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

However, the large eccentricity means its orbit ranges from as far as 2 astronomical units (300 million km/186 million miles — i.e. twice the Earth–sun distance) from its star to as close as 0.75 AU (112 million km/69.7 million miles). —Keith Cooper, Space.com, 28 Jan. 2025

Its companions, known as T Tauri South A and B, make up a binary system that's 100 astronomical units (9.3 billion miles/14.9 billion kilometers) away from the main star and orbit around T Tauri North once every 4,600 years. —Keith Cooper, Space.com, 23 Jan. 2025

One astronomical unit is the average distance between the Earth and the Sun, and Neptune's orbit is 60 astronomical units in diameter. —Greg Wehner, Fox News, 16 Jan. 2025

At their closest point, called periastron, the two stars are just 1.3 astronomical units (AU) from each other. —Keith Cooper, Space.com, 16 Jan. 2025

Word History

First Known Use

1848, in the meaning defined above

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)