Nice starscape effect! I would have liked the yellow light source to have been pointed at a different angle: either pointing up at the trees from directly below to follow the flow of movement of the stars, or lit from behind so it looks like one of the stars fell and lit up the earth.
Since this is Advanced Editing, I would have preferred if you had used two layers to have two white balances--one with the sky as is and one to correct for the yellow light on the bottom. That sickly yellow light always makes nature look dead to me. Dunno; maybe that's what you were going for, but if it was, you could have used a different title that would have made that more clear. I assume you weren't though : ) Some sharpening would have helped too, I think.
Only my opinion, but I would've made a little more of a leading line to the trees it looks like there are some very intrestring bolders to have featured a little more and then maybe a little less on the trees. That being said You DID actually PAINT with the light and your star trails are just the iceing on the cake here! Very Nice!