Tuesday, September 22 marks the first day of fall for 2020. Also on this day is the fall equinox—also known as the autumnal or September equinox, according to the Old Farmer’s Almanac. The fall equinox is used as a way of marking the transition from summer to fall in the Northern Hemisphere, the Washington Post reports.
The fall equinox is not simply a single day, instead it is an exact moment on September 22, which this year it happened precisely at 9:31 a.m. Eastern Time, according to the Old Farmer’s Almanac. This moment happens at the same moment all across the world.
The word “equinox” breaks down to Latin forms “aequus,” meaning “equal,” and “nox,” meaning “night,” writes the Old Farmer’s Almanac. With the meaning of the word in mind, on the equinox day and night are approximately the same length. According to the Almanac, the length of day in Joplin, Missouri, on the fall equinox was 12 hours and six minutes long, as sunrise took place at 7:07 a.m. with sunrise at 7:13 p.m. The Washington Post writes that “the autumnal equinox is roughly the halfway point between our longest and shortest days of the year,” as its equal counterpart, the Spring equinox, takes place in March.
On the equinox, the sun crosses what’s called the “celestial equator,” which is an imaginary line that draws Earth’s equator into space, according to the Old Farmer’s Almanac. The equinox happens precisely when the center of the sun passes through this equator. Following the fall equinox, days progressively shorten—as the sun rises later—and nights lengthen greatly—as nightfall comes sooner.
With the equinox comes the various signs of fall, as this day does mark fall’s beginning. Signs come in different forms, from colorful foliage—sporting reds, yellows, and oranges—progressively chillier weather, holiday preparations for Halloween and Thanksgiving, and various fall trends pumpkins and sweaters.
The Old Farmer’s Almanac predicts that weather for September 2020 will bring “cooler-than-normal temperatures,” and October will bring “milder-than-normal temperatures nearly everywhere,” and the Midwest is predicted to stay “dry or nearly so.” With cooler and shorter days, in addition to longer nights, in the near future, the autumnal equinox has now marked it fall.