That is really awesome. I disagree with Kens post about blending the planet in, it looks fine to me. The colours on the planet and the lighting fits with the backdrop so you cant really blend it any better than that,I think youv nailed it pretty damn well. One thing you could maybe do is you could add a shadow on big planet caused by the small planet floating above it. Very very cool stuff. I think your a bit like me. Photo manipulations are my favourite pieces of work to make and ive made a few like this in my time but its been ages now since ive done one. I think youv inspired me to go out there and make one 
glad to see your back in LC man i hope you start making some entries cuz your a really good graphic maker -)
glad to see your back in LC man i hope you start making some entries cuz your a really good graphic maker -)