Winter solstice: Tuesday brings shortest day, longest night of the year

Dec. 21 (UPI) -- The start of winter arrived right on schedule on Tuesday -- 10:58 a.m. EST -- as the Northern Hemisphere officially entered the year's coldest season.

The start of the season is marked by the winter solstice, which brings the shortest day and longest night of the calendar year. It is at this point that the Northern Hemisphere is tilted farthest from the sun.

The winter solstice occurs when the sun is directly over the Tropic of Capricorn.

After Tuesday, days will begin to get progressively longer until culminating with the summer solstice on June 21.

The March equinox on March 20 will mark the beginning of the astronomical spring season.

Seasons change on Earth because the planet is slightly tilted on its axis as it travels around the sun. During the first week in January, Earth is about 1.6 million miles closer to the sun.

Although the astronomical winter season began on Tuesday, meteorologists typically view Dec. 1 as the start of winter.

The date of the winter solstice varies between Dec. 20 and Dec. 23, but it most often falls on the 21st or 22nd.