Comets are always very impressive phenomena. Their appearances at regular, but mostly irregular, times excite people who see them. Astronomers have the obvious advantage of being able to see more of comets, and to study them. Their enthusiasm is reflected in the 50 papers in this book, written by more than 90 experts. The reviews in this book clearly describe a landmark in the history of cometary studies. Knowledge gathered up to and including Comet Halley are presented in two volumes. The first volume is about general aspects of observing and studying comets, where they originate and how their evolution develops. The second volume goes into the details of what a comet is: the nucleus, the coma, cometary dust, plasmas and magnetic fields. The book ends with a reflection by Fred Whipple about Comets in the Post-Halley Era. The book discusses all aspects of comets and is therefore suitable for use in graduate level courses. All astronomers and geophysicists interested in comets will find very useful and well-presented information in this book.

Definitive reference on comets seen from 1960 to 1982, for amateur and professional astronomers, and historians of science.

The conference was held in Snowbird, Utah, October 1988, as a sequel to the Conference on Large Body Impacts held in 1981, also in Snowbird. This volume contains 58 peer-reviewed papers, arranged into sections that cover the major themes of the conference: catastrophic impacts, volcanism, and mass mortality; geological signatures of impacts; environmental effects of impacts; patterns of mass mortality; volcanism and its effects; case histories of mass mortalities; and events and extinctions at the K/T boundary. Annotation copyrighted by Book News, Inc., Portland, OR

Proceedings of the Alexander von Humboldt Colloquium on Celestial Mechanics held in Ramsau, Austria, March 13-19, 1988