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Jets are ubiquitous in the Universe, but ill-understood. Conservative books base their interpretations on focused stellar winds, ejected'bullets', black-hole central engines, and in-situ upgrading of electron energies via shocks. This volume, however, attempts a uniform interpretation of the bipolar-flow family, involving extremely relativistic pair plasma as the jet substance, and rotating magnets (possibly burning disks) as the central engines. Among the discussed sources are SS 433, YSO jets, planetary nebulae, our galactic center, and the class of extragalactic QSOs, both radio-loud and radio-quiet.

For many years I was organizing a weekly seminar on dynamical astronomy, and I used to make some historical remarks on every subject, including some anecdotes from my contacts with many leading scientists over the years. I described also the development of various subjects and the emergence of new ideasindynamicalastronomy. Thenseveralpeoplepromptedmetowritedown these remarks, which cannot be found in papers, or books. Thus, I decided to write this book, which contains my experiences over the years. I hope that this book may be helpful to astronomy students all over the world. During my many years of teaching, as a visiting professor, in American Universities (1962-1994, Yale, Harvard, MIT, Cornell, Chicago, Maryland and Florida) I was impressed by the quality of my graduate students. Most of them were very bright, asking penetrating questions, and preparing their homework in a perfect way. In a few cases, instead of a?nal examination, I assigned to them some small research projects and they presented their results at the end of the course. They were excellent in preparing the appropriate slides and in presenting their results in a concise and clear way.

This set of lectures collects surveys of open problems in celestial dynamics and dynamical astronomy applied to solar, extra-solar and galactic systems. Emphasis is on questions of stability of planetary systems. In particular the discovery and thus the possibility to study many new extra-solar planetary systems have spurred new developments in the field and enabled the testing and enlargement of the domains of validity of theoretical predictions through the Nekhoroshev theorem.

An International Conference entitled'Close Binaries in the 21st Century: New Opportunities and Challenges', was held in Syros island, Greece, from 27 to 30 June, 2005. There are many binary star systems whose components are so close together, that they interact in various ways. Stars in such systems do not pass through all stages of their evolution independently of each other; in fact their evolutionary path is significantly affected by their companions. Processes of interaction include gravitational effects, mutual irradiation, mass exchange, mass loss from the system, phenomena of extended atmospheres, semi-transparent atmospheric clouds, variable thickness disks and gas streams. The zoo of Close Binary Systems includes: Close Eclipsing Binaries (Detached, Semi-detached, Contact), High and Low-Mass X-ray Binaries, Cataclysmic Variables, RS CVn systems, Pulsar Binaries and Symbiotic Stars. The study of these binaries triggered the development of new branches of astrophysics dealing with the structure and evolution of close binaries and the interaction effects displayed by these exciting objects. Close Binaries are classic examples of the fundamental contribution that stellar astrophysics makes to our general understanding of physical processes in the universe. Ground-based and space surveys will discover many new close binaries, which were previously unknown. In the future, new approaches will also be possible with highly efficient photometric searches looking for very shallow eclipses, such as those produced by Earth-like extra-solar planets. Contributions to this conference covered the latest achievements in the field and reflected the state of the art of the dynamically evolving area of binary star research.

Comets are small bodies, but of great cosmic relevance. Given its pristine nature, they may preserve valuable and unique information on thechemical and physical processes that took place in theearly solar system, and that may be occurring in the formation of other planetary systems. They might have even played a very important role in the origin of life on Earth. Beyond that, since ancient times comets have inspired awe, superstition, and also curiosity anddebate. Their sudden apparitions challenged the long-held view of the immutability of the heavens, which triggered a long debate on whether comets had a heavenly or terrestrial nature. Therefore, comets have a prominent role in the history of scienti?cthought, that goes back to the most ancient civilizations. The last apparition of comet Halley in 1986 was a landmark since it arouse a great expectation in the scienti?c community and in the public at large. For the?rst time, a?otilla of spacecrafts visited a comet. Agreat number of popular and technical books were written on Halley, and comets in general, around the mid-eighties. The interest in comets never subsided after Halley's passage which is re?ected in the large volume of printed material on these bodies. I have taken the challenge to write a new book on comets that summarizes most of the recent advances on thesubject, including my own workdeveloped during the last 25 years.

The Marcel Grossmann meetings were conceived to promote theoretical understanding in the fields of physics, mathematics, astronomy and astrophysics and to direct future technological, observational, and experimental efforts. They review recent developments in gravitation and general relativity, with major emphasis on mathematical foundations and physical predictions. Their main objective is to bring together scientists from diverse backgrounds and their range of topics is broad, from more abstract classical theory and quantum gravity and strings to more concrete relativistic astrophysics observations and modeling.This Tenth Marcel Grossmann Meeting was organized by an international committee composed of D Blair, Y Choquet-Bruhat, D Christodoulou, T Damour, J Ehlers, F Everitt, Fang Li Zhi, S Hawking, Y Ne'eman, R Ruffini (chair), H Sato, R Sunyaev, and S Weinberg and backed by an international coordinating committee of about 135 members from scientific institutions representing 54 countries. The scientific program included 29 morning plenary talks during 6 days, and 57 parallel sessions over five afternoons, during which roughly 500 papers were presented.These three volumes of the proceedings of MG10 give a broad view of all aspects of gravitation, from mathematical issues to recent observations and experiments.

