Asteroid and Comet Impact Hazards Information about the study and probability of asteroid-earth impacts. Included are articles, photographs, animations. From NASA.
Deep Impact NASA scientists plan to crash a spaceship into a comet to study the effect of the impact in 2005. Includes background information, news, mission timeline, general information about comet, and details of the flight system.
Doomsday Asteroid Describes comets such as Hale-Bopp and others, while also providing teacher activities and photographs.