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Why does spring start on March 20 and not March 21?

Why does spring start on March 20 and not March 21?

Why does spring start on March 20 and not March 21?

Spring this Monday, March 20th. If at a young age you learned that the season of renewal falls on March 21, then it has been several years since it begins 20. This variation is associated with the spring equinox, one of the two days of the year, with autumn, where the Sun is perfectly aligned with the equator, and the day lasts as long as the night.

What is the spring equinox?

If spring marks the return of sunny days, it is due, in part, to the vernal equinox: the moment when day and night are of the same length. This astronomical event is caused by the position of the Earth relative to the Sun. On this day, the sun is directly above the equator.

This relative position of the Earth and Sun causes equal amounts of sunlight to reach both hemispheres and marks the beginning of spring in the northern hemisphere and autumn in the southern hemisphere.

Why doesn’t it always fall on the same date?

The rate of rotation of the Earth and its orbit around the Sun varies slightly from year to year, which affects the length of the seasons. Although the Earth takes 365.2422 days to revolve around the Sun, our Gregorian calendar has only 365 days.

To correct this difference, the Gregorian calendar introduced a leap year that occurs every four years and includes an extra day (February 29). However, this correction is not enough for the vernal equinox to fall on the same date every year. Thus, in 2023, the spring equinox will occur on Monday, March 20, at 22:24 and 24 seconds.

March 19, 20 or 21?

The spring that falls on March 20 is not new: it has been that way since 2008. The last time spring fell on March 21, 2007. date of.

As for March 19, you need to go back to 1796 to find the last time spring started on that day. According to the Institute for Celestial Mechanics and Ephemeris Calculation (IMCCE) of the Paris Observatory, this will not happen again until 2044.


Source: Le Parisien

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