In the history of science the opening up of a new observational or experimental window is always followed by an increase in knowledge of the subject concerned. This is also the case with the subject of this book, ultraviolet radiation (hereafter UV). In principle, the ultraviolet range might be just one more of these windows, of no particular importance. However, the energy per UV photon provides the main peculiarity, its magnitude being great enough to produce important ch- ical reactions in the atmospheres of planets and satellites, thereby a?ecting the transmission of this radiation to the ground. The Sun is the main natural source of UV radiation in the Solar System and our planet is the body where its in?uences can be best tested and the only one where its relation with life can be studied. However, the terrestrial atmosphere blocksmostofthephotonsinthiselectromagneticrangeandastronomershavehad to develop various techniques (balloons, planes and rockets) to cross this barrier and access the information. These tools have been used in parallel to investigate the physical properties of the terrestrial atmosphere and the interaction of its constituents with light. This book will addresses most of these topics.

The 186th IAU Symposium came at an exciting and perhaps even historic time for extragalactic astronomy. New spacecraft observations plumbed the depths of the Universe out to redshifts of five, while revealing astounding details of nearby galaxies and AGN at intermediate redshifts. Theoretical ideas on structure formation, together with results from detailed numerical modeling, created a comprehensive framework for modeling the formation of galaxies and the transformation of galaxies by interactions and mergers. All these strands came together at the Symposium, as participants glimpsed a developing synthesis highlighting galactic encounters and their role in the history of the Universe. This volume offers professional astronomers, including PhD students, an overview of the rapidly advancing subject of galaxy interactions at low and high redshifts.

Recent years have seen increasing evidence that the main epoch of galaxy formation in the universe may be directly accessible to observation. An gular fluctuations in the background relict radiation have been detected by various ground-based instruments as well as by the COBE satellite, and suggest that the epoch of galaxy formation was not so very early. Combined optical and radio studies have found galaxies at redshifts above 2. 0, systems that at least superficially show the characteristics expected of large galaxies seen only shortly after their formation. And absorption lines in the spectra of quasars seem to be telling us that most cold gas at early to intermediate cosmological epochs was in clouds having roughly galaxy sized masses. What kinds of new observations will best help us study this high redshift universe in future? What new instruments will be needed? These are questions that loom large in the minds of the Dutch astronom ical community as we celebrate 25 years of operation of the Westerbork Synthesis Radio Telescope. Celebration of this Silver Jubilee has included a birthday party (on 23 June, 1995), a commemorative volume looking at both the history and the future of the facility ("The Westerbork Observa tory, Continuing Adventure in Radio Astronomy," Kluwer 1996), and an international workshop, held in the village of Hoogeveen on 28-30 August, 1995."

This book offers a systematic exposition of conformal methods and how they can be used to study the global properties of solutions to the equations of Einstein's theory of gravity. It shows that combining these ideas with differential geometry can elucidate the existence and stability of the basic solutions of the theory. Introducing the differential geometric, spinorial and PDE background required to gain a deep understanding of conformal methods, this text provides an accessible account of key results in mathematical relativity over the last thirty years, including the stability of de Sitter and Minkowski spacetimes. For graduate students and researchers, this self-contained account includes useful visual models to help the reader grasp abstract concepts and a list of further reading, making this an ideal reference companion on the topic. This title, first published in 2016, has been reissued as an Open Access publication on Cambridge Core.

This volume is the product of Lecturers in the fourth Course of the International School of Cosmic-Ray Astrophysics held at the Ettore Majorana Center in Erice, Sicily in November, 1984. The Course, devoted to "Cosmic Radiation in Contemporary Astrophysics," was concurrently a NATO-sponsored Advanced Study Institute (ASI). Cosmic-ray research is in a state of ferment. Precise measure ments - some made with instruments aboard sattelites and space probe- have been confronting models and theories with severe constraints. The observations of gamma-ray sources, notably Cyg X-3, at energies up to 16 10 eV, have opened up tantalizing possibilities of direct source iden tification. This ASI was devoted largely to interdisciplinary phenomena in cosmic-ray astrophysics whose understanding requires input from the other channels in astronomy. It explored the ways in which progress in cosmic-ray science might clarify phenomena observed in related disciplines. In trying to achieve this aim, we assembled a staff of lecturers representing various astrophysical specialties, such as radio astronomy, optical astronomy, X-ray astronomy, gamma-ray astronomy, and of course, particle astronomy (i.e., cosmic radiation). Students and other participants were likewise drawn from diverse backgrounds. Vigorous discussions enlivened almost every session."

