looks good, my main problem is teh sun, how it is placed mainly
then sun is made in the pic so it is smaller than the planet, which means it has to be father away, so somehow it is still shinning light on the planet? also the planet has no shadow at all, the shadow on the planet is what makes it looks professional
also, cmon, EARTH? make your own planet

also ill upload a good tut i have for making suns which you will enjoy.
the stars are ok, but tis a uniform spatter of them, there need to be more in 1 area than another, use the clone stamp tool with a solid brush, and set the tool to lighten, also make some spots have less stars.
the clouds look fine, gj on that
the moon though, seems to be a simple effect with holes in it, make a planet and desaturated it, and theres your moon, the moon also need shadows.
shading might seem like a bad thing, how it removes most of your planets from view, but it really makes it look better, and most of the times planets are shadded