Winter begins officially at 9:48 p.m. Monday, Dec. 21.
At that time the sun reaches its southernmost position in the sky and will start its slow trek back north until it reaches its northern most point in the sky at the summer solstice around June 21.
Technically, a solstice is a brief moment in time, but the term solstice is often applied to the solstice day. The winter solstice is the official beginning of winter, and it marks the shortest day of the year — though the lengths of daylight a few days before and a few days after the winter solstice are approximately the same.
On Monday the sun rises at 7:21 a.m. and sets at 5:23 p.m. giving us a total of 10 hours and 2 minutes when the sun will be at least partially above the horizon.
The exact date of a solstice varies by a few days every year, because our calendar has 365 days a year (or 366 days in a leap year), but the Earth actually takes 365.256 days to complete one orbit around the sun. This coupled with small variations in the daily rotation of the Earth and the slow wobble of the Earth’s axis contributes to slightly changing solstice dates.
