The timing of Solstice

My friends who celebrate the Winter Solstice were confused about the date this year.  Isn’t Solstice always on December 21?  Well, no: the actual date varies from Dec 20 to Dec 23, depending upon the Gregorian calendar.


The Winter Solstice, technically speaking, is a moment in time, not an entire day.  The moment of Solstice occurs when the Sun enters 0 degrees 0 minutes of Capricorn.  Put in scientific terms, Solstice is when the Earth reaches its maximum axial tilt away from the Sun.

For those of us living in Midwest USA, the Winter Solstice moment this year was Wednesday, December 21 at 11:30 p.m. Central Standard Time (CST).  The official date, however, was December 22.  


Why is this? Because it is convention to use Universal Time (UT) for such events.  UT is measured at the Prime Meridian, or 0 Longitude on planet Earth.  At 11:30 p.m. last Wednesday in Milwaukee it was 5:30 a.m. in Greenwich, England, the current site of the Prime Meridian.  (The Prime Meridian used to run through Paris, but that is another story!)  Solstice Day--the day that contains the Solstice moment, UT--is the first day of winter.  In the old times this day was called Midwinter, in the same way that Summer Solstice was known as Midsummer.


Shakespeare's wonderful play “A Midsummer Night’s Dream” takes place on the Summer Solstice.  The Summer Solstice is to the solar year as the full moon is to the lunar month.  That’s why the play is full of such antics—it's like a full moon, but much stronger!  The Winter Solstice symbolizes the rebirth of the Sun, just as the Moon is reborn at each new moon.


For some interesting information on the Gregorian calendar and how/why it came about:


First published Dec 26, 2011 on