IAU yakhala membala kuyambira 1922.
Ntchito ya International Astronomical Union (IAU), yomwe idakhazikitsidwa mu 1919, ndikulimbikitsa ndi kuteteza sayansi ya zakuthambo m'mbali zake zonse kudzera mu mgwirizano wapadziko lonse lapansi. IAU, kudzera m’magawo ake 12 a Sayansi ndi Makomiti 37 okhudza nkhani zonse zakuthambo, ikupitirizabe kuchita mbali yofunika kwambiri polimbikitsa ndi kugwirizanitsa mgwirizano wapadziko lonse wa sayansi ya zakuthambo.
Zochita za IAU zimachokera ku tanthauzo la zinthu zakuthambo komanso zosinthika komanso mawonekedwe osadziwika bwino a zakuthambo, kufalitsa mwachangu zinthu zatsopano zomwe zapezedwa, bungwe lamakampeni owonera padziko lonse lapansi, ndikulimbikitsa zochitika zamaphunziro mu zakuthambo mpaka kukambitsirana kosakhazikika komwe kungathe kuchitika padziko lonse lapansi. IAU ndiyonso yokhayo yomwe imadziwika padziko lonse lapansi popereka mayina ndi mayina ku zinthu zakuthambo komanso mawonekedwe ake.
Kukonzekera kwa misonkhano ya sayansi ndi ntchito yofunika kwambiri. Misonkhano ya General Assemblies ya zaka zitatu imakhala ndi mapulogalamu olemera a sayansi (zopereka zopitirira 800 zapakamwa ndi 2,100 zoperekedwa mu 2003), zomwe zotsatira zake zimalembedwa mu IAU Transactions and Highlights of Astronomy. Kuphatikiza apo, IAU imathandizira pafupifupi khumi ndi awiri symposia ndi colloquia chaka chilichonse; Zomwe zachitika pamisonkhanoyi zimasindikizidwa mothandizidwa ndi IAU monga mbiri yofunikira ya gawo lawo la sayansi.
IAU ikugwiranso ntchito kulimbikitsa maphunziro a zakuthambo ndi kafukufuku m'mayiko omwe sayansi ya zakuthambo sinakwaniritsidwebe kudzera mu IAU International Schools for Young Astronomers, Teaching for Astronomy Development, ndi mapulogalamu ena omwe amachitidwa mogwirizana ndi mabungwe osiyanasiyana a ICSU ndi mabungwe a UN.
IAU ikugogomezera kwambiri kutengapo gawo kwa mamembala ake opitilira 9,100 ochokera kumayiko 94 padziko lonse lapansi. Kulumikizana ndi Mamembala kumasungidwa kudzera mu Information Bulletin, yofalitsidwa kawiri pachaka ndikugawidwa kwaulere kwa Mamembala onse, Mabungwe Otsatira, ndi mabungwe akuluakulu a zakuthambo padziko lonse lapansi, komanso kupezeka pa intaneti. Izi zimaphatikizidwa ndi kugwiritsa ntchito intaneti komwe kumapereka nkhani ndi zolemba zakale pazosiyanasiyana zasayansi ndi kayendetsedwe ka Union, kuphatikiza zidziwitso zapamisonkhano yasayansi.