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
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Cugno alludes to the fact that CT Cha b is also positioned within a circumstellar planet-forming disk, albeit at a huge distance from its star of 440 astronomical units (41 billion miles/65 billion kilometers). Keith Cooper, Space.com, 30 Sep. 2025 That is, with Venus and earth-like planets at habitable distances from their stars as well as gas giants orbiting at Jupiter-like distances (which in our solar system’s case is 5 astronomical units), or five times the average distance between the Earth and sun. Bruce Dorminey, Forbes.com, 19 Sep. 2025 One astronomical unit, is the distance from the sun to Earth. Jenna Prestininzi, Freep.com, 17 Sep. 2025 See All Example Sentences for astronomical unit

Word History

First Known Use

1848, in the meaning defined above

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

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Cite this Entry

“Astronomical unit.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/astronomical%20unit. Accessed 17 Oct. 2025.

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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