Below is the result of some playing around with nodes I never used before.
It looks like a planet from above with nice clouds around it. But in the distance you can see a horizon.
It pretty simple really... A 'cloud fractal shader', plugged into a displacement shader (and into the compute terrain), as well as in the colour input of a slightly luminous surfacelayer.
Adding translucency between any of the surface nodes results in either nothing, or a loss of blue surface. Adding a second surface layer with 50% coverage and 0 fractal breakup might fix that...
