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The words of this preface were written when the book was ready to go to the press; and are limited to only a few points which are best made in this place. As is intimated by the sub-title, the whole volume was written with appli­ cations in mind to double-star astronomy. The latter is, however, not the only branch of our science which could benefit from its contents. The same is true of certain aspects of the dynamics of stellar systems or galaxies (the stellar popula­ tions of which are also characterized by the fact that the mean-free-path of their constituent stars are long in comparison with the dimensions of the respective systems); the central condensations of which are high enough to approximate the gravitational action of a "mass-point". This fact did not, to be sure, escape the attention of previous investigators (in the case of globular clusters, in particular, the Roche model was introduced in their studies under the guise of polytropic models characterized by the index n = 5); though no particular attention will be paid to these in this book. But possible applications of the Roche model are not limited to problems arising in stellar astrophysics. With Coulomb forces replacing gravitation, the equilibrium model finds a close analogy in the field of electrostatics-as was pointed out already at the beginning of this century by (then young) J. H. Jeans (cf.

In July 1967 ESRIN and ESLAB, the two ESRO laboratories primarily concerned with basic research, held a joint symposium on Satellite and Rocket Measurements of Corpuscular Radiation from Outer Space. This was followed in September 1968 by a second symposium: Low-Frequency Waves and Irregularities in the Ionosphere; and in September 1969 by a third: Intercorrelated Satellite Observations Related to Solar Events. A fourth symposium, on upper atmospheric models and related experiments, took place in Frascati, 6-10 July 1970. The main aim of the symposium was to ~ssess current experimental work - both field and laboratory - related to mesospheric struc­ ture and composition, in the light of theoretical work on atmospheric models and atomic and molecular processes. To foster an interdisciplinary approach, the meeting brought together approximately 50 scientists working with different techniques but having a common interest in the interpretation of meso spheric phenomena. Recent work such as that presented at the symposium has deepened our knowledge of upper atmospheric composition, and increased our understanding of upper atmo­ spheric temperature and dynamics. In particular, it has shown that the concentration of minor species in the atmosphere is somewhat different than expected. Theoretical models have not yet considered many of the minor constituents and have generally not included dynamical effects. It is now time to reconsider these models and elaborate them in the light of recent knowledge.

This conference is a tribute to those astronomers who pioneered the investigation of this subject such a short time ago and who carried it through to its present state. (H. Arp, Concluding Remarks of the Conference) A previous conference, covering mainly the observational aspects of Supernovae, was held at the Haute Provence Observatory in September 1963. In the following ten years this field of research has considerably increased; it seemed, therefore, the right time to organize an international conference on Supernovae taking into account that in the meantime important discoveries, such as the Pulsars, had been made, and new techniques of observation were available. This book contains the proceedings of this conference held at Porto Cesareo (Lecce), Italy, during the period May 7 through 11, 1973. About one hundred participants from eighteen countries attended the conference. It was also the first attempt to hold an international conference in the Salento, the southernmost region of Apulia, in whose capital, Lecce, the newly founded Faculty of Sciences of the University of Lecce is located. The program of the conference included the results and techniques of Supernova surveys, photometric and spectral studies, statistics of Supernovae, Supernova Rem­ nants, and finally, theories on Supernovae and Supernova Remnants.

My interest in the history of the Struve family is long-standing but lay dormant until 1972, when I found myself organizing a symposium of the International Astronomical Union in memory of the second Otto Struve. To satisfy my own curiosity, I investigated the precise relationships of the famous astronomers in the family and published an account of them, based mainly on secondary sources. The exercise made me a ware that there was no biography in English of the first and probably still the greatest astronomer in the clan -­ Friedrich Georg Wilhelm Struve. Wilhelm's son, the first Otto, wrote an account (in German) of his father's life, intended primarily for family and close friends and --though printed-- not generally available. Through the kindness of a family member I have a copy from which I have been able to work. The Soviet historian of science, Z. K. Sokolovskaya, wrote a biography in Russian, in 1964, to mark the centenary of Wilhelm's death. This had a limited edition, and my efforts to obtain a copy failed. Neither work has, in its entirety, been translated into English, although Michael Meo of Oakland, California, and Kevin Krisciunas of Hilo, Hawaii, have kindly made available to me their unpublished translations of some sections of the latter. In the of a complete copy, however, when I decided to attempt an English­ absence language biography, I thought it best to do so independently of Sokolovskaya's.

