The Winter Solstice The Winter Solstice occurs exactly when the earth's axial tilt is farthest away from the sun at its maximum of 23° 26'. Though the Winter Solstice lasts an instant in time, the term is also colloquially used like Midwinter to refer to the day on which it occurs. For most people in the high latitudes this is commonly known as the shortest day and the sun's daily maximum position in the sky is the lowest. The seasonal significance of the Winter Solstice is in the reversal of the gradual lengthening of nights and shortening of days.

The Winter Solstice is also the shortest day or lowest sun position for people in low latitudes located between the Tropic of Cancer (23°26'N) and the Tropic of Capricorn (23°26'S). Depending on the shift of the calendar, the winter solstice occurs some time between December 21 and December 22 each year in the Northern Hemisphere, and between June 20 and June 21 in the Southern Hemisphere.

Worldwide, interpretation of the event has varied from culture to culture, but most cultures have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time.

History and cultural significance

The solstice itself may have been a special moment of the annual cycle of the year even during Neolithic times. Astronomical events, which during ancient times controlled the mating of animals, sowing of crops and metering of winter reserves between harvests, show how various cultural mythologies and traditions have arisen. This is attested by physical remains in the layouts of late Neolithic and Bronze Age archaeological sites such as Stonehenge in Britain and New Grange in Ireland. The primary axes of both of these monuments seem to have been carefully aligned on a sight-line pointing to the winter solstice sunrise (New Grange) and the winter solstice sunset (Stonehenge). Significant in respect of Stonehenge is the fact that the Great Trilithon was erected outwards from the centre of the monument, i.e., its smooth flat face was turned towards the midwinter Sun.

An altar dating to 1800 BCE within an astronomically aligned Monte Alto complex in Guatemala

Neolithic site of the Goseck circle. The yellow lines represent the direction the Sun rises and sets at the winter solstice.

The winter solstice may have been immensely important because communities were not certain of living through the winter, and had to be prepared during the previous nine months. Starvation was common in winter between January and April, also known as the famine months. In temperate climates, the midwinter festival was the last feast celebration, before deep winter began. Most cattle were slaughtered so they would not have to be fed during the winter, so it was almost the only time of year when a supply of fresh meat was available. The majority of wine and beer made during the year was finally fermented and ready for drinking at this time. The concentration of the observances were not always on the day commencing at midnight or at dawn, but the beginning of the pre-Romanized day, which falls on the previous eve.

Observances

Direct observation of the solstice by amateurs is difficult because the sun moves too slowly at either solstice to determine its specific day, let alone its instant. Knowledge of when the event occurs has only recently been facilitated to near its instant according to precise astronomical data tracking. It is not possible to detect the actual instant of the solstice (by definition, one can not observe that an object has stopped moving until one makes a second observation in time showing that it has not moved further from the preceding spot, or that it has moved in the opposite direction). Further, to be precise to a single day one must be able to observe a change in azimuth or elevation less than or equal to about 1/60th of the angular diameter of the sun. Observing that it occurred within a two day period is easier, requiring an observation precision of only about 1/16th of the angular diameter of the sun. Thus, many observations are of the day of the solstice rather than the instant. This is often done by watching the sunrise and sunset or vice versa or using an astronomically aligned instrument that allows a ray of light to cast on a certain point around that time.

Before the scientific revolution many forms of observances; astronomical, symbolic or ritualistic, had evolved according to the beliefs of various cultures. Many of which are still practiced today.

Web Designer: Emma Jane Maddison

© Northumberland Astronomical Society 2010