The 12 Divisions of IAU (2006-2009)
Division I- Fundamental Astronomy
Division II- Sun & Heliosphere
Division III- Plaletary Systems Sciences
Division IV- Stars
Division V- Variable Stars
Division VI- Interstellar Matter
Division VII- Galactic System
Division VIII- Galaxies & the Universe
Division IX- Optical & Infrared Techniques
Division X- Radio Astronomy
Division XI- Space & High Energy Astrophysics
Division XII- Union-Wide Activities
The 40 Commissions of IAU
Commission 4- Ephemerides
Commission 5- Documentation & Astronomical Data
Commission 6- Astronomical Telegrams
Commission 7- Celestial Mechanics & Dynamical Astronomy
Commission 8- Astrometry
Commission 10- Solar Activity
Commission 12- Solar Radiation & Structure
Commission 14- Atomic & Molecular Data
Commission 15- Physical Studies of Comets & Minor Planets
Commission 16- Physical Study of Planets & Satellites
Commission 19- Rotation of the Earth
Commission 20- Position & Motions of Minor Planets, Comets & Satellites
Commission 21- Light of the Night Sky
Commission 22- Meteors, Meteorites & Interplanetary Dust
Commission 25- Stellar Photometry & Polarimetry
Commission 26- Double & Multiple Stars
Commission 27- Variable Stars
Commission 28- Galaxies
Commission 29- Stellar Spectra
Commission 30- Radial Velocities
Commission 31- Time
Commission 33- Structure & Dynamics of the Galactic System
Commission 34- Interstellar Matter
Commission 35- Stellar Constitution
Commission 36- Theory of Stellar Atmospheres
Commission 37- Star Clusters & Associations
Commission 40- Radio Astronomy
Commission 41- History of Astronomy
Commission 42- Close Binary Stars
Commission 44- Space & High Energy Astrophysics
Commission 45- Stellar Classification
Commission 46- Astronomy Education & Development
Commission 47- Cosmology
Commission 49- Interplanetary Plasma & Heliosphere
Commission 50- Protection of Existing & Potential Observatory Sites
Commission 51- Bio-Astronomy
Commission 52- Relativity in Fundamental Astronomy
Commission 53- Extrasolar Planets (WGESP)
Commission 54- Optical & Infrared Interferometry
Commission 55- Communicating Astronomy with the Public