Winter solstice

Winter solstice
Lawrence Hall of Science visitors observe sunset on the day of the winter solstice using the Sunstones II.
Also called Midwinter, Yule, the Longest Night, Jól
Observed by Various cultures
Type Cultural, astronomical
Significance Astronomically marks the beginning of shortening nights and lengthening days
Celebrations Festivals, spending time with loved ones, feasting, singing, dancing, fires
Date about December 21 (NH)
about June 21 (SH)
Frequency Twice a year (once in the northern hemisphere, once in the southern hemisphere, six months apart)
Related to Winter festivals and the solstice

The winter solstice (or hibernal solstice), also known as midwinter, is an astronomical phenomenon marking the day with the shortest period of daylight and the longest night of the year. It occurs when one of the Earth's poles has its maximum tilt away from the Sun. It happens twice yearly, once in each hemisphere. In the Northern Hemisphere this is the December solstice and in the Southern Hemisphere this is the June solstice.

The axial tilt of Earth and gyroscopic effects of its daily rotation mean that the two opposite points in the sky to which the Earth's axis of rotation points (axial precession) change very slowly (at the current rate it would take just under 26,000 years to make a complete circle). As the Earth follows its orbit around the Sun, the polar hemisphere that faced away from the Sun, experiencing winter, will, in half a year, face towards the Sun and experience summer. This is because the two hemispheres face opposite directions along Earth's axis, and so as one polar hemisphere experiences winter, the other experiences summer.

More evident from high latitudes, a hemisphere's winter solstice occurs on the day with the shortest period of daylight and longest night of the year, when the sun's daily maximum elevation in the sky is at its lowest.[1] Although the winter solstice itself lasts only a moment in time, the term sometimes refers to the day on which it occurs. Other names are "midwinter", the "extreme of winter" (Dongzhi), or the "shortest day". In some cultures it is seen as the middle of winter, while in others it is seen as the beginning of winter.[2] In meteorology, winter in the Northern Hemisphere spans the entire period of December through February. The seasonal significance of the winter solstice is in the reversal of the gradual lengthening of nights and shortening hours of daylight during the day. The earliest sunset and latest sunrise dates differ from winter solstice, however, and these depend on latitude, due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit (see earliest and latest sunrise and sunset).

Worldwide, interpretation of the event has varied across cultures, but many have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time.[3]

History and cultural significance

The solstice may have been a special moment of the annual cycle for some cultures even during neolithic times. Astronomical events were often used to guide activities such as the mating of animals, the sowing of crops and the monitoring of winter reserves of food. Many cultural mythologies and traditions are derived from this. This is attested by physical remains in the layouts of late Neolithic and Bronze Age archaeological sites, such as Stonehenge in England and Newgrange 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 (Newgrange) and the winter solstice sunset (Stonehenge). It is significant that at Stonehenge the Great Trilithon was oriented outwards from the middle of the monument, i.e. its smooth flat face was turned towards the midwinter Sun.[4] The winter solstice was immensely important because the people were economically dependent on monitoring the progress of the seasons. Starvation was common during the first months of the winter, January to April (northern hemisphere) or July to October (southern hemisphere), 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 plentiful 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 at the beginning of the pagan day, which in many cultures fell on the previous eve.[5]

Because the event was seen as the reversal of the Sun's ebbing presence in the sky, concepts of the birth or rebirth of sun gods have been common and, in cultures which used cyclic calendars based on the winter solstice, the "year as reborn" was celebrated with reference to life-death-rebirth deities or "new beginnings" such as Hogmanay's redding, a New Year cleaning tradition. Also "reversal" is yet another frequent theme, as in Saturnalia's slave and master reversals.

Iranian

Iranian people celebrate the night of the Northern Hemisphere's winter solstice as, "Yalda night", which known to be the "longest and darkest night of the year". In this night all the family gather together, usually at the house of the oldest, and celebrate it by eating, drinking and reading poems (esp. Hafez). Nuts, pomegranates and watermelons are particularly served during this festival.

Pagan

The pagan Scandinavian and Germanic people of northern Europe celebrated a twelve-day "midwinter" (winter solstice) holiday called Yule (also called Jul, Julblot, jólablót, midvinterblot, julofferfest). Many modern Christmas traditions, such as the Christmas tree, the Christmas wreath, the Yule log, and others, are direct descendents of Yule customs. Scandinavians still call Yule "Jul". In English, the word "Yule" is often used in combination with the season "yuletide" [6] a usage first recorded in 900. It is believed that the celebration of this day was a worship of these peculiar days, interpreted as the reawakening of nature. The Yule (Jul) particular god was Jólner, which is one of Odin's many names.

