Actually I think I did the same for my eggregor maps (and with a different ball). It's just a base method and it's no doubt better when you adapt it to your map. I really like your cracked moon btwBy Korash
The only thing I modified on the tut was to duplicate the ball and set it to multiply and full opacity. It looked a bit blurred when zoomed in on the last picture, though. Interesting tutorial for the rings, I've a very different method!