Autumn Equinox 2026

The autumn equinox is the moment when the Sun, in its apparent motion across the celestial sphere, crosses the celestial equator from the Northern Hemisphere to the Southern Hemisphere. From an astronomical point of view, at this moment the apparent geocentric ecliptic longitude of the Sun is equal to 180°.

In 2026, the autumn equinox occurs on Wednesday, September 23, at 00:05 UTC, corresponding to 03:05 local time in Romania (EEST). This moment marks the beginning of astronomical autumn in the Northern Hemisphere and, at the same time, the beginning of astronomical spring in the Southern Hemisphere.

The term "equinox" comes from the Latin words aequus ("equal") and nox ("night"), referring to the fact that, around this time of year, the lengths of day and night are approximately equal. They are not, however, exactly equal, mainly because of atmospheric refraction and the way sunrise and sunset are defined.

Around the time of the equinox, the Sun rises very close to due east and sets very close to due west. After the autumn equinox, in the Northern Hemisphere, the length of daylight continues to decrease, while the duration of nighttime increases until the winter solstice.

In Bucharest, on September 23, 2026, the Sun will rise at approximately 07:03 and set at approximately 19:11, resulting in a day length of about 12 hours and 8 minutes.

The date of the equinox is not fixed. In the Gregorian calendar, the autumn equinox generally occurs on September 22 or 23, with much rarer occurrences on September 21 or 24.

Further details on the exact times of the main astronomical phenomena occurring throughout the year can be found by accessing the following link: https://www.astro.ro:8080/static/data/2026/phenomena-2026.pdf

Published on: Sep 21, 2026