For those of us living in the Northern Hemisphere, Saturday will mark the official astronomical start of winter, also known as the Winter Solstice.
It occurs at the moment the sun is over the Tropic of Capricorn, 8:19 pm PT when the Northern Hemisphere will be tilted farthest away from the sun.
Just how much sunlight you actually get on Saturday will depend on where you are located but generally, most will get 8-10 hours of sunlight.
Here comes winter.
The winter solstice – which marks the beginning of astronomical winter in the Northern Hemisphere – is Saturday. It's the precise moment at which the Northern Hemisphere is tilted farthest from the sun.
The solstice occurs at the same instant everywhere on Earth: Here in the United States, it happens at 11:19 p.m. EST Saturday (10:19 p.m. CT, 9:19 p.m. MT, and 8:19 p.m. PT).
At that moment, the sun's rays are directly over the Tropic of Capricorn, a line of latitude that circles the Earth in the Southern Hemisphere.
Though the solstice is the astronomical beginning of winter, meteorologists view winter as starting Dec. 1, which is the start of the coldest three months in the Northern Hemisphere.
However, most locations don't have their earliest sunset or latest sunrise on the solstice. Those events occur either weeks before or after Dec. 21.