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- DictionaryE·qui·nox/ˈekwəˌnäks/
noun
- 1. the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of approximately equal length (about September 22 and March 20).
1. : either of the two points on the celestial sphere where the celestial equator intersects the ecliptic. 2. : either of the two times each year (as about March 21 and September 23) when the sun crosses the equator and day and night are everywhere on earth of approximately equal length.
The modern definition of equinox is the instant when the Sun's apparent geocentric ecliptic longitude is 0° ( northward equinox) or 180° ( southward equinox ). [35] [36] [37] Note that at that moment, its latitude will not be exactly zero, since Earth is not exactly in the plane of the ecliptic.
Mar 19, 2024 · equinox, either of the two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect.
Equinox definition: 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 )..
What Is the Equinox? And What Is the Solstice? By Graham Jones. Equinoxes and solstices are a result of two things: Earth’s tilt and its orbit around the Sun. Earth, like nearly all the planets, orbits the Sun in a tilted fashion. ©NASA Johnson Space Center.
Oct 19, 2023 · An equinox is an event in which a planet ’s subsolar point passes through its Equator. The equinoxes are the only time when both the Northern and Southern Hemispheres experience roughly equal amounts of daytime and nighttime. On Earth, there are two equinoxes every year: one around March 21 and another around September 22.
noun [ C ] us / ˈek.wə.nɑːks / uk / ˈek.wɪ.nɒks / Add to word list. either of the two occasions in the year when the center of the sun is directly above the Equator, and day and night are approximately equal in length: the vernal (= spring) equinox. the autumn equinox. Compare. equilux. SMART Vocabulary: related words and phrases. Astronomy.
