look all around the left planet. There are lines around it in the shape of a rectangle above and below/left of the planet. In the edges of you're planets I can see a few jagged parts. There are a bit too many stars and many off them are too low in opacity to look like stars. The whole thing seems a bit off in image quality also. I think you did a great job on some of the nebula clouds and what not. Keep up the good work.