The International Astronomical Union (IAU) is the largest international union of professional astronomers actively fostering scientific progress worldwide through international cooperation. With more than 12,000 active professional astronomers from more than 100 counties worldwide, the IAU strives to unite us all in appreciation of a shared sky. The IAU has both individual members and national members. The National Academy of Sciences serves as the U.S. national member.

The membership of individual scientists in the IAU offers access to travel grants to the IAU sponsored meetings, opportunities for leadership positions on committees and working groups, eligibility for IAU awards, possibilities for outreach and development funding and training, and access to regular email newsletters from the IAU and its Divisions, Commissions and Working Groups.

Professional scientists whose research is directly relevant to some branch of astronomy are eligible for admission. The IAU also accepts as members others who are professionals with comparable expertise directly related to astronomy, such as software, outreach, or engineering. Membership applications should be submitted under the national committee of the country where the applicant is employed. There are two categories of membership depending on career stage (see below). There are no membership fees for individuals. The link to submit the application is https://www.iau.org/OpenWater/OpenWater-Login.aspx

Individual Membership

Individual membership in the IAU is open to scientists employed in the US with a PhD or equivalent awarded before 2020 in a branch of astrophysics and other professionals with comparable expertise directly related to astronomy, such as software, outreach, or engineering.

Junior Membership

Scientists employed in the US who have completed their PhD studies between the years 2020 and 2025 are eligible candidates for Junior membership in this call. Junior membership is temporary and may not exceed six years.

The annual period to apply for membership in the International Astronomical Union is now open, with a deadline for receipt of applications of December 31, 2025. Following review for eligibility by the U.S. National Committee for the IAU and the IAU Executive Committee, new Individual and Junior members will be notified of their acceptance by May 2026. 

More information about membership qualifications, the application process, and the timeline can be found at:  https://www.iau.org/IAU/News/Ann2025/ann25022.aspx