Chuck Taylor wrote:
dave black wrote:
I've always been puzzled that even 'planet-sized' moons such as Titan
don't have any satellites going round them.

Is there a particular reason?

A moon orbiting a moon is going to have a chaotic orbit. It
will be tugged at by the planet and other moons, changing the
orbit constantly. The orbit would become more and more
eccentric until it either crashed or escaped.

And by virtue of similar facts, no moon shall ever possess a stable
ring system around it either.