On the night of Friday, September 23, the sun crossed the celestial equator and moved from the Northern celestial hemisphere to the Southern one. This means that astronomical autumn has come in the Northern Hemisphere of the Earth, the Moscow Planetarium said.
As the planetarium staff clarified, astronomical autumn came to the Northern Hemisphere on September 23 at 4:03 Moscow time, informs TASS.
The Sun’s crossing of the celestial equator on September 23 is also called the autumnal equinox, because the Sun rises exactly in the east and sets exactly in the west, while being exactly 12 hours above the horizon and 12 hours below the horizon. Accordingly, on this day, the day is equal in duration to the night.
After the autumnal equinox, the Sun will rise south of the east and set south of the west. At the same time, the duration of daylight hours at the latitude of Moscow will begin to rapidly decrease, decreasing by five hours in three months.
The Moscow Planetarium said that on September 23 the daylight hours in the capital will be 12 hours, and on December 21 – only seven hours.
Despite the onset of astronomical autumn, climatic summer is expected in a number of subjects of the Russian Federation. Weather conditions in some regions of the Volga, Urals, Siberian, Southern and North Caucasian federal districts will not correspond to the calendar: the air temperature will exceed the norm by 6-10°C.