The Winter Solstice means the earth's darkest day is upon us.
It also means the days will only get brighter from here on.
That is, if you live in the Northern Hemisphere; in the Southern Hemisphere, it's the summer solstice, and their days will grow increasingly shorter.
Technically, the Winter Solstice happens at the same time for everyone no matter where you live in the world, but the earth's different time zones means people on different continents will experience it on different days.
New York had its Winter Solstice late Monday night/early Tuesday morning, at 11:48 p.m., but those in Europe, Africa, Asia, and Australia will have to wait till Tuesday to celebrate the longest night.
Winter Solstice, the day that traditionally signals the start of winter, has been celebrated by civilizations and cultures around the world for centuries, but what does it mean?
Solstice comes from the Latin word solstitium, or sun standing still, according to the Telegraph.
The earth's tilt is what causes our different seasons of the year, and the winter solstice marks the day when the North Pole is tilted farthest away from the sun. That leaves earthlings in the Northern hemisphere with the least amount of sunlight.
The lack of sunlight can bring on seasonal disorders in people whose mood is affected by the amount of light their bodies receive. The brain's serotonin levels are affected by the amount of sunlight they're exposed to, which helps explain why people have less energy during the winter.
Ancient people didn't have telescopes or satellites, yet they were able to mark the solstices by looking at the sky.
In England, modern day druids still flock to the prehistoric ruins of Stonehenge to celebrate the birth of a new sun. The monument is aligned on a sight-line to point to the winter solstice sunrise and pagans, druids, and nature worshippers spend the day clad in medieval costumes drinking and celebrating, senior druid King Arthur Pendragon told the National Geographic.
"What we're here for is to celebrate the fact that the cycle of the world turns. It's a time [when] change and hope is renewed."In ancient times, the solstice marked the time to slaughter the cattle, so they wouldn't have to be fed during the winter, and ferment the last wine and beer before the cold. Ancient Britains were known to celebrate the solstice with mistletoe.
The Romans held their annual festival of Saturnalia around this time. The traditional seven-day festival began December 17, and began as far back as 217 BCE. During this time, discipline was forgotten and chaos reigned -- even wars were put on hold.
The Mayans created a building specially designed to capture the sun's rays during sunrise on the summer and winter solstice, and cast the light into a room through a small hole.The Feast of Juul was celebrated in Scandinavia before the rise of Christianity. People would bring an entire tree, called a Yule log, into their homes and light it on fire to symbolize the returning of the sun.
The Irish built a huge Stone Age tomb, called Newgrange, some 1,000 years before Stonehenge. One of its tunnels, which may have been used for burial, lets in light from the solstice sunrise and illuminates a special chamber for 17 minutes.
The ancient Egyptian pyramid of Karnak was built to align with the winter solstice at Luxor, as was Angkor Wat and Machu Picchu.
The year's shortest day isn't always the coldest day. That will happen later in winter, usually during January.[Photo by Matt Cardy/Getty Images]