Astronomiske observationer: observatorier, udstyr og metoder

The XVlllth General Assembly of the International Astronomical Union was held in Patras, Greece, from 17-26 August 1982. It was marked by the tragic death of the President of the IAU, Professor M.K.V. Bappu, on August 19, 1982. This sad event, without precedent in the history of the Union, posed serious problems to the organization of the General Assembly, which could only be overcome by the full collaboration of all members, the organizers, and the Executive Committee. A tribute to the memory of Prof. Bappu was paid during a plenary meeting on 23 August 1982. The full texts of the speeches are published in Chapter I of this . volume. The excellent scientific programme in Patras was organized by the Presidents of the 40 IAU Commissions and coordinated by the IAU General Secretary (1979-1982), Professor P.A. Wayman. The local arrangements were taken care of by Professor C. Goudas and his collaborators from the Patras University. Due to the unexpected withdrawal in 1979 of another invitation to host the 1982 IAU General Assembly, the organizers in Greece had less than two years available for the extensive preparations, and our hearty thanks are due to them for their persistent efforts, which made this General Assembly an outstanding success.

The lAU Symposium No. 78, "Nutation and the Earth's Rotation," was held in Y~ev, USSR, from 23 to 28 May, 1977. The Organizing Committee included E. P. Fedorov and R. O. Vicente (Joint Chairmen), W. Fricke, J. Kovalevsky, P. Melchior, N. Pariisky, M. Rochester, C. Sugawa, G. Wilkins and Ya. Yatskiv, who presided over the Local Organizing Com­ mittee. The meeting was sponsored by Commission 19 and co-sponsored by Commissions 4, 8, and 31. There were 114 registered participants from 14 countries. The main topics covered were as follows: the specification of nutation in the lAU system of astronomical constants; determination of forced nutation and nearly diurnal free polar motion from astronomical observations; expected use of lunar ranging data and long baseline interferometers for precise measurement of the nutation terms; models of the internal constitution of the Earth as the basis of a new theory of nutation; the effect of the ocean and liquid core on the rotation of the Earth; and the interaction between Earth tides and nutation.

This volume of the Highlights of Astronomy contains the Invited Discourses and the proceedings or summaries of Joint Discussions, Special Sessions, and Working Group Meetings held at the XIInd IAU General Assembly in August 1994 in The Hague. While the three Invited Discourses are reproduced in the order of their appearance in the meeting programme, the Joint Discussions have been reordered according to their topics. Not included in this volume are the proceedings of the GA Symposia which will be published individually in the IAU Symposia series. I am most grateful to the authors of the invited discourses for preparing manuscripts in spite of heavy other commitments. It is a pleasure to express my appreciation of the work by Dr. Jacqueline Bergeron in organizing the XXIInd General Assembly, and I wish to thank all authors and meeting chairpersons for their cooperation and for providing their contributions in time to meet the customary publication schedule of this series. Special thanks are due to Ms. Monique Leger-Orine from the IAU office for considerable and patient assistance in the final editing, and to Dr. Tom Herbst from the Max­ Planck-Institute for Astronomy for permission to reproduce on the cover of this volume one of his IR images of Jupiter obtained just after the Comet Shoemaker-Levy 9 impact, one of the definite Highlights of Astronomy in 1994.

" The Hunt for Planet X is a fascinating tale by one of the world's premier astronomy writers. Govert Schilling is not only scrupulously accurate, he writes beautifully as well." Stephen P. Maran, Author of "Astronomy for Dummies" and Press Officer, American Astronomical Society " The Hunt for Planet X is an adventure story or, more accurately, a series of adventure stories. Schilling tells them well, capturing both the science and the people involved. It starts with the classics: Uranus, Neptune and Pluto; and moves all over the solar system as ground-based astronomers and space scientists pour over measurements and observations to try to understand the worlds around us. Current debates about the Pioneer Anomaly and the definition of what is a planet make the book current as well as a good history." Dr. Louis Friedman, Executive Director, The Planetary Society "This exciting tale of the centuries-old search for new planets in the solar system reads like a thriller. It is an adventure packed with fierce competition, brilliant discoveries, dumb errors, lucky coincidences and artful intrigue - in short, the full spectrum of the human drama. The story reaches an exciting climax in 2006, when we lost Pluto as a planet but gained a number of ice dwarfs in return. This colorful account chock-full of fascinating details is an excellent metaphor for the great adventure of science." Robbert Dijkgraaf, Professor of Mathematical Physics at the University of Amsterdam   The Hunt for Planet X: New Worlds and the Fate of Pluto goes beyond a standard scientific read, encompassing who, and what, is involved in the pursuit of planetary endeavors. Touching on over three-hundred years of debates, debacles and discoveries, this book offers the reader insight into the minds and motives of planetary astronomers and their findings. The "hunt" continues tothe outer-most regions of the solar system, and Govert Schilling states this search will not cease: "Astronomy is an adventurous science," he writes, and without adventure and those who seek it out the universe would otherwise remain mysterious. The real-life characters presented in The Hunt for Planet X look for glimpses of light in the dark, from icy Kuiper Belt objects to full-fledged planets, in the process challenging how such worlds should be defined and ultimately describing the Universe.

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.

How can shadows determine the date and time of a painting by Johannes Vermeer? How did the Moon and tides cause the loss of King John's crown jewels?In his newest book, Professor Olson, author of Celestial Sleuth and Further Adventures of the Celestial Sleuth, explores how astronomical clues can uncover fascinating new details about art, history, and literature. He begins with an accessible introduction to amateur "e;celestial sleuthing,"e; showing how to use your astronomical knowledge, software, archives, vintage maps, historical letters and diaries, military records, and other resources to investigate the past.Follow along as Professor Olson then explores twenty real-world cases where astronomy has helped answer unresolved questions or correct longstanding interpretations about an event. Examples involve artists such as Vermeer, Monet, and O'Keeffe; the historical exploits of Alexander the Great, the desert travels of the Death Valley '49ers, and a meeting between Franklin D. Roosevelt and Winston Churchill in Marrakech; and literary works by Chaucer, Shakespeare, and Longfellow.Packed with dozens of full-color illustrations, this book will enrich your knowledge of the past and equip you with all the tools you'll need to become a celestial sleuth yourself."e;Many people have a passion for art, or world history, or great literature, or even astronomy - but seldom in all these things at once. This remarkable book by Donald Olson of Texas State University will put you in touch with such seemingly unrelated endeavors. It will open your eyes and broaden your mind as little else could."e;Roger W. Sinnott, Sky & Telescope