2023-06-20 19:15:05
Every year on the same date — or almost — it’s the same thing. The June solstice marks the beginning of summer in the northern hemisphere. However, there are certainly things that you do not know regarding this phenomenon…
You may also be interested
[EN VIDÉO] The enigma of the Stonehenge solstices Traditionally, there are thousands of people who gather on the site of Stonehenge (Great Britain) to…
Over the weeks, most of the time quite imperceptibly, the sun has resumed its quarters. And today, here it is. The one which for us, in the northern hemisphere, is the longest day of the whole year. Astronomers call it the summer solstice. It marks the start of their summer season — because the meteorologist’s season begins on June 1 each year. But that, everyone knows.
The date of the summer solstice varies over the years
What we may know a little less is that the summer solstice in the northern hemisphere does not always fall on June 21. The result of small variations in the Earth’s orbit around the Sun. But also the organization of our calendar, with its leap years.
In the 20th century, the summer solstice occurred 64 times on June 21 and 36 times on June 22. Regarding the 21st century, forecasts announce 47 summer solstices on June 20 and 53 on June 21. For it to fall on June 19, it will be necessary to be patient. It won’t happen until 2488.
This year, the summer solstice, the moment when the Sun will therefore reach its highest point in the sky (not the zenith), will occur, as far as France is concerned, this Wednesday, June 21 at 4:57 p.m. very precise .
The day the sun stands still
The origin of the term solstice is perhaps another thing that we do not know. It dates from the 13th century. We inherited it from Latin sol for Sun and stare to stop. Because we must remember that our ancestors did not know why the day star rose and fell in their sky over the year. A matter of good or bad, they thought. So when they saw him climbing, they might only hope his run would stop. That it would eventually come down and herald the start of the harvest season. That is, science tells us, what it will continue to do for billions of years. At the time of the solstice…
The day the Earth occupies a special place in its orbit
Another thing that not only is generally ignored, but also seems completely counter-intuitive to us inhabitants of the northern hemisphere: the summer solstice corresponds to the day when the Earth is, in its orbit, almost at its aphelion, that is to say, furthest from our Sun! Some 152 million kilometres. If this day marks the beginning of summer, it has nothing to do with the position of our planet in space, but more with the inclination in its orbit. And a northern hemisphere directed « face » under the sun.
A solstice day not always quite so long
At the time of the summer solstice, Parisians can enjoy around 4:10 p.m. of sunshine. It is undoubtedly the longest day of the year. But its length may vary somewhat from year to year. A matter of variation in mass distributions on the Earth’s surface. As a result, scientists estimate that the longest day since the 1830s must have occurred at the summer solstice of 1912. Difficult to perceive, all the same, because it would not have lasted more than 4 milliseconds longer than the mean.
An average that does not take into account the special case of regions located at high latitudes. Indeed, on the polar circle, the day of the solstice is also that of the midnight sun. A 24 hour day. On the side of the North Pole, that day, the Sun literally settles in the sky at a height of regarding 23°.
The summer solstice, a day of celebration
Finally, this date of the summer solstice is so special that since the dawn of time, traditions have celebrated it all over the world. Regardless of cultures and religions. The celebrations were first of all pagan. We celebrated the harvest. Then some religions made it a festival of light. This is the symbolism of the feast of Saint John.
Even today, many people celebrate this day, dancing in the woods, putting on sometimes improbable costumes, lighting bonfires or… celebrating music!
1687328773
#phenomenon
