Throughout his career, George Ellery Hale thought globally. “Make no small plans” he was often heard to say (Seares 1939). His early sojourns to Europe, encountering the talent and resources in England and the Continent, contributed to his outlook. He knew that their patronage was critical to reach his personal goals. Here I outline the steps Hale took to establish the new “astrophysics” as a discipline, by creating the Astrophysical Journal, establishing a common language and then, through the first decades of the 20th Century, building an international collaboration to coordinate solar and later all astronomical research. The latter effort, which began in 1904, had expanded by 1910 to encompass stellar astronomy, when the Solar Union deliberated over spectroscopic classification systems, a standard wavelength system and stellar magnitude systems. This work continued through the fifth Union meeting in Bonn in 1913, which turned out to be the last because of the First World War. During the war, Hale became Chair of the National Research Council of the U.S. National Academy of Sciences, applying scientific talent to winning the war. He was also the Academy’s Foreign Secretary, so Hale became deeply involved in re-establishing international scientific relations after the war. In conjunction with Arthur Schuster and Emile Picard, he helped found the International Research Council in 1919, which formed the framework within which the worlds of science reorganized themselves. From this, the International Astronomical Union was born. It was not an easy birth in a world still filled with tension and anger over the war; formative conferences in London and Brussels reflected the extremes. Nevertheless, its first General Assembly was held in Rome in 1922. It would be years before it became truly international, “in the complete sense of the word” (Elis Strömgren), but many of the proposals made during the years of the Solar Union concerning disciplinary standardization were ratified. I will concentrate on this latter story, remembering Hale for his devotion to true internationalism.

A century of existence: it may seem short on the time-scale of the evolution of the universe, but very consequential to that of a scientific association. The fact that the IAU may be able to celebrate such a milestone is in itself a meritorious collective achievement, for it was not obvious at the very beginning that this organization was going to last more than a decade. Drawing on the historical sociology of scientific institutions, my paper will discuss the moral economy through which the IAU – and its dated but persistent form of scientific internationalism – has stabilized and maintained its identity since its creation in 1919, under the unifying auspices of a global scientific object to be known as: Under One Sky.

The IAU is like an old house: Each of the IAU General Secretaries brings her/his individual skills, trying to fix it up. After the collective efforts of several General Secretaries, the house is hopefully kept in reasonable overall shape. But each General Secretary is also in principle responsible for everything, which means that priorities for the way you spend your time must be set – remembering that surprises may occur at any moment.

In my case, I’d like to single out five major initiatives taken during my term, which have probably proved useful in the longer term.

The International Astronomical Union was conceived in 1918, and was formed one year later in Brussels. One of the 32 initial Commissions was the Committee on Stellar Photometry that later on became IAU Commission 25 Astronomical Photometry and Polarimetry, and since 2015 Commission B6 with the same name. The initial functions to be exercised by the Committee were

1. (a) to advise in the matter of notation, nomenclature, definitions, conventions, etc., and

2. (b) to plan and execute investigations requiring the cooperation of several observers or institutions.

The basic philosophy was that IAU Commission 25 was to be an advisory body, rather than a decision-making committee that imposes its regulations. This position was reconfirmed at the 10th IAU General Assembly in 1958.

From the early days on, the Commission members engaged in the teaching of the principles of photometric measurement – either via the Commission meetings and the ensuing reports, or via external means, such as lectures and publications. The topics of instruction dealt with absorption of light in the atmosphere, the modification imposed by the character of the receiving apparatus, the unequal response of different receivers to a same stimulus, and variations in the data-recorder response from one experiment to another.

From the 1930s on it was suggested that IAU Commission 25 takes responsibility in matters of standard stars, standard filters and standard calibration methods.

During the first half-century since its foundation, Commission 25 was an active forum for discussions on the basic principles of astronomical photometry, including the associated problems of transformability of magnitudes and colour indices from one instrumental configuration to another. During the second half-century of its existence, the Commission has served as a sort of news agency reporting on the developments in detector engineering, filter technology and data reduction. All along the Commission members were committed to accuracy and precision, a struggle that was primarily driven by the jumps forward in performance and sensitivity of every new detector that was introduced.

The development over one century shows that the Commission was continuously touching on the philosophy of precise measurement, where accurate measuring – for a select group of pioneers – was an end in itself.

