definitions

astronomical unit

noun Astronomy.

a unit of length, equal to the mean distance of the earth from the sun: approximately 93 million miles (150 million km). Abbreviation: AU

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Nearby words

astronomical frame of reference, astronomical refraction, astronomical telescope, astronomical triangle, astronomical twilight, astronomical unit, astronomical year, astronomy, astrophotography, astrophotometry, astrophysicist

Origin of astronomical unit

First recorded in 1900–05
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for astronomical unit

astronomical unit

noun

a unit of distance used in astronomy equal to the mean distance between the earth and the sun. 1 astronomical unit is equivalent to 1.495 × 10 11 metres or about 9.3 × 10 7 miles
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for astronomical unit

astronomical unit

[ ăs′trə-nŏm′ĭ-kəl ]

A unit of length equal to the average distance from Earth to the Sun, approximately 149.6 million km (92.8 million mi). It is used especially to measure distances within the solar system. Compare light-year parsec.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for astronomical unit

astronomical unit

The mean distance between the Earth and the sun, about 93 million miles or 150 million kilometers. It is often abbreviated as AU.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.