Space exploration and advanced astronomy have dramatically expanded our knowledge of outer space and made it possible to study the indepth mechanisms underlying various natural phenomena caused by complex interaction of physical-chemical and dynamical processes in the universe. Huge breakthroughs in astrophysics and the planetary s- ences have led to increasingly complicated models of such media as giant molecular clouds giving birth to stars, protoplanetary accretion disks associated with the solar system's formation, planetary atmospheres and circumplanetary space. The creation of these models was promoted by the development of basic approaches in modern - chanics and physics paralleled by the great advancement in the computer sciences. As a result, numerous multidimensional non-stationary problems involving the analysis of evolutionary processes can be investigated using wide-range numerical experiments. Turbulence belongs to the most widespread and, at the same time, the most complicated natural phenomena, related to the origin and development of organized structures (- dies of different scale) at a definite flow regime of fluids in essentially non-linear - drodynamic systems. This is also one of the most complex and intriguing sections of the mechanics of fluids. The direct numerical modeling of turbulent flows encounters large mathematical difficulties, while the development of a general turbulence theory is hardly possible because of the complexity of interacting coherent structures. Three-dimensional non-steady motions arise in such a system under loss of la- nar flow stability defined by the critical value of the Reynolds number.

The date: September 30, 1880 The place: A private observatory in Hastings-on-Hudson Profession of the observer: A medical doctor The instrument: An l1-inch Clark refractor. The significance of that night marked one of the truly great turning points in the development of astronomical techniques: Dr Henry Draper, a wealthy New York medical doctor, had secured the first photograph of a nebula: a 51-minute exposure on a dry gelatinobromide plate showing the wispy nebulosity of the Orion Nebula. By March 1882, Draper had secured an exposure of 137 minutes, showing far richer detail of both bright and dark features. The rest is histapy. The photographic era heralded in a universe where hints of the presence of cosmic dust were strongly alluded to: from star-forming regions such as Messier 17, to the Horsehead Nebula in Orion, to the striking dark finger in the Cone Nebula, to the magnificent dark bands in the plane of our Milky Way. "Historically, astromomers from the very beginning have been afraid of dust.

This volume contains a number of essays by experts in areas of theoretical physics and astrophysics including cosmology, classical and quantum gravity, string theory and relativistic astrophysics. It will provide the reader with excellent reviews of current research in these frontier areas. Several of the essays emphasise alternative views of the Universe by leading astronomers and physicists who are known for their pioneering contributions. The volume is dedicated to Professor Jayant Narlikar, who has concerned himself with fundamental issues in cosmology and gravitation theory over a long and distinguished research career.

The aim of the present book will be to provide a comprehensive account of our present knowledge of the theory of dynamical phenomena exhibited by elose binary systems; and on the basis of such phenomena as have been attested by available observations to outline probable evolutionary trends of such systems in the course of time. The evolution of the stars - motivated by nuelear as weIl as gravitation al energy sources - constitutes nowadays a well-established branch of stellar astronomy. No theo­ ries of such an evolution are as yet sufficently specific - let alone infallible - not to require continual tests by a confrontation of their consequences with the observed prop­ erties of actual stars at different stages of their evolution. The discriminating power of such tests depends, of course, on the range of information offered by the test objects. Single stars which move alone in space are now known to represent only a minority of objects constituting our Galaxy (cf. Chapter 1-2); and are, moreover, not very revealing of their basic physical characteristics - such as their masses or absolute dimensions. If there were no binary systems in the sky, the only star whose vital statistics would be fully known to us would be our Sun.

