Comets have fascinated mankind since humans first noticed the distinctive tail streaking across the night sky. We mark the date that we saw a comet that comes around only once a century or even once in four centuries and we remember the sight for the rest of our lives. Astronomers find comets fascinating, too. Comets are remarkable pieces of our universe's past, and they tell us a great deal about how the universe was formed.

Photo courtesy of NASA
Comet Kohoutek appears in this image taken by members of the lunar and planetary laboratory photographic team from the University of Arizona at the Catalina Observatory on January 11, 1974.

Almost every year, we are visited by comets from the outer reaches our solar system. Most recently, comet LINEAR rounded the sun and broke apart. In this edition of How Stuff Works, we will examine the fascinating world of comets. We will find out what comets are, what they are made of, where they come from and how to observe them. You can learn where to look for comets and maybe even discover one yourself!