astronomical unit

noun

: 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 At its orbital distance of 1 astronomical unit from the sun, Earth receives about 1.4 kilowatts per square meter from sunlight. Karl Schroeder, IEEE Spectrum, 24 Feb. 2024 And the light emission during the dimming suggests that the material can't be more than 16 astronomical units out. John Timmer, Ars Technica, 11 Oct. 2023 These arms feed the triplet stars like a cosmic river flowing towards them, extending up to 400 astronomical units (AU; 1 astronomical unit is equal to the average Earth-Sun distance of 93 million miles). Elizabeth Gamillo, Discover Magazine, 11 Sep. 2023 Astronomers call these, the ones that approach within 1.3 astronomical units of the sun, near-Earth asteroids. Conor Feehly, Discover Magazine, 12 July 2023 The average distance between Earth and the sun, what astronomers call an astronomical unit, is defined as 149,597,870.7 km. Phil Plait, Scientific American, 30 June 2023 Ring Rules Quaoar orbits the Sun at a distance of about 43 astronomical units (1 astronomical unit is the distance from the Earth to the Sun). The Physics Arxiv Blog, Discover Magazine, 21 Apr. 2023 Based on statistics alone, these two facts allowed scientists to estimate that the number of similar interstellar interlopers per unit volume of space is about one per 10 cubic AU (one AU, or astronomical unit, is the distance between Earth and the sun). David Jewitt, Scientific American, 1 Oct. 2020 But Proxima Centauri is a star that's much smaller than the Sun, so its dust belt sits much closer, about 1 to 4 times the distance of the Earth to the Sun (called an astronomical unit or AU in space parlance). John Wenz, Discover Magazine, 3 Nov. 2017

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'astronomical unit.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1848, in the meaning defined above

Time Traveler
The first known use of astronomical unit was in 1848

Dictionary Entries Near astronomical unit

Cite this Entry

“Astronomical unit.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/astronomical%20unit. Accessed 19 Mar. 2024.

Kids Definition

astronomical unit

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

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