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
[編輯]睇埋：地球軌道
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
[編輯]使用
[編輯]歷史
[編輯]註
[編輯]- ↑ 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 149597870700 metres, in agreement with the value adopted in IAU 2009 Resolution B2
出面網頁
[編輯]- 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)
