* Vernal (Spring) Equinox: Occurs around March 20-21 in the Northern Hemisphere and around September 22-23 in the Southern Hemisphere.
* Autumnal (Fall) Equinox: Occurs around September 22-23 in the Northern Hemisphere and around March 20-21 in the Southern Hemisphere.
It's important to note that the equinox doesn't mark the official start of the seasons, but rather the point when day and night are approximately equal in length.