Rendering a texture on the Atmosphere Sun.

Does anybody know of a way to render a texture 2D on the sun-disc generated by the Atmosphere actor, or even a way to map it to a skySphere?

I’m basically trying to do two sun discs, one for the sun, the other for the moon. Gears of War 3’s Anvil Gate levels managed to somehow texture the moon. Anybody know how this was done?