Make the inner shadow of the main planet a more "goldish" color and those two planets really shouldn't be the same size imo..
The line in the middle should be up the front btw but it's really not bad! good job
Honestly that will end up looking really unnatural.
I would actually either pentool that roughness out of it then feather it by 1-2 px.
Another way is to actually smudge them out, do some corrective erasing, then add a sharpen layer to crisp it out.
Could even use the clone tool. There are a bunch of ways to fix stuff like that really.
Blurring works sometimes, but there is just way too much of an area there to fix up.
I'm not sure if you did the stars yourself or its just a background but they look very plain, also the edge of the biggest planet is pixely.
I would take one or both of the planets on the top left and right out and focus on one