This Saturday, December 21, 2024, you're bound to hear about the winter solstice. But what exactly is it? It's the shortest day of the year. To be more precise, on this day, the sun is at its lowest point of the year. This astronomical event is due to the inclination of the Earth's axis of rotation in relation to the plane of its orbit.
This date also marks the first day of winter, although meteorological winter begins earlier. "While the astronomical or calendar seasons begin with the equinoxes (spring and autumn) and solstices (summer and winter), in meteorology they begin earlier and correspond to periods of three full months," explains Météo France, which indicates that the meteorological winter thus begins on December 1 and ends on February 28 or 29. But officially, from an astronomical point of view, the date of winter starts this year on Saturday December 21, 2024 at exactly 9:20 and 30 seconds (Paris time). This is according to theInstitut de mécanique céleste et de calcul des éphémérides.
But there's good news to consider with this winter solstice. From December 21, 2024 onwards, the days will get longer, with more minutes of daylight every day until the first day of summer. As a result, the sun will appear earlier and earlier, and set later and later. As La Chaîne Météo reveals, " we will have regained 1 minute of luminosity by the end of the year ".
The specialized site also details the difference between the winter solstice and theequinox, i.e. when the duration of daylight is equal to that of night. Again, this phenomenon is made possible by " the tilt of the Earth's axis ". In winter, this tilt reduces our star's exposure to the sun, favoring the southern hemisphere.
In general, the winter solstice falls on December 21, as was also the case in 2022. However, in 2023, the winter solstice fell on December 22. So how do we explain this shift in the winter solstice? The answer lies in the calendar drawn up by the Institut de mécanique céleste et de calcul des éphémérides atParis Observatory, which lists the winter solstices between 1583 and 2999! Depending on the year, the winter solstice may fall on December 21 or 22, or even December 20, as will be the case in 2080, or even December 23, as was the case in 1903.
