There are two equinoxes each year:

* Vernal (Spring) Equinox: Around March 20 or 21, when the sun is directly overhead at the equator, marking the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

* Autumnal (Fall) Equinox: Around September 22 or 23, when the sun is again directly overhead at the equator, marking the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

During the equinoxes, day and night are approximately equal in length across the globe.