Transparent gaseous/foggy sphere

I'm developing for the iPhone and want to make a gaseous sphere with a collider (to detect touches). It needs to be somewhat transparent; I'll be using a LineRenderer inside it for lightning and that should be visible. Are shaders necessary for this? Does one already exist? Maybe it can be done with a partially transparent texture?

If I could get a solid sphere out of this shader that would be perfect: http://unifycommunity.com/wiki/index.php?title=Planet

Edit: I found [another example which I think is closer... I just want the outer sphere! ]

Most of the pages I can find on Google relate to fog of war, or scene-wide fog, or glass-like transparency, so I want to be clear those aren't what I'm looking for.