The astronomical winter has begun this Tuesday: places in the northern hemisphere of the Earth, including the United States, will experience their shortest day and longest night.
We explain what the winter solstice is and the importance of this date throughout history.
When does the solstice occur?
The winter solstice date usually occurs between December 21 and 22.
This Tuesday it happened at 10:59 am
(Eastern Time).
This occurs simultaneously at all points on Earth, although with opposite effects on opposite sides of the equator.
[The so-called 'star of Bethlehem' will be visible this Christmas for the first time in 800 years]
What exactly is a solstice?
Although in meteorology the winter season for the northern hemisphere, and the summer season for the southern hemisphere, began on December 1, the December solstice introduces the winter and summer astronomical seasons, respectively.
After the winter solstice in the northern hemisphere,
the days will be longer and the nights shorter
until the summer solstice, June 21, 2022, when things are reversed.
People enjoy the sunrise as they welcome the winter solstice at the 5,000-year-old stone age passage tomb of Newgrange in the Boyne Valley, Ireland, on December 21, 2021.CLODAGH KILCOYNE / REUTERS
At 10:59 am, the sun's rays entered directly over the Tropic of Capricorn, a line of latitude that circles Earth in the southern hemisphere.
The seasons change on Earth because the planet is slightly inclined on its axis as it travels around the Sun. Although the inclination of the Earth with respect to the plane of its orbit around the Sun is more or less constant (23.5˚), at the solstice of In December,
all places north of the equator receive less than 12 hours of light,
leading to cooler temperatures.
While in the southern hemisphere they receive more than 12 hours of light and, with it, experience warmer temperatures, so it is summer there.
At the June solstice, this effect is reversed, with the northern hemisphere receiving the most direct sunlight, causing warmer temperatures, and the southern hemisphere receiving the most indirect sunlight, causing cooler temperatures.
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What is the difference between a solstice and an equinox?
The solstices occur twice a year: the summer solstice, between June 20 and 21 in the northern hemisphere, and the winter solstice in December.
The March equinox, which the following year will be March 20, 2022, marks the beginning of the astronomical spring and the September equinox, which will be September 22, 2022, marks the beginning of the astronomical autumn.
From left to right, Charlotte Gardiner, Sasha Udell, Andrea Taylor, Clare Donoghue, Patricia Yeyti and Agnes Pachacz participate in the winter solstice bath on Portobello beach, Edinburgh, Scotland, to mark the solstice and witness the sunrise after The longest night of the year, this Tuesday, December 21, 2021.Jane Barlow / PA Images via Getty Images
Because it is important?
Ancient cultures knew that the path of the Sun across the sky, the length of daylight, and the location of sunrise and sunset changed regularly throughout the year.
And this was important because their survival depended on an accurate knowledge of seasonal cycles.
To track the annual progress of the Sun and predict its movements, people built monuments, such as Stonehenge in England and the Torreón in Machu Picchu, Peru.
Indigenous people from the Aymara community hold flags during the winter solstice on June 21, 2021 in Tiwanaku, Bolivia.
The winter solstice marks the beginning of the year 5529 in the Aymara calendar, officially known in Bolivia as the Andean Amazonian calendar.Gaston Brito Miserocchi / Getty Images
From a spiritual point of view, these celebrations symbolize the
opportunity to renew oneself.
Many rituals on this date focus on "cleaning up the bad stuff from the year before and starting over," Dr. Natalie Kononenko, a retired professor of Ukrainian ethnography at the University of Alberta, told The Wall Street Journal.
[The so-called 'star of Bethlehem' will be seen tonight, the first close encounter of Jupiter and Saturn in hundreds of years]
"There is a human sense of reality that this is a point of change and transition," he
added.
With information from
NASA
,
The Wall Street Journal
,
USA Today
and
CNN
.