autumnal equinox

autumnal equinox

n.

1. The point at which the ecliptic intersects the celestial equator, the sun having a southerly motion.

2. The moment at which the sun passes through the autumnal equinox, about September 23, marking the beginning of autumn in the Northern Hemisphere.

---

autumnal equinox

n

1. (Earth Sciences / Physical Geography) 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)

2. (Astronomy) Astronomy

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

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

---

autumnal equinox  (ô-tmnl)

See under equinox.

Thesaurus

Noun	1.	autumnal equinox - September 22                         fall equinox, September equinox Sep, Sept, September - the month following August and preceding October equinox - either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length autumn, fall - the season when the leaves fall from the trees; "in the fall of 1973" March equinox, spring equinox, vernal equinox - March 21
	2.	autumnal equinox - (astronomy) the equinoctial point that lies in the constellation of Virgo astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole equinoctial point, equinox - (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic