Get ready for the winter solstice, signifying the start of winter and the shortest day of the year.
The winter solstice for 2017 will occur at 11:28 am ET on Thursday, Dec. 21. At that moment, the sun will be directly over the Tropic of Capricorn, south of the equator, as the U.S. National Weather Service notes.
The winter solstice is when the Northern Hemisphere is tilted the farthest from the sun, making for the year’s longest night. Conversely, people living in the Southern Hemisphere will experience its summer solstice at the same time.
Traditionally, thousands of people worldwide celebrate the event by taking part in rituals that date back thousands of years. For instance, crowds of pagans and tourists typically flock to Stonehenge, the ancient British stone ruin that was built in alignment with the sun’s movement, the English Heritage, which oversees Stonehenge, told the BBC in 2015
Get Data Sheet, Fortune’s technology newsletter.
People will also trek to the Newgrange monument in Ireland, built around 3200 BCE. During the winter solstice, sunlight should shine into a special chamber at sunrise.
For those who can’t make it to Ireland, the country’s tourism department is hosting a live-stream.
Sunrise at the winter #solstice at Newgrange is being live streamed this week! https://t.co/jaC9sDkyd7 pic.twitter.com/HbCnTCsM8s
— Embassy of Ireland, USA (@IrelandEmbUSA) December 18, 2017