This volume contains the fifteenth tri-annual reports of the Presidents of the forty Commissions of the International Astronomical Union; it refers to the progress in our discipline during the three years 1970, 1971 and 1972. As compared to earlier volumes a gradual change in character is unmistakable. The ever increasing flow of publications, combined with the obvious necessity to keep the Reports at a reasonable size and price level has gradually forced the Commission Presidents to be more selective than before in drafting their Reports. I have certainly stimulated them into that direction - in order that Reports like these be valuable and lasting, it seems imperative that the individual contributions have the character of a critical overall review, where a fairly complete summary is given of the major develop ments and discoveries of the past three years, and in which the broad developments and new trends be clearly outlined, while at the same time essential problems for future research are identified. With respect to the latter item I have suggested the Commission Presidents to add to their reports a brief section on scientific priorities for future research in the field of their Commissions. In order to save space I have suggested to Commission Presidents that references to published papers are given on the basis of their number in the published issues of Astronomy and Astrophysics Abstracts. For instance, the indication (06. 078. 019) or (AAA 06. 078."

After a year's successful operation, the European DENIS project is now a scientific reality and its close cousin 2MASS (USA) is about to come into operation. The observational and data reduction processes of both DENIS and 2MASS are fully described in this volume. Already the impact of DENIS is making itself felt in the astronomical community in areas of research as diverse as cosmology, the evolution of galaxies, the interstellar medium, the search for brown dwarfs, and stellar structure and evolution. The first routine results from DENIS and the preliminary results from the 2MASS prototype camera are discussed and compared with other surveys across the wavelength spectrum, both space- and ground-based, including the Digitized Sky Survey, ISO and ROSAT.

A pocket-style edition based on the New York Times bestseller A Brief Welcome to the Universe offers a breathtaking tour of the cosmos, from planets, stars, and galaxies to black holes and time loops. Bestselling authors and acclaimed astrophysicists Neil deGrasse Tyson, Michael A. Strauss, and J. Richard Gott take readers on an unforgettable journey of exploration to reveal how our universe actually works. Propelling you from our home solar system to the outermost frontiers of space, this book builds your cosmic insight and perspective through a marvelously entertaining narrative. How do stars live and die? What are the prospects of intelligent life elsewhere in the universe? How did the universe begin? Why is it expanding and accelerating? Is our universe alone or part of an infinite multiverse? Exploring these and many other questions, this pocket-friendly book is your passport into the wonders of our evolving cosmos.

This volume addresses the history and epistemology of early modern cosmology. The authors reconstruct the development of cosmological ideas in the age of 'scientific revolution' from Copernicus to Leibniz, taking into account the growth of a unified celestial-and-terrestrial mechanics. The volume investigates how, in the rise of the new science, cosmology displayed deep and multifaceted interrelations between scientific notions (stemming from mechanics, mathematics, geometry, astronomy) and philosophical concepts. These were employed to frame a general picture of the universe, as well as to criticize and interpret scientific notions and observational data. This interdisciplinary work reconstructs a conceptual web pervaded by various intellectual attitudes and drives. It presents an historical-epistemological unified itinerary which includes Copernicus, Kepler, Galileo, Descartes, Huygens, Newton and Leibniz. For each of the scientists and philosophers, a presentation and commentary is made of their cosmological views, and where relevant, outlines of their most relevant physical concepts are given. Furthermore, the authors highlight the philosophical and epistemological implications of their scientific works. This work is helpful both as a synthetic overview of early modern cosmology, and an analytical exposition of the elements that were intertwined in early-modern cosmology. This book addresses historians, philosophers, and scientists and can also be used as a research source book by post-graduate students in epistemology, history of science and history of philosophy.

