December 21 marks the winter solstice, which is the shortest day of the year. It happens every time the Sun reaches its most southerly declination of -23.5 degrees, meaning that the North Pole is tilted farthest from the Sun. Because of this, the days are shorter and the nights are longer in the Northern Hemisphere.
The winter solstice occurs at the same time for all of us. This year it takes place on Wednesday, December 21 at 10:44 GMT (Universal time). To commemorate this time of the year, thousands have headed to the prehistoric monument Stonehenge, gathering for pagan celebrations.
Is December 21 the first day of winter?
The term solstice derives from the Latin word “solstitium,” which means “Sun standing still.” It’s is an astronomic event that occurs twice a year, in June and December, when the Sun reaches it most northerly or southerly position relative to the equator.
During the Winter solstice, the Sun reaches its most southerly position, which is why days are shorter. The North Pole is the farthest to the sun with a 23.5 degrees inclination. The winter solstice generally occurs on December 21, but it is not always like that. It can happen on December 20, 21, 22 or even 23, though solstices on December 20 and 23 are extremely uncommon.
The last December 23 solstice took place in 1903, and the next one is set to happen on 2303. This variation is due to the simplifications of modern calendar, which has 365 days of 24 exact hours. However, in reality, the solar year last 354.2422 days.
There is a dispute about if Wednesday is actually the first day of winter, and the truth is that it depends on what you consider. There are two types of winter the astronomical and the meteorological one. The astronomical one is happening this year on December 21st –ending on March 19th – but the meteorological winter started a few weeks ago, specifically on December 1st, and it ends on February 28th (or 29, in the case of leap years). The astronomical winter is determined by the position of the Earth around the Sun, while the lowest average temperatures set the meteorological winter.
However, it is important to remember that while in the northern hemisphere days are shorter and night are longer with low temperatures – because it receives less amount of sunlight – in the southern hemisphere is quite the opposite, days are hotter and last more. The dawn comes early, and the dusk comes late.
Pagans gather in Stonehenge for the Winter Solstice
Today, thousands of people have gathered in Stonehenge, the monument in Wiltshire to celebrate the shortest day of the year. The reason behind it is that Stonehenge is aligned on a sight-line that points to the winter solstice sunset. The monument is believed to be created from 3000 BC to 2000 BC. Back then, people thought that the winter solstice was more significant that the summer solstice because the winter solstice was a time when they killed cattle –with the aim of not feeding them during winter- and wine and beer were fermented. Therefore, it was a time of celebration, that managed to continue to our days.