equinox
From Glossary of Meteorology
- Either of the two points of intersection of the sun's apparent annual path and the plane of the earth's equator, that is, a point of intersection of the ecliptic and the celestial equator.
- Popularly, the time at which the sun passes directly above the equator; the "time of the equinox."
In northern latitudes the vernal equinox falls on or about 21 March, and the autumnal equinox on or about 22 September. These dates are reversed in the Southern Hemisphere.
Compare solstice.
