September equinox


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Related to September equinox: December solstice, June solstice

equinox

equinoxclick for a larger image
Positions of sun and the earth at spring and autumnal equinoxes.
i. One of the two points of intersection of the ecliptic and the celestial equators, occupied by the sun when its declination is 0°. Also called an equinoctial point. That point occupied on or about March 21, when the sun's declination changes from south to north, is called the vernal equinox, spring equinox, March equinox, or first point of Aries that point occupied on or about September 23, when the declination changes from north to south, is called the autumnal equinox, September equinox, or first point of Libra. Equinox is often used to mean vernal equinox, when referring to the origin of measurement of right ascension and celestial longitude. At the time of equinox, the duration of day and night is the same or equal.
ii. That instant the sun occupies one of the equinoctial points.
References in periodicals archive ?
Next month sees the September equinox - meaning we're halfway from mid-summer and halfway towards midwinter.
The full Moon of September is often called the Harvest Moon, but Harvest Moon is usually defined as the full Moon closest to the September equinox.
Day and night are roughly equal in length, and from now until the September equinox, nights in the Southern Hemisphere will be longer than days, giving us more time to enjoy the stars
I refer to the full Moon nearest the September equinox (or nearest the March equinox for those living south of the equator), the one commonly called the Harvest Moon.