In recent years, it has become clear that the red-giant phase is one of the most dramatic periods in a star's life, when all of its parts become involved in ways that have both direct and indirect observational consequences. This is most particularly true of low- and intermediate mass stars during the second ascent of the giant branch. Such stars bring to their surfaces products of nucleosynthesis currently taking place in their deep interiors, they pulsate as Mira variables, develop extended outward-flowing atmospheres that may exhibit maser properties, and shed great quantities of matter, sometimes highly processed, into the inter stellar medium. The manner in which processed matter is brought to the surface is far from being completely explained, and the precise mechanism or mechanisms whereby matter is ejected from the stellar surface (whether by deposition of Alfven waves, radiation pressure on grains, or as a consequence of so me large scale envelope instability) has yet to be elucidated to every one's satisfaction. The purpose of the second workshop in Astrophysics, organized by the "Advanced School of Astronomy," was to bring together experts on all the physical processes occurring in red giants in an effort to emphasize the interrelatedness of these individual processes, and to encourage a dia logue among experts that might serve to initiate a synthesis, or at least sharpen our understanding of the most important problems to address in the future."

The large-scale structure of the Universe and systems Clusters, and Groups of galaxies are topics like Superclusters, They fully justify the meeting on "Clusters of great interest. and Groups of Galaxies." The topics covered included the spatial distribution and the clustering of galaxies; the properties of Superclusters, Clusters and Groups of galaxies; radio and X-ray observations; the problem of unseen matter; theories concerning hierarchical clustering, pancakes, cluster and galaxy formation and evolution. The meeting was held at the International Center for Theoretical Physics in Trieste (Italy) from September 13 to September 16, 1983. It was attended by about 150 participants from 22 nations who presented 67 invited lectures (il) and contributed papers (cp), and 45 poster papers (pp). The Scientific Organizing Committee consisted of F. Bertola, P. Biermann, A. Cavaliere, N. Dallaporta, D. Gerba1, M. Hack, J . V . Peach, D. Sciama (Chairman), G. Setti, M. Tarenghi. We are particularly indebted to D. Sciama, A. Cavaliere and F. Bertola for their work of coordination. We were acting as the three members of the Local Organizing Committee. Moreover, we are pleased to thank the Chairmen of the Sessions (M. Hack, N. Da11aporta, G. Burbidge, B. Mills, M. Rees, P. Biermann, L.Z. Fang, L. Gouguenheim) for their valuable help.

Our conference - opening today - has two aims in view: first, to commemorate some milestones in the development of the studies of close binary systems whose anniversaries fall in these years, as well as to take stock of our present knowledge accumulated through out preceding decades, in order to consider where do we go from here. This summer, 310 years will have elapsed since the first ec lipsing binary - Algol - was discovered in Bologna by Geminiano Montanari (1633-1687) to be a variable star; and 198 years have gone by since John Goodricke of York (1764-1786) established the fact that Algol's light changes were periodic. Moreover, it is al most exactly (to a month) now 100 years since Edward Charles Pickering (1846-1919) of Harvard Observatory in the United States took the first steps towards the development of systematic methods of analysis of the light changes of Algol and related systems - a topic which will constitute the major part of the programme of our present conference. The three dates recalled above illustrate that the discoverers of such celestial objects and observers of their light changes have been systematically ahead of the theoreticians endea vouring to understand the significance of the observed data by de cades and centuries in the past - a fact which, incidentally, con tinues to hold good (albeit with a diminishing lead-time) up to the present.

The Second International Conference on Atomic and Nuclear Clusters '93 was orga nized in a joint effort by the 'Demokritos' National Center for Scientific Research, G. S. Anagnostatos (representing the atomic physics) and the Hahn-Meitner-Institut, W. von Oertzen (representing the nuclear physics). The subject of clusters - small aggregates of particles - is a topic of primary interest in both atomic and nuclear physics, and also in other fields like in the case of quark-structure of baryons and in cosmology. The interplay between atomic and nuclear physics is a particularly fascinating one because many concepts are common to both fields (quantal effects, shells, geometric structures, collective modes, fission etc. ) This conference was the second after the first one organized by Professor M. Brenner in Abo (Finland) in 1991. The general atmosphere of a joint forum for atomic and nuclear physicists was very fruitful and thus the decision to have a sequence of such meetings has been taken. A third one is planned in St. Petersburg (Russia) with Professor K. Gridnev (St. Petersburg) and Mme. Professor C. Bnkhignac (Orsay) as Chairpersons. The conference site, Fin\. on Santorini island (Greece), was a wonderful choice for a conference. It is small, which helps to keep people concentrated in a smaller community, it has a perfect convention center, the P. Nomikos Conference Center, and a very beautiful landscape formed by a large volcanic crater.

