems to lack the vast scale of the rest of the image, perhaps this could be ammended by a different material or choice of terrain?

atmosphere I see the atmospheric work now. It is subtle just as it should be. There is something so splendid and beautiful about the piece. Your color choices for the nebulas are great. Placing the viewer on a lunar surface is a cool and comforting choice. I wonder if the piece would gain any power if the viewer were floating hopelssly in the vacuum of space instead of safely on a moon. I think the moon provides a "safety" that may take away from the potential of the nebulas.

Yes, its not a realistic picture, but it looked better this way. It's more 'fi' than 'sci'. But the big planet does have an atmosphere, clouds and all. I only have Bryce5 and am not sure what you mean by faking a HDRI? Thanks anyway.

I wonder how this would look like if this backdrop was made to a light probe and the scene lit by it. I've tried that once with the Great Orion Nebula, but have not published it. You might have to boost up the power of zeta and epsilon Orionis and fake an HDRI. There are some hints how you can do in the tutorial section of Bryce 6.1.

You are well on your way to an amazing scene. Like you said, this piece is not in the least bit bad! The planets are too close to one another, The laws of gravity would cause them to clump together. You might consider atmospherics for the planets. Very nice work!