Monday, December 21, 2009

The Winter Solstice: Where Physics Meets Culture for All

Sunrise over Sweden, December 21, 2009

The Winter Solstice in the Northern Hemisphere occurs at some time between Dec 20-22 each year, at the precise time when the earth is on its maximal tilt from/toward the sun and appears to stand still before reversing the direction of its tilt. In fact, “solstice” is Latin for the sun (sol) standing still (sistere). It is one of 4 major astronomical events, along with the Summer Solstice, and the Vernal and Autumnal Equinoxes.

Astronomical events in the Northern Hemisphere and their cultural attributions

The Winter Solstice, or Midwinter in some regions, more broadly construed, also marks the shortest day of the year, the day when there are the fewest hours of daylight; or, more optimistically, the day when the days will start to lengthen again, until the longest day of the year on the Summer Solstice, approximately June 21 in the Northern Hemisphere. In the Southern Hemisphere, these days are reversed: June 21 marking the Winter Solstice, and December 21 the Summer Solstice.

The Earth's Orbit around the Sun in the Northern Hemisphere

The Physics

Thus a solstice is an astronomical event which occurs twice a year, with opposite results in each hemisphere. The solstices occur twice a year because the Earth is tilted on its axis an average 23.5 degrees as it orbits the sun. During the warmer half of the year in the Northern Hemisphere the North Pole is tilted toward the sun. The Northern Winter Solstice occurs when the earth is tilted at its greatest extreme away from the sun, making it the darkest but not necessarily the coldest day of the year.

Or, attempting to speak physics: the declination of the sun (δ) is the angle between the rays of the sun and the plane of the earth's equator. A solstice happens when the projection of the earth’s axis on the plane of the earth’s orbit is on the same line linking the earth and the sun. At that time the angle between the rays of the sun and the plane of the earth equator is at a maximum, and its value is 23°27'. δ = +23°27' at the northern hemisphere summer solstice and δ = -23°27' at the northern hemisphere winter solstice. The sun's declination is equal to the inverse sine of the product of the sine of the sun's maximum declination and the sine of the sun's tropical longitude, at any given moment.[!!!!!?????!!!!!]

The Culture

Fortunately, for those of us who prefer declination as something we do in linguistics to Latin nouns, and our life free of trigonometry (although I once dreamt of doing Latin declensions with trigonometry functions--very stressful exam period), the Winter Solstice represents a cultural event as well as an astronomical one. Ancient cultures the world over noted the shortest and longest days of their year and built their scientific, mythological, social and cultural understandings around it.

In ancient times, all agricultural activities were set to the sun, and winter was often a time of famine. Livestock were killed before they would starve, and so they would provide meat, and not have to be fed; and, late harvests were done, and wine and beer fermented. Thus it was a time of feast before the famine, and celebrations were held with the fruits of the fall on the eve of the shortest day, the first day of winter. Neolithic and early Bronze Age monuments like New Grange (Ireland) and Stonehenge (England) are testimonies to those early rituals and celebrations. The primary axis of each is aligned to the solstice: New Grange to the Winter Solstice sunrise, and Stonehenge to the Winter Solstice sunset. The Great Trilith (massive 3 stone structure) of Stonehenge was turned to face the midwinter sun.

Contemporary celebration of the Winter Solstice by neo-Druids and Wiccans at Stonehenge, England

Judeo-Christian religious celebrations were built on to these. The Jewish festival of lights, or Hanukah, while a celebration of the divine mystery of the lamp oil during the Exodus from Egypt, also is timed to celebrate the rebirth of the sun and everlasting light at the time of the Winter Solstice. Early Christians focused their calendar and religious celebration around Pasqua or Easter, and the death of Jesus during the Jewish Passover, which Jesus had gone with his disciples to celebrate in Jerusalem. The idea of the birth as well as the death of Christ became more important over time.

As Christianity spread west and north, it incorporated elements of the Roman Saturnalia, and the pre-Christian traditions of Northern Europe: particularly those of the Germans, Anglo-Saxons, and Celts, still notable today in Yule. All were based on the Winter Solstice, and the death and rebirth of the sun. This annual birth of the sun became the day designated as the birth of Jesus, December 25, the day of the Winter Solstice, or Saturnalia, in the Roman Julian calendar.

Celebrating Saturnalia

Saturnalia was a carnivalesque celebration, with a carefully structured role reversal between masters and slaves, one which would release social tensions and provide for merriment without subverting the social order. For example masters served the slaves dinner but it was in fact prepared by the slaves, and slaves mocked the masters but within carefully codified bounds. This was essentially a harvest festival, based in part on the Greek celebration of Kronia, in honour of the god of agriculture Cronos. While Cronos was not much loved by the Greeks, his Roman counterpart Saturn, was much loved by the Romans, whose military and empire carried the Saturnalia across the Middle East and Europe.

