astronomical unit


Definition of astronomical unit

: a unit of length used in astronomy equal to the mean distance of the earth from the sun or about 93 million miles (150 million kilometers)

Examples of astronomical unit in a Sentence

Recent Examples on the Web The distance between Earth and the sun is one astronomical unit. Ashley Strickland, CNN, 26 July 2021 To be sure, these planets — the two largest in our solar system — are far apart from each other, about 4.5 times the average distance between the Earth and the sun, what’s considered one astronomical unit. Marisol Chávez, Dallas News, 21 Dec. 2020 In this system, the two inner stars, GW Ori A and B, orbit each other at a distance from Earth to the sun, called an AU or astronomical unit. Ashley Strickland, CNN, 3 Sep. 2020 One astronomical unit is equal to the distance between the Earth and the sun. Ashley Strickland, CNN, 16 Oct. 2019 The research team mapped the structure of a newborn star system called L1527, which has only 0.18 times the mass of the sun but whose surrounding envelope of gas stretches to more than 1,000 astronomical units (AU). Sarah Lewin Frasier, Scientific American, 14 Feb. 2017 Voyager 1 hit the boundary at about 122 astronomical units from the Sun (an AU is the average distance from the Earth to the Sun); Voyager 2 hit it at 119 AU. John Timmer, Ars Technica, 4 Nov. 2019 The gaps are located at 87, 140 and 237 astronomical units from their host star. Ashley Strickland, CNN, 16 Oct. 2019 The previous record holder orbited the sun at about 120 AU (one AU, or astronomical unit, is the distance from the Earth to the sun). David Grossman, Popular Mechanics, 25 Feb. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'astronomical unit.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of astronomical unit

1848, in the meaning defined above

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The first known use of astronomical unit was in 1848

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Dictionary Entries Near astronomical unit

astronomical twilight

astronomical unit


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Cite this Entry

“Astronomical unit.” Dictionary, Merriam-Webster, Accessed 3 Dec. 2021.

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