If Zdenek Kopal Department of Astronomy University of Manchester Your Magnificences, my Lord Mayor, ladies and gentlemen! It is a great pleasure for me to respond, on behalf of your foreign guests, to your gracious words of welcome; and to thank you for the wonderful reception which you nave extended to us. The city of Bamberg and its Remeis Sternwarte nas indeed been renowned allover the world for a great many years - as the place where your Observatory's first director, Professor Ernst Hartwig (1851-1923) - in addition to his other titles to fame - collaborated (with Gustav Muller of Potsdam) on the construc­ tion of the monumental Geschichte und Literatur des Lirhtwechsels der Veranderlichen Sterne, which since 1918 has (together with its sub­ sequent continuation) been a veritable vade-mecum of a1l students of variable stars; where the second director, Professor Ernst Zinner (1886-19]~ prepared his valuable Katalog der Verdachtigen Veranderlichen Sterne (192@ which safeguarded many an astronomer (including the present speaker in the days of his innocence) from premature discovery claims; and whose third director, Professor Wolfgang Strohmeier, initiated in 1959 the tradition of the international colloquia of which ours is the latest successor. It is indeed a great pleasure to welcome Professor Strohmeier - now Emeritus - among us; and to congratulate him on the grace with which he is carrying his years.

OPENING ADDRESS XI LIST OF PARTICIPANTS XV SESSION 1 THE ATMOSPHERE AND IONOSPHERE BELOW 150 km L. Thomas SOME OUTSTANDING PROBLEMS IN THE NEUTRAL AND IONIZED ATMOSPHERE BETWEEN 60 AND 150 km ALTITUDE 3 Peter M. Banks HIGH-LATITUDE IONOSPHERE-ATMOSPHERE INTERACTIONS (Abstract) 19 V. Domingo SOLAR RADIATION VARIATION AND CLIMATE 21 R. Bernard MAREES ET ONDES PLANETAIRES DANS LA BASSE THERMOSPHERE ET LA HAUTE MESOSPHERE 43 Michel Blanc and Paul Amayenc CONTRIBUTION OF INCOHERENT SCATTER RADARS TO THE STUDY OF MIDDLE AND LOW LATITUDE IONOSPHERIC ELECTRIC FIELDS 61 SESSION 2 THE OZONOSPHERE T. M. Donahue BASIC PROCESSES IN THE STRATOSPHERE AND THE MESOSPHERE (Abstract) 93 VI TABLE OF CONTENTS Ivar S. A. Isaksen CHEMICAL MODELS OF THE NEUTRAL ATMOSPHERE 95 M. Ackerman MEASUREMENTS OF MINOR CONSTITUENTS IN THE STRATOSPHERE 107 A. Vidal-Madjar, R. G. Roble, W. G. !iankin,G. Artzner, R. M. Bonnet, P. Lemaire, and J. C. Vial HIGH-RESOLUTION ATMOSPHERIC EXTINCTION MEASUREMENTS FROM THE FRENCH EXPERIMENT ON BOARD THE NASA SPACECRAFT OSO-8 117 M. Anderegg, J. E. Beckman, A. F. M. Moorwood, H. H. Hippelein, J. P. Baluteau, E. Bussoletti, A. Marten, and N. Coron HIGH-R~rOLUTION ATMQrPHERIC EMISSION SPECTROSCOPY AT 120 cm AND 535 cm WITH A RAPID-SCAN INTERFEROMETER AND 91 cm AIRBORNE TELESCOPE 129 Erwin Schanda, Joachim Fulde, and Klaus Kunzi MICROWAVE LIMB SOUNDING OF STRATOSPHERE AND MESOSPHERE 135 SESSION 3 METEOROLOGY IN THE IONOSPHERE AND STRATOSPHERE Hans-Jurgen Bolle CRITICAL CLIMATE PARAMETERS AND THEIR MONITORING FROM SPACE 149 R. J. Murgatroyd, A. O'Neill, and S. A.

