First day of fall 2022: What to know about the autumn equinox

Equinoxes and solstices mark the change of seasons, but they mean different things and occur at different times

There are only two equinoxes that happen in a year – autumnal (fall) and vernal (spring) – and they happen when the earth’s subsolar point passes through the equator, according to National Geographic. "The equinoxes are the only time when both the Northern and Southern Hemispheres experience roughly equal amounts of daytime and nighttime," the nature magazine reports.