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.

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Another name for the autumnal equinox.

September 22-23

The sun crosses the plane of the earth's equator twice a year: on or about March 21 (see Vernal Equinox) and again six months later, on or about September 22 or 23. On these two occasions, night and day are of equal length all over the world. In the Northern Hemisphere, September 22 or 23 is the first day of autumn.

Autumnal Equinox Day is a national holiday in Japan, observed on either September 23 or 24 to celebrate the arrival of autumn and to honor family ancestors.


See also Higan, Shunbun-no-Hi

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i. The point of intersection of the ecliptic and celestial equator (equinoctial) when the sun is moving from north to south. Also called the first point of Libra.



ii. The time of the crossing of the sun across the celestial equator from north to south, when day and night are of equal length.

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For a list of words related to autumnal equinox, see:

• Cyclical Events - autumnal equinox: first day of autumn, usu. September 22 in Northern Hemisphere
• Annual National and Religious Holidays - autumnal equinox: U.S.: September 22, first day of fall
• Fixed Times - autumnal equinox: September 22 in Northern Hemisphere

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