1st April 2011 Seeing Impacts in Planet Rings

Over the years, lines have been observed in the rings of Jupiter.  These lines can be traced back to when a comet is known to have hit Jupiter in 1993.

Sources

1. SETI - How to Catch a Comet
2.  Greg Laden - Ripples in Planetary Rings Are Traces of Decades-Old Cometary Collisions
3.  NASA - Forensic Sleuthing Ties Ring Ripples to Impacts