The astronomical unit (AU or au or a.u. or sometimes ua) is a unit of length nearly equal to the semi-major axis of Earth's orbit around the Sun. The currently accepted value of the AU is 149 597 870 691 ± 30 metres (about 150 million kilometres or 93 million miles).

The symbol "ua" is recommended by the Bureau International des Poids et Mesures but in the United States and other anglophone countries the reverse usage is more common. The International Astronomical Union recommends "au" and international standard ISO 31-1 uses "AU". In general, capital letters are only used for the symbols of units which are named after individual scientists, while "au" or "a.u." can also mean atomic unit or even arbitrary unit: however, the use of "AU" to refer to the astronomical unit is widespread.

au - Wikipedia, the free encyclopedia

.au is the Internet country code top-level domain (ccTLD) for Australia. The domain name was originally allocated by Jon Postel, operator of IANA to Kevin Robert Elz of Melbourne University in 1986 ...

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Au - Wikipedia, the free encyclopedia

Au or AU may refer to: In science * Astronomical unit (AU, au, a.u., or ua), a unit of length approximately equal to the distance between the Earth and the Sun * Atomic units (au), a system of ...

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