Chemistry of Comets

Abstract

From the earliest of times until the recent advent of exil tensive outdoor lighting, comets have drawn the attention of the public. A bright comet is undoubtedly second only to a total solar eclipse in presenting a spectacular and unusual variety in the otherwise very regular phenomena of the sky. Comets usually have been interpreted as portents of forthcoming catastrophes. In 69 AD, residents of Jerusalem observed a bright comet just before the destruction of their city by the Emperor Vespasian; a subsequent comet 10 years later heralded the death of Vespasian himself. As recently as the 1910 apparition of the famous Halley's comet, sheriffs deputies in Oklahoma stopped a group of people calling themselves Select Followers from sacrificing a virgin as a ritual for warding off potential disaster. Comets may, in fact, be true harbingers of disaster. On statistical grounds we expect that comets occasionally will collide with Earth. It has been suggested, ...