Hello,
I used the legacy atmosphere shader for the effect. It has a slight trick to it which is you need to attach it in the render tree. basically...
get sphere
(render tree) --> nodes-->environment-->more go into the soft3d folder and get the legacy_atmosphere.
attach the node directly to the surface input of the sphere without an illlumination node. that should do it. to get the space effect change the view altitude and find a cool map of the world - i think i found that one at nasa.gov. also try scaling the sphere way up.
hope that helps...
mark