ekvinoktiumene

Ekvinoktiumene, often anglicized as equinox, refers to the two points in the Earth's orbit where the Sun is directly above the planet's equator. During these times, day and night are of approximately equal length across the globe. This phenomenon occurs twice a year, around March 20th or 21st (the vernal equinox in the Northern Hemisphere, autumnal equinox in the Southern Hemisphere) and around September 22nd or 23rd (the autumnal equinox in the Northern Hemisphere, vernal equinox in the Southern Hemisphere).

The equinoxes are significant because they mark the transition between seasons. The vernal equinox heralds the start of spring in the Northern Hemisphere and autumn in the Southern Hemisphere, while the autumnal equinox signifies the beginning of autumn in the North and spring in the South. This seasonal change is a direct result of the Earth's axial tilt, which remains constant at approximately 23.5 degrees relative to its orbital plane.

At the equinox, neither of the Earth's poles is tilted toward or away from the Sun. This equal illumination of both hemispheres is what leads to the near-equal duration of daylight and darkness. The precise moment of the equinox is determined by astronomical calculations and is not a fixed date, though it typically falls on the 20th or 21st of March and September. The word "equinox" itself derives from the Latin words "aequus" (equal) and "nox" (night), reflecting the characteristic of equal day and night.