8 Things to Know About the Winter Solstice

The winter solstice—arguably the least popular of the two solstices—occurs on the shortest day and longest night of the year. After this day toward the end of December, we say goodbye to short days and look forward to the extra hours of sunlight ahead in the new year.

Want to learn more about the winter solstice and why it occurs each year? Here is a collection of curious winter solstice facts.

1. There Are Actually Two Winter Solstices Every Year

Did you know the other side of the planet gets a winter solstice, too? With the planet's orbit tilted on its axis, Earth's hemispheres swap who gets direct sun over the course of a year.

Even though the Northern Hemisphere is closer to the sun during December, the tilt away from the sun results in less direct sunlight and that causes cold temperatures—and in turn, the Southern Hemisphere gets more direct sunlight and is toasty.

So while our winter solstice is around Dec. 21, the Southern Hemisphere celebrates the same around June 21.

2. The Winter Solstice Happens in the Blink of an Eye

Although the solstice is marked by a whole day on the calendar, it's actually just the brief moment when the sun is exactly over the Tropic of Capricorn that the event occurs.

3. It Happens on Different Days in the Same Year

In 2015, the solstice happened on Dec. 22, at 04:49 on the Coordinated Universal Time (UTC) time clock, the time standard that the world regulates its hours by. This means any location at least five hours behind UTC experienced the solstice on Dec. 21.

But in 2017, pretty much the whole world celebrated on Dec. 21. The solstice happened at 4:28 p.m. on the UTC time clock, or 11:48 a.m. Eastern Standard Time (EST).

4. The Winter Solstice Marks the First Day of Winter... Usually

Meteorologists consider the first day of winter to be Dec. 1. But ask an astronomer, and they'll likely answer that the winter solstice marks the start of the season.

There are two ways to look at it: meteorological seasons and astronomical seasons. Meteorological seasons are based on the annual temperature cycle while astronomical seasons are based on the position of the Earth in relation to the sun.

5. It's a Time of Gloriously Long Shadows

If you're inclined to take pleasure in the little things, like shadows that seem cast from a funhouse mirror, then the winter solstice is the time for you.

Because the sun is at its lowest arc across the sky, shadows from its light are at their longest. In fact, your noontime shadow on the solstice is the longest it will be all year. Relish those long legs while you can.

6. Full Solstice Moons Are Rarer Than Blue Ones

Since 1793, the full moon has only occurred on the winter solstice 10 times, according to the Farmer's Almanac. The last one was in 2010, which was also a lunar eclipse! The next full moon on a winter solstice won't be until 2094.

7. There's a Christmas Connection

Humans have been celebrating the winter solstice throughout history: The Romans had their feast of Saturnalia, early German and Nordic pagans had their yuletide celebrations, and even Stonehenge has connections to the solstice.

Eventually Christian leaders, endeavoring to attract pagans to their faith, added Christian meaning to these traditional festivals. Many Christmas customs, like the Christmas tree, can be directly traced to solstice celebrations.

8. The Winter Solstice Is a Reminder to Thank Copernicus

The word "solstice" originates from the Latin solstitium, meaning "point at which the sun stands still." But since when has the sun ever moved?

Of course, before Renaissance astronomer Nicolas Copernicus came up with the heliocentric model, we all figured that everything revolved around the Earth, sun included. Our continued use of the word "solstice" is a beautiful reminder of just how far we've come and provides a nice opportunity to give a tip of the hat to great thinkers who challenged the status quo.