This presentation looks back on the opinions of key players in the photometric standardisation debate, and briefly presents two case studies that illustrate the illusionary accuracy reached over a century in determining, as Commission member Ralph Allan Sampson put it, “a detail like magnitude”.

In this presentation the author narrates some key episodes of his life of serving the IAU for more than seventy years.

Astronomy, more than most sciences, requires an international collaboration. It is the duty of the IAU to insure, between astronomers of the whole world, scientific and human relations. Less than 1,000 astronomers at the time (1946) of my first papers, more than 10,000 today: this means many international collaborations, and many faithful friendships, through several General Assemblies, and many Symposia and Colloquia. To the young astronomers, I must only wish : Cheer up !

Not being able to participate to the XXXth General Assembly in Vienna, the author sent a video presentation (available on the Vienna GA web site), and also provided a spoken text (in French) that was rendered in written form by a voice-to-text software. This text, a recollection of the author’s life “inside the IAU”, was then translated and formatted by Chris Sterken. The English version follows; the original French text is included as an Appendix.

The 5-decade old ISYA program is evaluated in the context of the experience gathered in the field: 41 schools organized in 27 countries with a total of more than 1400 students to date. In the new era of fast internet connectivity, social media, virtual networks, big data and machine learning, the value of face-to-face graduate schools for regions with limited up-to-date astrophysics research is presented, together with the plan to develop the ISYA program into the next decade.

It is no coincidence that IAU and Saha’s ionization formula are about the same age. Both events are related to World War 1 and connected with Germany though in entirely different ways.

Once sufficiently large number of stellar spectra had been obtained and empirically classified according to the Harvard scheme, it was inevitable that theoretical explanation would be forthcoming. The only surprise was that the breakthrough came from the far-off Calcutta which was nowhere on the world research map.

History chose the hour; the hour produced an unlikely hero: Meghnad Saha. Calcutta University had just become a research centre under Indian auspices. By a fortuitous combination of circumstances immediately after the war, the latest German language physics publications arrived in Calcutta as a personal library. While Europe needed time to resume scientific exchanges and activity, India seized the opportunity and produced two outstanding pieces of theoretical work: Saha’s ionization formula (1920), and Bose statistics (1926). It is to the credit of The Royal Society that it elected Saha as a member (1927) in spite of the government’s objections arising from Saha’s anti-British stance. Saha however was unable to carry out further observational and experimental work suggested by the theory.

Saha was a multi-faceted personality with strong views on political ideology, the role of science in a new nation and other topics. India’s charismatic Prime Minister, Jawaharlal Nehru, during 1947-1964 had a soft corner for sophisticated, suave, upper-crust people. Impatient and angry, confrontational rather than persuasive, Saha did not qualify.

Saha is justly regarded as one of the founders of theoretical astrophysics. Examination of his life and work is a rewarding exercise from various points of view: development of modern astronomy; Western science and the non-West; and political and social activism of a leading scientist and educator.

Publications of the International Astronomical Union (IAU), such as Proceedings of IAU Symposia and Colloquia, contain biographical notes and papers as well as obituaries. Of great value are also the death announcements in the IAU Information Bulletins that contain the only biographical data known for about 200 astronomers. The kind of data given in these announcements varied over time. References to these data can be found in the Biographical Index of Astronomy. Recently the printed announcements were replaced by entries in the on-line IAU membership database.

Inspiring Stars (IS) is an itinerant international exhibition promoted by the International Astronomical Union (IAU) to disseminate world initiatives addressing inclusion in astronomy at the professional level. It encompasses (but is not limited to) outreach, teaching and professional aspects of astronomy, with the ultimate goal of evolving from a levelling the playing field to egalitarian participation by all. Here we present the work-in-progress, a framework of bridging activities and inclusion in the social context, which may provide Inspiring Stars with the potential to motivate the next generation and to document comparable data on inclusion in astronomy.

The Arab Astronomical Society (ArAS) was officially created during the constitutional assembly held in Marrakech (Morocco) on November 30, 2016, and legally recognized on May 15, 2017. ArAS is composed of a group of Arab researchers and students in the field of astrophysics who aim to develop research in this field in the Arab world (22 countries). ArAS is working on bridging the gap between the Arab astrophysicists in the Arab world and those around the world by organizing collaborative workshops and international scientific meetings, offering scholarships and developing graduate programs in astrophysics. Presently, the Society is working on establishing personal and material scientific infrastructure in the Arab world by training advanced undergraduate and graduate students in astrophysics and stimulating the building of new telescopes on the best sites in the Arab world. This will be accomplished through the hosting of specialized schools and conferences in astrophysics, international collaborations, facilitation of students’ and post-docs’ training in international research centres and universities, the establishment of prizes in astronomy to honour leading Arab scientists in astronomy and to motivate junior researchers to present notable works in astronomy. In this work, we present the on-going ArAS activities as well as future projects. ArAS is a young but energetic organization which is welcoming collaborations and partnership with other groups.

