The Winter Solstice has been an important way in which people have marked the passing of the year for centuries. 21st December or the Winter Solstice marks the shortest day of the year in the Northern Hemisphere. The same day marks the Summer Solstice, the year's longest day, in the Southern Hemisphere.
A solstice is a moment in the year when the Sun's apparent path is farthest north or south from Earth's Equator. There are two solstices each year—one in December and one in June. The word solstice comes from the Latin words sol, meaning sun, and sistere, meaning to stand still.
At the solstice, the tilt of Earth toward the Sun is at a maximum angle in one hemisphere and a minimum angle in the other. The word solstice comes from the Latin words sol, meaning sun, and sistere, meaning to stand still.
The Northern Hemisphere’s winter solstice is the day of the year with the fewest hours of daylight and the most hours of darkness in the northern hemisphere.
Winter solstice, the two moments during the year when the path of the Sun in the sky is farthest south in the Northern Hemisphere (December 21 or 22) and farthest north in the Southern Hemisphere (June 20 or 21).
At the winter solstice the Sun travels the shortest path through the sky, and that day therefore has the least daylight and the longest night. (See also solstice.)
During this, countries in the Northern Hemisphere are farthest from the Sun and the Sun shines overhead on the Tropic of Capricorn (23.5° south).
This situation will be reversed on 21st June, when the Northern Hemisphere will see the Summer Solstice, the year’s longest day and the Southern Hemisphere will see the year’s shortest day.