The winter solstice is finally upon us, but what exactly does that mean?
The winter solstice, also known as the December solstice, marks the beginning of what is referred to as astrological winter — i.e., winter based on the position of the Earth in relation to the sun, rather than temperature. At the precise moment of the winter solstice, the Earth’s Northern Hemisphere is tilted furthest away from the sun, resulting in the year’s shortest day, or, more accurately, the day with the shortest period of daylight.
Typically, this event occurs in the northern hemisphere between Dec. 20 and Dec. 23. This year, the winter solstice falls on Dec. 21, at 10:59 EST.
But even though there’s less perceivable daylight in the Northern Hemisphere, the winter solstice actually marks the longest day of the year in terms of the Earth’s rotation on its axis, according to NASA. Specifically, the “solar day” — measured on a sundial between noon on Dec. 21 and noon on Dec. 22 — will last for 24 hours and 29.8 seconds, officially making it the longest of the year, in addition to the day with the least amount of daylight.
Every day thereafter, however, the Northern Hemisphere will see a few additional seconds of daylight, with some days between January and May lengthening for up to a few minutes each, according to WGN meteorologist Tom Skilling.
Interestingly, the winter solstice also doesn’t necessarily mark the coldest day of the year, despite the Northern Hemisphere being the furthest from the sun. Lots of factors — including snow cover, weather patterns, etc. — determine the coldest day, the Old Farmer’s Almanac explains. The Earth could also see residual heat from the sun’s previous rays, delaying colder temperatures. The year’s coldest days in the Northern Hemisphere can actually occur several weeks later, according to WSYR meteorologist Dave Longley.
However, one thing is certain: The winter solstice in the Northern Hemisphere can only mean more daylight ahead, and our eventual arrival at the summer solstice.
We’ll have to wait a bit for sunnier skies, though. The summer solstice — which marks the longest day of 2022 — is expected on June 21.