I hadn't seen his work before, it is cool (and also very Frazetta-like!)
You asked me in your message (separate from this thread) to explain about what I meant in my comment about the planets. First of all, as they're lit by a sun somewhere (far away), both planets would have the exact same lighting on them: Shadow on left, terminator (line between dark and light) in the same place, etcetera. (That same sun would also be illuminating the main character too.) Both planets are feeling a bit dull and muddly (especially the back planet which looks like it has oceans and atmosphere but is just looking kind of grey.) Both would be bright and lit by he sun. Think of how bright the full moon gets - it doesn't have any inherent glow, it's just reflecting light from the sun. And think about how much light our full moon casts. Your green moon is 10 times larger, it should positively glow! But of course the 2nd planet would as well. Sort of like this:
If you wanted to really push it, you might even see some of the atmostphere on the second world:
You also might consider using bounced light from those planets as another light source, because light would bounce off of them and, as noted with the full moon example above, be pretty bright! (and personally, I think it's always great to have an excuse to make a strong rim light on a character which always helps them pop.)
Hope this helps! 
