The Winter Solstice

The Winter Solstice.

The start of December means winter is coming, and soon. This year, the winter solstice will take place on Thursday, Dec. 21 for the Northern Hemisphere. The specific time the winter solstice happens depends on which time zone you’re in.

What is the winter solstice?

The winter solstice marks the start of winter — the day with the smallest amount of daylight, sometimes referred to as the “darkest day of the year” or the “shortest day of the year.” But just because there isn’t a lot of sunlight doesn’t mean it is always cold on the winter solstice. In fact, the NWS explains, the coldest and warmest temperatures typically occur weeks after the winter and summer solstices, respectively.

What happens during the winter solstice?

The NWS notes that seasons are not caused by how close the Earth is to the sun, but rather how the Earth is tilted. While the Earth is always tilted at 23.5 degrees, during the winter, that tilt is facing away from the sun. In fact, the winter solstice marks when the earth is tilted furthest away from the sun. As the Earth starts tilting further from the sun following the autumnal — or fall — equinox, temperatures in the Northern Hemisphere start to drop, which is why the December solstice marks the beginning of winter. Temperatures won’t start picking up until around the time the Earth starts tilting toward the sun after the vernal, or spring, equinox.

When is the winter solstice in the Northern and Southern Hemisphere?

The winter solstice in the Northern Hemisphere will occur on Thursday, Dec. 21. But not everyone celebrates the winter solstice on the same date. The winter solstice occurs in the Southern Hemisphere when the Northern Hemisphere experiences its summer solstice, which falls on June 21, 2018.

What does Stonehenge have to do with the winter solstice?

Stonehenge is a popular destination for the winter solstice. The site is often visited by pagans celebrating the sun’s “rebirth” for the new year and is just one of the few ways people celebrate the winter solstice around the world. The stone formation —a prehistoric monument in Wiltshire, England, about an hour and a half outside of London — creates a sight line toward the winter solstice sunset.

Credit: Lisa Marie Segarra for Time, 14 December 2017.