For a fleeting moment this Monday, September 22, 2025, the world will experience a rare balance: day and night will be nearly equal in length, signaling the arrival of the autumnal equinox. For those in the Northern Hemisphere, it marks the official start of fall, while the Southern Hemisphere welcomes spring. But what exactly happens during this celestial event, and why do so many cultures celebrate its arrival?
According to the Associated Press, the autumnal equinox occurs when the sun crosses directly over the Earth’s equator. This year, that precise moment lands at 2:19 p.m. Eastern Time. At that instant, the sun will be directly overhead at the equator, casting nearly equal amounts of daylight and darkness across the globe—about 12 hours of each. The term “equinox” itself comes from two Latin words: “aequus,” meaning equal, and “nox,” meaning night. It’s a striking reminder of the delicate balance that governs our planet’s journey around the sun.
But the equinox is more than an astronomical curiosity. It’s a seasonal milestone that has been marked and celebrated for centuries. In the Northern Hemisphere, it ushers in a time of shorter days and cooler temperatures, a shift that many eagerly anticipate. After September 22, sunlight will gradually diminish each day until the winter solstice on December 21, when the night is longest and the day is shortest. In the words of NJ.com, “It’s almost time to bid farewell to summer and say hello to fall.”
For many, the equinox is deeply intertwined with tradition. Harvest festivals abound, from Dozynki in Poland and other Eastern European countries—once thought to have been originally tied to the equinox itself—to the gatherings at Chichen Itza in Mexico. There, crowds assemble to witness a breathtaking spectacle: as the sun sets, it casts a shadow on the steps of El Castillo, creating the illusion of a serpent slithering down the ancient pyramid. These rituals, described by the Associated Press, are a testament to the enduring human need to mark the passage of the seasons.
Closer to home, towns like Avon, Connecticut, are already in full autumnal swing. As Patch reports, “The autumnal equinox on Monday, Sept. 22, signals the official arrival of fall, but the season is already in full swing in the Avon, Connecticut area with various events and traditions celebrating autumn.” Sunny days and crisp evenings provide the perfect backdrop for outdoor festivals, pumpkin picking, and neighborhood gatherings. The community spirit is palpable, as locals plan and share their own seasonal events to make the most of the changing weather.
Meanwhile, in the Maritimes, residents are feeling the first nip of cool air as the equinox approaches. According to CTV News Atlantic, “Cool weather is arriving in the Maritimes during the weekend leading up to the autumnal equinox on Monday, September 22, 2025.” The shift is subtle at first—autumn doesn’t boldly announce its presence but rather creeps in, as USA Today poetically observes. Schools are back in session, pumpkin-flavored treats are appearing in coffee shops, and the anticipation of Halloween and Thanksgiving hangs in the air.
Of course, not everyone agrees on when fall truly begins. While the astronomical equinox is the official marker for many, meteorologists take a different approach. As explained by NJ.com, “Meteorologists consider September 1 as the start of autumn based on temperature cycles, differing from the astronomical start on September 22, 2025.” Meteorological seasons are divided into neat three-month blocks: September 1 ushers in autumn, December 1 brings winter, March 1 signals spring, and June 1 marks the start of summer. This system, based on temperature patterns rather than celestial events, is favored by those who prefer to let the weather—not the stars—dictate the seasons.
While the equinox brings balance to the day and night, it also brings a spectacle to the skies. This year, skywatchers in the Southern Hemisphere are in for a treat: a partial solar eclipse will occur the day before the equinox, on Sunday, September 21, 2025. According to USA Today, “A partial solar eclipse will occur the day before, on Sunday, September 21, 2025, visible in parts of the Southern Hemisphere including New Zealand, Antarctica, and some South Pacific islands.” During this event, roughly 86% of the sun will be obscured—a dramatic sight for those lucky enough to be in its path. For the rest of the world, the eclipse will be live-streamed from Dunedin, New Zealand, from 1:29 p.m. to 5:53 p.m. Eastern Time, with the maximum eclipse at 3:41 p.m. ET. NASA reminds viewers not to look directly at the sun without proper eye protection, as the partial eclipse can still cause serious eye damage.
Equinoxes are unique in that they are the only times of the year when both the north and south poles are illuminated by sunshine at the same time. For a brief window, the Earth’s axis and its orbit align so that both hemispheres receive an equal share of the sun’s rays. The solstices, by contrast, mark the extremes: the longest and shortest days of the year, when the hemispheres are tilted most toward or away from the sun. In the Northern Hemisphere, the summer solstice falls between June 20 and 22, bringing the longest day, while the winter solstice between December 20 and 23 delivers the shortest. These astronomical markers have shaped human calendars, agriculture, and cultural rituals for millennia.
Yet, as the world spins on, the equinox remains a subtle transition. As USA Today notes, “Autumn doesn’t boldly announce its presence but rather creeps in.” For some, fall began weeks ago—schools reopened, pumpkin spice lattes made their annual debut, and Halloween costumes quietly appeared in store aisles. For others, the equinox is a sacred moment, a time to pause and reflect on the passage of time and the cycles of nature.
Whether you’re celebrating with a festival, marveling at the balance of light and dark, or simply savoring a mug of cider on a cool evening, the autumnal equinox is a reminder of the rhythms that connect us all. This year, as day and night briefly share the stage, communities around the world will gather in their own ways to welcome the season—each tradition a thread in the fabric of our shared experience.
With the sun poised above the equator and the world in balance, the arrival of autumn is both a scientific marvel and a cultural touchstone. As the days grow shorter and the air turns crisp, the equinox invites us to embrace change, celebrate tradition, and look with wonder at the sky above.
