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The galaxy and the solar system
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 constraints, e~ch of which contains an overview and review paper. Thirteen contributed papers, mainly on geochemistry, magnetism, and thermal state, are included in these sections. There are then four long sections, containing 15 papers, on the various theories of lunar origin including capture or fission, coaccretion, large impacts and collisions, and close approaches 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 considered 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.
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 astronomical progress being made by overcoming cosmogonic prejudice, the suggestion that biological evolution 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 geologists 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 particularly enjoyed "Stars within 25 parsecs of the Sun" by Gliese, Jahreiss, and Upgren, "Observational Constraints 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 neighborhood.
650 0019-1035/87 $3.00 Copyright© 1987by AcademicPress. Inc. All rightsof reproductionin any formreserved.
BOOK REVIEWS The rest of the book consists of expositions of the various proposed mechanisms for producing the alleged periodicities by their proponents as well as some discussion of the veracity of the periodicities themselves. For an overall review of the geological evidence for periodic activity, the article by Shoemaker and Wolfe on "Mass Extinctions, Crater Ages, Comet Showers" is recommended. However, with a few exceptions, the remaining articles do not present an accepted scientific view. Indeed, 1 do not feel that there has been a consensus on whether or not any of the hypotheses explains the periodicities or if the periodicities exist at all. In fact, Tremaine and I-Ieisler have performed Monte Carlo tests to reassess the confidence of the Raup-Sepkoski periodicity and have found that the significance is much lower than claimed. In view of this result, it is then possible that multiple cratering events leading to mass extinctions could be due to comet showers caused by stochastic encounters with passing stars or giant molecular clouds with the comet cloud. However, further calculations have shown that these encounters are not sufficiently frequent. Finally, it is worth noting that there are claims that strong showers are ruled out by the cratering record in the inner solar system and that the paleontological record does not necessarily imply global mass extinctions. To summarize, given the paucity of data and the questions regarding their interpretation, my guess is that most of the hypotheses will remain unproven and be eventually forgotten. Rather, I think that the legacy of the purported periodic extinctions has been renewed contact between the planetary scientists and galactic astronomers and a resurgence of interest in cometary dynamics. Contrary to the publisher's intent to produce a reference text, the bulk of this volume is proceedings (and rather tardy ones at that) from a particularly contentious conference and should be read as such. MARTIN D. WEINBERG
Center for Radiophysics and Space Research Cornell University Ithaca, New York 14853
Satellites. J. A. Burns and M. S. Matthews (Eds.). University of Arizona Press, Tucson, 1986. 1021 pp., $55.00.1 This is the 12th book in the University of Arizona Space Science Series, a burgeoning library destined to stand as the consummate literary legacy of our era's revolution in Solar System exploration. Each book in Associate Editor J. Veverka oversaw the handling of this review.
651
this series has been better than the previous one and sets standards that challenge the next. Satellites, which meets this challenge admirably, inevitably will be measured as the sequel to the 1977 volume Planetary Satellites, completed before the Viking landings and edited by Burns as the third book in the series. Satellites' effective date is August 1985, but notes added in proof summarize initial highlights from the Voyager Uranus encounter. Side by side, these two books document an important dimension of the phenomenal advances in planetary science fueled by the successes of American spacecraft launched during 1969-1978. The first chapter in the book, an introduction by Burns, tabulates data on discovery circumstances, orbits, and physical properties. It also introduces a scheme for classifying satellites as regular, irregular, or as collisional shards, and outlines the rationale for the book's two-part organization. The first part explains our current understanding of general physical principles and discusses processes common to most satellites or satellite systems. The second part is half as long as the first and is devoted to chapters on particular satellites. Satellites has a color plate section, projection maps of major satellites, and sketch maps of small satellites with identified features, as well as a comprehensive bibliography, a glossary, and an index. The index has an outline format, but unfortunately the reader must struggle to get oriented within the outline's hierarchy because primary headings are inconspicuous throughout and are not printed at the tops of pages. A hasty sampling of the index's accuracy revealed too many errors. For example, the "Ganymede resurfacing" citations overlook a major section on that topic in Chapter 15, while the "radar observations" entry sends the reader to a discussion of Io spectrophotometry. These minor structural mistakes should be rectified in the next printing. Similarly, it is desirable to eliminate discrepancies between the values for physical properties tabulated in Chapter 1 and those in subsequent chapters. The introduction is followed by a chapter by Stevenson, Harris, and Lunine on origins. They argue that a diversity of circumstances can lead to satellites and that caution is called for in drawing generalizations from patterns noticed in satellite systems. Simultaneously assessing patterns along with their variations is held to be more productive than seeking a unified picture of satellite origin. Therefore, this chapter considers patterns and diversity by discussing specific issues and their ramifications, aiming toward an assessment of the relative contributions of different processes in the origin of individual satellites. Following a brief survey of ideas about Solar System origin and planet formation, the authors discuss implications of planetesimal dynamics, the planetesimal size spectrum, and the timing of nebula dispersal for satellite formation in gas-free and gas-rich scenarios. Finally, they offer hypotheses about formation of individual
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 constraints, e~ch of which contains an overview and review paper. Thirteen contributed papers, mainly on geochemistry, magnetism, and thermal state, are included in these sections. There are then four long sections, containing 15 papers, on the various theories of lunar origin including capture or fission, coaccretion, large impacts and collisions, and close approaches 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 considered 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.
