Winter is coming. Our ancestors celebrated the winter solstice, the longest night of the year, with festivals marking the cycle of death and rebirth. Since then, astronomers have determined the scientific basis for Earth’s seasons, and even discovered winters on other planets, while communities around the world still celebrate with age-old traditions. This year, snuggle up under a cozy blanket with a toasty cup of hot cocoa and learn more about the science, culture, and legends behind this annual event.
The Winter Solstice Occurs at a Specific Moment
Most people observe the winter solstice as a day on the calendar — usually December 21 or 22 in the Northern Hemisphere — that marks the beginning of the coldest season. Astronomically speaking, however, the winter solstice occurs when the sun appears directly overhead at noon at the Tropic of Capricorn. This invisible line circles the planet at 23°26’22” south latitude and runs through Paraguay, Namibia, Australia, and other countries. The winter solstice corresponds with the exact moment the Northern Hemisphere reaches its maximum tilt away from the sun.
In the Southern Hemisphere, the timing and location are reversed. The winter solstice there occurs around June 20 or 21 at the moment when the sun appears overhead at noon at the Tropic of Cancer, which circles Earth at 23°26’22” north latitude (crossing Mexico, Saudi Arabia, India, and other places). The timing coincides with the Southern Hemisphere’s maximum tilt away from the sun.
The Winter Solstice Marks the Shortest Day and Longest Night of the Year
When either hemisphere is tilting away from the sun to its greatest possible extent, people who live there experience the least daylight and most night of the year. But just how short the day is depends on your precise location — specifically, how close you are to the equator. More southerly locations in the Northern Hemisphere have longer shortest days; the shortest days in northerly locations last only a few hours. For example, Manila in the Philippines lies near the equator and experiences 11 hours, 15 minutes, and 57 seconds of daylight on the winter solstice. In Reykjavik, Iceland, daylight lasts just four hours, seven minutes, and nine seconds.
Sweden Marks the Winter Solstice With Cat-Shaped Cookies
St. Lucia Day is Sweden’s winter solstice celebration, though it takes place on December 13 (the shortest day of the year according to the Julian calendar, not the Gregorian calendar). Swedish people commemorate the feast of St. Lucia, a fourth-century woman who brought food to Christians hiding from persecution. She lit her path by wearing a crown of candles. Today, St. Lucia Day processions air on national TV, while families bake special treats such as gingerbread cookies (pepparkakor) and saffron-tinted sweet rolls in the shape of “Lucia’s cats” (lussekatter). The festivities are topped off with swigs of mulled wine.
The Persian Holiday Yalda Celebrates Light Banishing the Darkness
Like St. Lucia Day, Yalda marks the victory of light over darkness as the days begin to lengthen after the winter solstice. In ancient Iran, the solstice itself was believed to be the night when evil spirits were at the height of their powers, so people kept fires burning and held raucous feasts to drive them away. That tradition continues in modern celebrations, in which Persian families gather to eat red fruits like pomegranate and watermelon (symbols of light and fertility), share hearty stews, read poetry, and stay up until morning to welcome the next day’s sun.
In Northern European Folklore, Plants Symbolize the Winter Solstice
To communities in northern Europe, the vibrant green foliage of certain plants symbolized life amid the dead of winter, and their leaves and boughs were part of winter solstice celebrations heralding the return of the sun. Evergreen trees like pines and hollies represented peace, joy, and good luck, while ancient yews stood for the death of the old year and a connection to the next one. Mistletoe was sacred to Celtic and Norse peoples and linked to fertility and health. Oak trees, even though they’re deciduous, were associated with the winter solstice as the preferred source of Yule logs; people burned the logs to encourage prosperity and protection from harm. Some traditions called for Yule logs to be lit with a remnant of the previous year’s log, perhaps to represent the cycle of time.
Pliny the Elder Had a Specific To-Do List for the Winter Solstice
The first-century historian Pliny the Elder, in his multivolume work Natural History, laid out the agricultural tasks that ancient Romans should perform on or just after the winter solstice. People should avoid handling grapevines on the day. Cherry trees should be planted, and farmers should soak acorns to soften them for oxen feed, in the amount of one modius (about 9 liters) of acorns per ox. People can also cut timber for the winter, and then fashion baskets, trellises for their crops, and torches for lighting during the “hours of the night, which are then so greatly prolonged,” Pliny wrote.