Among the many works devoted to our space environment, this serious and objective book by Mr. Delobeau should occupy a special place. It has become rare for works on such a subject to be written by competent physicists who are not specialists in the use of space vehicles. While performing research on the ionosphere, Mr. Delobeau was directly involved with the terrestrial environment long before it became common to explore it with sounding rockets and satellites. His professional obligations no longer require him to study aeronomy, only his regular collaboration with a great scientific journal inspires him to keep up to date on this subject. He is particularly motiva­ ted by a disinterested appreciation of the information which he hopes to share with his readers. It is a sign of the times that the results of space research should no longer be confined to the circle of space technicians. All of the new tools available to the service of science, for example:-particle accelerators, magnetic resonance, electron microscopy, lasers - have entered the general arsenal following a period of adaptation. Like them, the rocket is now a classical instrument, and gives information even to those for whom it holds no interest in itself. This book was quite up-to-date when the author submitted his manuscript. Despite the efforts of the editor, this will no longer be completely true when it appears in print. There is scarcely any branch of science that evolves more rapidly than space research.

This title details the essential roles that small telescopes should play in 21st century science and how their future productivity can be maximized. Over 70 experts from all corners of the international astronomical community have created a reference on the future of big science with small telescopes. at national facilities and their omission from national science priority studies, the oft-lamented demise of the small telescope has been greatly exaggerated. In fact, the future of these workhorses of astronomy will be brighter than ever if creative steps are taken now. This three-volume set defines essential roles that small telescopes should play in 21st century science and the ways in which a productive future for them can be realized. A wide cross-section of the astronomical community has contributed to a definitive assessment of the present and a vision for the future. volume one of this three-volume set examines the public's and the astronomical communities' own perceptions and misconceptions of small telescope productivity. These shape the future scientific research that will be done with telescopes smaller than 4-m in aperture and the number of astronomers that will have access to them.

Intelligent information Retrieval comprehensively surveys scientific information retrieval, which is characterized by growing convergence of information expressed in varying complementary forms of data - textual, numerical, image, and graphics; by the fundamental transformation which the scientific library is currently being subjected to; and by computer networking which as become an essential element of the research fabric. Intelligent Information Retrieval addresses enabling technologies, so-called `wide area network resource discovery tools', and the state of the art in astronomy and other sciences. This work is essential reading for astronomers, scientists in related disciplines, and all those involved in information storage and retrieval.

Man, through intensive observations of natural phenomena, has learned about some of the basic principles which govern nature. The aurora is one of the most fascinating of these natural phenomena, and by studying it, man has just begun to comprehend auroral phenomena in terms of basic cosmic electrodynamic processes. The systematic and extensive observation of the aurora during and after the great international enterprise, the International Geophysical Year (lGY), led to the concept of the auroral substorm. Like many other geophysical phenomena, auroral displays have a dual time (universal- and local-time) dependence when seen by a ground-based observer. Thus, it was a difficult task for single observers, rotating with the Earth once a day, to grasp a transient feature of a large-scale auroral display. Such a complexity is inevitable in studying many geophysical features, in particular the polar upper atmospheric phenomena. However, it was found that their complexity began to unfold when the concept of the auroral substorm was introduced. In a book entitled Polar and Magnetospheric Substorms, the predeces­ sor to this book, I tried to describe the auroral phenomena as completely as possible in terms of the concept of the auroral substorm. At that time, the first satellite observations of particles and magnetic fields during substorms were just becoming available, and it was suggested that the auroral sub storm is a manifestation of a magnetospheric phenomenon called the magnetospheric substorm.

A strange field of speculation is opened by this phenomenon ... here we have a star fitfully variable to an astonishing extent. and whose fluctuations are spread over centuries. apparently in no settled period. and with no regularity of progression. What origin can we ascribe to these sudden flashes and relapses? What conclusions are we to draw as to the comfort or habitability of a system depending for its supply of light and heat on so uncertain a source? -- J. F. W. Herschel! We can imagine, at least, that the study of Luminous Blue Variable stars began as the official court astrophysicists of Eridu speculated about a new 5000 years ago first-magnitude star which persisted in their southern sky for several years.2 After that the topic languished for a while, but now it has been renewed following recent observations by Blaeu (P Cygni, c.1600) and Herschel (1] Argus, c.1840) ... -- More soberly, it is only within the past few years that we have begun to understand LBV's and to recognize their coherence as a class. Thus only a minority of astronomers are familiar yet with this relatively new topic, whose potential impli­ cations are of great interest (see below). One purpose of this book, we hope, will be to provide an accessible overview of the subject for interested astronomers and astrophysicists in general.

