I think one of the problems is the small moon looks like a big rock. Like the stone ball chasing Indiana Jones. I think one thing that bothers me is the moon don't pick up the very bright light being given off by the blue thing. Also you may want to play with the objects seperately. Even though the front ship may render like that, you may want to render it seperately and push the perspective lens effect on it more. you know how perspective makes the nacelles want to touch in the back.
blurring the background may help... but I would add the blue into the shadows (add a tiny bit of blue to the ambient lighting) And add a blue light hitting the ship and moon from the gas giant.
i think that would help.
