September equinox 2026: All you need to know

Facebook Tweet PinShares

The September equinox is the time of year when the sun appears to cross the celestial equator—an imaginary line in the sky directly above Earth’s equator—from north to south.

September equinox in 2026

Satellite view of Earth during equinoxes and solstices. On the September equinox, the terminator – the line between light and dark – moves from pole to pole because the sun sits directly above the equator. (Image credit: NASA’s Earth Observatory)

When it occurs: The September equinox will occur on September 23, 2026, at 00:06 UTC (8:06 p.m. EDT on September 22).

Effect on day and night: As the sun appears directly above Earth’s equator at the September equinox, Earth’s two hemispheres receive nearly equal amounts of sunlight. In other words, day and night are nearly equal in length across the globe—about 12 hours each.

After the September equinox, the sun appears to move southward as seen from Earth. As a result, people living in the Northern Hemisphere receive less sunlight—the days become shorter and the nights become longer—while people living in the Southern Hemisphere receive more sunlight—the days become longer and the nights become shorter.

Effect on season: The September equinox marks the beginning of autumn (autumnal equinox) in the Northern Hemisphere and the beginning of spring (vernal equinox) in the Southern Hemisphere.

Effect on sunrise and sunset: As the sun crosses the celestial equator at the September equinox, its apparent path across the sky—the ecliptic—intersects the celestial equator.

The ecliptic and the celestial equator intersect on the equinoxes. (Image credit: NASA)

Now, the celestial equator intersects your horizon at points due east and due west, no matter where you are on the globe. So, the sun rises due east and sets due west at the September equinox.

After the September equinox, the sun rises and sets a bit farther south on the horizon each day until the December solstice (see the image below).

Zaid M. Al-Abbadi captured the sunrise direction each month in 2019 from near the city of Amman, Jordan. The sun rises due east on the equinoxes. However, it rises furthest north of east on the June solstice and furthest south of east on the December solstice. (Image credit: Zaid M. Al-Abbadi/APOD)

Why do equinoxes occur?

The equinoxes and solstices occur due to Earth's tilt on its axis as it orbits the sun — The equinoxes and solstices occur due to Earth’s tilt on its axis as it orbits the sun. (Image credit: NOAA)

Earth’s rotational axis is tilted about 23.5° from the perpendicular to its orbital plane around the sun. As a result, the extent to which Earth’s axis tilts toward or away from the sun varies throughout the year.

There are two times a year when Earth’s axis is tilted neither toward nor away from the sun. In fact, the axis is then perpendicular to the sun, resulting in a nearly equal length of day and night across the globe. These instances are referred to as equinoxes.

The word “equinox” comes from two Latin words: aequus (equal) and nox (night).

Please bookmark Spaceandtelescope.com or follow us on Facebook and Twitter to get latest space news, upcoming skywatching events and astronomy-related content.