The autumnal equinox is the day when the sun crosses the equator from the Northern to the Southern Hemisphere. On this day, the sun rises exactly in the east and sets exactly in the west, and day and night become the same length.

The autumnal equinox is an astronomical event that marks the start of autumn (or “fall”). It is also called the September equinox or fall equinox.

After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier. This ends with the winter solstice, after which days start to grow longer once again.

The word “equinox” comes from Latin aequus, meaning “equal,” and nox, ”night.” On the equinox, day and night are roughly equal in length.

Some say that during an equinox, day and night is equal. Well, not exactly. It depends on where you live.

On the equinox, the center of the Sun is indeed above the horizon for 12 hours. However, “sunrise” is said to begin when the upper edge of the Sun’s disk becomes visible above the horizon (which happens a bit before the center rises) and ends when the entire Sun has set. In this case, daylight is still a bit longer than nighttime.

Not only that, but the Sun is actually visible when it is below the horizon, as Earth’s atmosphere refracts the Sun’s rays and bends them in an arc over the horizon. Yes, you can see the Sun before the edge actually reaches the horizon! This causes daylight to be longer than 12 hours as well.

However, they are very close to equal (the total lengths may differ by only a few minutes).