The concept of Yule occurs in a tribute poem to Harold Hårfager from about AD 900, where someone said "drinking Jul". Julblot is the most solemn sacrifice feast. At the "julblotet", sacrifices were given to the gods to earn blessing on the forthcoming germinating crops. Julblotet was eventually integrated into the Christian Christmas. As a remainder from this Viking era, the Midsummer is still important in Scandinavia, and hence vividly celebrated.

Roman cult of Sol

Sol Invictus ("The Unconquered Sun") was originally a Syrian god who was later adopted as the chief god of the Roman Empire under Emperor Aurelian. His holiday is traditionally celebrated on December 25, as are several gods associated with the winter solstice in many pagan traditions.[7] It have been speculated to be the reason behind Christmas' proximity to the solstice.[8]

East Asian

In East Asia (except in the Philippines), the winter solstice has been celebrated as one of the Twenty-four Solar Terms, called Dongzhi in Chinese. In Japan, in order not to catch cold in the winter, there is a custom to soak oneself in the yuzu hot bath (Japanese: 柚子湯 = Yuzuyu). [9]

Observances

Although the instant of the solstice can be calculated,[10] direct observation of the solstice by amateurs is impossible because the sun moves too slowly or appears to stand still (the meaning of "solstice"). However, by use of astronomical data tracking, the precise timing of its occurrence is now public knowledge. One cannot directly detect the precise instant of the solstice (by definition, one cannot observe that an object has stopped moving until one later observes 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 1/60 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 1/16 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 observing the sunrise and sunset or using an astronomically aligned instrument that allows a ray of light to be cast on a certain point around that time.

Holidays celebrated on the winter solstice

Length of the day on the northern winter solstice

The following tables contain information on the length of the day on the winter solstice of the Northern Hemisphere and the summer solstice of the Southern Hemisphere (i.e. December solstice). The data was collected from the website of the Finnish Meteorological Institute on 22 December 2015, as well as from certain other websites.[11][12][13][14]

The data is arranged geographically and within the tables from the shortest day to the longest one.

