Thian-bûn tan-ūi
(Tùi Thian-bûn tan-uī choán--lâi)
Thian-bûn tan-ūi (AU, au, a.u., ū-sî ua) sī niû tn̂g-té ê 1-ê tan-ūi, iok-lio̍k téng-î Tē-kiû kàu Ji̍t-thâu ê pêng-kin kī-lî. Hiān-chú-sî hông chiap-siū ê ta̍t sī 149 597 870 691 ± 30 m (tāi-iok 1-ek 5-chheng kong-lí).
Bureau International des Poids et Mesures kiàn-gī iōng "ua" chò tan-ūi ê hû-hō, m̄-koh Kok-chè Thian-bûn Chó·-ha̍p (International Astronomical Union) kiàn-gī iōng "au", ah ISO 31-1 iōng "AU". Tī Eng-gí ûi-chú ê kok-ka khah koàn-sì iōng "au" a̍h-sī "AU".