Other
Killer Asteroid Project: Asteroids and Comets
Explains the differences between asteroids and comets. Presents a chart showing a size comparison between some known asteroids and comets.
National Earth Science Teachers Association
Windows to the Universe: Comets
This site takes readers on a comet adventure. Learn everything you ever wanted to know about comets--including how and where they come from, specific comets throughout history and different comet exploration missions. Interactives are...