WINTER DATE 2025. Like every year, a few days before Christmas, the winter solstice takes place. But do you know what this term means, and what actually happens on the shortest day of the year?
From Sunday, the days will finally get longer, to the great pleasure of sun and vitamin D lovers. If on the date of December 21 in 2024, the length of the day is the shortest of the year, with a duration of the longest night, the days that follow will gradually lengthen until the summer solstice in June, the opposite phenomenon.
The solstice is an astronomical event that lasts only an instant, when the apparent position of the sun as seen from our planet reaches its northern or southern extreme. This astronomical event opposes the equinox, the moment when day and night have the same length. What time is Saturday? Definition, length of day and night, rituals around the winter solstice, we take stock of the astronomical phenomenon in our file.
This winter, our hemisphere will mainly receive grazing rays with limited heating effect and the North Pole will even find itself plunged into darkness! At the same time, summer will begin in the Southern Hemisphere, with the sun at its zenith above the Tropic of Cancer (each in turn).
During the winter solstice, the Earth’s position relative to the sun reaches its maximum tilt. Result : the sun seen from our planet is at its southernmost point (furthest south in relation to the horizon), the sunshine is as short as possible. During the summer solstice, it is the opposite. The sun is furthest north and we then experience the longest day of the year, marking the arrival of summer. All this should not be confused with the autumn or spring equinoxes, during which night and day have the same duration…
Scientifically, the winter solstice corresponds to the time of year when the trajectory of the sun, seen from the earth, reaches its southern (in the northern hemisphere) or northern (in the southern hemisphere) maximum. In other words, in our latitudes, at the time of the winter solstice, the sun only rises 18° from the horizon (when during the summer solstice, it is visible at 65° altitude, always relative to the horizon ). It is also the day when the inequality of day and night is maximum, with maximum night in the northern hemisphere and maximum day in the southern hemisphere (which is actually experiencing its summer solstice) . The diagram below will help you better visualize the phenomenon of the winter solstice (shown here on the right):
The Institute of Celestial Mechanics and Ephemeris Calculation (IMCCE) provides the exact date and time of the winter solstice each year. For 2024, according to observations and calculations, the winter solstice takes place on Saturday the 21st December at 9:20 minutes and 30 seconds (Paris time).
But how does the Paris Observatory calculate the occurrence of the solstices, which it currently estimates until 2999? In scientific terms, the dates of the seasons are determined from the “apparent geocentric longitude of the sun”: “The winter solstice corresponds to the moment when the apparent geocentric longitude of the Sun is equal to 270°”, specifies the IMCCE on its website. “Geocentric longitude” is the apparent distance from the sun as seen from Earth.
More prosaically, in our current Gregorian calendar (which is a solar calendar), the winter solstice is likely to occur on December 20, 21, 22, or 23. And most often takes place on December 21 or 22. In our calendar, the length of the seasons varies based on a large period of time: the dates of the seasons are not fixed, but the establishment of a solar calendar has made it possible to limit their drift.
The lengths of day and night depend on the latitude as well as the place of habitation. Overall, on the day of the winter solstice, it is light for just over 8 hours in the northern hemisphere. For a night which therefore spans almost two-thirds of a 24-hour cycle, or 16 hours!
The event of the solstice is opposed to that of the equinox, the moment when day and night have the same length. The equinox is a moment of the year which marks the crossing of the sun from one celestial hemisphere to another. On this day, the star passes right at the zenith on the earth’s equator (in other words, the point in the sky located exactly vertical to the equator). The solstice is the opposite of the equinox. It does not mark an equal duration between day and night, but a minimum (winter) or maximum (summer) day length. And sometimes to the extreme: it is night all day in the North Polar Circle and day all the time in the South Polar Circle! In the northern hemisphere, the spring equinox occurs in March and the autumnal equinox in September when the solstices occur in June (for the summer solstice) and in December (for the winter solstice). In the southern hemisphere, it’s quite the opposite! But equinoxes and solstices still have one thing in common: by convention, the equinox and solstice dates mark the transition from one season to another.
The date of the winter solstice marks the start of astronomical winter, and it is a landmark in societies to demarcate the highlights of the calendar and seasons. The solstices have therefore been celebrated by many civilizations, from ancient Egypt to Christian societies. We note, for example, that in Europe, the celebration of Christmas corresponds, within a few hours, to the time of year when the northern hemisphere enters winter. In “Christmas: Such a Long History”, historians Alain Cabantous (Paris-I) and François Walter (University of Geneva) focus on a winter solstice considered to be the day of birth of the “unconquered sun”, where the daylight begins to grow again. For the authors, the solstice is in fact the bearer of a “cosmic symbolism” among Christians: it thus becomes for them “the day on which the “true” sun of justice identified with Christ is born.”
In fact, Christianity relied on a pagan festival, which existed long before the coming of Christ into the world was celebrated. Christmas takes its etymology from Latin birthday (day of birth), which in the West designated the moment from which the days become longer again.
The pagan festival from which Christians were inspired corresponds to the Saturnalia, these celebrations in honor of the Roman god of sowing and fertility : Saturn. Practiced in Ancient Rome, the festivities then spread over seven days, from December 17 to 24. The Romans gathered with family or friends, among vegetation and garlands, and gave each other figurines made of bread or terracotta. The tunic of the poor and slaves replaced the usual toga. When Julius Caesar reformed the lunar calendar, the “Julian” solar calendar replaced it. And the winter solstice is incorrectly fixed on December 25 (even though it takes place on the 21st or 22nd!). The festive spirit has indeed remained and spanned the ages. When we tell you that there is reason to rejoice…
Today, we almost no longer celebrate the winter solstice. As Slate explains, Christianity’s introduction of Christmas on December 25 actually contributed to the disappearance of certain pagan rites that traditionally took place that same month, including the Yule festivalwhich marked among Germanic peoples the winter solstice and therefore the arrival of this snow season. This celebration was thus a festival of light since from the winter solstice, the days begin to lengthen. Concretely, people who still celebrate the Yule festival today light candles, make fires, collect things in nature, make wreaths and give each other gifts, most often handmade.
Here are the precise dates and times of the next seasonal changes moving us into winter, for the years to come, until 2027, in Paris time:
- December 21, 2024 at 9:20 a.m.
- December 21, 2025 at 3:03 p.m.
- December 21, 2026 at 8:50 p.m.
- December 22, 2027 at 2:42 a.m.
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