Twice a year day and night fall into balance, lasting for nearly equal lengths. Known as equinoxes, Latin for “equal night,” they occur in March and September and along with solstices, mark the changing of seasons as Earth travels around the sun.
Why is it Called “Equinox”?
On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it's called an “equinox”, derived from Latin, meaning "equal night". However, in reality equinoxes don't have exactly 12 hours of daylight
What Happens on the Equinox?
The Earth's axis is always tilted at an angle of about 23.4° in relation to the ecliptic, the imaginary plane created by the Earth's path around the Sun. On any other day of the year, either the Southern Hemisphere or the Northern Hemisphere tilts a litte towards the Sun. But on the two equinoxes, the tilt of the Earth's axis is perpendicular to the Sun's rays, like the illustration shows.
Celebrating new Beginnings
The March equinox has long been celebrated as a time of rebirth in the Northern Hemisphere. Many cultures celebrate spring festivals and holidays around the March equinox, like Easter and Passover.