Astronomical autumn officially began across Russia on September 23 at 03:05 Moscow time as the Sun crossed the celestial equator. The precise timing of the seasonal transition was reported by the Russian state news agency TASS, citing the press service of the Moscow Planetarium.
During the event, known as the autumnal equinox, the center of the Sun's visible disk passed from the Northern Hemisphere of the celestial sphere into the Southern Hemisphere. The solar crossing marks the official conclusion of astronomical summer in the Northern Hemisphere and initiates shifting daylight patterns around the globe.
Following the equinox, nighttime hours in the Northern Hemisphere will gradually begin to exceed daylight hours. Conversely, the Southern Hemisphere enters astronomical spring, where daylight hours become longer than the night. The term equinox originates from Latin roots meaning equal night, reflecting the temporary balance of sunlight across Earth.
Equinoxes take place twice each year as Earth completes its orbit around the Sun. Next spring, the Sun will cross back into the Northern Hemisphere, bringing the return of astronomical spring to Russia. The Moscow Planetarium, one of the oldest astronomical institution centers in Russia, regularly tracks planetary alignments and solar phenomena.
Upcoming Moscow weather and seasonal transition
Despite the formal arrival of autumn, weather forecasters previously warned that temperatures in Moscow are expected to remain unseasonably mild over the coming weekend. On Saturday and Sunday, September 26 and 27, temperatures in the Russian capital are projected to reach approximately 2.5 degrees above normal.
In spherical astronomy, the celestial equator represents an imaginary projection of Earth's terrestrial equator into space onto an abstract celestial sphere. Equinoxes occur when Earth's rotational axis is tilted neither toward nor away from the Sun, yielding nearly equal periods of day and night across the planet before axial tilt causes seasonal variations.
For Russia, a vast country spanning northern Eurasia across eleven time zones, the autumnal equinox serves as an important seasonal marker. Following the equinox, daylight hours in northern latitudes contract steadily as the region prepares for the onset of winter.
