The IAU was founded in 1919 to promote and safeguard the science of astronomy in all its aspects through international cooperation. Its individual members are professional astronomers from all over the world, at the Ph.D. level and beyond, who are active in professional research and education in astronomy.
How to join
Professional scientists whose research is directly relevant to some branch of astronomy are eligible for election as Individual Members. The RAS, as the UK 'National Member' of the IAU , is responsible for vetting and forwarding nominations to the IAU in time for their consideration at the next General Assembly (GA). To apply for membership of the IAU please contact the RAS Membership Officer.
The General Assembly is held every three years, the next one will take place in Vienna, Austria from 20th to 31st August 2018. The deadline for applications forms to be received by the RAS is 2nd February 2018. For more information about the qualification rules and application procedure please see the IAU website.
While it is not a condition that UK members of the IAU are Fellows of the RAS this is strongly encouraged since the President of the Society is called upon to vote on behalf of all UK members. Clearly it is preferable that they can be consulted through the Society's normal channels. An additional consideration is that IAU Members do not pay dues to the Union, fees are covered by the RAS and Royal Society.