At a later point, the Romans also spread the cult of Mithras, originally a Persian Zoroastrian mystery cult, and considerably Romanized and Helenized it. Most of what is known about the cult which was prevalent in the Roman military from 1-4 CE, is known from carved stone reliefs. These emphasize motifs of tauromachy, and a banquet seen of Mithras with Sol the Sun God feasting on a bull. Evidence of Mithraism has been found in Syria, and farther west into Germany with the epicenter seeming to be Rome. Yet Mithra was also conflated by some with Jesus Christ. The birth of Mithra is still celebrated in Iran on the Winter Solstice, as Shab-e Yalda (the birth of the sun), with prayer, the symobolic sharing of fruits, a special feast, fire, poetry reading of the poems of the mystic Iranian poet, Hafez.

Thai Pongal Celebration

Farther east, in Hindu culture, Makara Sankranti is celebrated at the beginning of Uttarayana (the 6-month period of the northern trajectory of the sun), and is the only Hindu festival which is based on the sun rather than the moon. It is celebrated in diverse ways throughout India and the Indian diaspora, depending on the region of origin. For example, Thai Pongal, originating in Tamil Nadu, is an analogous festival to the Winter Solstice which marks the end of the harvest, and the beginning of the new year; it falls over the same period of the end of December to the beginning of January.

Tang Yuan Day Celebration, Beijing

Even farther east, Tang Yuan Day in China is a winter solstice celebration over the longest night of the year, Dong zhi, corresponding to December 21, and has analogous manifestations with similar names throughout East and South East Asia. Tang Yuan are sweetened rice or bean paste balls presented in different colours, 7 of which must be consumed on the day, for longevity.

Tang Yuan balls

 For those with a greater interest in the diverse festivals, including European, Near Eastern, South Eastern, and Far Eastern ones, Wikipedia  provides a very good starting point.

The sun colour-coded by degrees of heat


To me, this ancient and contemporary celestial event represents a shared physical experience for all, and given the global and historical interpretations of the “death of the sun” and the celebration of its return, a shared “cultural unconscious”. That is not to advocate any religious significance to the event, or its celebration, but just to see in our common physical world, and biological (seasonal moods), and cultural responses to it, one piece of evidence of our shared humanity and a place to ground our commonality. Particularly in a multi-cultural setting, it has proven for me a way to have a “Winter Solstice Gathering” of friends of all faiths, at a time of year where many in a country organized on Christian celebrations feel left out. Also, in a northern clime one needs all celebrations possible to get one past the short days of dark to 7:30am and again by 4:30pm!

This year the Winter Solstice occurs:
December 21 12:47 EST (New York)
December 21 17:47 UT (London)
December 21 18:47 UT+1 (Algiers)
December 21 20:47 UT+3 (Riyadh/ Middle East)
December 21 22:47 UT+5 (Pakistan)

The sun from aclose

Happy Winter Solstice to all!

And especially to those of us living in Northern climes, where we need the sun to return the most!

The surface of the sun

And for those readers who insist on living upside down,
on the bottom half of the globe,
I appreciate that my envy of sun and warmth on this day is palpable;
and still wish you a
Happy Summer Solstice!

The surface of the sun

Do you take notice of, or celebrate the Winter Solstice? How?
Do you see it as a point of commonality with others around the globe? Why or why not?
Does the idea that other religious holidays were built on it have any significance for you? What and why?
Any other comments, thoughts, or experiences?

*This year I celebrated the Winter Solstice by being the supportive medical aunt to my canine niece and my sister, her human mother, during the dog’s urgent consultations with a veterinary cardiologist. Canine niece and human sister are both now doing well.


NidalM said...

From an anthropological viewpoint, its interesting to see the overlap of so many celebrations, even those of modern religions, to pagan traditions.

Most Arab/Muslim cultures don't take notice of the event at all, perhaps because of the proximity to the equator, which makes the difference between the lengths of night and day during the seasons relatively small.

From a personal viewpoint, the only reason I attach any significance to it at all was becaus I was born around this time :P

Chiara said...

NidalM--Happy Birthday! A Winter Solstice baby! A Dionysian heralding of the New Year, the changing seasons, the promised rebirth after winter, the return of the Sun! You are verrrrry special, and fortunately Muslim, other wise like my Dad (Dec 20) you would be impossible to buy for 2x in the same week, birthday and Christmas!!!

How about when you were in Michigan? Any compulsion like us Nordics (or rather Mediterraneans displaced Northward) to watch for the potential lengthening of the days?

Excellent point on the diurnal variation being narrower the closer one is to the equator. I guess I can only be greatful my ancestors didn't have any North Pole compulsions.

Thanks for your comment!


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