Autumnal Equinox: Astronomical Autumn Has Begun

Today, at 9:19 PM, the autumn equinox occurred, and the astronomical autumn officially began in Bulgaria, the National Institute of Meteorology and Hydrology reported.

Today, the day will last 12 hours and 10 minutes, and the Moon is in the phase one day after the new moon.

Autumn

Autumn, one of the four seasons in temperate latitudes, ranks alongside spring, summer, and winter. Its astronomical start is marked by the autumn equinox, also known as the autumnal equinox point. For the Northern Hemisphere, this occurs around September 22, and for the Southern Hemisphere – around March 20. At this moment, direct sunlight reaches the equator. After the equinox, the angle of incidence of the sun"s rays gradually decreases, leading to a significant decrease in solar radiation. This is a precursor to lower temperatures and the onset of predominantly cool weather.

Calendar-wise, autumn encompasses the months of September, October, and November in the Northern Hemisphere, and March, April, and May in the Southern Hemisphere. Characteristic of the autumn season is that it is a transitional period. Sometimes its beginning is distinguished by unexpectedly high temperatures – the so-called "Indian summer_q_, which subsequently gives way to more moderate, and later lower temperatures. The transition is smooth, with unstable weather and frequent changes in meteorological conditions. The onset of astronomical autumn marks the beginning of seasonal changes in nature, traditionally noted by changes in leaf colors, reduced daylight, and the preparation of flora and fauna for winter. This is a period of unique charm, reflected both in the landscapes and in human sensations. The onset of astronomical autumn is a significant event, marking the end of summer and the beginning of the cooler months.