autumnal equinox

American  

[aw-tuhm-nl ee-kwuh-noks, ek-wuh-noks] / ɔˈtʌm nl ˈi kwəˌnɒks, ˈɛk wəˌnɒks /

noun

1. equinox1

2. Also called autumnal point.  the position of the sun at the time of the autumnal equinox.

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autumnal equinox British  

noun

1. the time at which the sun crosses the plane of the equator away from the relevant hemisphere, making day and night of equal length. It occurs about Sept 23 in the N hemisphere (March 21 in the S hemisphere)

2. astronomy

   1. the point, lying in the constellation Virgo, at which the sun's ecliptic intersects the celestial equator

   2. the time at which this occurs as the sun travels north to south (23 September)

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autumnal equinox Scientific  

/ ô-tŭm′nəl /

1. See under equinox

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Etymology

Origin of autumnal equinox

First recorded in 1670–80

Example Sentences

Or, as we say north of the equator, happy autumnal equinox!

From Scientific American • Sep. 22, 2023

On September 23, 2023, the autumnal equinox will signal the coming of fall for the Northern Hemisphere.

From National Geographic • Sep. 21, 2023

The crop was planted unusually late, after the autumnal equinox, the traditional last day of planting in the area.

From New York Times • May 11, 2022

The French revolutionaries overthrew both the government and the Gregorian calendar, and in 1792, Sept. 22, the day of the autumnal equinox, became day one of the new year.

From Seattle Times • Sep. 21, 2021

At the autumnal equinox a wild boar wounded thee!

From The Temptation of St. Antony or A Revelation of the Soul by Flaubert, Gustave