As Christmas lights illuminate the streets and the season of merriment begins, December 21st marks the winter solstice this year – a reminder that the darkest day of the year is just around the corner.

For the more than 6 billion people living in the Northern Hemisphere, this astronomical event means not only the shortest day but also the longest night of the year.

Here’s everything you need to know about the winter solstice and its meaning.

What is the winter solstice?

The winter solstice occurs on Saturday, December 21st in the Northern Hemisphere.

This celestial event occurs when the Northern Hemisphere is furthest from the Sun due to the Earth’s axial tilt, resulting in the least amount of daylight per year.

At 4:20 a.m. ET, the solstice occurs, marking “the beginning of winter in the Northern Hemisphere and summer in the Southern Hemisphere,” according to NASA.

This dual phenomenon occurs because the Earth rotates around a tilted axis. Twice a year the sun’s path reaches its northernmost or southernmost point, creating solstices that mark the transition between seasons.

Is December 21st the shortest day of the year?

Yes! If you live anywhere north of the equator, this is the day with the least amount of sunlight. How much natural light you get depends on where you live. For example, places further north like Alaska will barely see the sun, while areas further south like Florida will still get a little more light.

“At all locations north of the equator, daylight is shorter than 12 hours, and at all locations south of the equator, daylight is longer than 12 hours,” NASA says.

Why is the winter solstice called the first day of winter?

The two solstices are considered the beginning of the astronomical winter and summer seasons.

According to the National Centers for Environmental Information, astronomical seasons are marked by solstices and equinoxes, the points at which the sun is aligned with the equator.

These seasons are based on the Earth’s natural rotation. In contrast, meteorological seasons divide the year into three-month groups based on temperature patterns, making them more closely aligned with our monthly civil calendar than astronomical seasons.

Will the days get longer after December 21st?

Yes! After the solstice, each day there will be slightly more sunlight than the day before. When we reach the summer solstice on June 20, 2025, it will be the longest day of the year.

Although December 21st feels dark, it is actually the turning point towards brighter days.

How did people celebrate the winter solstice?

People have been celebrating the winter solstice for thousands of years. According to NASA, ancient civilizations built landmarks such as Stonehenge in England and Torreon in Machu Picchu, Peru, to track the movements of the sun.

For many cultures, the solstice was a time to reflect on the prospect of the return of light after the darkest days. Today, many winter holidays and traditions are still rooted in the idea of ​​hope and renewal.

The winter solstice is more than just an astronomical event. It symbolizes the cyclical nature of time, marking the end of a phase and the gradual return of light. While December 21st may bring the darkest night, it also heralds the prospect of longer, brighter days.