SHORTEST DAY OF THE YEAR?
December solstice is when the sun reaches its most southerly declination of -23.5 degrees, when the North Pole is tilted 23.5 degrees away from the sun. Depending on the Gregorian calendar, the December solstice occurs annually on a day between December 20 and December 23.
This year it was today, as all places above a latitude of 66.5 degrees north (Arctic Polar Circle) are now in darkness, while locations below a latitude of 66.5 degrees south (Antarctic Polar Circle) receive 24 hours of daylight.