Sharp edge ring mystery reported in New Scientist 10 July 2004, p10. Photos from the Cassini probe, currently exploring Saturn and its rings, have revealed "a host of ringlets with unexpected sharp edges – a mystery, as collisions (over billions of years) between the particles should smooth out the edges."

Editorial Comment: The solution to this "mystery" may be that Saturn and its rings are really only thousands, rather than billions of years old, and there hasn’t been time for the edges to smooth out. (Ref. Saturn, planets, ages)