John Dyson has contributed to the study of the hydrodynamic processes that govern a wide variety of astrophysical sources which he has helped explain. In this volume dedicated to him, introductory reviews to a number of the key processes and to the sources themselves are given by leading experts. The mechanisms in which the multi-component natures of media affect their dynamics receive particular attention, but the roles of hydromagnetic effects are also highlighted. The importance of cosmic ray moderation and mass transfer between different thermal phases for cosmic ray moderation and mass transfer between different thermal phases for the evolution of flows are amongst the topics treated. The main types of regions considered include those where starts form, the circumstellar environments of evolved stars, the larger scale interstellar structures caused by the mass loss of stars, and those where the lines of AGNs form.

The primary inducement for organizing an international Conference on 'Image Processing Techniques in_Astronomy' was the fact that the recording microdensitometer VAMP ('Vol Automatische Micro Photometer') of the Utrecht Astronomical Institute was operative for a few years. The necessity of comparing the in strument and its performance with similar instruments nowadays available at many other institutes, was stimulating enough to organize a meeting on the above subject. It took place in Utrecht on March 25, 26 and 27, 1975. The Scientific Organizing Committee consisted of J. Borgman (Groningen), R.B. Dunn (Sacramento Peak), H. Elsasser (Heidelberg), L.D. de Feiter, T. de Groot, J.R.W. Heintze, C. de Jager, H. Nieuwenhuijzen (Utrecht) and W. Wiskott (Geneve). About 175 scientists from 14 countries participated in the meeting which appeared to be successful and offered a good opportunity of exchanging information and comparing experiences. The VAMP was bought with financial support of the Utrecht University and the Netherlands Foundation for Scientific Research (Z.W.O.). The conference was organized with financial support from The Netherlands Ministry of Science and Education, The European Southern Observatory, The Leids Kerkhoven-Bosscha Fonds, The Astronomical Institute of Utrecht, to which Institutes and Organisations we express our sincere gratitude. C. de Jager H. Nieuwenhuijzen editors PAR T WHAT INFORMATION DO WE NEED, FOR WHICH ASTRONOMICAL PROBLEM? ASTROMETRY K. Aa. Strand U. S. Naval Observatory Washington, D. C, INTRODUCTION Considerable progress has taken place in astrometry over the past two decades."

Kepler's Physical Astronomy is an account of Kepler's reformulation of astronomy as a physical science, and of his successful use of (incorrect) physics as a guide in his astronomical discoveries. It presents the only reliable account of the internal logic of Kepler's so-called first and second laws, showing how and to what extent Kepler thought he had derived them from his physical principles. It explains for the first time Kepler's attempt to use an obscure discovery of Tycho Brahe to unify and confirm all of his own physical theories. It also describes the intricate (and neglected) theory which Kepler developed to account for the additional anomalies needed for the theory of the moon.

The three years since the Brighton General Assembly have been the most active period in the history of the Union. 33 IAU Symposia and Colloquia, the first Regional Meeting under the Auspices of the IAU, several co-sponsored Meetings and many other special projects. All this culminating with two General Assemblies in two opposite parts of the Earth, Australia and Poland. At the same time the membership of the Union rose to 3200, the number of Commissions to 40, the number of adhering countries to 47. The present Volume gives a general picture of the Union's recent activity. It contains the report of the Executive Committee, the report of the General Assembly, including the Commissions, Meetings, a short report on the Extraordinary General Assembly and an Appendix with the Members and Commissions of the IAU and the approved names of Lunar and Martian features. I take this opportunity to thank all our collaborators, members of the Executive Committee, Presidents of Commissions, Chairmen of Specific Projects, IAU Secrt;taries and all the Members of the IA U for their contribution to keep our Union a living body of active scientists and a big inter national family. G. CoNTOPOULOS General Secretary CONTENTS Page No."

