In a Rare View, Rings on Uranus Show Their Changes

NY Times ^ | August 28, 2007 | HENRY FOUNTAIN

[Steely Tom]

I think I remember reading somewhere that the structure of the rings has something to do with the gravitational pull of the other moons of the planet; these are called “shepherd moons.” The gentle, cyclic tidal forces they exert over long periods of time (hundreds of millions of years) act to “filter out” all but a very select population of ring particle energy states. As a result, a number of "forbidden orbits" are defined over time; the more moons, the more complex is the structure. The gaps in the rings of Saturn (and, presumably, Uranus) are the result of these tidal forces.

Imagery acquired by the Cassini spacecraft revealed that the rings of Saturn are unbelievably complex, made up of countless thin ring sections that look almost like the grooves of an LP phonograph record.

[beezdotcom]

Do I read this article as possibly implying that the rings could actually be suffering from a decaying orbit, and may not last too many more centuries?

[Izzy Dunne]

Thanks for that second article.:

From that vantage, the normally-bright outer rings grow fainter because their centimeter- to meter-sized rocks obscure one another, while the dim inner rings get brighter as their material merges into a thin band along the line of sight.

I still don't understand from this why the inner band rocks wouldn't "obscure one another" or why the outer band wouldn't "merge into a thin band along the line of sight."