astronomical unit

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astronomical unit

n. Abbr. AU

A unit of length used in measuring astronomical distances within the solar system or other planetary system equal to the mean distance from Earth to the sun, approximately 150 million kilometers (93 million miles).

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

astronomical unit

(Units) 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 × 10¹¹ metres or about 9.3 × 10⁷ miles

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

astronom′ical u′nit

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

[1900–05]

as·tro·nom·i·cal unit

(ăs′trə-nŏm′ĭ-kəl)

A unit of length equal to the average distance from Earth to the sun, approximately 93 million miles (150 million kilometers). It is used to measure distances within the solar system.

The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

astronomical unit

1. (au) The mean Sun to Earth distance, equal to 92,955,807 mi (149,597,870 km). Agreed internationally in 1964, but its value has altered.

2. (au) A unit of measure based on the distance between the Earth and the Sun. Approximately equal to 1.5 x 108 km.

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Noun

Astronomical Unit - a unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers)

astronomy unit - a linear unit used for astronomical distances

Translations

Astronomische Einheit

unita astronomica

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Previously, astronomers knew that planets could form in exceptionally wide binary systems, in which stars are 1,000 times farther apart than the distance between Earth and the sun, or 1,000 astronomical units. Of the approximately 200 planets discovered so far outside our solar system, about 50 orbit one member of a wide stellar duo.