Autumn Equinox 2026: Date, Time, Facts and Traditions

And so, a new season begins...

The astronomical event known as the autumn equinox occurs on Wednesday 23 September 2026. The Sun will cross the celestial equator heading south at approximately 1:05am BST, or 00:05 UTC, marking the changing of the astronomical seasons here on Earth and the transition from summer to autumn for those of us in the Northern Hemisphere.

Around the equinox, we experience almost equal lengths of day and night.

Happy Autumn Equinox, everyone! 💖

Here at Astro Dog, we’re very excited for the longer, darker and starrier nights that follow the autumn equinox. We’re looking forward to the beautiful autumnal colours, foraging in the woods, gathering around campfires, drinking hot chocolate, gazing up at the night sky and being able to get outside with our telescopes more often.

There is also plenty more aurora borealis, or Northern Lights, activity to look forward to! We have already seen some incredible displays, and solar activity remains elevated around the current solar maximum period.

The weeks around the equinoxes can also be particularly favourable for geomagnetic activity. This is thought to be partly due to the orientation of Earth’s magnetic field at these times, which can allow the interplanetary magnetic field carried by the solar wind to connect more effectively with Earth’s magnetosphere. So, fingers crossed for more Northern Lights! 🌌

If you would like to learn more about the autumn equinox, please read on. ❤

Information about equinoxes

Because of the Earth’s axial tilt of approximately 23.5 degrees, the Northern and Southern Hemispheres usually receive different amounts of sunlight. One hemisphere is tilted more towards the Sun while the other is tilted away.

However, twice each year, during March and September, neither hemisphere is tilted significantly towards or away from the Sun. At these points, both hemispheres receive almost equal amounts of sunlight.

The word equinox comes from the Latin words aequus, meaning equal, and nox, meaning night.

We experience almost equal lengths of day and night around an equinox. However, because of atmospheric refraction, where the Earth’s atmosphere bends the Sun’s light, and the way sunrise and sunset are measured, daylight usually lasts slightly longer than 12 hours.

During an equinox, the Sun rises approximately due east and sets approximately due west. This is because the Earth’s equator is aligned with the centre of the Sun as it appears to cross the celestial equator.

The March equinox can occur between 19 and 21 March, while the September equinox can occur between 21 and 24 September. Depending on the season, it is known as either the spring or vernal equinox or the autumn or autumnal equinox. In the Southern Hemisphere, the seasons are reversed.

Cultural and religious significance

The equinoxes have held cultural, spiritual and practical importance for many societies throughout history.

• Britain’s traditional harvest celebrations were often held around the time of the full moon closest to the September equinox.
• The Jewish festival of Sukkot takes place during the Hebrew month of Tishrei, usually beginning close to a full moon during the Northern Hemisphere’s autumn.
• The autumn equinox marked New Year’s Day in the French Republican Calendar, which was used from 1793 until 1805. The French First Republic was proclaimed and the monarchy abolished on 21 September 1792, with the following day marking the beginning of the Republican Era.
• Some modern Pagans observe the September equinox as a point on the Wheel of the Year known as Mabon. In the Southern Hemisphere, the spring equinox is sometimes associated with Ostara.
• The autumn equinox marks the beginning of Mehr, or Libra, in the Iranian calendar. It is also associated with Mehregan, an ancient Iranian and Zoroastrian festival connected with friendship, love and gratitude.
• In Japan, Autumnal Equinox Day, or Shūbun no Hi, is a public holiday. The period known as Higan is observed by many Japanese Buddhists around both the spring and autumn equinoxes.
• In Korea, Chuseok is a major three-day harvest festival. Its date is determined by the lunar calendar and usually falls around the time of the autumn equinox.
• Traditional East Asian calendars divide the year into 24 solar terms. The autumnal equinox, known as Qiūfēn in Chinese, marks the middle of the autumn season. In this context, the character meaning “division” refers to the equal division of the season.
• Dożynki is a traditional Slavic harvest festival. In pre-Christian times, harvest celebrations were often associated with the autumn equinox.
• The reconstructed Cahokia Woodhenge, a large timber circle at the Cahokia archaeological site near Collinsville, Illinois, is used for annual equinox and solstice sunrise observances.

Other interesting equinox facts

• Sunrises and sunsets generally happen more quickly around the equinoxes than at other times of the year. This is because the Sun’s path crosses the horizon at a steeper angle.
• At the equator, the Sun is almost directly overhead at solar noon on the days of the equinoxes. A vertical object can therefore cast very little shadow.
• The weeks around the spring and autumn equinoxes can be particularly favourable for geomagnetic activity. This is thought to be partly due to the relative orientation of Earth’s magnetic field and the interplanetary magnetic field carried by the solar wind. This orientation can make magnetic reconnection more favourable, allowing energy from the solar wind to connect more effectively with Earth’s magnetosphere. This is known as the Russell–McPherron effect and can increase the likelihood of geomagnetic storms and auroral displays.
• Earth is not the only planet to experience equinoxes. Any planet with an axial tilt can have equinoxes as it travels around the Sun.
• Four astronomical events mark the beginning of the astronomical seasons: the March and September equinoxes and the June and December solstices.

Closing words from Astro Dog

We hope you all have a wonderful autumn and enjoy the beautiful dark skies during your stargazing adventures on the longer nights ahead.

Clear skies, everyone! 💖🔭🌌