Monday night marks the 2015 winter solstice, the shortest day and longest night of the year.
The winter solstice will take place at the exact same moment everywhere in the world. For the United States, this year's solstice will take place at exactly 11:48 p.m. ET.
The winter solstice will take place on Tuesday, December 22 for those in Europe, Asia, Africa, and Australia.
According to the International Business Times, a solstice depends on the Earth's tilt on its axis and its orbit around the sun. The winter solstice occurs when the Earth is tilted so that the Northern Hemisphere is the farthest all year from the sun.
This solstice is the beginning of winter from the astronomical standpoint. Meteorologists say the beginning of winter is actually December 1, the first day of the Northern Hemisphere's three coldest months, as reported by USA Today.
Even though the solstice is the beginning of winter, it definitely won't be the coldest day of the year. According to the Washington Post, the weather will actually be warmer than usual. Temperatures are expected to be 10 to 20 degrees higher than average in the eastern U.S. and Canada, and the majority of Europe as well.
Because the winter solstice is the shortest day of the year, the days following will gradually get longer. However, the solstice is not the day of the earliest sunrise or the latest sunset. According to the Telegraph, the word "solstice" comes from the Latin word "solstitium," which means "Sun standing still." This day is given the term "solstice" because of the way the sun appears to stand still directly over the Tropic of Capricorn, then reverse its direction.
Because the winter solstice marks the return of longer days, meaning more sunlight, it was a time of celebration for ancient people. These people held festivals to celebrate the return of the sun. A few of the most notable winter solstice festivals include Saturnalia, the Feast of Juul, and Yalda.
Saturnalia was an ancient Roman festival that began on December 17 and lasted seven days. The celebration honored the father of the gods, Saturn. The holiday was characterized by rampant debauchery. It was custom during this solstice celebration to give gifts.
Another ancient winter solstice celebration was a pre-Christian Scandinavian festival called the Feast of Juul. This is actually where the term "Yule" was derived. This winter solstice festival was celebrated by lighting fires, which symbolized the return of the sun. A Yule log was brought to the hearth to honor the Norse god Thor. Often, the Yule log was an entire tree. The log was lit with the ashes from the previous year's tree, and the ashes burned with the new tree over the course of 12 days.
Yalda was a winter solstice festival celebrated by ancient Iranians. Yalda celebrated the winter solstice and the return of the sun every year on December 21. In the Iranian calendar, it is the first day of the month of Dey. The winter solstice represented good conquering evil, or light triumphing over darkness. Yalda night is still celebrated in Central Asia countries today.
Perhaps the most popular celebration of the winter solstice that is still celebrated today takes place at the prehistoric monument Stonehenge. Every year in Wiltshire, England, people gather to celebrate the shortest day of the year. It is believed that the winter solstice was very important to the ancient people who built Stonehenge because the formation is aligned to the winter solstice sunset. In ancient days, the winter solstice marked the day when all of the cattle were slaughtered so they did not have to be fed over winter.
Don't miss the sunset on the winter solstice, which will take place at 5:33 p.m. ET.
[Photo by Matt Cardy/Getty Images]