Astrobiology, a new exciting interdisciplinary research field, seeks to unravel the origin and evolution of life wherever it might exist in the Universe. The current view of the origin of life on Earth is that it is strongly connected to the origin and evolution of our planet and, indeed, of the Universe as a whole. We are fortunate to be living in an era where centuries of speculation about the two ancient and fundamental problems: the origin of life and its prevalence in the Universe are being replaced by experimental science. The subject of Astrobiology can be approached from many different perspectives. This book is focused on abiogenic organic matter from the viewpoint of astronomy and planetary science and considers its potential relevance to the origins of life on Earth and elsewhere. Guided by the review papers in this book, the concluding chapter aims to identify key questions to motivate future research and stimulate astrobiological applications of current and future research facilities and space missions. Today's rich array of new spacecraft, telescopes and dedicated scientists promises a steady flow of discoveries and insights that will ultimately lead us to the answers we seek.

Since Newton's time many have proposed that gravitation arises from the absorption by material bodies of minute particles or waves filling space. Such absorption would cause bodies to be pushed into each other's shadows. The principal early proponent of this idea was Georges-Louis Le Sage. The essays in this book explore the remarkable three hundred year saga of Le Sage's theory, gravitational shielding and the experiments of Q. Majorana, and new and recent Le Sage Models.

A group of leading experts in the field of starbursts and active galactic nuclei have joined hands to produce this review volume which covers the starburst-AGN connection, and the tests to be carried out with the upcoming new astronomical facilities to ascertain the relevance of both components to the formation and evolution of galaxies.The book is addressed to advanced graduate students and researchers in the fields of active galactic nuclei and young galaxies.

The Local Group is a small cluster of galaxies that includes the Milky Way. At least half of all galaxies in the Universe are thought to belong to similar groups. This authoritative volume provides a comprehensive synthesis of what is known about the Local Group. It begins with a summary of each member galaxy, as well as those galaxies previously regarded as possible members. The book examines the mass, stability and evolution of the Local Group as a whole and includes many important previously unpublished results and conclusions. With clarity, Professor van den Bergh provides a masterful summary of all that is known about the galaxies of the Local Group and their evolution, and expertly places this knowledge in the wider context of on-going studies of galaxy formation and evolution, the cosmic distance scale, and the conditions in the early Universe.

This unique volume is a collection of papers on various problems in astrophysics and cosmology — from planetary motion to the arrow of time — that are closely linked by the common spirit, technique and methodology of chaos.

This volume comprises lectures delivered at the First Equatorial School of Relativistic Astrophysics. It covers various topics related to observational and theoretical problems of galaxies, quasars and cosmology. The aim is to analyze current problems.

Recent research on the theory of perturbations, the analytical approach and the quantitative analysis of the three-body problem have reached a high degree of perfection. The use of electronics has aided developments in quantitative analysis and has helped to disclose the extreme complexity of the set of solutions. This accelerated progress has given new orientation and impetus to the qualitative analysis that is so complementary to the quantitative analysis.The book begins with the various formulations of the three-body problem, the main classical results and the important questions and conjectures involved in this subject. The main part of the book describes the remarkable progress achieved in qualitative analysis which has shed new light on the three-body problem. It deals with questions such as escapes, captures, periodic orbits, stability, chaotic motions, Arnold diffusion, etc. The most recent tests of escape have yielded very impressive results and border very close on the true limits of escape, showing the domain of bounded motions to be much smaller than was expected. An entirely new picture of the three-body problem is emerging, and the book reports on this recent progress.The structure of the solutions for the three-body problem lead to a general conjecture governing the picture of solutions for all Hamiltonian problems. The periodic, quasi-periodic and almost-periodic solutions form the basis for the set of solutions and separate the chaotic solutions from the open solutions.

Together with Virgo, the Coma Berenices cluster is one of the most well-studied clusters at all wavelengths and in all aspects, from the Sunyaev-Zeldovich effect to star formation in galaxies. In a way, it is the prototype of rich clusters. Recent observational results, linked to the improvement of techniques such as X-ray and UV observations, along with multi-object spectroscopy, have shown that they could change our vision of this cluster. It is thus time for observers and theoreticians to confront all these new ideas and observations on the Coma cluster.The topics in this volume include: cosmological aspects of the Coma cluster, comparison with distant clusters; substructures; matter content and distribution; Sunyaev-Zeldovich effect; dynamical modelling, cluster dynamics; environmental effects on galaxies, star formation.