The Comet Shoemaker-Levy 9 (named after it's discoverers Eugene and Carolyn Shoemaker and David Levy) collided with Jupiter in the first ever observed collision between two objects in our solar system. Observatories around the world, as well as the Hubble Space Telescope, have obtained spectacular imagery of impact zones and plumes (or fireballs). The impacts occurred on the side of Jupiter facing away from Earth and then rotated into view a few hours later. The Galileo spacecraft had a more direct view of the impacts as they occurred. The last impact (fragment W) occurred July 22, 1994 at 2:59:45 EDT.
Here are some images of the impact events with the captions provided at the time of their release:
European Southern Observatory Images
Images from other Observatories
Keck Movie of R-Fragment Impact (1.2 meg)
Exploring The Planets
CEPS Home Page
Last revision:October 20, 1998