IAU Colloquium 168
Cometary Nuclei in Space and Time
May 18-22, 1998
We have just witnessed two dramatically bright comets - Hyakutake and Hale-Bopp and the observation of these comets is leading to dramatic, new results particularly on the chemical composition of comets, but also on the physical properties of the nuclei and on evolutionary effects. New techniques have been applied (such as the first ever millimeter-wave maps with interferometers) and dramatically improved sensitivities have enhanced results with other techniques (radar detection of comet Hyakutake, dramatically improved sensitivities at infrared wavelengths and so on). Most cometary scientists have been so busy with observational programs that there has been little opportunity to integrate the results into a coherent picture of the cometary nucleus, despite several international meetings at which comets have been discussed. In particular, results from C/Hyakutake are just now beginning to appear in other than preliminary form while we are in the midst of studying C/Hale-Bopp. We also will have just witnessed the last readily observable apparition of comet Wirtanen prior to the launch of the Rosetta mission and the observations of this comet will be of special significance for the design of the rendezvous of Rosetta with that cometary nucleus. While a special session at the Kyoto General Assembly has been proposed and a meeting in the Canary Islands is planned for February of 1998, these meetings will be emphasizing the observational results on comet Hale-Bopp. Cometary results will also be presented at an array of much broader meetings but what is needed at this time is a meeting of cometary scientists to integrate the results of the last two spectacular comets with ongoing results for a variety of fainter comets and with efforts to model the chemistry and structure. We therefore are proposing a meeting which is devoted to the cometary nucleus.