A brilliant shade of orange/pink dominates the piece, and it's hard to complain about it. Nonetheless, there are a few inconsistencies and issues that put it just below perfect.
The jagged nature of the moon is in much contrast to the otherwise suave piece, and the light on the planet does not complement the bright sun in the center.
It doesn't look bad at all, however, considering that the sun is about halfway up, the surface of the planet should be much brighter, particularly closer to the sun. Either this, or the Sun should be a much more covered by the planet, in order to compensate for the little light.
Besides that though, this piece is spot on! If you could fix that brightness issue (and the moon one), I could not honestly say there is anything wrong with it that logically needs to be addressed, because at that point, only preference determines rating, eh?