Each September, the Northern Hemisphere experiences the autumnal equinox, which marks the official beginning of fall. Shortly after the autumnal equinox, days begin to become shorter and nights become longer.
According to Farmers’ Almanac, the 2022 autumnal equinox is at 9:04 p.m. Eastern Daylight Time today, Thursday, Sept. 22. At this time, the sun will be directly over Earth’s equator.
At the autumnal equinox, day and night are approximately equal in length. The name equinox comes from the Latin word aequus, meaning equal, and nox, meaning night.
There are two measures for seasons — the astronomical seasons, which follow equinoxes and soltices, and the meteorological seasons.
“Astronomical fall is essentially the time period from the autumnal equinox up to the winter solstice. Those dates can vary by a day or two each year,” Allison Chinchar, CNN meteorologist, says. “Meteorological fall is different … in that the dates never change and are based on climatological seasons rather than Earth’s angle relative to the sun.”