ICARUS 72, 650--655 (1987) BOOK REVIEWS Origin of the Moon. Edited by W. K. Hartmann, R. J. Phillips, and G. J. Taylor. Lunar and Planetary Institute, 1986. 781 pp., $25.00. In this reviewer's opinion this is the most important contribution to lunar science that has yet appeared. It transcends lunar science and is essential reading for all students of the early solar history, the planets, and the Earth. Formally, it is a presentation of the results of a Conference on the Origin of the Moon, held in Kona, Hawaii, in October 1984. However, because of the care of the editors, reviewers, and authors it is not your standard conference proceedings volume. It is a complete reference book on the Moon as a planetary object. It is also a valuable source book for science historians and philosophers. The book starts with major historical reviews of lunar observation and exploration and early ideas of lunar origin. It is then divided into sections covering the dynamical, geochemical, and geophysical con- straints, e~ch of which contains an overview and review paper. Thirteen contributed papers, mainly on geochemistry, magnetism, and thermal state, are in- cluded in these sections. There are then four long sections, containing 15 papers, on the various theories of lunar origin including capture or fission, coac- cretion, large impacts and collisions, and close ap- proaches in the early solar system. The well-prepared Glossary, Subject Index, and Author Index make this a valuable source and reference work. The Kona meeting will be remembered as a symbol of a remarkable convergence of ideas about lunar origin. Two major ideas now dominate the field. Giant impacts in early Solar System history are now con- sidered not only possible but inevitable. The giant impact model explains the silicate-rich, volatile-poor nature of the Moon and its Earth-like oxygen isotope ratios. The Moon is now viewed as a minor by-product of a collision between planetary sized objects, perhaps a Mars-sized object impacting the Earth. About 10 papers are devoted to this theme. The trauma that the Earth must have suffered, when fully appreciated by Earth scientists, may result in a paradigm shift for Earth theories as well. A second idea, perhaps related to the first, is the coaccretional compositional filter provided by the evolution of a debris disk around the Earth. These ideas reflect a paradigm expansion in planet formation theory, from early small-body accretion to problems of later planet-forming processes and the roles of large bodies and circumplanetary disk systems. 0019-1035/87 $3.00 Copyright© 1987by Academic Press.Inc. All rightsof reproduction in any formreserved. Many of the early and current workers in lunar science have contributed to this book but it represents a fresh look at an ancient body. The reviews and syntheses make this book worth the price, and the poem by Pieters and the preface and painting by Hartmann add to the delight. DON L. ANDERSON Seismological Laboratory California Institute of Technology Pasadena, California 91125 The Galaxy and the Solar System. Edited by R. Smoluchowski, J. N. Bahcall, and M. S. Matthews. University of Arizona Press. Tucson, 1987. 483 pp., $30. Over the last 5 years, there have been many reports of periodicities in the geological record evidenced by mass extinctions and cratering. The reported periods of 20-38 myr are much longer than can be accounted for by any terrestrial mechanism but are common in an astronomical context. Given the long history of astro- nomical progress being made by overcoming cosmo- gonic prejudice, the suggestion that biological evolu- tion might depend on the galactic environment was more than slightly captivating for a number of us. Whatever the motivation, the controversy attracted galactic astronomers, planetary scientists, and geolo- gists who gathered for a 3-day conference in Tucson, Arizona, in January 1985. The collection of review articles that make up the volume The Galaxy and the Solar System is the result. The book is divided into six parts plus a glossary and complete bibliography. The inclusion of a glossary is an interesting idea considering the interdisciplinary audience, although I noticed that it contained a few inaccuracies. About half of the book (Sects. I-II1 and part of Sect. IV) is devoted to a detailed description of the physical environment in the solar neighborhood by some of the recognized experts in the held. I particu- larly enjoyed "Stars within 25 parsecs of the Sun" by Gliese, Jahreiss, and Upgren, "Observational Con- straints on the Interaction of Giant Molecular Clouds with the Solar System" by Scoville and Sanders, and "Interstellar Clouds near the Sun" by Frisch and York. Although much of the material can be found elsewhere, these first four parts are a worthwhile introduction for anyone interested in the solar neigh- borhood. 650