The North Pole is tilted furthest from the Sun.

December Solstice: Shortest day of the year in the Northern Hemisphere

The December solstice is on either December 20, 21, 22 or 23. It is called Winter Solstice in the Northern Hemisphere, where it is the shortest day of the year. In the Southern Hemisphere, it is the Summer Solstice and the longest day of the year.

The December solstice, also known as the southern solstice, is the solstice that occurs each December, typically between the 20th and the 22nd day of the month according to the Gregorian calendar. In the southern hemisphere, the December solstice is the summer solstice, whilst in the northern hemisphere it is the winter solstice.

The Sun's position

The Sun is directly overhead of the Tropic of Capricorn in the Southern Hemisphere during the December Solstice.

The December Solstice occurs when the Sun reaches its most southerly declination of -23.5 degrees. In other words, when the North Pole is tilted furthest – 23.5 degrees – away from the Sun.

Midnight Sun or complete darkness

Being the longest day of the year, also means that people in the areas south of the Antarctic Circle towards the South Pole will see the Midnight Sun, i.e. have 24 hours of daylight, during this time of the year.

Sunrise & Sunrise times worldwide

For people in the Northern Hemisphere, the December solstice marks the exact opposite, the day of the year with fewest hours of daylight. North of the Arctic Circle towards the North Pole there is no direct sunlight at all during this time of the year.

Solstices importance in culture

The December solstice has played an important role in cultures worldwide from ancient times until our day. Even Christmas celebrations are closely linked to the observance of the December solstice.

There are also customs linked to the June solstice along with traditions linked to the Spring (vernal) equniox and the Fall (autumnal) equinox.

The December solstice in the calendar

December 21 or 22 solstices happen more often than December 20 and 23 solstices. The last December 23 solstice was in 1903 and will not happen again until 2303. A December 20 solstice has occurred very rarely, with the next one in the year 2080.(*)

Why do the dates vary?

As with the June solstice, the December solstice’s varying dates are mainly due to the calendar system. The Gregorian calendar, which is used in most western countries, has 365 days in a common year and 366 days in a leap year.

However, the tropical year, which is the length of time the sun takes to return to the same position in the seasons cycle (as seen from Earth), is different to the calendar year. The tropical year is approximately 365.242199 days but varies from year to year because of the influence of other planets. The exact orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession), also contributes to the changing solstice dates.

The solstices can also be observed by noting the point of time when the sun rises or sets as far south as it does during the course of the year (winter in the northern hemisphere) or maximally north (summer in the northern hemisphere).

Is the year's earliest sunset on the winter solstice?

December solstice and seasons

It is important to note that Earth does not move at a constant speed in its elliptical orbit. Therefore the seasons are not of equal length: the times taken for the sun to move from the vernal equinox to the summer solstice, to the autumnal equinox, to the winter solstice, and back to the vernal equinox are roughly 92.8, 93.6, 89.8 and 89.0 days respectively. The consolation in the northern hemisphere is that spring and summer last longer than autumn and winter (when the December solstice occurs).

The relative position of the Earth's axis to the sun changes during the cycle of seasons. This phenomenon is the reason why the sun’s height above the horizon changes throughout the year. It is also responsible for the seasons through controlling the intensity and duration of sunlight received at various locations around the planet.

End of the world in Mayan calendar

In 2012, the December Solstice coincided with the end of the Mayan calendar. Many saw this as a prophecy of the end of the world.

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