The annual meeting of the Astronomische Gesellschaft in Cologne, June 1988, featured extensive reviews of the chemical processes relevant to astrophysics. The twelve contributions to this book, written by experts from the US, UK, France, Belgium, Switzerland and Germany, deal in depth with the chemistry of comets and meteorites, of stars and their shells, of the interstellar medium and galaxies. A comprehensive review of nucleosynthesis and two reports on observations round off an up-to-date presentation of cosmic chemistry.

The Alfonsine Tables of Toledo is for historians working in the fields of astronomy, science, the Middle Ages, Spanish and other Romance languages. It is also of interest to scholars interested in the history of Castile, in Castilian-French relations in the Middle Ages and in the history of patronage. It explores the Castilian canons of the Alfonsine Tables and offers a study of their context, language, astronomical content, and diffusion.

The Alfonsine Tables of Toledo is unique in that it: includes an edition of a crucial text in history of science; provides an explanation of astronomy as it was practiced in the Middle Ages; presents abundant material on early scientific language in Castilian; presents new material on the diffusion of Alfonsine astronomy in Europe; describes the role of royal patronage of science in a medieval context.

The underlying astrophysical mechanisms of the objects known as asymptotic giant branch stars - the structures that occur during the dramatic period prior to a star's death - is the main theme of this text. Over the past three decades, asymptotic giant branch stars have become a topic of their own, and the contributions to this volume all focus on these entities themselves, rather than their connections to other fields of astronomy. Among the many topics covered are new methods of high- quality infrared observation and the more detailed and realistic simulations made possible by increasingly fast computers. This collection should be useful to graduate students who work in the field, teachers who want to address the subject in their courses, and to astronomers from various backgrounds who are interested in the astrophysics of AGB stars.

In the course of editing this volume I discovered that I am temper amentally unsuited to the task, an impediment that in no small way accounts for the fact that its publication is later than I would have hoped or anticipated. I am, at heart, a pedant, particularly with respect to the use and abuse of the English language. Many of my scientific colleagues are a good deal less punctilious; they take the reasonable view that if the message is clear, the manner of expression is unimportant. Experience has taught me that what is clear to the author is often quite unclear to the reader unless the author takes the trouble to express himself with precision. I have also found that most scientists are unwilling to devote to the presentation of their results the care that they lavish on obtaining them. But I found myself slipping beyong this often justifiable complaint into a state of inexcusable self-righteousness. It began innocently enough. Conscious of the need for speed, I read the first two or three texts with murmurs of approval, and scribbled 'no changes needed' on the title page of the copy. Then I began to notice one or two grammatical mistakes, plural verbs with singular nouns, mixtures of tenses, and so on, which had to be corrected; not serious, I told myself, a matter only of changing a word here, retyping a line there. Quickly I sank deeper."

The subject of interstellar magnetic fields is of increasing interest to both observational and theoretical astronomers. Consequently, it was opportune for both groups to convene and discuss the current state of research and future prospects. For this purpose, the Max-Planck-Gesellschaft zur Forderung der Wissenschaften e.V. generously provided its unique conference centre SchloB Ringberg. The scientific organising committee consisted of Profs. W. Hillebrandt (Max-Planck-Institut fUr Physik und Astrophysik, Munchen) and R. Wielebinski (Max-Planck-Institut fUr Radioastronomie, Bonn). The lo- cal organising committee comprised Gabriele Breuer (conference secretary) and the Editors. ' These proceedings summarise the lectures and short contributions pre- sented at the workshop. Although extremely productive, the discussions could not, unfortunately, be included. We thank the staff of the castle, and especially its administrator, Mr. Hormann, for providing the excellent environment conducive to smooth run- ning of the conference. We acknowledge the Max-Planck-Gesellschaft for its support in financing the workshop. Thanks are also due to all participants for their enthusiasm and (generally!) prompt submission of manuscripts. Last but not least, we thank Gabriele Breuer for her invaluable help before, dur- ing and after the days at SchloB Ringberg. She skillfully typed and retyped many of the manuscripts for these proceedings and unstintingly performed last minute corrections. We hope that some of the ideas presented here will stimulate further discussion and research in this area. R.Beck Bonn, December 1986 R. Grave v 1 Arp, H. 15 Kundt, W. 29 Furst, E. 2 Grave, R. 16 Aly, J.J.

