Search

See under equinox (def 1).
Also called autumnal point. the position of the sun at the time of the autumnal equinox.
the time when the sun crosses the plane of the earth’s equator, making night and day of approximately equal length all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox)
either of the equinoctial points.
Historical Examples

Spica, however, is a star of the first magnitude, and lies a little east of the place of the autumnal equinox.
Letters on Astronomy Denison Olmsted

Albategni, the Arabian astronomer, observes the autumnal equinox, September 19th.
The Great Events by Famous Historians, Volume 5 Various

At the vernal and at the autumnal equinox I take a good meal, and that lasts me for half a year.
The Bee-Man of Orn and Other Fanciful Tales Frank R. Stockton

This fish resorts here in vast numbers, and is in season after the autumnal equinox, and continues so till the ice begins to run.
Personal Memoirs Of A Residence Of Thirty Years With The Indian Tribes On The American Frontiers Henry Rowe Schoolcraft

As each year started anew on the autumnal equinox, the dates varied a little from those here given.
The Sword of Honor, volumes 1 & 2 Eugne Sue

The autumnal equinox now approached, and the Euboean gulf, called Coela, is reckoned dangerous by mariners.
History of Rome, Vol III Titus Livius

In Norfolk, many are caught at the autumnal equinox in the fowlers’ nets.
British Birds in their Haunts Rev. C. A. Johns

Now, this is just the case of the moon at the time of the harvest home, about the time of the autumnal equinox.
Letters on Astronomy Denison Olmsted

And after the autumnal equinox, he proceeded onwards on his way to Amida.
The Roman History of Ammianus Marcellinus Ammianus Marcellinus

Harvest-Moon, the full moon which in our latitude, at the autumnal equinox, rises for an evening or two about the same time.
The Nuttall Encyclopaedia Edited by Rev. James Wood

noun
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)
(astronomy)

the point, lying in the constellation Virgo, at which the sun’s ecliptic intersects the celestial equator
the time at which this occurs as the sun travels north to south (23 September)

noun
either of the two occasions, six months apart, when day and night are of equal length See vernal equinox, autumnal equinox
another name for equinoctial point
n.

late 14c., from Old French equinoce (12c.) or directly from Medieval Latin equinoxium “equality of night (and day),” from Latin aequinoctium “the equinoxes,” from aequus “equal” (see equal (adj.)) + nox (genitive noctis) “night” (see night). The Old English translation was efnniht. Related: Equinoctial.
autumnal equinox
(ô-tŭm’nəl)
See under equinox.
equinox
(ē’kwə-nŏks’)

Either of the two points on the celestial sphere where the ecliptic (the apparent path of the Sun) crosses the celestial equator. ◇ The point at which the Sun’s path crosses the celestial equator moving from south to north is called the vernal equinox. The vernal equinox marks the zero point in both the equatorial and ecliptic coordinate systems; horizontal angular distances (right ascension in the equatorial system and celestial longitude in the ecliptic system) are measured eastward from this point. The vernal equinox is also known as the first point of Aries because when first devised some 2,000 years ago this point occurred at the beginning of Aries in the zodiac. Because of the westward precession of the equinoxes, the vernal equinox is now located at the beginning of Pisces. ◇ The point at which the Sun’s path crosses the celestial equator moving from north to south is called the autumnal equinox.

Either of the two corresponding moments of the year when the Sun is directly above the Earth’s equator. The vernal equinox occurs on March 20 or 21 and the autumnal equinox on September 22 or 23, marking the beginning of spring and autumn, respectively, in the Northern Hemisphere (and the reverse in the Southern Hemisphere). The days on which an equinox falls have about equal periods of sunlight and darkness. Compare solstice.

equinox [(ee-kwuh-noks, ek-wuh-noks)]

The twice yearly times when the lengths of day and night are equal. At equinox, the sun is directly over the Earth’s equator. The vernal equinox occurs about March 22 and the autumnal equinox about September 21.