Implications of Comet Research

Abstract

In this chapter we seek to summarize the progress and implications of comet research. We do not wish to leave the impression that comet data are sufficiently complete to draw unique conclusions, but the perspective we paint may be useful for assessing the current state. The attempted synthesis emphasizes not only new directions in thinking, but serves also as a guide for the future. However, the leap in knowledge gained by the spacecraft explorations of Comets Giacobini-Zinner and Halley and complemented by the Earth-bound observations of these comets is restrictive in the sense that the data, analyses, and interpretations pertain to only two comets and most of them to only one. The results can at best provide suggestions about the properties of comets in general, but even that may be a dangerous extrapolation. Ground-based observations of several comets show very different behaviors from that of P/Halley. Comets Morehouse and Humason are two extreme examples. Nevertheless, the P/Halley results hold the key to an improved understanding of comets if the limitations of the generalizations are kept in mind.