Really easy to do. I used only two textures, color and normal. Rendered with BI.
it's freeeeeeee!
Used this as one of the main planets in an animation i made (the one surrounded by asteroids) Although I ended up taking the blue texture away from it, to suit my needs better. https://www.youtube.com/watch?v=r-sjktFMOE8
Your name is near the end of the credits, with the other scene/planet modelers. :) ~Noah Wardell
Sorry bro... I don't know anything about Unity. Look for the textures on the NASA website and follow a tutorial of how to do apply the textures on Unity. That's all your gonna get from me. EDIT: This is a very old .blend file. I suggest you to look for something a little bit more recent.
AWESOME! :) Thanks!