This monograph is devoted to the basic aspects of the physics of highly ex cited (Rydberg) states of atom's. After almost twenty years, this remains a hot topic of modern atomic physics. Such studies are important for many areas of physics and its applications including spectroscopy, astrophysics and radio astronomy, physics of electronic and atomic collisions, kinetics and di agnostics of gases, and low- and high-temperature plasmas. Physical phenom ena in radiative, collisional, and spectral-line broadening processes involving Rydberg atoms and ions are primarily determined by the peculiar properties and exotic features of highly excited states. The growth of interest and research activity in the physics of Rydberg the last two decades was stimulated by an extremely rapid de atoms over velopment of high-resolution laser spectroscopy, methods of selective excita tion and detection of highly excited states, atomic-beam techniques as well as radio astronomy. This has facilitated significant progress in the differ ent directions of the physics of highly excited atoms being of fundamental and practical importance. In particular, evident advances were achieved in studies of the structure and spectra of highly excited atoms, their behavior in static electric and magnetic fields, interactions with electromagnetic ra diation, spectral-line broadening and the shift of Rydberg series, collisions with electrons, ions, atoms, and molecules, etc. The principle objective of the present book is to reflect the most important physical approaches and efficient theoretical techniques in the modem physics of highly excited atoms and ions."

This volume is presented as a companion study to my translation of Galileo's MS 27, Galileo's Logical Treatises, which contains Galileo's appropriated questions on Aristotle's Posterior Analytics - a work only recently transcribed from the Latin autograph. Its purpose is to acquaint an English-reading audience with the teaching in those treatises. This is basically a sixteenth-century logic of discovery and of proof about which little is known in the present day, yet one that arguably guided the most significant research program of the seventeenth century. Despite its historical and systematic importance, the teaching is difficult to explain to the modern reader. Part of the problem stems from the fragmentary nature of the manuscript in which it is preserved, part from the contents of the teaching itself, which requires a considerable propadeutic for its comprehension. A word of explanation is thus required to set out the structure of the volume and to detail the editorial decisions that underlie its organization. Two major manuscript studies have advanced the cause of scholarship on Galileo within the past two decades. The first relates to Galileo's experimental activity at Padua prior to his discoveries with the telescope that led to the publication of his Sidereus nuncius in 1610. Much of this activity has been uncovered by Stillman Drake in analyses of manuscript fragments associated with the composition of Galileo's Two New Sciences, fragments now bound in a codex identified as MS 72 in the collection of Galileiana at the Biblioteca Nazionale Centrale in Florence.

This volume contains the proceedings of the workshop "Astrophotography 87," which was held in Jena, April 21-24, 1987. The workshop was organized by the Central Institute of Astrophysics of the Academy of Sciences of the German Democratic Republic and is the latest in a series devoted to the problems of photography in astronomy. The previous workshops, which have taken place every three years, were held in Edinburgh (1984), Nice (1981) and Geneva (1978). For telescopes with large fields of view, in particular Schmidt telescopes, photographic plates are the only suitable radiation receiver. Thus the effi ciency of the photographic plate determines the quality of the observation. The treatment of the plates in the photographic laboratory is also very im portant. Additional factors affecting the scientific results are the measuring machines and the methods of interpretation. All these topics were discussed in the workshop by the 62 participants (26 from the GDR and 36 from 13 other countries. Thanks go to David Malin, the chairman of the working group "Astropho tography" of the International Astronomical Union, for writing an introduc tory article for the proceedings. I am grateful to all participants who pre sented papers during the workshop for sending in their manuscripts on time. Poster papers are arranged among the other papers according to the topics they treat. All participants also wish to express their thanks to Springer Verlag for publishing the proceedings."

Progress towards an understanding of the dynamics and interactions of galaxies has been spurred on more than ever by a wealth of new observations and numerical experiments. The Heidelberg Conference 1989, the papers of which are collected in this volume, was extremely successful in presenting a synoptic view of the field in all its aspects: galaxy interactions in the early universe and in recent times, interactions of our galaxy and its neighbours, dynamical problems of elliptical and disk galaxies, groups and clusters, starburst and nuclear activity triggered by interactions, merger scenarios, and numerical experiments. Researchers and graduate students, specialists or not, will find here a complete overview of a rapidly growing field of astronomy.

