Definition of astronomical unit in English:

astronomical unit

Syllabification: as·tro·nom·i·cal u·nit
(abbreviation: AU)


  • A unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun.
    More example sentences
    • Bodies that formed from the Sun out to a distance of about 2.5 astronomical units are primarily rocky and metallic.
    • Typical distances from the Sun are 10,000 astronomical units, and typical orbital periods are on the order of 1 million years.
    • Today the distance between the Earth and sun, known as an astronomical unit, is accurately measured by radar.

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Word of the day skosh
Pronunciation: skəʊʃ
a small amount; a little