How can I create a natural fading effect on planets in cycles? I've have experience with CAD but am a complete Blender (especially the Cycles engine) noob. Recently I've been doing a lot of self-learning, then I came across this image:



Could anyone please tell me how to achieve a natural fading effect on the planets? My nodes are a mess but the result still comes off as too "stiff" and "mechanical".

Hope that I've explained myself well enough and that you guys understand!
Use Volume absorption and volume scattering as volume on a mesh that completely surrounds your scene.





Play around with a  texture for the density and you'll be able to make clouds and all kinds of fun stuff.