I got rid of the rings, they bothered me too much. Right now, I'm working on a moon, but it's not turning out too well. This is what I have so far:
I just made a copy of the planet, scaled it down, and made adjustments. It's just a placeholder for now until I can make a better looking moon. I'm also still working on the nebulae, as it's proving to be a pain.
Also, in case anyone missed the reason why the planet is green, and the moon is blue: Both are composed of Tiberium, the planet being composed of green Tiberium, and the moon being composed of blue Tiberium. Tiberium is the main resource in the game
Command & Conquer: Tiberian Sun. Tiberium is a crystal that absorbs nutrients from any object it comes in contanct with, and the more nutrients it is able to absorb, the more valuable it is. Blue Tiberium is the most valuable of the two, plus it's the most dangerous as it's highly volatile to any explosions.