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Equinox
01
(astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic
02
either of the two moments in a year when the Sun, in its apparent motion along the ecliptic, crosses the celestial equator, resulting in approximately equal periods of daylight and darkness worldwide
Example
During the autumn equinox, the length of day and night are nearly equal.
The equinoxes are important for astronomers studying the Earth's tilt and orbit.
On the equinox, the Sun rises due east and sets due west.
Ancient civilizations often built monuments aligned with celestial events, such as solstices and equinoxes.
The equinox occurs twice a year, once in March and once in September.