Recent years have witnessed the expansion and multiplication of the observations of star formation and fragmentation accompanied by a consequent growth in the study of the underlying physical processes, the chemistry, the sites, the times, etc. Moreover, recent studies have shown that the formation of stars is likely to share many features with the formation of other self-gravitating objects. The present volume, therefore, discusses the formation of such objects in a systematic and comparative manner.

During the last week of September 1968, ESRIN (the European Space Research Institute) held the ESRIN-ESLAB Symposium on 'Low-Frequency Waves and Irregularities in the Ionosphere' in Frascati, near Rome. The symposium was attended by about 60 participants, including speakers from most of the ESRO member states, the U.S.A., the U.S.S.R., and Peru. The main topics covered were: (a) observations of ionospheric irregularities by radar scattering, (b) scintillations of satellite signals, (c) geomagnetic micropulsations, and (d) whistlers. Both theoretical and observational aspects were treated. In addition, laboratory results on low-frequency waves in plasmas were discussed, emphasis being given to their possible relevance to low-frequency ionospheric phenomena. Finally, a brief presentation (not included in these proceedings) of the ESRO rocket and satellite program was given by Dr. Pedersen of ESLAB. The symposium provided an exchange of information among workers in closely related fields. It was also valuable in bringing together people whose experience is predominantly in ionospheric observations with others whose field of interest is mainly in plasma physics (theoretical or laboratory) - a combination that seemed particularly appropriate to ESRIN's program and functions.

Proceedings from the Second Trieste Colloquium on Astrophysics, September 12-17, 1968

TO SOLAR TERRESTRIAL RELATIONS PROCEEDINGS OF THE SUMMER SCHOOL IN SPACE PHYSICS HELD IN ALPBACH, AUSTRIA, JULY 1S-AUGUST 10,1963 AND ORGANIZED BY THE EUROPEAN PREPARATORY COMMISSION FOR SPACE RESEARCH (COPERS) Edited by J. ORTNER European Space Research Organisation. Paris and H. MAS ELAND Sterrewacht ' Sonnenborgh' . Utrecht D. REIDEL PUBLISHING COMPANY DORDRECHT-HOLLAND e-ISBN-13:978-94-010-3590-3 IS8N-13:978-94-0 10-3592-7 00110. 1007/978-94-010-3590-3 '96' Softoover reprint of the hardcover 1st edition 1965 All rights reserved No part of this book may be reproduced in any fonn. by print, photoprint, microfilm, or any other means without permission from the publisher FOREWORD The textbook presented in the following is composed of the proceedings of the Summer School in Space Physics held during the summer months of 1963. This Summer School was organized by the Preparatory Commission (COPERS) of the European Space Research Organisation (ESRO). It was the first time that such a summer course was held in Europe on a subject of space physics. Thanks to an invitation from the Austrian Government these lectures were given in the College House of Alpbach, Tyrol. Eight outstanding European scientists each presented five two-hour lectures on topics covering the region between the Sun and the Earth. The courses contained the physics of the Sun, the Interplanetary Medium and Trapped Radiation, the Ionosphere and High Latitude Phenomena. Furthermore, a course on space instrumentation was given. Sixty students were selected to attend the courses.

