Atmospheric refraction will add several minutes to the daylight on September 23

At the Moscow Planetarium, they explained that on the day of the autumn equinox, day and night on the planet are almost equal, but daylight still lasts a little more than 12 hours. The reason is refraction — the bending of sunlight in Earth’s atmosphere, which acts on it like a prism.

Near the horizon, the Sun is actually about 1.5 degrees below where the observer sees it. Because of this, sunrise begins a little earlier, and sunset lasts longer.

Astronomical autumn in the Northern Hemisphere will begin on September 23 at 03:05 MSK, when the Sun crosses the celestial equator and moves from the Northern Celestial Hemisphere to the Southern. In mid-latitudes, the difference between day and night at this time is about 8–11 minutes.

According to astronomers, two to three days after the equinox, the length of day and night will become equal. Then, until the winter solstice, daylight will decrease.

Sources

• TASS