These travelling masses of ice and dust galloping throughout the universe are believed to have shaped the course of life on this planet. As a result of comet-hunting, many deep-sky objects including nebulae and galaxies have been discovered with perhaps the most obvious collection being the 109 (or 110) DSO's attributed to Charles Messier. With over 1000 comets now having been catalogued and approximately 200 having been established as being periodic, historical records suggest comets to have been observed and documented as far back as 240 BC (Comet Halley by the Chinese).

Comets are appealing to amateurs for a variety of reasons: they lead to incredible photographs thanks to their glowing and colourful tails extending millions of kilometers as they approach the sun and the ice and various frozen gases in the nucleus begin to vaporize; they are the precursors of meteor showers as remnants left behind on prior visits are encountered by our planet while we orbit the sun; and they represent an active adventure and form the basis of a "culture" (comet hunters) based on the discovery of new comets during the early dawn hours on the eastern horizon or just after sunset on the western horizon.

Note: Comet 17P/Holmes illustrated below while passing through the constellation of Perseus was discovered in November 1892 by Edwin Holmes when he accidently turned his scope for one last peek at Andromeda before he was about to call it a night during that fateful evening. Much to his surprise, he noted an object measuring 5 arc-minutes in diameter and which immediately caught his attention. The comet proceeded to pose a challenge for the astronomers of the time in their attempts to derive its elements in relation to orbit and periodicity. It is now established that the comet is elliptical in nature with a period of 7.35 years. Perhaps its most characteristic feature is its ability to exhibit very dramatic outbursts in brightness which was the case during its discovery in 1892 as well as late 2007 when it underwent a dramatic change in magnitude (from 19+ to 2.6) representing a million-fold increase.

For ephemeris and orbital elements on this periodic comet from Harvard's Minor Planet Center, click here. For a simulation of the comet including various orbital elements and physical parameters, click here.