The IAU promotes astronomy as a tool to strengthen science education of young people in developing regions through its International Schools for Young Astronomers (ISYA) and a Teaching for Astronomy Development (TAD) programme. This article describes briefly the strategy, organization and development of these programmes. The contents of the courses, tutorials and aims for longer-term effects of these programmes are described with focus on the ISYAs.

This work aims to present the partial results of a project to collect and analyze all the issues of the Newsletters of Commission C1 (Astronomy Education and Development), formerly named Commission 46. The sources and the (hard) work to obtain printed editions, digitalize and make them available on the Internet are shown. Over 40 years, 86 issues from 1977 until 2017 were published. The Newsletters list the structure of the Commission featuring the names of presidents, vice-presidents, organizing committee, editors, printing and distribution responsible with editorial and presidential letters in the cover. A preliminary analysis of contents of the published material is done. The results present the main subjects of stories that were related to papers, teaching materials, book reviews, courses and meetings. Many solar eclipses and other phenomena were reported. Reports of important projects of the commission were published, such as: International Schools for Young Astronomers (ISYAs), the travelling telescope among others WG projects. Stories of travels and triennial reports from many countries were continuously published presenting many actions and activities for all school levels, non-school activities such as planetariums and many other astronomy subjects. Reports of the education sessions and business meetings held during the IAU GAs and projects in developing countries complemented these publications. Occasionally, papers dealing with great questions and subjects can be found. There are many published contributions that show the participation of many members from many countries and the efforts to improve the astronomy education throughout the world. The surveyed material can be very useful for the next generations of astronomy education researchers, practitioners and teachers, not only as a repository of historical documents, but also as an inspiration for future projects.

This paper tells the story behind the succession of reforms that, for the last twenty years, progressively brought the IAU in line with the fast developments of astronomy and the public awareness of the sky worldwide. One major difficulty was how to organize the scientific activities of an exponentially growing population of astronomers, from 200 at its creation in 1919, in the aftermath of WW I, to over 13 500 a century later. The first attempts at “restructuring the IAU”, as the expression went, can be dated back to the 1988–1991 triennium. As shown by the Minutes of the successive meetings of the Executive Committee, the attempted strategy was to encourage and even propose Commission mergers, but this policy met with strong opposition, even though a need for change was felt increasingly necessary. The new approach proposed by L. Woltjer, then incoming IAU President, during the 1994 General Assembly at The Hague, was to retain the existing Commissions (along with their Working Groups) but grouping them, more or less topically, into a dozen Divisions. Putting an end to the Commission merger deadlock, this new structure was adopted very quickly, and confirmed at the following GA in Kyoto (1997). But even after this restructuring, there was little evolution of the Commissions, and in some areas the scientific classification and breakdown of the IAU activities reflected by Divisions became questionable. As a result, a new reform was undertaken in 2009, based on a more global approach, but keeping the Division/Commission/Working Group three-tier structure as the backbone of the reforming efforts. Thanks to a close collaboration between the Executive Committee and the Division Presidents, the Divisions were first redefined and approved at the Beijing GA in 2012, followed by a historic, full-fledged “Commission reset”, itself approved at the Honolulu GA in 2015. This marked the end of a structure created almost a century before, at the foundation of the IAU: the Standing Committees, precursors to the Commissions. But in response to a Call for Proposals issued by the Executive Committee, the “reset” gave birth to a whole new Commission structure, conceived by the community itself.

The aim of this work is to provide new information about the history of astronomical science and the efforts of the people that have enriched our discipline, often coming from anonymity. Here we compile the attempts made in our country to prove the theory of General Relativity through experiments that, as they were without success, fell into oblivion.

