(CNN) – Over the past six months, the days have grown shorter and the nights have lengthened in the northern hemisphere. But it’s about to be reversed.
The 2021 winter solstice, the shortest day of the year and the first official day of winter, is Tuesday, December 21. Its operation has fascinated people for thousands of years.
First, we’ll take a look at the science and the exact time behind the Solstice. Next, we will explore some ancient traditions and celebrations around the world.
The science and timing behind a winter solstice
The winter solstice marks the shortest day of the year in the northern hemisphere, when the sun appears in its southernmost position, directly above the far tropic of Capricorn.
The situation is the opposite in the southern hemisphere. There, the December solstice marks the longest day of the year – and the start of summer in places like Australia, Chile and South Africa.
These three images from NOAA’s GOES East (GOES-16) satellite show us what Earth looks like from space near the winter solstice. The images were captured approximately 24 hours before the 2018 winter solstice.
When exactly does this happen?
The solstice is usually – but not always – on December 21. The time at which the solstice occurs changes every year because the solar year (the time it takes for the sun to reappear in the same location as seen from Earth) doesn’t exactly match our calendar year.
A worker uses a snowblower to clear snow from a courtyard in Gyeongbokgung Palace in central Seoul on December 13, 2020.
ED JONES / AFP / AFP via Getty Images
Here are some examples of times where 15:59 UTC will be for various local times in locations around the world. Due to time zone differences, the solstice will technically fall on Wednesday in parts of East Asia.
– Seoul: 12:59 am Wednesday
– Bangkok: 11:59 p.m. Tuesday
– Qatar: 6:59 p.m. Tuesday
– Milan, Italy: 4:59 p.m. Tuesday
– Orlando, Florida: 10:59 a.m. Tuesday
– Calgary, Canada: 8:59 a.m. Tuesday
– Honolulu: 5:59 a.m. Tuesday
Which places see and feel the effects of the winter solstice the most?
Daylight decreases dramatically as you get closer to the North Pole on December 21.
People take advantage of the brief daylight hours in Helsinki, Finland on December 20, 2020.
Alessandro Rampazzo / Anadolu Agency / Getty Images
What causes the winter solstice?
Because the Earth is tilted on its axis of rotation, we experience seasons here on Earth. As the Earth moves around the sun, each hemisphere experiences winter when it moves away from the sun and summer when it is tilted towards the sun.
Wait. Why is the Earth tilted?
Scientists are not sure exactly how this happened, but they believe that billions of years ago, as the solar system was taking shape, the Earth was subjected to violent collisions that caused the Earth to tip over. axis.
What other seasonal transitions do we mark?
Equinoxes, both in spring and fall, occur when the sun’s rays are directly above the equator. During these two days, everyone has an equal length of day and night. The summer solstice is when the sun’s rays are most northerly over the Tropic of Cancer, giving us our longest day and the official start of summer in the northern hemisphere.
Winter solstice traditions and celebrations
The decorated evergreen trees have roots that stretch back beyond the beginnings of Christianity to ancient Egypt and Rome. New York’s famous Rockefeller tree was lit up for the 2021 season on December 1.
Ed Jones / AFP via Getty Images
It’s no surprise that many cultures and religions celebrate a holiday – be it Christmas, Hanukkah, Kwanzaa, or pagan holidays – that coincides with the return of longer days.
Ancient peoples whose survival depended on precise knowledge of seasonal cycles marked this first winter day with elaborate ceremonies and celebrations. Spiritually, these celebrations symbolize the opportunity for renewal, letting go of bad habits and negative feelings, and embracing hope in the midst of darkness as the days begin to lengthen again.
Lots of ancient symbols and winter solstice ceremonies continue today or have been incorporated into new traditions. Here are some of them:
As the Roman Empire fell under Christian influence and eventual rule, some of the festival customs were incorporated into the celebrations surrounding Christmas and the New Year.
It was not only the former Europeans who marked the annual occasion. The Dongzhi Winter Solstice Festival has its roots in ancient Chinese culture. The name roughly translates to “the extreme of winter”.
Celebrations in the age of Covid
Many places around the world traditionally hold festivals that honor the winter solstice. But due to the ongoing pandemic which now extends through the Second Winter Solstice, events may again be canceled or changed to allow for a safe and socially distant occasion.
Oh, the glories of pre-pandemic times! A choir sings at Stonehenge to mark the winter solstice before words like Covid and Omicron join everyday vocabulary.
Ben Birchall / PA Images / Getty Images
For 2020, the festival was a video-only affair. This year, they’re slacking off with in-person, but small-scale neighborhood events. Live streaming will still be an option in 2021.
CNN’s Katia Hetter and Autumn Spanne contributed to this article.