How Comets Work

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 Jan, 11, 1974. See more comet pictures.
Photo courtesy of NASA

­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. They're remarkable pieces of our universe's past, and they tell us a great deal about how the universe was formed.


Almost every year, we are visited by comets from the outer reaches our solar system, like ISON or LINEAR. 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.