In May 1986 a two-day workshop on Physical Processes in Comets, Stars and Active Galaxies was held at the Ringberg Castle near Lake Tegernsee, and this rather unusml. l collection of topics needs a few words of explanation. When we first thought of organizing a workshop on such a large variety of astrophysical objects our main motivation was to honor Rudolf Kippenhahn and Hermann Ulrich Schmidt on the occasion of their 60th birthdays, and we planned to cover at least a fraction of their fields of active research. We then realized immediately that despite the fact that the objects are so different, the physical processes involved are very much the same, and that it is this aspect of astrophysics which governed the scientific lives of both of our distinguished colleagues and friends and allowed them to make major contributions to all those fields. Apparently this viewpoint was shared by many colleagues and it was therefore not surprising that in response to our invitation everybody who had been invited agreed to come and to present a talk. The workshop then turned out to be a real success. In contrast to highly specialized conferences, fundamental problems as well as very recent devel opments were discussed and the participants appreciated the opportunity to exchange ideas."

Particle astronomy - the study of cosmic radiation - was the first of the new astronomies to emerge in the twentieth cen- tury. Although cosmic-ray phenomena have been fruitfully investi- gated for some seventy years, the central engima - the origin of these high-energy particles - remains a challenge. Among the ob- servational clues to possible sites and mechanisms of cosmic-ray production, none carries more information than the composition and energy distribution of the particles arriving in the solar system. The present volume is the work of many participants in a NATO Advanced Study Institute on "The Composition and Origin of Cosmic Rays" held from the 20th to the 30th of June, 1982 under the aus- pices of the Ettore Majorana Centre for Scientific Culture. Par- ticipants came to the Centre in Erice, Sicily from eight countries. This Institute was also the third Course of the International School of Cosmic-Ray Astrophysics, which has been meeting bienni- ally 1n Erice. Of the two previous Courses, likewise sponsored by the Majorana Centre, the first (1978) provided a broad introduction to th~ field. It was entitled "Progress and Problems in Cosmic- Ray Physics." The second (1980) was devoted to "Acceleration of Particles in Nature." It treated mechanisms of acceleration, some candidate sites, and observational and theoretical constraints. Director of the Majorana Centre is Prof. Antonino Zichichi.

x about a sequence of reVlew lectures, each followed by contributed talks and discussions. The opening session was devoted to reviewing the most recent results concerning the determination of chemical abundances in particularly inte resting objects providing direct evidence for stellar nucleosynthesis (like planetary nebulae, supernovae and supernova remnants). In Session 2 recent results on some relevant nuclear reaction rates have been presented. Session 3 grouped the contributions concerning the quasi-static evolution of normal stars, its relevance for the nucleosynthesis of the varlOUS elements and isotopes, and the comparison of the evolutionary models with the observations. Session 4 addressed the important questions of identifying the precursors of both Type I and Type II supernovae, and of determining the detailed composition of the ejecta by explosive nucleosynthesis associated with these events. Finally, Session 5 was devoted to a presentation of recent calculations of the evolution of hypothetical pre-galactic very massive objects (in cluding their potential role in pre-galactic nucleosynthesis), and to reviewing the progress that has been made in understanding the chemical evolution of galaxies. The discussion during and after talks was spirited and contributed signi ficantly to the succes of the workshop. We regrett for not having been able of reporting it "in toto" in the proceedings. Nevertheless, we hope that what has been recorded may still give to the reader at least part of the excitement we have experienced during the ten days of the workshop."

This volume contains the detailed text of the major lectures and the abstracts of the lectures delivered during the seminar sessions. The subject of our NATO Advanced Study Institute in 1981 was the Application of Modern Dynamics to Celestial Mechanics and Astrodynamics. This Preface will first explain the terminology, then it will review shortly the content of the lectures and will outline how all this was made possible and, finally, it will disclose our future aspirations. Periodicity is an extremely important concept in our field, therefore, it should not be unexpected that our NATO Advanced Study Institute is enjoying a period of three years. Since 1972 we conducted four Institutes with increasing interest and en thusiasm displayed by the participants, lecturers and by this Director. Celestial Mechanics or Dynamical Astronomy is part of Astronomy dealing mostly with the motion of natural celestial bodies. Astrodynamics or Orbital Mechanics is the application of dynamics to problems of Space Engineering and it treats mostly the dynamical behavior of artificial satellites and space probes. The underlying mathematical and dynamical principles are, of course, the same for Celestial Mechanics and for Astrodynamics. This Director of the Institute and Editor of the Proceedings was extremely fortunate to have obtained the cooperation of out standing lecturers who were clear, thorough, understandable, patient to answer questions, but above all, had knowledge of the ix V. Szebehely (ed.). Applications of Modern Dynamics to Celestial Mechanics and Astrodynamics. ix-x."