Socrates knew all that was known by his contemporaries. But already in the Middle Ages it was becoming difficult for a single man to have a truly encyclopedic view of all human knowledge. It is true that Pico della Mirandola, Pius II, Leonardo da Vinci, and several other great minds were thoroughly in possession of considerable know­ ledge, and knew all that one could know, except no doubt for some techniques. The encyclopedists of the 18th century had to be content with an admirable survey: they could not go into details, and their work is a collective one, the specialized science of each collaborator compensating for the insufficiencies of the others. We know very well that our science of today is a science of specialists. Not only is it impossible for anyone person to assimilate the totality of human knowledge, it is impossible even to know ones own discipline perfectly thoroughly. Each year the presses of science pro­ duce a frightening quantity of printed paper. Even in very limited fields, new journals are created every day, devoted to extremely specialized, often very narrowly defined subjects. It is indeed evident that in a field whose scope extends well beyond astronomical or astrophysical research, it is materially impossible to be informed of everything, even with the richest of libraries at hand.

The seeds of this conference were sown with the publication by Press, in 1965, of a paper in which he suggested that the displacement field due to a major earthquake may extend over much greater distances than had been thought possible before. Later on, Mansinha and Smylie pointed out that if Press was correct then, since the redistri­ bution of significant quantities of mass was involved, the inertia tensor of the earth would be altered and thus cause the earth to wobble; this revived the idea that earth­ quakes might be the long sought source for maintaining the Chandler Wobble. They argued that since earthquakes are sudden events it should be worthwhile trying to determine if there was any correlation between sudden changes in the Chandler term of the pole path and major earthquakes. Furthermore, since displacements occur both before and after an earthquake it might be possible to obtain a few days warning of a major earthquake by making instantaneous observations of the pole path. Analysis of the data indicated some correlation but, as often happens in science in general and in geophysics in particular, the results were not conclusive because of imperfect theory and the need for more accurate determinations of the pole position. It soon became clear that a meeting between geophysicists and astronomers involved in this type of work would be of mutual benefit.

This book contains the lecmres presented at the Summer Advanced Study Institute, 'Physics and Chemistry of Upper Atmospheres' which was held at the University of Orleans, Orleans, France, during the period July 31 through August 11,1972. One­ hundred thirty nine persons from 14 different countries attended the Institute. The authors and the publisher have made a special effort for rapid publication of an up-to-date status of the particles, fields, and processes in the earth's magnetosphere, which is an ever changing area. Special thanks are due to the lecturers for their diligent preparation and excellent presentations. The individual lectures and the published papers were deliberately limited; the authors' cooperation in conforming to these specifications is greatly appreciated. The contents of the book are organized by sub­ ject area rather than in the order in which papers were presented during the Institute. Many thanks are due to Warren Berning, Donald M. Hunten, Edward Llewellyn, J. Ortner, Henry Rishbeth, Harold I Schiff, Lance Thomas, Alister Vallance Jones, and Gilbert Weill, who served as session chairmen during the Institute and contributed greatly to its success by skillfully directing the discussion period in a stimulating manner after each lecture.

The International Association of Geochemistry and Cosmochemistry was organized in 1967, and held its first meeting at UNESCO Headquartels that year in association with its symposium on The Origin and Distribution of the Elements'. The Association is a member of the International Union uf Geological Sciences, and holds regular meetings at the time of the I nternatlOnal Geological Congresses, the last of which was held in Montreal, in August. 1972. The IAGC was organized to coordinate activities on an international scale in a wide variety of branches of geochemistry. Its activities are carried on through Commissions and Working Groups, and by means of symposia and other international activities. It has national, corporate, and individual members. One of the first actions taken by the Council of the [AGC when it met in 1967 was to establish an initial set of Working Groups to commence the activity of the organization. Among these Working Groups was one on Extraterrestrial Chemistry, established under the chairmanship of the writer. This Working Group recognized that its basic concern with the chemical composition of cosmic systems was a problem with ramifications in many fields in addition to geochemistry. The other scien­ tific disciplines which are involved include physics, astronomy and astrophysics, and geophysics. The Working Group thus included scientists in these disciplines from the beginning; many of the scientists had already participated in the first symposium of the IAGe. The Working Group has recently been elevated to the status of a Commission.

