Although in some parts of the country, it may seem like it’s been winter for a few weeks, it’s still technically fall in the Northern hemisphere until the winter solstice, which occurs this year on Saturday, December 21, and marks the shortest day and the longest night of the year.
But the solstice isn’t just a day, it’s a minute.
According to The Farmer’s Almanac, the precise moment that the winter solstice will occur this year is at 11:19 p.m. The Weather Channel explains that during that moment, the sun is directly overhead at the Tropic of Capricorn, meaning the sun is further away in the Northern Hemisphere and there is less direct radiation to heat the ground.
So why does this happen? Throughout the year, the earth tilts on its axis at a diagonal away from or toward the sun, causing the change in seasons. Following that minute, the Northern hemisphere begins to tilt toward the sun, eventually leading to longer days and warmer temperatures until the spring equinox, when day and night are exactly the same length. It also causes a shift in the jet stream, which affects weather patterns.
Solstices occur twice a year, one in the winter and once in the summer, while the equinoxes occur once in the spring and once in the fall. During an equinox, the sun passes directly over the equator, while during a solstice, it is the furthest distance away.
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Last year’s winter solstice was special, as it fell on the night of December’s Full Cold Moon. Although the moon did not peak until the following night, for most people around the world, a near full moon was visible for many nights during this time period. The last time these events coincided was 2010, and according to the Almanac, the next time a full moon will actually peak during a winter solstice won’t be until 2094.