The Winter Solstice
Today marks the Winter Solstice in the Northern Hemisphere. The shortening of daylight is finally over. For the next six months, our sunlight durations will only increase.
Despite speaking of the solstice as a date, it is actually a moment. Precisely, the solstice is the moment one of our planet’s poles is tilted maximally away from the sun. The word solstice comes from the Latin solstitium, which combines sol (sun) and stit (stopped or stationary). Broadly defined, though, the winter solstice is the date on which we experience the shortest amount of daylight during a calendar year. Conversely, things are switched in the opposite hemisphere. In the southern half of the planet, today is the longest day of the year and the pole is pointed toward the sun.
The winter solstice marks the end of astronomical autumn and moves us officially into winter, which will reign for the next three months. Despite winter being connotatively the darkest and coldest season, during winter the days actually gain in length. Perhaps we should view winter as a metaphorical spring!
Check out the following short video for graphics on the tilting of the earth and how it causes seasons:
Because the exact instant the tilt is at maximum is the precise moment of the solstice and because of the shift in our calendars (a year is not exactly 365 days), the solstice is not always on the same day each year. The solstice does, however, usually occur on either December 21 or 22.
If you were to transport yourself to a point north of the Arctic Circle, the pole is tilted so far away from the sun that you would experience darkness all the time! Conversely again, in Antarctica, at the South Pole, you would currently be in the midst of never-ending sunlight. The amount of daylight currently increases as you move from the Arctic Circle toward the equator.
For example, in Columbus, the sun shone for about 9 hours and 20 minutes today. In Fairbanks, Alaska, that total was 3 hours and 41 minutes. Miami, viewed as part of the sunny south, only has one additional hour of daylight more than Columbus or New York City.
The date is also known by other names, including midwinter, the hiemal solstice, or the hibernal solstice. Cultures around the world celebrate this astronomical event with festivals, rituals, and holidays. Many ancient structures were constructed by ancient peoples to align with the heavens, especially on the summer and winter solstices.
In Ireland, Newgrange, a prehistoric monument, was constructed so that the rising sun on the winter solstice aligns directly with the main passage of the structure. The main axis of Stonehenge in England points directly at the setting sun today. The Great Trilithon of Stonehenge was also placed so its smooth surface faces toward the sun on the solstice.
Check out the following video with fascinating footage of the solstice sun in Newgrange:
As you might remember from Friday’s article, today really is packed full of wonderful astronomical fare. In addition to the solstice, today also marks the Great Conjunction between Jupiter and Saturn. The weather here was a bit too cloudy to really take in the planets, but the live streams have been phenomenal.
This date, each year, marks a shift in my mental health. The lengthening sunlight makes everything seem a bit better, even the cold and snow! Here’s to longer days! Unless, of course, you live in the Southern Hemisphere.
Further Reading and Exploration
Dates and times of solstices since 1600
Newgrange – Official website
What’s the winter solstice? – National Geographic
2020’s December solstice is Monday – EarthSky
2021’s December solstice falls on the 21st – EarthSky
December Solstice Brings Winter, Summer Seasons – NASA’s Watch the Skies