The 1969 ESLAB symposium 'Intercorrelated Satellite Observations Related to Solar Events' was held at a time when the importance of bringing together measure­ ments made simultaneously in different regions of space was beginning to be appreciated. To-day it is universally accepted that the major experimental steps forward in understanding the physics of the Sun-Earth relationships are likely to be made through pre-planned correlated satellite studies. Such considerations have led to the organisation of the International Magnetospheric Study and the joint ESROj NASA International Magnetospheric Explorer, (Mother-Daughter-Heliocentric) mission. The seventh ESLAB symposium was planned as a follow up to that of 1969 with the aim of deriving maximum benefit from those spacecraft which through good fortune found themselves simultaneously operating in different regions of the magnetosphere and interplanetary space. ESRO had launched in early 1972 its HEOS-2 satellite to investigate fields and particles in the unexplored region far above the North pole of the Earth and it became clear that the interesting new results arriving from that mission could profitably be linked with those from various American and the U.S.S.R. PROGNOZ satellites. The book follows the order of the symposium (unfortunately the PROGNOZ contribution did not materialise) concentrating, through both review lectures and of new experimental results, on the nature of the boundaries between the presentation the interplanetary medium and the magnetosphere and the interaction of each region on the other.

This book contains the lectures presented at the Summer Advanced Study Institute, 'Earth's Particles and Fields' which was held at the University of Sheffield, England, during the period August 13-24, 1973. One hundred thirty nine persons from sixteen different countries attended the Institute. The authors and publisher have made a special effort for rapid publication of an up-to-date status of the particles, fields, and processes in the Earth's magnetosphere, which is an ever changing area. Special thanks are due to the lecturers for their diligent preparation and excellent presentations. The individual lectures and the published papers were deliberately limited; the authors' cooperation in conforming to these specifications is greatly appreciated. The contents of the book are organized by subject area rather than in the order in which papers were presented during the Institute. Many thanks are due to Drs Rolf Bostrom, J. Ronald Burrows, Robert W. Fredricks, Thomas R. Kaiser, Bernt N. Maehlum, Christopher T. Russell, and Martin Walt who served as session chairmen during the Institute and contributed greatly to its success by skillfully directing the discussion period in a stimulating manner after each lecture.

The Symposium 'The Magnetospheres of the Earth and Jupiter' (May 28th-June 1st, 1974 in Frascati) was organized by the 'Laboratorio Plasma Spazio' of the CNR, on the occasion of its moving to the Frascati area. The main theoretical topic was to be covered by N. Brice, but he died on January 31st, in a plane crash at Pago Pago (Samoa). It seemed appropriate to all of us to honor Neil Brice by renaming the meeting: 'Neil Brice Memorial Symposium'. The Symposium covered problems of magnetospheric dynamics, of both the Earth and Jupiter, with emphasis on the comparison between the two objects. The collaboration of American scientists participating in the recent NASA plan­ etary missions has made it possible to have new important scientific results presented to and discussed by the scientific community. Of the many people who helped to make the meeting such a success, very special thanks goes to Prof. C. Kennel ofU.C.L.A. whose contribution to the organization of this symposium has been extremely important.

Over the past decade the study of the formation and properties of interstellar grains has assumed a growing importance, going much beyond what might have been guessed only a few years ago. It has come to be understood that grains playa role in processes other than the simple absorption and scattering of starlight, which was all that the astronomers of a generation aga considered to be their relevance. Grains indeed playa critical role in controlling the temperature, composition, and states of aggregation of the whole interstellar medium. Among the still mysterious problems is the origin of the vast clouds of obscuring material that is observed in radiogalaxies like NGC 5128 and M 82, which may weIl be associated with the explosions of very massive objects. It is safe to say that from this growing field of study much still remains to be dis­ covered. The topics discussed in this volume will make clear to the reader the range and versatility of the subjects. F. HOYLE FOREWORD by THE PRINCIPAL The Symposium on Solid State Astrophysics held in July 1974 brought to University College Cardiff a large and very distinguished gathering of astronomers. It was the first time that such a collection of scholars, absorbed with the problem of the systems of outer space, had collected together in Wales, and so provided a splendid spring­ board for the researches of the newly founded group of astronomers in the Department of Applied Mathematics and Astronomy at University College.