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Winter begins Tuesday in the Northern Hemisphere.

It will be this hemisphere’s shortest day–but so much more!

  • It occurs tomorrow in the northern hemisphere at 9:59am Chicago time (CST) which is 15:59 Universal Time (UTC)
  • The solstice is the moment the North Pole is tilted farthest away from the equator
  • It’s the moment the sun reaches it southernmost position in the sky as viewed from Earth
  • It’s the moment the sun’s most direct rays fall on the Tropic of Capricorn in the southern hemisphere (23.5-deg S latitude)
  • The day surrounding the winter solstice is the shortest of the year in the northern hemisphere
  • There in NO SUNLIGHT in northern arctic regions of Earth the day of the winter solstice and, contrarily, 24 hours of daylight in the southern arctic regions (including Antarctica)
  • Sun is as low in Chicago’s sky during the day of any day in the year–just 24.5-deg above the horizon at solar noon here
  • The winter solstice marks the moment the sun’s most direct rays begin falling farther north in the northern hemisphere. We’ll see that in the sun’s daily trek across the sky shifts slowly north through the beginning of summer on June 21, 2021. It’s that northward trek across the sky which allows the sun to remain visible to us longer and longer thus leading to lengthening days
  • The sun is actually closest to the Earth during northern hemispheric winter—91.442-million miles Dec 21st–and Earth’s orbit around the sun actually positions our planet closest to the sun (the “perihelion”) just a few weeks beyond the winter solstice in January
  • The winter solstice occurs at the precise moment of the SUMMER SOLSTICE (i.e the astronomical beginning of summer) in the southern hemisphere–that hemisphere’s longest day of the day
  • Chicago receives 6 hours 6 minutes less daylight on the day of the winter solstice compared to its longest day 6 months late on or about June 21st, which is the northern hemisphere’s longest
  • Chicago will record a potential 9 hours and 7 minutes between sunrise and sunset Tuesday Dec 21, 2021
  • The dates of the WINTER SOLSTICE can vary from Dec 20, 21, 22, 23–but the last time the winter solstice occurred on the 23rd WAS 118 years ago on DEC 23, 1903–and the next time won’t be for another 282 years on Dec 23, 2303
  • The day surrounding the solstice is the northern hemisphere’s shortest day of the year and the southern hemisphere’s longest.
  • Days lengthen after the winter solstice–but SLOWLY at first–gaining just 2 seconds Dec 22 and 6 seconds Dec 23. But by January 5, days are lengthening by 1 minute and past January 24, days lengthen over 2 minutes per day through May 15. The rate at which days lengthen slows beyond May 15–reversing and beginning to shorten beyond the summer solstice which will occur 4:14am CDT the morning of Tuesday, June 21st.