Saturn, Chiron and the Centaurs - To the Edge and Beyond by Melanie Reinhart. Part I - Saturn: Time. Heritage and Substance Material on Saturn, planet of "the edge" of structure, manifestation and the preservation of what has already been established. Traditional meanings of Saturn are explored in consideration of our contemporary condition of rapid change, and how this affects our relationship with our own Saturn. Mythological images discussed include the Greek Kronos and Pan, Parsifal and the Fool, and the processes of Alchemy and Karma. The traditional domicile of Saturn is reviewed, its transit cycle explored in detail, and the final section includes Saturn discussed through the 12 houses. Part II - The Centaurs: Chiron, Pholus and Nessus Brings ground-breaking new ideas drawn from recent astronomical discoveries in the outer solar system.Several new celestial objects that behave somewhatlike Chiron have been catalogued, and officially named "Centaurs." This unique compilation presents new material concerning the orbit cycle of Chiron, and a summary and elaboration of astrological research to date on Pholus, the second Centaur. In addition, original material on the meaning of the third Centaur, 1992HA2, 'Nessus' is included. This book is still the most comprehensive source of astrological information about the Centaurs. Their meaning is re-contextualised, and an ephemeris for Chiron, Pholus and Nessus is included, as well as several explanatory diagrams. All technical material was specially computed by Dieter Koch, and revised in 2011. The reader can participate in seminars where seed ideas were being expressed for the first time. There is enough material in this seminar for those interested to begin understanding the Centaurs in the horoscope.

This volume has grown out of lectures addressing primarily graduate students and researchers working in related areas in both astrophysics and space sciences. All contributions are self-contained and do not require prior in-depth knowledge of solar physics. The result is a unique textbook that fulfills the needs of those wishing to have a pedagogic exposition of solar physics bringing them up-to-date in a field full of vitality and with exciting research.

The Hidden Hypotheses Behind the Big Bang It is quite unavoidable that many philosophical a priori assumptions lurk behind the debate between supporters of the Big Bang and the anti-BB camp. The same battle has been waged in physics between the determinists and the opposing viewpoint. Therefore, by way of introduction to this symposium, I would like to discuss, albeit briefly, the many "hypotheses," essentially of a metaphysical nature, which are often used without being clearly stated. The first hypothesis is the idea that the Universe has some origin, or origins. Opposing this is the idea that the Universe is eternal, essentially without beginning, no matter how it might change-the old Platonic system, opposed by an Aristote lian view Or Pope Pius XII or Abbe Lemaitre or Friedmann versus Einstein or Hoyle or Segal, etc. The second hypothesis is the need for a "minimum of hypotheses" -the sim plicity argument. One is expected to account for all the observations with a mini mum number of hypotheses or assumptions. In other words, the idea is to "save the phenomena," and this has been an imperative since the time of Plato and Aristotle. But numerous contradictions have arisen between the hypotheses and the facts. This has led some scientists to introduce additional entities, such as the cosmologi cal constant, dark matter, galaxy mergers, complicated geometries, and even a rest mass for the photon. Some of the proponents of the latter idea were Einstein, de Broglie, Findlay-Freundlich, and later Vigier and myself."

Thisbookpresentsmaterialwhichismorealgorithmicallyorientedthanmost alternatives.Italsodealswithtopicsthatareatorbeyondthestateoftheart. Examples include practical and applicable wavelet and other multiresolution transform analysis. New areas are broached like the ridgelet and curvelet transforms. The reader will ?nd in this book an engineering approach to the interpretation of scienti?c data. Compared to the 1st Edition, various additions have been made throu- out, and the topics covered have been updated. The background or en- ronment of this book's topics include continuing interest in e-science and the virtual observatory, which are based on web based and increasingly web service based science and engineering. Additional colleagues whom we would like to acknowledge in this 2nd edition include: Bedros Afeyan, Nabila Aghanim, Emmanuel Cand' es, David Donoho, Jalal Fadili, and Sandrine Pires, We would like to particularly - knowledge Olivier Forni who contributed to the discussion on compression of hyperspectral data, Yassir Moudden on multiwavelength data analysis and Vicent Mart' ?nez on the genus function. The cover image to this 2nd edition is from the Deep Impact project. It was taken approximately 8 minutes after impact on 4 July 2005 with the CLEAR6 ?lter and deconvolved using the Richardson-Lucy method. We thank Don Lindler, Ivo Busko, Mike A'Hearn and the Deep Impact team for the processing of this image and for providing it to us.

