Astronomical unit | |
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![]() The grey line indicates the Earth–Sun distance, which on average is about 1 astronomical unit. | |
General information | |
Unit system | Astronomical system of units (Accepted for use with the SI) |
Unit of | length |
Symbol | au or AU or AU |
Conversions | |
1 au or AU or AU in ... | ... is equal to ... |
metric (SI) units | 1.495978707×1011 m |
imperial & US units | 9.2956×107 mi |
astronomical units | 4.8481×10−6 pc 1.5813×10−5 ly 215.03 R☉ |
The astronomical unit (symbol: au[1][2][3][4] or AU) is a unit of length defined to be exactly equal to 149,597,870,700 m.[5] Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012.
The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec.[6] One au is equivalent to 499 light-seconds to within 10 parts per million.
... recommends ... 5. that the unique symbol "au" be used for the astronomical unit.
The units of length/distance are Å, nm, μm, mm, cm, m, km, au, light-year, pc.
AAS_style
was invoked but never defined (see the help page).... recommends [adopted] that the astronomical unit be re-defined to be a conventional unit of length equal to exactly 149,597,870,700 metres, in agreement with the value adopted in IAU 2009 Resolution B2
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