Astronomical winter begins at 5:38pm on December 21st. The Winter Solstice is the day the sun reaches it's lowest point on the horizon as it sits directly over the Tropic of Capricorn in the southern hemisphere.
The days leading up to and after the 21st are the shortest of the year with only 9 hours and 49 minutes of daylight.
The word Solstice means "Sun Stands Still". By December 27th, the sun begins it's journey back toward the equator and the days slowly begin to lengthen as we head toward Spring.
Ed explains what other celestial event will take place on December 21 in this edition of Weather 101.