International Astronomical Union - Composition

Composition

The IAU has 9,902 individual members, all of whom are professional astronomers and most of whom hold PhDs. There are also 70 national members who represent countries affiliated with the IAU. 87% of individual members are male, while 13% are female, among them the union's former president, astronomer Catherine J. Cesarsky.

The sovereign body of the IAU is its General Assembly, which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union (and amendments proposed thereto) and elects various committees.

The right to vote on matters brought before the Assembly varies according to the type of business under discussion. The Statutes consider such business to be divided into two categories:

• issues of a "primarily scientific nature" (as determined by the Executive Committee), upon which voting is restricted to individual members, and
• all other matters (such as Statute revision and procedural questions), upon which voting is restricted to the representatives of national members.

On budget matters (which fall into the second category), votes are weighted according to the relative subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid. An absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union.