International Astronomical Union

• 1. Introduction

  ›

  The International Astronomical Union holds the power to name things. Worlds, craters, stars, asteroids drifting through the dark between planets: every official designation attached to a body in the sky passes through one organization, founded on the 28th of July 1919 in Brussels, Belgium. That authority was not invented recently. It was written into the IAU's charter from the moment of its birth, just eight months after the end of the first World War, when scientists from seven nations gathered to decide how the heavens would be catalogued by all of humanity together. What kind of organization earns that trust? How does an assembly of astronomers set the rules for an entire planet's sky? And what happens when those rules collide with a world that does not want to be reclassified?

• 2. Born From War's Aftermath

  ›

  Benjamin Baillaud of France became the IAU's first President when the organization formally came into existence at the Constitutive Assembly of the International Research Council in Brussels. The founding roster was spare but globally distributed: Belgium, Canada, France, Great Britain, Greece, Japan, and the United States. Italy and Mexico joined soon after. Alfred Fowler of the United Kingdom served as the first General Secretary, and four vice presidents rounded out the executive committee: William Campbell of the United States, Frank Dyson of the United Kingdom, Georges Lecointe of Belgium, and Annibale Riccò of Italy.

  Thirty-two bodies, called Standing Committees at the time and later renamed Commissions, were appointed at that Brussels meeting. Their topics ranged from relativity to minor planets. When the first General Assembly convened in Rome in May 1922, the reports of those thirty-two Commissions formed the backbone of the proceedings. Ten more nations had joined by the end of that Rome gathering, bringing total membership to nineteen countries. Australia, Brazil, Czechoslovakia, Denmark, the Netherlands, Norway, Poland, Romania, South Africa, and Spain all entered in that first wave of expansion.

  What made the founding feel less like a new invention and more like a formalization was the weight of existing cooperation behind it. Astronomical collaboration had been alive well before the war. The Astronomische Gesellschaft Katalog projects had been running since 1868. The Astrographic Catalogue began in 1887. The International Union for Solar Research was active from 1904. The IAU was, in part, an architecture built to house something that already existed.

• 3. The Naming Authority

  ›

  On the second floor of the Institut d'Astrophysique de Paris, in the 14th arrondissement, sits the head office of the organization that decides what the craters on Mars are called. The IAU's authority over naming is not ceremonial. It is the recognized global standard for assigning designations and names to celestial bodies including stars, planets, and asteroids, and to any surface features on them.

  Two working groups carry the day-to-day weight of that responsibility. The Working Group for Planetary System Nomenclature maintains the conventions and systems for naming features on planetary bodies. The Working Group on Star Names catalogues and standardizes the proper names given to individual stars. These are not small rosters: the IAU's membership spans 90 countries and territories.

  In 2015 and again in 2019, the Union held contests called NameExoWorlds, opening the naming of exoplanets to public participation under IAU oversight. The contests extended the naming function outward from professionals toward the public, while the formal authority remained with the Union. The Minor Planet Center, which operates under the IAU, serves as the clearinghouse for every non-planetary and non-moon body in the Solar System, tracking and cataloguing the objects that fall outside the major categories.

  The IAU also coordinates the system of astronomical telegrams, produced and distributed through the Central Bureau for Astronomical Telegrams. That bureau was created alongside the IAU itself at the 1919 Brussels assembly, initially seated in Copenhagen, Denmark. It has carried the function of rapid, verified communication about celestial events across the entire history of the organization.

• 4. How the Assembly Governs

  ›

  The General Assembly is the sovereign body of the IAU, and every individual member belongs to it. Since 1922, it has met every three years, with one gap: the period between 1938 and 1948 was skipped because of World War II. In September 1973, after a Polish request in 1967, the then-President of the IAU made the controversial decision to hold an Extraordinary General Assembly in Warsaw, Poland. Its purpose was to mark the 500th anniversary of the birth of Nicolaus Copernicus, held separately from the regular 1973 assembly that had already convened in Sydney.

  Voting inside the Assembly is divided. On matters the Executive Committee designates as primarily scientific, only individual members vote. On everything else, including changes to the Statutes and procedural questions, national member representatives hold the vote. Budget votes are weighted by subscription level. A second-category vote requires at least two-thirds of national members to participate for the result to be valid. Statute changes require a two-thirds majority to pass. When votes end in a tie, the President of the Union casts the deciding ballot.

  As of the 1st of August 2019, the IAU had 13,701 individual members drawn from 102 countries. Of those members, 81.7% were male and 18.3% were female. National members at that time numbered 82, representing professional astronomical communities from across the globe: bodies such as the Chinese Astronomical Society, the French Academy of Sciences, the Royal Astronomical Society of the United Kingdom, the Russian Academy of Sciences, and the National Academies of the United States, among many others.

• 5. Teaching the Sky

  ›

  Commission 46 occupies a specific role among the IAU's internal structures: it sits on the Executive Committee and engages directly with governments and national scientific academies about astronomy education. Its reach extends into classrooms. The Teaching Astronomy for Development program, known as TAD, focuses on countries where formal astronomical education is scarce or absent.

  A second initiative under Commission 46 is the Galileo Teacher Training Program. The GTTP began as a project of the International Year of Astronomy 2009 and includes a component called Hands-On Universe, which concentrates resources on activities designed for children and schools. The program's explicit aim is advancing sustainable global development through science education, and it works to transfer astronomy tools and methods into existing classroom curricula. A strategic plan for the decade 2010-2020 was published to guide that work.

  In 2004, the IAU entered a publishing contract with Cambridge University Press to produce the Proceedings of the International Astronomical Union. Three years later, in 2007, a working group assessed whether a dedicated journal for public astronomy communication was feasible. That study led toward the Communicating Astronomy with the Public Journal, reflecting the IAU's ongoing interest in bridging professional research and wider audiences. Starting in 2024, the IAU entered a partnership with the United Nations to help shape the legislation and framework for the industrialization of the Moon.