An equinox is an astronomical event that occurs twice a year when the Sun is directly above the Equator, resulting in nearly equal lengths of day and night across the planet. This phenomenon happens around March 20-21, marking the vernal (or spring) equinox in the Northern Hemisphere, and around September 22-23, marking the autumnal equinox.
During an equinox, the tilt of the Earth's axis is such that both the Northern and Southern Hemispheres receive sunlight more equally. The term "equinox" is derived from the Latin words "aequus" (equal) and "nox" (night), signifying the balance of day and night.
Equinoxes are significant not only in astronomy but also in various cultural calendars and agricultural practices.