E-Book Overview
Nine years has passed since the 1992 second edition of the encyclopedia was published. This completely revised third edition, which is a university and professional level compendium of chemistry, molecular biology, mathematics, and engineering, is refreshed with numerous articles about current research in these fields. For example, the new edition has an increased emphasis on information processing and biotechnology, reflecting the rapid growth of these areas. The continuing Editor-in-Chief, Robert Meyers, and the Board prepared a new topical outline of physical science and technology to define complete coverage. Section editors are either Nobel Laureates or editors of key journals in their fields. Additional Board members representing the global scientific community were also recruited.
E-Book Content
P1: ZCK Final Qu: 00, 00, 00, 00 Encyclopedia of Physical Science and Technology EN003E-124 June 13, 2001 22:11 Cometary Physics W.-H. Ip Institutes of Astronomy and Space Science, National Central University, Taiwan I. II. III. IV. V. VI. VII. VIII. IX. X. Introduction Orbital Dynamics General Morphology Cometary Spectra Cometary Nuclei Dust Atmosphere Plasma Origin Prospects GLOSSARY a Semimajor axis of an orbit. AU Astronomical unit = 1.496 × 1013 cm, which is the semimajor axis of the earth’s orbit around the sun. Blackbody An idealized perfectly absorbing body that absorbs radiation of all wavelengths incident on it. Bow shock A discontinuity defining the interface of the transition of a supersonic flow to a subsonic flow as it encounters an obstacle. Carbonaceous chondrites A special class of meteorites containing up of a few percent carbon. Contact surface A surface separating two flows of different chemical and/or flow properties. Comet showers The infrequent injection of a large number o