I stumbled Greg Martin’s fantastic work and just had to try a couple of his tutorials. If you get a chance visit his site its well worth the trip.
This planet while not hand painted like his example uses many of the same tricks to achieve the final look. In this case I built a fairly simplistic shader for the surface on a lit sphere. I have no doubt a more naturalistic result could be achieved using a combination of techniques and I want to play with the idea some more.
P.S. Greg if you catch this I’d love to get a sphere from you.