Winter solstice 2022, the shortest day of year and the official first day of winter, is on Wednesday, December 21 (well, for a decent chunk of the world anyway). The winter solstice marks the shortest day of the year in the Northern Hemisphere, when the sun appears at its most southerly position, directly overhead at the Tropic of Capricorn. The situation is the reverse in the Southern Hemisphere, where only about 10% of the world’s population lives. There, the December solstice marks the longest day of the year — and the beginning of summer — in places like Argentina, Madagascar, New Zealand and South Africa.