Home   Sun & Moon   December Solstice

Shortest Day of the Year in the Northern Hemisphere

The December solstice is on either December 20, 21, 22 or 23.

December solstice illustration

The North Pole is tilted furthest from the Sun.

The North Pole is tilted furthest away from the Sun at the December solstice. (Not to scale)

It is the 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.

December Solstice in Washington DC, District of Columbia, USA is on
Thursday, December 21, 2017 at 11:28 am EST (Change city)

December Solstice in Universal Coordinated Time is on
Thursday, December 21, 2017 at 16:28 UTC

The Sun's Position

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

10 Facts on the December Solstice

The December Solstice occurs when the Sun reaches its most southerly declination of -23.4 degrees. In other words, when the North Pole is tilted furthest away from the Sun.

Midnight Sun or Polar Night

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.

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 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.

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 “Great Cycle” of the Long Count in the Mayan calendar. Many saw this as a prophecy of the end of the world.

(*) All dates refer to Coordinated Universal Time (UTC). Dates may vary depending on the time zone.

Topics: Astronomy, Sun, Earth, Seasons, December, Solstice

Astronomical Season Calculator


Winter & Summer Solstices

  1. What Is the June Solstice?
  2. June Solstice Facts
  3. What Is the December Solstice?
  4. December Solstice Facts
  5. When Is the Summer Solstice?
  6. When Is the Winter Solstice?
  7. June Solstice Celebrations
  8. December Solstice Celebrations

Equinox & Solstice Worldwide

Sunrise & Sunset Times

You might also like

A tree changing through the four seasons.

What Causes Seasons?

Seasons change because Earth's rotational axis tilts away or towards the Sun during the course of a year. more

2017 Cosmic Calendar

List of cosmic events in 2017 including supermoons, solar and lunar eclipses, meteor showers, solstices, and equinoxes. more

A sundial casting a shadow.

Equation of Time

Why doesn't the year's earliest sunset occur on the winter solstice, even though it is the shortest day of the year in terms of daylight? more