From September 5 until September 9, 1968, the IVth Colloquium on Variable Stars was held in Budapest, Hungary. The Colloquium was organized by a committee consisting of G. H. Herbig (President), A. Boyarchuk, M. W. Feast, D. McNamara, J. E. Merrill, D. J. K. O'Connell, V. Tsessevich, W. Wenzel. The local organization was placed in the hands of a Committee consist- ing of members of the Konkoly Observatory, Budapest: L. Detre (Chairman), 1. Almar, Julia Balazs-Detre, K. Barlai, M. Ill, S. Kany6, M. Lovas and of J. Kovacs (Hungarian Academy of Sciences). The Colloquium was attended by about 90 scientists representing Argentina, Austria, Bulgaria, Canada, France, GDR, GFR, Hungary, Italy, The Netherlands, Poland, Roumania, South Africa, Sweden, United Kingdom, U.S.A., U.S.S.R. As chairmen acted at the sessions: M. W. Feast, G. H. Herbig, J. Sahade, A. Boyarchuk, W. Wenzel, F.B. Wood and L. Rosino. The contents of the present volume parallel closely the programme of the individual sessions of the Colloquium.

This book is an updated and modified translation of the Russian edition of 1984. In the present edition, certain sections have been abridged (in particular, Sects. 6.1 and 8.3) and the bibliography has been expanded. There are more detailed discus sions of the group properties of integrable systems of equations of mathematical physics (Sect. 3.4) and of the Riemannian problem in the context of the infinite dimensional internal symmetry groups of these systems of equations. There is an extended discussion of the reasons for the acceleration and retardation of pulsars in connection with more recent achievements of X-ray astronomy. Part of the material of Chap. 8 of the Russian edition has been included in Chap. 7; thus the number of chapters has been reduced to seven. S. Chandrasekhar set for me an example of brilliant analytical penetration into the essence of physical problems, and my book touches on his work in many in stances. The results of modem quantum theories of strong fields are not presented, but they can be found in the fundamental monographs Quantwn Electrodynamics of Strong Fields by W. Greiner, B. Muller, J. Rafelski (Sprioger-Verlag, Berlin, Heidelberg, New York 1985) and Quantwn Effects in Intense External Fields in Russian] by A. Grib, S. Mamaev, W. Mostepanenko (Energoatomizdat, Moscow 1988). This book was translated by Dr. N. M. Queen; I am very grateful to him. I thank sincerely H. Latta, C.-D. Bachem, V. Rehman, S. von Kalckreuth for preparing of the english manuscript."

In the twenties the new atomic physics opened the way toward a quantitative interpretation of stellar spectra. It was one of the aims in this new branch of astrophysics to determine in a quantitative way the chemical composition of stellar atmospheres, i. e. of those parts of the stars which are accessible to spectro scopic observation. It was only in the forties that the first reasonably accurate and complete analyses became available. In the meantime nuclear physics and the theory of the internal constitution of the stars had reached the important conclusion that the main sequence of the Hertzsprung-Russell-diagram is taken up by stars which in their central parts produce energy by the conversion of hydrogen into helium. It was BAADE who in the early fifties stimulated observational and theoretical work concerning the colour-magnitude-diagrams of star clusters and their connection with the nuclear evolution of stars. Obviously, this type of research opened also the way towards much more difficult and far reaching fields of research: the formation of galaxies and the origin of the chemical elements and their abundance distributions."

