Have you noticed how the light changes in September? It becomes softer, as if nature itself is preparing for rest. This subtle change reaches its peak on the day of the September equinox. It is a moment of perfect harmony: the day is almost equal to the night, and the Sun illuminates both hemispheres equally, without favoring either one.
Image Credit & Copyright: Pexels / Magda Ehlers
Our ancestors did not have scientific explanations, but they had something more important – intuition. They felt this turning point not with their heads, but with their hearts. For them, it was a time to take stock, thank the earth for the harvest, and accept the inevitable cycles of nature. This ancient connection has not gone anywhere. It is simply waiting for you to pay attention to it again. So let’s dive into the magic of the September equinox and find out why its echo is so important in the modern world.
Що таке осіннє рівнодення
Image Credit & Copyright: Wikipedia / Przemyslaw “Blueshade” Idzkiewicz
Forget about complicated terms. The whole essence of the equinox can be summed up in one word: tilt. The Earth is constantly tilted. Because of this, the Sun never shines on it evenly – one part always receives more light and heat, the other less. This unevenness is what we call the change of seasons: when our hemisphere “turns its cheek” to the sun’s rays, we have summer, and when it “turns away”, winter comes.
But there are two days a year when the system reaches perfect balance. The light falls directly on the equator, and for a moment, everyone gets an equal share. The September equinox is the day after which the Sun, having crossed the equator, begins its journey south, and for us in the Northern Hemisphere, astronomical autumn begins.
As for the balance between day and night (exactly 12 hours each), this is simply a beautiful myth. In reality, light always steals a few extra minutes from darkness. Our atmosphere is to blame for this, as it acts like a lens, refracting the sun’s rays and allowing us to see the Sun above the horizon even when it has already set. Add to this the fact that the beginning of the day is considered to be the appearance of the first ray of sunlight, not the center of the disc. This adds a few extra minutes of light. The perfect balance between day and night will only be achieved a few days after the September equinox.
Humanity has always treated this day with respect. Stonehenge in England, the Goseck Circle in Germany, or the pyramid of Kukulkan in Mexico are not just piles of ancient stones for tourists. They are giant calendars built with one trick in mind: on the day of the September equinox, the Sun puts on incredible light shows there, emphasizing the special significance of this moment. This proves how well our ancestors understood celestial mechanics.
It is also important not to confuse the September equinox with the autumn solstice. While the equinox represents balance, the solstice, which awaits us in December, represents an extreme, the shortest day of the year.
When is the September equinox?
Image Credit & Copyright: Emili Vilamala
In 2025, the September equinox will occur on September 22 at 6:19 UTC (Coordinated Universal Time). For Ukraine, this will be 9:19 Kyiv time (UTC+3).
Interestingly, this moment is the same for the entire planet, no matter where you are. However, the date of the September equinox sometimes shifts. It is all due to a slight conflict between the cosmic clock and our human one.
The astronomical year – the time it takes for the Earth to complete one full revolution around the Sun – lasts not exactly 365 days, but approximately a quarter of a day longer. Our Gregorian calendar rounds off this remainder to avoid complications. Every year, the “extra” hours accumulate, and the equinox gradually shifts forward in time.
To compensate for this inaccuracy and prevent winter from starting in June, we have leap years. Once every four years, the extra day on February 29 seems to “pull back” the accumulated difference. Due to these shifts, the September equinox usually “floats” between September 22 and 23.
However, there are also real calendar paradoxes – when the dates of the equinoxes fall outside their usual range. For example, the last equinox on September 21 was in the first millennium, and it will not return until 2092. And we will have to wait until 2303 for the equinox on September 24.
Such huge time gaps clearly show that our usual calendar is just an attempt to organize the rhythm of the Solar System.
September equinox in different places on Earth
Image Credit & Copyright: Luca Vanzella
Although the moment of the equinox is the same for everyone, it is felt very differently in different parts of the planet.
For us in Ukraine and throughout the Northern Hemisphere, the nights are getting longer, the air is getting cooler, and nature is preparing for sleep. What is more, on the days of the equinox, the Earth’s magnetic field weakens slightly, increasing the chances of seeing the northern lights. So it makes sense to look at the sky more often.
In the Southern Hemisphere, the situation is mirrored. There, the September equinox marks the arrival of spring, warmth, and long, bright days. It is a fantastic reminder of how different the same moment can be on the same planet.
The real drama unfolds at the poles. At the North Pole, the Sun touches the horizon for the last time and hides for six long months. The polar night begins. At the South Pole, on the contrary, the first ray of light appears after six months of darkness. Perhaps nowhere else is the uniqueness of the equinox felt so acutely.
Only at the equator is everything stable. There, day and night are always equal, lasting about 12 hours. But even here, there is a peculiarity: at noon on the September equinox, the Sun is directly overhead, at its zenith. And vertical objects… cast no shadows. A small miracle that proves once again how amazing our world is.