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 astronomical progress being made by overcoming cosmogonic prejudice, the suggestion that biological evolution 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 geologists 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 particularly enjoyed "Stars within 25 parsecs of the Sun" by Gliese, Jahreiss, and Upgren, "Observational Constraints 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 neighborhood.
650 0019-1035/87 $3.00 Copyright© 1987by AcademicPress. Inc. All rightsof reproductionin any formreserved.
BOOK REVIEWS The rest of the book consists of expositions of the various proposed mechanisms for producing the alleged periodicities by their proponents as well as some discussion of the veracity of the periodicities themselves. For an overall review of the geological evidence for periodic activity, the article by Shoemaker and Wolfe on "Mass Extinctions, Crater Ages, Comet Showers" is recommended. However, with a few exceptions, the remaining articles do not present an accepted scientific view. Indeed, 1 do not feel that there has been a consensus on whether or not any of the hypotheses explains the periodicities or if the periodicities exist at all. In fact, Tremaine and I-Ieisler have performed Monte Carlo tests to reassess the confidence of the Raup-Sepkoski periodicity and have found that the significance is much lower than claimed. In view of this result, it is then possible that multiple cratering events leading to mass extinctions could be due to comet showers caused by stochastic encounters with passing stars or giant molecular clouds with the comet cloud. However, further calculations have shown that these encounters are not sufficiently frequent. Finally, it is worth noting that there are claims that strong showers are ruled out by the cratering record in the inner solar system and that the paleontological record does not necessarily imply global mass extinctions. To summarize, given the paucity of data and the questions regarding their interpretation, my guess is that most of the hypotheses will remain unproven and be eventually forgotten. Rather, I think that the legacy of the purported periodic extinctions has been renewed contact between the planetary scientists and galactic astronomers and a resurgence of interest in cometary dynamics. Contrary to the publisher's intent to produce a reference text, the bulk of this volume is proceedings (and rather tardy ones at that) from a particularly contentious conference and should be read as such. MARTIN D. WEINBERG
Center for Radiophysics and Space Research Cornell University Ithaca, New York 14853
Satellites. J. A. Burns and M. S. Matthews (Eds.). University of Arizona Press, Tucson, 1986. 1021 pp., $55.00.1 This is the 12th book in the University of Arizona Space Science Series, a burgeoning library destined to stand as the consummate literary legacy of our era's revolution in Solar System exploration. Each book in Associate Editor J. Veverka oversaw the handling of this review.
651
this series has been better than the previous one and sets standards that challenge the next. Satellites, which meets this challenge admirably, inevitably will be measured as the sequel to the 1977 volume Planetary Satellites, completed before the Viking landings and edited by Burns as the third book in the series. Satellites' effective date is August 1985, but notes added in proof summarize initial highlights from the Voyager Uranus encounter. Side by side, these two books document an important dimension of the phenomenal advances in planetary science fueled by the successes of American spacecraft launched during 1969-1978. The first chapter in the book, an introduction by Burns, tabulates data on discovery circumstances, orbits, and physical properties. It also introduces a scheme for classifying satellites as regular, irregular, or as collisional shards, and outlines the rationale for the book's two-part organization. The first part explains our current understanding of general physical principles and discusses processes common to most satellites or satellite systems. The second part is half as long as the first and is devoted to chapters on particular satellites. Satellites has a color plate section, projection maps of major satellites, and sketch maps of small satellites with identified features, as well as a comprehensive bibliography, a glossary, and an index. The index has an outline format, but unfortunately the reader must struggle to get oriented within the outline's hierarchy because primary headings are inconspicuous throughout and are not printed at the tops of pages. A hasty sampling of the index's accuracy revealed too many errors. For example, the "Ganymede resurfacing" citations overlook a major section on that topic in Chapter 15, while the "radar observations" entry sends the reader to a discussion of Io spectrophotometry. These minor structural mistakes should be rectified in the next printing. Similarly, it is desirable to eliminate discrepancies between the values for physical properties tabulated in Chapter 1 and those in subsequent chapters. The introduction is followed by a chapter by Stevenson, Harris, and Lunine on origins. They argue that a diversity of circumstances can lead to satellites and that caution is called for in drawing generalizations from patterns noticed in satellite systems. Simultaneously assessing patterns along with their variations is held to be more productive than seeking a unified picture of satellite origin. Therefore, this chapter considers patterns and diversity by discussing specific issues and their ramifications, aiming toward an assessment of the relative contributions of different processes in the origin of individual satellites. Following a brief survey of ideas about Solar System origin and planet formation, the authors discuss implications of planetesimal dynamics, the planetesimal size spectrum, and the timing of nebula dispersal for satellite formation in gas-free and gas-rich scenarios. Finally, they offer hypotheses about formation of individual