Spacecraft study of the Solar system is one of humanity's most outstanding achievements. Thanks to this study, our present knowledge of properties of and conditions on the planets exceeds many-fold that of 20 years ago: planets have been rediscovered. This is especially the case for planetary atmospheres, whose properties were for the most part either not at all or only erroneously known. Much research has been invested in the study of the atmospheres of Mars and Venus, and their chemical composition and photochemistry are basic problems in these studies. In the present publication I have tried to summarize all findings in this field. The English version of the book includes new data in the field from the last 3 years since the book was published in Russian. I wish to thank U. von Zahn, who initiated my talks with Springer-Verlag and acted as technical editor. December 2, 1985 V. A. KRASNOPOLSKY Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Chemical Composition and Structure of the Martian Atmosphere 4 1. 1 Carbon Dioxide and Atmospheric Pressure . . . . . . . . . . . . . . . . . . . 4 1. 2 CO and O Mixing Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 1. 3 Ozone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1. 4 Water Vapor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1. 5 Composition of the Upper Atmosphere as Determined from Airglow Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1. 6 Mass Spectrometric Measurements of the Atmospheric Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 1. 7 Ionospheric Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1. 8 Temperature Profile of the Lower Atmosphere. . . . . . . . . . . . . . . . 36 1. 9 Temperature of the Upper Atmosphere . . . . . . . . . . . . . . . . . . . . . . 40 1. 10 Eddy Diffusion Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2 Photochemistry of the Martian Atmosphere . . . . . . . . . . . . . . . . . .

The inaugural Symposium on Turbulent Shear Flows was held at The Pennsylvania State University in 1977. Thereafter the locations for the biennial symposium have alternated between the USA and Europe. However, the ninth Symposium on Turbu lent Shear Flows was awarded to Japan in recognition of the strong support researchers of the Pacific Rim countries have given previous symposia. The University of Kyoto was the host institution and the meeting was held in the Inter national Conference Hall. The Local Arrangements Committee did a superb job scheduling traditional Japanese dinners and arranging visits to the many cultural treasures in the Kyoto region. The meeting attracted more than 260 offers of papers. Thirty-three sessions were scheduled to accommodate the 138 papers accepted for oral presentation. In addition a poster session was scheduled on each of the three days to accommodate a total of 42 poster presentations. From the presentations at the symposium 24 have been selected for inclusion in this volume. The authors of these papers have revised them taking into consideration comments made during their oral presentation and recommendations made by the Editors. Four subject areas are identified, namely closures and fundamentals, free flows, wall flows, and combustion and recirculating flows. Eminent authorities have prepared introductory articles fot each topic to put the individual contributions in context with each other and with related research.

Apart from Hotine's work on Mathematical Geodesy, several previously unpublished reports are collected in this monograph, complemented by extensive comments on these contributions and a complete bibliography of Hotine by the editor.

This book is a translation, by Mr. S. Dunlop, FRAS, of the second German edition of Veranderliche Sterne published by Johann Ambrosius Barth Ver lag, Leipzig, DDR, and Springer-Verlag, Berlin Heidelberg New York Tokyo. We have used the opportunity to make improvements and changes in a few places and to add details of new results and discoveries. The foreword to the second German edition remains no less valid for this one, including the changes. We would like to express our thanks to Mr. Dunlop for his expert and sympathetic translation and for the many improvements he suggested. December 1984 G. RICHTER and W. WENZEL Preface to the Second German Edition The suggestion that a second edition of this book should be prepared came equally from the readers, the publishers, and from the editors of the first edition. By a lucky coincidence the completion of the manuscript and the composition of these lines comes at the time of the 90th anniversary of the birth of Cuno Hoffmeister, the author of the first edition, and consequently this current work may be dedicated to his memory."

One of the most fundamental discoveries of the solar system was the detection of four moons in orbit around Jupiter by Galileo Galilei in 1610. The discovery was significant not only in the context of Jupiter; it gave credence to and was instrumental in firmly establishing the heliocentric system of Nicolaus Copernicus. Almost four centuries after Galileo's discovery, exten sive observations by the two Voyager spacecrafts have once again revolu tionized our thinking about the major planets, their composition, structure, origin, and evolution. This book is an attempt at summarizing our present understanding of the atmospheres and ionospheres in the outer solar system, with particular emphasis on the relevant physics and chemistry. I was motivat ed to prepare this manuscript for the following reasons. First, after under going rapid expansion in the recent past, the subject has finally attained suf ficient maturity to warrant a monograph of its own. Second, I have felt that as a result of recent observations, new and challenging problems have arisen whose resolution requires unconventional analysis and theoretical interpreta tion of existing data, as well as the collection of new kinds of data. I believe the time is ripe to put these issues in the appropriate scientific perspective, with the hope of stimulating novel theoretical, observational, and laboratory studies. I have highlighted the significant scientific problems throughout the book, especially at the end of each chapter.