The Winter Solstice Has Been Linked to Superstitions
Within the Catholic liturgical calendar, the winter solstice used to coincide with St. Thomas’ feast day (though now that’s celebrated on July 3). In some parts of Europe and Canada, people marked the shortest day of the year by baking pies or distributing bread to the poor. There were also several superstitions associated with St. Thomas’ day, according to folk tradition. It was unlucky to sift flour, making the pie production and bread distribution somewhat more complicated. If you cut an apple in half and found the same number of seeds in each half, you’d be married soon. And if the temperature dropped below freezing on December 21, the prices of grain would also fall.
The Winter Solstice Was Thought to Bring About Calm Days
In ancient Greece and Rome, the winter solstice was believed to herald “halcyon days,” a period of calm seas and gentle breezes. Pliny the Elder — yep, him again — explained the origin of this story in Book X of Natural History. The halcyon, or kingfisher (Alcedo atthis), a bird that dives into rivers to prey on fish, was thought to build nests seven days before the winter solstice. The birds incubated their eggs for one week after the solstice, at which point the young hatched, “from which circumstance those days are known as the ‘halcyon days’: during this period the sea is calm and navigable,” Pliny wrote. The tale was based on a Greek myth — and it’s a scientific myth, too. Kingfishers actually nest in burrows in riverbanks. Today, “halcyon days” can refer to any period of tranquility and repose.
Winter Starts Earlier for Meteorologists
Astronomers and meteorologists have different criteria for determining the seasons. Technically, the cold season that begins on the winter solstice is astronomical winter, determined by the position of the sun. Astronomical spring, summer, and fall begin on the vernal equinox, summer solstice, and autumn equinox, respectively.
But the varying dates of the equinoxes and solstices make it difficult to compare weather data from one year to the next, so weather forecasters typically use meteorological seasons based on temperature averages and the regular calendar. In the meteorological calendar, each season is assigned a three-month period: Winter is December through February, spring is March through May, summer is June through August, and fall is September through November.
Ancient Monuments May Mark the Winter Solstice
Human civilizations around the world built monuments that may have noted the change of seasons as they related to planting and harvesting crops. Newgrange, a 5,000-year-old dome-shaped monument in Ireland, features a small opening in its roof through which the sun shines on the winter solstice. Stones at Stonehenge, built around 2500 BCE in southern England, are aligned to the sun’s angles on the summer and winter solstices. Indigenous peoples in North America also built monumental calendars. The Chaco Culture of northwest New Mexico recorded the winter solstice at special observatories built between 800 and 1100 CE. The Mississippian Culture established “Woodhenge,” a calendar of upright logs, around 1000 CE at Cahokia in modern-day Illinois. In southeast Ohio between 100 BCE and 400 CE, the Hopewell Culture built earthworks that aligned with the rising sun at the winter solstice.
Many Cultures Observe the Winter Solstice With a Festival
Winter solstice celebrations often note the passage of time with feasts and gatherings. People in ancient Rome held Saturnalia, a holiday on which social conventions were turned upside down to honor Saturn — the god of the harvest — and the conclusion of the planting season. The Venerable Bede, an English monk who lived in the eighth century, wrote about the Germanic winter solstice festival called Yule; over time, Europeans blended Yule and Christmas traditions. Celebrants of the Chinese festival Dongzhi observe the winter solstice by making holiday foods, including tangyuan (glutinous rice balls served in a sweet broth), wontons, nuts, and soups. Scientists in Antarctica celebrate Midwinter Day in June with a holiday meal, athletic events, and movie marathons.
Other Planets Have Winter Solstices
Each planet in the solar system has seasons determined by the tilt of its axis and the shape of its orbit, just like on Earth. Smaller tilts and more circular orbits correspond with less-noticeable seasons: On Venus and Jupiter, with minimal tilts and roundish orbits, summer and winter are pretty similar. On Mars, the tilt of 24 degrees and oval orbit give it dramatic seasonal shifts. Seasons on the solar system’s outer planets are not well understood, but scientists do know their winters last a lot longer than on Earth — about seven years on Saturn, 20 years on Uranus, and more than 40 years on Neptune.