International Astronomical Union

Roles and responsibilities

The IAU has several core responsibilities. It establishes conventions and definitions used across astronomy, adjudicates formal names for planets, moons, asteroids and surface features, and promotes best practices for astronomical data and nomenclature. The union organizes international meetings to set community standards, issues resolutions adopted at its General Assembly, and supports outreach and educational efforts worldwide. For information about the IAU as an international body and for links to partner organizations see official resources such as national astronomical societies and observatories like the ones listed by national members.

Organization and membership

Membership is composed of two main categories: National Members, which are generally national academies or professional societies that represent the astronomical community of a country, and Individual Members, who are professional astronomers. The IAU also maintains formal links with amateur groups and other science organizations. Its governance includes an Executive Committee, a number of Divisions and Commissions (or their modern equivalents), and many working groups that focus on specialized tasks. Details on governance and membership categories are available through institutional contacts and documentation such as those provided to astronomical communities and collaborating bodies listed at global partner pages.

History and notable decisions

Established in 1919, the IAU has played a central role in formalizing astronomical terminology and standards. One of its most publicized decisions was the 2006 resolution that defined the term "planet" for the Solar System and introduced the formal category "dwarf planet," a change that affected Pluto's classification. The union's triennial General Assembly is where major resolutions and policy statements are debated and adopted; past assemblies have set standards for coordinate systems, timekeeping conventions, and nomenclature rules. Historical context and records of resolutions can be consulted through archival summaries and institutional reports accessible via member organizations and the IAU's documentation pages such as founding history and subsequent assemblies summarized at assembly records.

Working groups, naming, and examples

Specialized working groups carry out much of the IAU's technical work. Two well-known examples are the Working Group for Planetary System Nomenclature (WGPSN), which maintains official names for features on planets and moons, and the Working Group on Star Names (WGSN), which curates approved proper names for stars. Other groups advise on small-body designations, exoplanet naming procedures, and conventions for astronomical catalogues. The IAU also recognizes and cooperates with entities that catalog discoveries, and it acts as the international authority when a consistent name or designation is required. For procedural details and naming protocols consult the IAU's thematic pages such as those referenced by nomenclature resources, star-name guidelines, and related working group pages like working group listings.

Importance, outreach and how to engage

Beyond professional standards, the IAU fosters public engagement with astronomy through outreach initiatives and partnerships with educational organizations. It supports programs aimed at capacity building in under-resourced regions and works to make astronomical knowledge accessible. Researchers and institutions interested in IAU activities can participate through membership, attend the General Assembly, submit proposals to working groups, or follow public naming campaigns and educational projects. Official announcements, membership information and public resources are maintained by the union and by cooperating organizations; see links for engagement and resources such as membership information, public outreach, naming procedures, planetary feature rules and general documentation at official records.

• Example groups: WGPSN, WGSN and numerous task forces coordinate specific domains of nomenclature and standards.
• Meetings: the IAU General Assembly is typically held every three years and gathers astronomers worldwide.
• Public impact: IAU decisions shape textbooks, databases and public understanding of celestial classifications.