The International Astronomical Union (IAU) was founded in 1919, in the wake of the First World War, together with its sister Unions in related natural sciences. It will thus turn 100 years in 2019. Written by a mixed team of insiders and outsiders, this book presents the IAU in the changing context of the historical, scientific and technological development of astronomy during the past 100 years. While much important scientific progress took place already before 1945, the book naturally focuses on the accelerating evolution during the second half of the century. In the past few decades, the previously narrow IAU focus on organising professional astronomy has broadened to include societally relevant activities such as addressing the hazard of asteroid impacts, the planetary status of Pluto in the Solar System, and the hugely successful International Year of Astronomy. Most recently, it is spearheading a combination of science literacy and public outreach. The book will be of interest to professional astronomers as well as an astronomically interested general audience. The book features live personal interviews with as many of the key actors as still possible.

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.

The XIXth General Assembly of the International Astronomical Union was held in New Delhi, India, from November 19 to 28, 1985. It was dedicated to the memory of a former IAU President, Professor M. K. V. Bappu, who tragically passed away on August 19, 1982. On the occasion of the Delhi General Assembly, the IAU Minor Planet Center announced that Minor Planet (asteroid) No. 2596 henceforth will carry the name Vainu Sappu. The full text of the announcement reads: "(2596) VAINU BAPPU = 1979 KN (diameter about 8 kilometers, period 5 years 4 months, mean distance from the Sun around 450 million kilometers) Discovered 1979, May 19, by R. M. West at the European Southern Observatory. Named in memory of Manali f

Seen from “inside the IAU,” this book tells the in-depth story of a major crisis in which China “divorced” from the International Astronomical Union in 1960 as a protest against the admission of Taiwan. This happened to all the scientific unions at the same time, and to the Olympic Games, which, unexpectedly, would serve as a laboratory for the “reconciliation” which took place following the re-opening of China to the world 20 years later. The so-called “China conflict” is the most important crisis in the post-WWII history of the IAU. Yet, many details about this conflict and its links to broader geopolitical events have long remained unsettled, obscure, or altogether absent. In particular, the book describes for the first time the “separation” period, which covered the Cultural Revolution, and in which the IAU made desperate official efforts to reach out to China, while some groups of Western and Chinese astronomers managed to keep contact at times. On the occasion of the IAU Centenary celebrations in 2019, the book revisits this painful succession of events using unpublished documents from the IAU Archives and the International Council of Scientific Unions. The book also contains supplementary typescripts of selected handwritten correspondences and the full translation of key original Chinese documents unknown to readers outside China. What emerges is a complex and fascinating story of human relations and science diplomacy under the shadow of the Cold War. Readers will learn how the 20-year “China conflict” as lived by astronomers and scientists is important not only for the history of the IAU, but also for the history of contemporary China. “This book is full of so many original documents of the IAU office, very reliable and good to open to the public readers.” Shuhua Ye, Shanghai Observatory (IAU Vice-President, 1988-1994) This book is a companion book to "Astronomers as Diplomats," published at the same time in the same series.

IAU Transactions XXIIB summarizes the work of the XXIInd General Assembly. The discourses given during the Inaugural and Closing Ceremonies are reproduced in Chapters I and III, respectively. The proceedings of the two sessions of the General Assembly will be found in Chapter II, which includes the Resolutions and the report of the Finance Committee. The Statutes, Bye-Laws and a few working rules of the Union are published in Chapter IV. The Accounts and other aspects of the administration of the Union are recorded in Chapter V, together with the report of the Executive Committee for this last triennium, and provide the permanent record for the Union in the period 1991-1994. This volume also contains the Commission reports from The Hague compiled by the Presidents of the Commissions (Chapter VI). Finally, Chapter VII contains the list of countries adhering to the Union and the alphabetical, geographical and commission membership lists of about 8000 individual members. The IAU still appears to be unique among the scientific Unions in maintaining this category of individual membership which contributes in a crucial way to the spirit and the aims of the Union.

The General Assemblies of the International Astronomical Union are landmarks in the life of the world-wide astronomical community, as they review, at triennial intervals, the progress made in this scientific field, promulgate the most spect acular astronomical achievements, formulate scientific programmes for the years to come and, last but not least, deal with the administration and finances of the IAU. The Reports on Astronomy 1976, published as Transactions XVIA (in 3 volumes) before the XVlth General Assembly, are a synopsis of the work done in astronomy from 1973 to 1975. The volume "Highlights of Astronomy , as presented at the XVlth General As sembly of the IAU in Grenoble, 1976" includes some selected scientific topics, and will appear in the first half of 1977. Apart from the Invited Discourses and the Proceedings of the seven Joint Discussions, the Highlights volume No.4 con tairsthe proceedings of two Joint Commissions Meetings.

The changing character of the IAU General Assemblies becomes most clear from a comparison of the agenda of the Brighton meeting with that of one of the earlier meetings. The fourth General Assembly (Cambridge Mass. , 1932) had about 240 participants, registered guests included, the Brighton meeting had about 2300 people attending. The Cambridge meeting lasted 5, working days, of which, however, three half days were exclusively devoted to excursions, leaving four real meeting days. At that time the nearly 30 commissions had each only one meeting, during part of a morning or afternoon; some commissions did not meet at all. There was one public lecture, by Sir Arthur Eddington, on 'The Expanding Universe'. Most of the small European countries were represented by two or three delegates only, but the delegations of France and Great Britain were composed of 20 and 18 scientists respectively; at that time there were only two delegates from Germany. After the Brighton General Assembly, with about 200 commission meetings - one commission met eleven times! - six Joint Discussions, four Invited Discourses, a Special Meeting and hardly time for excursions, there were a few complaints about too many overlapping meetings.