This is the standalone version of the earth shader seen in The Planets node group pack. Node group contains a robust slider set for customizing every detail for terrain, atmosphere, and oceans, including river/lake sliders. Nested node groups provide streamlined options for further customization.
No separate spheres or materials needed - just drop the node group onto the material slot of a sphere(or cube, if you want an earth box) and plug into the surface!
1.1 - Added cloud shadows, blurred atmosphere edges
1.2 - Added cloud shadows to small scale clouds, reworked cloud system, added horizon glare to diffuse layer