i think it is pretty good. i think it would be better if you moved the planet a little further to the top left. i don't know if you're capable of it, but if you could make the star behind the planet a little darker that would be good. the star distracts from the planet, and i think the planet should be the focus point. show a little more space in the bottom right. the cloud does a good job drawing your eye to the planet.
nice job!