The idea of the organization of a Symposium on Spiral Structure came at a special meeting of Commission 33 on Spiral Structure during the 12th General Assembly of the IAU in Prague, 1967. So much interest was shown during this meeting that one of us proposed a special Symposium on the 'Spiral Structure of Our Galaxy' for 1969. The response was immediate and it was finally agreed upon holding the Symposium in Basel, a center of galactic research in the center of Europe. During the next months a special 'List of Problems', related to this Symposium, was sent to many prospective participants by the president of Commission 33. This stimulated an increase of interest in problems of galactic spiral structure and a con centrated effort on some problems. The organizing Committee of the Symposium was composed of Drs. L. Woltjer (president), W. Becker, A. Blaauw, B. J. Bok, G. Contopoulos, F. J. Kerr, C. C. Lin, S. W. McCuskey and S. B. Pikel'ner. Most of the work for the organization of the Symposium was carried by Dr. L. W oltjer. The Local Committee, composed of Drs. W. Becker, U. W. Steinlin, R. P. Fenkart, and G. A. Tammann, made every effort to secure the success of the Symposium. Most of the credit goes to Dr. Steinlin. The Symposium was supported financially by the IAU and by the Swiss National Science Foundation. The meetings took place at the University of Basel, which provided also secretarial help and many other facilities.

How does it happen that billions of stars can cooperate to produce the beautiful spirals that characterize so many galaxies, including ours? This book presents a theory of spiral structure that has been developed over the past three decades under the continuous stimulus of new observational studies. The theory unfolds in a way that can be grasped by any reader with an undergraduate science background who is interested in astronomy, as well as by graduate students and scientists actively involved in astronomy or related subjects who want to see the "backbone" and the physical content of the theory. The foundations of this theoretical framework were laid in the early 1960s, following the pioneering work of B. Lindblad. C. C. Lin had already contributed significantly to the field of fluid mechanics when he turned his attention to spiral structures, and he has focused on the problem ever since. Giuseppe Bertin joined this research effort when he first visited at MIT in 1975, bringing to the project knowledge from his work on elliptical galaxies and plasma astrophysics. Together, Bertin and Lin have contributed to the exciting developments on spiral structure of the last few decades, working closely with many observers and other theorists. In this book they describe the density-wave theory with the goal of making the key concepts and astrophysical implications explicit and accessible. The essence of the solution Bertin and Lin present is that the spirals are wave rather than material phenomena and generally trace intrinsic characteristics of the individual galaxies. The book is in three parts--Physical Concepts, Observational Studies, and Dynamical Mechanisms--with most of the technical details confined to the last part.

How does it happen that billions of stars can cooperate to produce the beautiful spirals that characterize so many galaxies, including ours? This book reviews the history behind the discovery of spiral galaxies and the problems faced when trying to explain the existence of spiral structure within them. In the book, subjects such as galaxy morphology and structure are addressed as well as several models for spiral structure. The evidence in favor or against these models is discussed. The book ends by discussing how spiral structure can be used as a proxy for other properties of spiral galaxies, such as their dark matter content and their central supermassive black hole masses, and why this is important.

'Bite-sized, cutting edge science delivered with enormous enthusiasm - all you need to travel the cosmos' CHRIS LINTOTT 'A lot of astrophysics is packed into this neat little book . . . I guarantee you will come away knowing your dark matter from your supermassive black holes' JIM AL-KHALILI This book is for anyone who wants to easily understand the mind-blowing fundamentals of our extraordinary, expanding universe. Written by Oxford astrophysicist Dr Becky Smethurst and composed of ten captivating, simple essays, it guides you swiftly through the galaxies, explaining the mysteries of black holes, dark matter and what existed before the Big Bang, presenting the evidence as to whether we really are alone, illuminating what we still don't know, and much more besides. If you have big questions about Space, this book will provide you with the answers in an engaging and succinct way.

A concise and up-to-date guide to the shape of galaxies and how they can be classified, by one of the pioneers of the field.

Prior to the 1920s it was generally thought, with a few exceptions, that our galaxy, the Milky Way, was the entire Universe. Based on the work of Henrietta Leavitt with Cepheid variables, astronomer Edwin Hubble was able to determine that the Andromeda Galaxy and others had to lie outside our own. Moreover, based on the work of Vesto Slipher, involving the redshifts of these galaxies, Hubble was able to determine that the Universe was not static, as had been previously thought, but expanding. The number of galaxies has also been expanding, with estimates varying from 100 billion to 2 trillion. While every galaxy in the Universe is interesting just by its very fact of being, the author has selected 51 of those that possess some unusual qualities that make them of some particular interest. These galaxies have complex evolutionary histories, with some having supermassive black holes at their core, others are powerful radio sources, a very few are relatively nearby and even visible to the naked eye, whereas the light from one recent discovery has been travelling for the past 13.4 billion years to show us its infancy, and from a time when the Universe was in its infancy. And in spite of the vastness of the Universe, some galaxies are colliding with others, embraced in a graceful gravitational dance. Indeed, as the Andromeda Galaxy is heading towards us, a similar fate awaits our Milky Way. When looking at a modern image of a galaxy, one is in awe at the shear wondrous nature of such a magnificent creation, with its boundless secrets that it is keeping from us, its endless possibilities for harboring alien civilizations, and we remain left with the ultimate knowledge that we are connected to its glory.