First of all: nice to see that you're still active in the field of space art. We need more participating artists like you!

Now to your image:

+ Pros
light
colors
concept / placement of the objects
starfield

- Cons
nebula
asteroids
missing depth
oversharpened

Some thoughts
I really like the way you colored the picture. Nice variation and good blending. Also the light looks like light and has a shining effect. And on the edges of the nebula, you can see some really nice depth. There, it looks like the light is coming out of a hole, which adds a lot of scale. There's also a nice line for the eye to follow, given by the direction of the nebula and the asteroids. Keep it up! Ah and I really like your starfield. Looks a bit random but works well here.

Unfortunately the execution of the nebula is not as good. The used textures are too clear and distracting. I would recommend to smudge them a bit or to soften them. The next point are the asteroids, which acutally look very flat. There are also too much repetitions. Both, the nebula's textures and the asteroids really destroy the depth. I think it would have been very helpful to add more asteroids and especially some larger ones in the foreground to easily generate depth. The last point I'm not really happy with is the sharpness. Maybe it's only my personal taste but I don't like such sharp edges on planets, asteroids and nebulatextures.

I hope my direct input helps you and you don't feel bothered by it. I really would like to see more of your space art and some development there Maybe try to do some new concepts like you told me in my journal: space meet's abstract art or something like that.