There are two equinoxes each year:

* Vernal Equinox (Spring Equinox): Around March 20th or 21st, marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

* Autumnal Equinox (Fall Equinox): Around September 22nd or 23rd, marks the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

During an equinox, day and night are approximately equal in length all over the world.