I think your concept for this challenge was wonderful. The star trails look a little blurry....even for showing motion trails. I'm going to guess that your tripod was either setup on an unstable surface or that there may have been some wind when this photo was taken. I'm more likely to guess the latter looking at some of the motion in the tree tops. When I have taken night sky pic I try to keep my tripod legs close to the ground and widen them further then normal for a lower center of gravity. If you where setup on a surface like a wooden deck just the motion of walking to and from the camera may have caused some shake. If knowing I had a little light pollution in the pic I may have tried taking the pic later or at a different location. I got a sense from your comment on this pic that you thought it might have some negative effect.
The tree line looks like it shows some side effects of editing and doesn’t feel like it blends well with the sky. Replacing the tree line with a solid more stable foreground subject may have helped. By adding a little clarity and some scale to your pic. I find the larger the object to compare the sky to just makes the sky that much bigger and would have added to your “The Universe” title.
I had a good look through you profile and see some definite improvements in subject, composition, and clarity from your early challenge entries. I also really like your B&W work in your prints folder. Keep up the good work. If I’m right I think that your pics that generally do better in challenges are the ones you are more comfortable shooting. More like your profile pics. May I suggest not trying so hard for challenges and let your natural eye take the pic. (Don’t take that the wrong way-trying new things is a great way to improve) Just don’t second guess yourself. If your have any questions or comments please feel free to PM me.