Earth takes a year to orbit the sun, while Hale-Bopp takes several thousand earthly years to complete a single orbit. We do not know how many times this comet has come near the sun, but it is thought not to be a first time visitor. It probably passed near the sun on its last visit when the pyramids were built. For most of its orbit, Hale-Bopp travels far from the sun. It is only when the comet is near the sun that sunlight heats its crust and Hale-Bopp sprouts its comet tail.
Scientists believe that about a meter of a comet's surface evaporates on each passage near the sun.
This means that most comets are good for only about 100 to 1000 appearances in earth's sky. Written by Neil Stone. Photographs by Matt Grudzielanek. Email us with a question or a suggestion. All rights reserved.