It doesn't have to be ray-traced, or dynamically shadow-mapped, it can be approximated with just a projection of the cloud texture onto the surface texture as a subtractive layer, or something. That's probably how Celestia did it, right

It threw me off because he asked about ring shadows, not cloud shadows, but then changed direction and described cloud shadows and not ring shadows. So I just answered the question that he asked most clearly.

Oh! Wow... does that mean that you intend to do it?

Or would it be too tempting to 'kill two birds with one stone', and implement landscape shadowing - and possibly drive up the computational load too much?

Translated names of all named stars (in Russian), made via built-in wiki database:

You could find a remote planet a few megaparsecs away and imagine your own civilization there; you could pick stars out from that planet's pov and name them as if you were an inhabitant looking up at the stars.

It would be really fun if we could draw lines between stars to make our own constellations, too, or define them in scripts.

So you can see a square in the sky while you sit in a mountain range.