The December Winter Solstice happens at the same instant for everyone, everywhere on Earth. And this year’s Winter Solstice occurs on Sunday, December 22, at 4.19am GMT in the Northern Hemisphere.
The Winter Solstice happens every year when the Sun reaches its most southerly declination of -23.4 degrees.
This means the Solstice takes place when the North Pole is tilted farthest away from the Sun.
Consequently, the year fewest hours of sunlight are delivered on this date.
The Sun is directly overhead of the Tropic of Capricorn in the Southern Hemisphere during the December Winter Solstice and is closer to the horizon than at any other time in the year.
Does the Winter Solstice always fall on December 22?
The Winter Solstice usually falls on December 21 or 22.
However, the exact time of the Solstice varies each year.
In the Northern Hemisphere the Winter Solstice is the shortest day of the year, as it is tilted away from the Sun, and consequently receives the least amount of sunlight on that day.
However, the earliest sunset does not technically occur on the Solstice, because of the slight difference between “solar time” and the clocks used on Earth.
The shortest day of the year often falls on December 21, but the modern calendar of 365 days a year – with an extra day every four years – does not correspond exactly to the solar year of 365.2422 days.
The Winter Solstice can therefore happen on December 20, 21, 22 or 23, though December 20 or 23 Solstices are particularly rare.
The last December 23 Winter Solstice took place in 1903 and will not happen again until 2303.
The term “Solstice” derives from the Latin word ‘solstitium’, meaning ‘Sun standing still’.
On this day the Sun seems to stand still at the Tropic of Capricorn and then reverses its direction as it reaches its southernmost position as seen from the Earth.
Some astronomers prefer the more teutonic term “Sunturn” to describe the event.