Detailed spherically-mapped planet with daylight diffuse,
night light illumination, bump (and alternate normal) maps, with separate cloud layer.
Adjust opacities on the maps to yield better daylight and night light mapping if
your view is dominated by one or the other. Replace bump with normal map and/or
place normal in displacement for better relief, depending on the light angle.
Animate terrain and clouds independently.
Maps supplied by NASA.