天文單位

天文單位（粵拼：tin1 man4 daan1 wai2）係個長度單位，大約係地球同太陽之間嘅遠。以前曾經定佢係1495億9787萬0691米，上下差30米，即係大約1億5千萬千米。喺2012年8月嘅國際天文學大會（IAU）第28屆全體會議入面，天文學家投票將天文單位固定咗喺149,597,870,700米^[1]。由嗰時起天文單位唔再同地球同太陽之間嘅實際距離掛鈎。

基礎

天文單位個名由英文 astronomical unit 譯過來，符號AU、au、a.u.或者ua等等。

測量

使用

歷史

註

↑ International Astronomical Union, 編 (31 August 2012), "RESOLUTION B2 on the re-definition of the astronomical unit of length" (PDF), RESOLUTION B2, Beijing, Kina: International Astronomical Union, The XXVIII General Assembly of International Astronomical Union recommends [adopted] that the astronomical unit be re-defined to be a conventional unit of length equal to exactly 7011149597870700000♠149597870700 metres, in agreement with the value adopted in IAU 2009 Resolution B2

出面網頁

Chasing Venus, Observing the Transits of Venus Smithsonian Institution Libraries
Units outside the SI (at the NIST web site)
Recommendations concerning Units (at the IAU web site)
Solar Mass Loss, the Astronomical Unit, and the Scale of the Solar System (a discussion of the relation between the AU and other quantities)

[1] International Astronomical Union, 編 (31 August 2012), "RESOLUTION B2 on the re-definition of the astronomical unit of length" (PDF), RESOLUTION B2, Beijing, Kina: International Astronomical Union, The XXVIII General Assembly of International Astronomical Union recommends [adopted] that the astronomical unit be re-defined to be a conventional unit of length equal to exactly 7011149597870700000♠149597870700 metres, in agreement with the value adopted in IAU 2009 Resolution B2

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