Although the development of ideas about the motion and trajectory of comets has been investigated piecemeal, we lack a comprehensive and detailed survey of ph- ical theories of comets. The available works either illustrate relatively short periods in the history of physical cometology or portray a landscape view without adequate details. The present study is an attempt to review - with more details - the major physical theories of comets in the past two millennia, from Aristotle to Whipple. My research, however, did not begin with antiquity. The basic question from which this project originated was a simple inquiry about the cosmic identity of comets at the dawn of the astronomical revolution: how did natural philosophers and astronomers define the nature and place of a new category of celestial objects - comets - after Brahe's estimation of cometary distances? It was from this turning point in the history of cometary theories that I expanded my studies in both the pre-modern and modern eras. A study starting merely from Brahe and ending with Newton, without covering classical and medieval thought about comets, would be incomplete and leave the fascinating achievements of post-Newtonian cometology unexplored.

The scientific meetings of the !AU are the !AU Symposia, !AU Colloquia, Regional Meetings in Astronomy held under the auspices of the !AU, the Commission Meetings, which may be Joint Meetings of Commissions, and !AU Joint Discussions. This variety means that almost any demand for a meeting can be provided for by the !AU structure, pro vided it is international in character, whatever may be the preferences of the proposers. The !AU General Assemblies include Co~ssion Meetings and Joint Discussions arranged by Commissions, together with the Invited Discourses, and it is these meetings that feature in this volume. The administrative work of the General Assembly is reported in the Transactions of the !AU and the Proceedings of the !AU Symposia, held in the host country or neighbouring countries during the year of a General Assembly, appear in the !AU Symposium Volume series. !AU Collo quium volumes are published separately. The Invited Discourses are a popular feature of the !AU General Assemblies and each of the three discourses presented at the XVIIth General Assembly in Montreal in 1979 appear in this volume. 1979 was the Centenary Year of the birth of Albert Einstein and the occasion was marked, for the !AU, by a discourse of great distinction from Professor S. Chandrasekhar of the University of Chicago, whose contri butions to astrophysics themselves cover fully a half-century. The Invited Discourse by G. Herzberg of the National Research Council of Canada, a Nobel Prizewinner, was equally notable as an !AU occasion.

Taking both a theoretical and observational perspective, this book is an introduction to recent developments in the field of celestial mechanics. It emphasizes the application to extended celestial bodies and devotes much attention to rotational aspects. In particular, it explains the state of art for accurate modelling of the rotation of celestial bodies such as the Earth, the Moon, and Mercury, which involves principles related to hydrodynamics and geodesy. Comparisons between the light curves of the asteroids and their rotational state are made and spatial techniques leading to the determination of the Earth's gravitational field are explained. Also, the book provides a general overview of the collisional processes in the solar system and of the dynamics of the rings. It is addressed to graduate students and researchers in space sciences and celestial dynamics.

Astronomy on the Personal Computer provides the reader with a thorough introduction to the computation of celestial mechanics, which is of particular significance to astronomical observation. Covering everything from astronomical and computational theory to the construction of rapid and accurate applications programs, this book supplies the necessary knowledge and software solutions for determining and predicting the positions of the Sun, Moon, planets, minor planets and comets, solar eclipses, stellar occultations by the Moon, phases of the Moon and much more. This completely revised edition makes use of the widely implemented programming language C++, and individual applications may be efficiently realized through the use of a powerful module library. The accompanying CD-ROM contains, in addition to the complete, fully documented and commented source codes, the executable programs for use with the Windows 95/98/NT and Linux operating systems.