Astronomical Unit

by Dominic Ford, Editor
Last updated: 24 Nov 2018

The astronomical unit is a unit of length which is approximately equal to the average distance of the Earth from the Sun. One astronomical unit is equal to:

\( 149.6 \times 10^{9} \) m

\( 15.81 \times 10^{-6} \) light years

\( 4.848 \times 10^{-6} \) parsecs.

The astronomical unit is used almost universally for measuring distances between bodies within our Solar System, and when discussing the sizes of planetary systems around other stars. For example, Jupiter orbits the Sun at an average distance of 5.2 AU.

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