Autumn: why does the start of this season occur on a different date from one year to the next?

In 2022, fall will begin this Friday, September 23. We explain why.

Many thought we were already there when they saw September 21 appear on their calendars and the dead leaves piled up in their gardens and on the sidewalks. But this year, autumn does not begin until this Friday, September 23.

You really have to wait the equinox: the date when the day has the same length as the night, i.e. 12 hours each. As our colleagues from La Voix du Nord remind us, the equinox corresponds to the moment when the sun is exactly vertical to the equator.

Equinoxes and solstice

The phenomenon takes place twice a year and marks the change of season between summer and autumn and between winter and spring. As TF1 indicates, the Earth takes 365 days, 5 hours and 46 minutes to go around the sun. In fact, every four years, the year is said to be a leap year and lasts 366 days.

These variations mean that the beginning of autumn can fall between 21 and 24 September depending on the year, while the equinox marking the first day of spring occurs between March 19 and 21.

On the contrary, the passages from autumn to winter and from spring to summer correspond to the time of the solstices which are respectively the shortest day and the longest day of the year.

Until the winter solstice, autumn will last 89 days. And the daily sunshine time is expected to drop by 4 minutes every 24 hours by December 22.

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