The IAU was founded in 1919 “to facilitate the relations between astronomers of different countries where international co-operation is necessary or useful” and “to promote the study of astronomy in all its departments”. These aims have led the IAU throughout the century of its existence, but the way it has tried to fulfil them has changed. We have tried to trace the changing role of the IAU in the international astronomical community through the twentieth century and into the twenty-first. The IAU has striven – occasionally struggled – to protect international scientific cooperation across the deep political divides that characterized the 20th century, while maintaining an important function in the context of the rapidly evolving science itself and the changing fabric of institutions involved in astronomy. We especially argue how the emphasis of the IAU’s activities has shifted from the first aim – facilitating collaboration by organizing meetings and defining common standards – to the second aim: promoting astronomy by outreach and development programs.

During its XXXth General Assembly, the International Astronomical Union (IAU) welcomed the island of Madagascar, under the Malagasy Astronomy & Space Science (MASS), as one of its new National Members. Founded in 2016, MASS is a non-profit association, a community of young professional astronomers and graduate students from Madagascar. As various organizational structures are gradually being established towards the development of Astronomy & Astrophysics in the country, the IAU has played a vital role and is still actively involved in achieving such ambitious goals.

The Minor Planet Center, established in 1947 by the IAU, is the international repository and clearinghouse for the world’s minor planet observations. Since 1989, CCD surveys of Near Earth Objects at ground-based astronomical observatories are operational, mainly in the USA. As of 23 August, 2018, a total of 18,545 Near Earth Asteroids (NEAs) and 107 Near Earth Comets (NECs) have been registered and daily updates are made publicly available on the internet by the MPC, NASA-JPL-CNEOS and ESA-SSA-NEOCC.

Concern about the possibility of NEO impacts has been picked up by the United Nations Committee on the Peaceful Uses of Outer Space (UN-COPUOS), where the IAU has observer status, and formally expressed since 1999. This led in 2014 to the formation of two international coordinating bodies for NEO detection and NEO impact mitigation: the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG).

In support of these developments, the IAU 28th General Assembly, Session II, held in Beijing on 30 August 2012, adopted a Resolution (3B) recommending the establishment of an International NEO EarlyWarning System, as proposed by the IAU Division III (now Division F) Working Group on Near-Earth Objects. The GA recommended “… that the IAU National Members work with the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) and the International Council for Science (ICSU), to coordinate and collaborate on the establishment of an International NEO Early Warning System, relying on the scientific and technical advice of the relevant astronomical community, whose main purpose is the reliable identification of potential NEO collisions with the Earth, and the communication of the relevant parameters to suitable decision makers of the nation(s) involved. ….”

The NEO hazard issue received world-wide attention on 13 February 2013 when a NEA with an estimated size of 17 to 20 meters and an estimated mass of 11,000 tons exploded over Chelyabinsk (Russia), releasing 440 kT TNT of energy at an altitude of ∼23 km.

Subsequently, on 5 December 2014, the United Nations General Assembly adopted a Resolution (69/85, 9–10), noting “… the importance of information-sharing in discovering, monitoring and physically characterizing potentially hazardous near-Earth objects to ensure that all countries, in particular developing countries with limited capacity in predicting and mitigating a near-Earth object impact, are aware of potential threats, emphasizes the need for capacitybuilding for effective emergency response and disaster management in the event of a near-Earth object impact, .…”

In spite of all dedicated NEO surveys operational to date, the present inventory and thus our assessment of the level of threat of NEOs is severely limited by their huge number and by the available observational capabilities. E.g., while the estimated number of all NEOs larger than 40 meters in diameter is ∼700, 000, only ∼2% have been detected to date. For NEOs with sizes between 40 and 140 meters, the detection percentage amounts to less than 1% of the estimated number. Only dedicated space-based surveys, preferably in the infrared, will be able to provide the much needed orders of magnitude improvement in the detection, tracking and characterizing of NEOs. One promising project is the NASA-JPL NEOCam mission, studied since 2005 but not yet approved: a dedicated infrared observatory aiming to detect, track and characterize NEO’s from the Sun-Earth Lagrange point L1.

As Yeomans puts it: we better find them before they find us (Yeomans 2013). Traditionally, astronomers are looking back into the past, if only because of the limited speed of light. But we should realize that the clear and present danger posed by hazardous Near Earth Objects to mankind and all other life forms obliges us to look also forward, into the future. Provided with the proper means, we astronomers can do that, as a small service to society, including ourselves. The astronomical community at large should give high priority to NEO survey projects, in particular space-based surveys.

I have written elsewhere from a (mostly) celebratory point of view about early international astronomical projects. This version looks at some of the same projects, but from a less cheerful point of view.