Comets

Comet Hale-Bopp

Comets are made of ice and dust -- just dirty snowballs in space, with a nucleus only a few miles across.

Comets normally stay in the cold outer parts of the solar system, beyond Pluto. Sometimes a comet nucleus gets nudges by the gravity of another object, and it begins a really lopsided orbit that carries it in toward the sun.

When the comet's nucleus gets close to the Sun, the ice on its surface gets heated and begins spewing off gasses and dust into space, forming a long, beautiful tail. The tail always points away from the Sun, because the Sun sends out a "wind" of charged particles into space in all directions, blowing the tail with it. The tail can stretch millions of miles into space.

Near the Sun, comets travel at about 100,000 miles per hour.

Links

Activity Idea: visit www.solarviews.com/eng/edu/comets.htm to learn how to make a comet nucleus with dry ice, ammonia, dirt, corn starch, and a few other common household items.