The Nordic countries and the Baltic states
City Sunrise
22 Dec 2015
Sunset
22 Dec 2015
Length of the day
Bodø11:3612:250 h 49 min
Rovaniemi11:0813:222 h 14 min
Luleå9:5513:043 h 09 min
Reykjavík11:2215:294 h 07 min
Trondheim10:0114:314 h 30 min
Tórshavn9:5114:595 h 08 min
Helsinki9:2415:135 h 49 min
Oslo9:1815:125 h 54 min
Tallinn9:1715:206 h 02 min
Stockholm8:4314:486 h 04 min
Riga9:0015:436 h 43 min
Copenhagen8:3715:387 h 01 min
Vilnius8:4015:547 h 14 min
Europe
City Sunrise
22 Dec 2015
Sunset
22 Dec 2015
Length of the day
Edinburgh8:4215:406 h 57 min
Moscow8:5715:587 h 00 min
Berlin8:1515:547 h 39 min
London8:0415:537 h 49 min
Kiev7:5615:568 h 00 min
Paris8:4116:568 h 14 min
Rome7:3416:429 h 07 min
Madrid8:3417:519 h 17 min
Lisbon7:5117:189 h 27 min
Athens7:3717:099 h 31 min
Africa
City Sunrise
22 Dec 2015
Sunset
22 Dec 2015
Length of the day
Cairo6:4716:5910 h 12 min
Dakar7:3018:4611 h 15 min
Addis Ababa6:3518:1111 h 36 min
Nairobi6:2518:3712 h 11 min
Kinshasa5:4518:0812 h 22 min
Dar es Salaam6:0518:3612 h 31 min
Luanda5:4618:2412 h 38 min
Antananarivo5:1018:2613 h 16 min
Windhoek6:0419:3513 h 31 min
Johannesburg5:1218:5913 h 47 min
Cape Town5:3219:5714 h 25 min
Americas
City Sunrise
22 Dec 2015
Sunset
22 Dec 2015
Length of the day
Fairbanks10:5814:403 h 41 min
Anchorage10:1415:425 h 27 min
Vancouver8:0516:168 h 11 min
Seattle7:5516:208 h 25 min
Ottawa7:3916:228 h 42 min
Toronto7:4816:438 h 55 min
New York City7:1616:329 h 15 min
Washington, D.C.7:2316:499 h 26 min
Los Angeles6:5516:489 h 53 min
Dallas7:2517:259 h 59 min
Miami7:0317:3510 h 31 min
Honolulu7:0417:5510 h 50 min
Mexico City7:0618:0310 h 57 min
Managua6:0117:2611 h 24 min
Bogotá5:5917:5011 h 51 min
Quito6:0818:1612 h 08 min
Recife5:0017:3512 h 35 min
Lima5:4118:3112 h 50 min
La Paz5:5719:0413 h 06 min
Rio de Janeiro6:0419:3713 h 33 min
São Paulo6:1719:5213 h 35 min
Porto Alegre6:2020:2514 h 05 min
Santiago6:2920:5214 h 22 min
Buenos Aires5:3720:0614 h 28 min
Ushuaia4:5122:1117 h 19 min
Asia and Oceania
City Sunrise
22 Dec 2015
Sunset
22 Dec 2015
Length of the day
Magadan8:5414:556 h 00 min
Petropavlovsk9:3617:107 h 33 min
Khabarovsk8:4817:078 h 18 min
Ulaanbaatar8:3917:028 h 22 min
Vladivostok8:4017:408 h 59 min
Beijing7:3216:529 h 20 min
Seoul7:4417:179 h 34 min
Tokyo6:4716:319 h 44 min
Shanghai6:4816:5510 h 07 min
Lhasa8:4619:0110 h 14 min
Delhi7:0917:2810 h 19 min
Hong Kong6:5817:4410 h 46 min
Manila6:1617:3211 h 15 min
Bangkok6:3617:5511 h 19 min
Singapore7:0119:0412 h 03 min
Jakarta5:3618:0512 h 28 min
Denpasar5:5818:3612 h 37 min
Darwin6:1919:1012 h 51 min
Papeete5:2118:3213 h 10 min
Brisbane4:4918:4213 h 52 min
Perth5:0719:2214 h 14 min
Sydney5:4120:0514 h 24 min
Auckland5:5820:3914 h 41 min
Melbourne5:5420:4214 h 47 min
Invercargill5:5021:3915 h 48 min

Length of day increases from the equator towards the South Pole in the Southern Hemisphere in December (around the summer solstice there), but decreases towards the North Pole in the Northern Hemisphere at the time of the northern winter solstice.

See also

Further reading

References

  1. An Introduction to Physical Science, 12th Ed., James Ship-man, Jerry D. Wilson, Aaron Todd, Section 15.5, p 423, ISBN 978-0-618-92696-1, 2007.
  2. "When does spring start?". Met Office. June 3, 2016. Retrieved December 22, 2016.
  3. "Winter Solstice celebrations: a.k.a. Christmas, Saturnalia, Yule, the Long Night, start of Winter, etc." Religious Tolerance.org. December 3, 1999. Retrieved December 22, 2011.
  4. Johnson, Anthony (2008). Solving Stonehenge: The New Key to an Ancient Enigma. Thames & Hudson. pp. 252–253. ISBN 9780500051559.
  5. "History of Christmas". History.com. Retrieved January 2, 2017.
  6. Yule. The American Heritage Dictionary of the English Language, Fourth Edition. Retrieved December 3, 2006.
  7. Capoccia, Kathryn (2002). "Christmas Traditions". Retrieved 2008-12-27.
  8. Bishop Jacob Bar-Salabi (cited in Christianity and Paganism in the Fourth to Eighth Centuries, Ramsay MacMullen. Yale:1997, p. 155)
  9. Goin’ Japanesque!: Japanese Winter Solstice Traditions; A Day for Kabocha and Yuzuyu
  10. Meeus, Jean (2009). Astronomical Algorithms (2nd English Edition with corrections as of August 10, 2009 ed.). Richmond, Virginia: Willmann-Bell, Inc. ISBN 0-943396-61-1.
  11. "Paikallissää Helsinki" [‘Local weather in Helsinki’] (in Finnish). Finnish Meteorological Institute. 2015-12-22. Retrieved 2015-12-22.
  12. "Perth, Australia". Retrieved 2015-12-22.
  13. "São Paulo, Brazil". Retrieved 2015-12-22.
  14. "Denpasar, Indonesia". Retrieved 2015-12-22.
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