Here come the cold and the dark.
The winter solstice — marking the longest night and fewest hours of daylight of the year — is Thursday. The winter solstice is the precise moment at which the Northern Hemisphere is tilted farthest from the sun.
The solstice occurs at the same instant everywhere on Earth. In the United States, it happens at 11:28 a.m. ET Thursday (10:28 a.m. CT, 9:28 a.m. MT, 8:28 a.m. PT).
One of the most famous solstice celebrations occurs at the ancient Stonehenge ruins in Wiltshire, England, where druids, pagans and other revelers gather each year to celebrate the event.
The winter and summer solstices, along with the equinoxes, loom large in myth and folklore.
"Culturally, the solstices and equinoxes are typically used to denote either the beginnings of the seasons or the center points of the seasons," as in England, said Rick Kline of the Spacecraft Planetary Imaging Facility at Cornell University.
This lag in temperature occurs because even though the amount of daylight is increasing, the Earth's surface continues to lose more heat than it receives from the sun. In most locations across the U.S., the minimum daily temperature occurs around two or three weeks later, in early to mid-January.
For example, the coldest days in Boston, on average, are Jan. 17-26. In Chicago, it's Jan. 17-20, and in Miami, it's Jan. 2-22. At the end of January, more heat finally begins arriving than leaving, and days slowly start to warm up.
The Earth's tilted axis causes the seasons. During the Northern Hemisphere's winter, the land north of the equator is tilted away from the sun, which lowers the amount of the sun's energy warming the Northern Hemisphere.
Of course, it's all opposite in the Southern Hemisphere, where Dec. 21 marks the beginning of astronomical summer.
And why is the Earth tilted? It's probably the result of collisions with various proto-planets and other massive objects during the formation of the solar system billions of years ago, according to NASA.
Always fascinating to realize that the reason the Earth has the perfect temperature for life to form is a few random collisions with other space rocks uncounted eons ago.
Contributing: Elizabeth Weise, USA TODAY