Editing Solstice (section)

==Cultural aspects==

===Ancient Greek names and concepts===
The concept of the solstices was embedded in ancient Greek [[celestial navigation]]. As soon as they discovered that the Earth was spherical<ref>{{cite book
|author=Strabo
|author-link=Strabo
|title=The Geography
|at=II.5.1
|quote=sphairikē ... tēs gēs epiphaneia, spherical is the surface of the Earth}}</ref> they devised the concept of the [[celestial sphere]],<ref>{{cite book
|author=Strabo
|author-link=Strabo
|title=The Geography
|pages=II.5.2
|quote=sphairoeidēs ... ouranos, spherical in appearance ... is heaven}}</ref> an imaginary spherical surface rotating with the heavenly bodies (''ouranioi'') fixed in it (the modern one does not rotate, but the stars in it do). As long as no assumptions are made concerning the distances of those bodies from Earth or from each other, the sphere can be accepted as real and is in fact still in use. The Ancient Greeks use the term'' "ηλιοστάσιο" (heliostāsio)'', meaning ''stand of the Sun''.

The [[star]]s move across the inner surface of the celestial [[sphere]] along the [[circumference]]s of [[circle]]s in [[Parallel (geometry)|parallel]] planes<ref>Strabo II.5.2., "aplaneis asteres kata parallēlōn pherontai kuklōn", "the fixed stars are borne in parallel circles"</ref> [[perpendicular]] to the Earth's axis extended indefinitely into the heavens and intersecting the celestial sphere in a celestial pole.<ref>Strabo II.5.2, "ho di'autēs (gē) aksōn kai tou ouranou mesou tetagmenos", "the axis through it (the Earth) extending through the middle of the sky"</ref> The Sun and the [[planet]]s do not move in these parallel paths but along another circle, the ecliptic, whose plane is at an angle, the [[obliquity of the ecliptic]], to the axis, bringing the Sun and planets across the paths of and in among the stars.*

[[Cleomedes]] states:<ref>{{cite book
|title=Cleomedes' Lectures on Astronomy: A Translation of The Heavens
|author=Cleomedes
|author-link=Cleomedes
|others=Translated by Alan C. Bowen and Robert B. Todd
|publisher=[[University of California Press]]
|location=Berkeley
|date=2004
|isbn=0-520-23325-5
|page=41}} This translation cites this passage at the end of Book I Chapter 2 but other arrangements have it at the start of Chapter 3. In the Greek version of {{cite book|title=Cleomedis De motu circulari corporum caelestium libri duo|url=https://archive.org/details/kleomedouskyklik00cleo|author=Cleomedes |editor-first=Hermann|editor-last=Ziegler |publisher=B. G. Teubneri|date=1891|pages=[https://archive.org/details/kleomedouskyklik00cleo/page/32 32]}} the passage starts Chapter 4.</ref><blockquote>The band of the [[Zodiac]] (''zōdiakos kuklos'', "zodiacal circle") is at an oblique angle (''loksos'') because it is positioned between the tropical circles and equinoctial circle touching each of the tropical circles at one point ... This Zodiac has a determinable width (set at 8° today) ... that is why it is described by three circles: the central one is called "heliacal" (''hēliakos'', "of the sun").</blockquote>

The term heliacal circle is used for the ecliptic, which is in the center of the zodiacal circle, conceived as a band including the noted constellations named on mythical themes. Other authors use Zodiac to mean ecliptic, which first appears in a gloss of unknown author in a passage of Cleomedes where he is explaining that the [[Moon]] is in the zodiacal circle as well and periodically crosses the path of the Sun. As some of these crossings represent [[eclipse]]s of the Moon, the path of the Sun is given a synonym, the ''ekleiptikos (kuklos)'' from ''ekleipsis'', "eclipse".

===English names===
[[File:McGraw-Hill sundial jeh.JPG|thumb|Sun Triangle in New York points at Sun upon equinox and solstices]]
The two solstices can be distinguished by different pairs of names, depending on which feature one wants to stress.
* '''[[Summer solstice]]''' and '''[[winter solstice]]''' are the most common names, referring to the seasons they are associated with. However, these can be ambiguous since the [[Northern Hemisphere]]'s summer is the [[Southern Hemisphere]]'s winter, and vice versa. The [[Latin]]ate names '''estival solstice''' (summer) and '''hibernal solstice''' (winter) are sometimes used to the same effect,<ref>{{cite book
|last=Kent
|first=April Elliott
|title=The Essential Guide to Practical Astrology
|url=http://google.com/books?id=DOfnC5vAff4C&pg=PA284
|access-date=December 9, 2015
|date=June 7, 2011
|publisher=Penguin
|isbn=978-1-61564-093-5
|page=284}}</ref> as are '''midsummer''' and '''midwinter'''.
* '''[[June solstice]]''' and '''[[December solstice]]''' refer to the months of year in which they take place,<ref>{{cite book
|last=Bass
|first=Charles O.
|title=Astronomy Essentials
|url=http://google.com/books?id=wwsqvLL10KEC&pg=PA35
|access-date=December 9, 2015
|date=1994
|publisher=Research & Education Assoc
|isbn=978-0-87891-965-9
|page=35}}</ref> with no ambiguity as to which hemisphere is the context. They are still not universal, however, as not all cultures use a solar-based calendar where the solstices occur every year in the same month (as they do not in the [[Islamic calendar]] and [[Hebrew calendar]], for example).
* '''Northern solstice''' and '''southern solstice''' indicate the hemisphere of the Sun's location.<ref name="Kiddle1877">{{cite book
|last=Kiddle
|first=Henry
|title=A new manual of the elements of astronomy, descriptive and mathematical: comprising the latest discoveries and theoretic views : with directions for the use of the globes, and for studying the constellations
|url=http://google.com/books?id=NkwAAAAAYAAJ&pg=PA82
|access-date=June 2, 2011
|date=1877
|publisher=Ivison, Blakeman, Taylor, & Company
|page=82}}</ref> The northern solstice is in June, when the Sun is directly over the [[Tropic of Cancer]] in the [[Northern Hemisphere]], and the southern solstice is in December, when the Sun is directly over the [[Tropic of Capricorn]] in the [[Southern Hemisphere]].<ref>{{cite book
|last=Jain
|first=R.K.
|title=ICSE Geography
|url=http://google.com/books?id=s4SdkMyKHNUC&pg=PA25
|access-date=December 9, 2015
|publisher=Ratna Sagar
|isbn=978-81-8332-579-0
|page=25}}</ref> These terms can be used unambiguously for other planets.
* '''First point of [[Cancer (astrology)|Cancer]]''' and '''first point of [[Capricorn (astrology)|Capricorn]]''' refer to the [[zodiac|astrological signs]] that the sun "is entering" (a system rooted in Roman Classical period dates).<ref>{{cite book
|last=Stewart
|first=Alexander
|title=A Compendium of ModernGeography
|url=http://google.com/books?id=Y3QDAAAAQAAJ&pg=PA383
|access-date=December 9, 2015
|date=1869
|publisher=Oliver & Boyd
|location=Edinburgh
|page=383}}</ref> Due to the [[precession of the equinoxes]], the [[constellation]]s the sun appears in at solstices are currently [[Taurus (constellation)|Taurus]] in June and [[Sagittarius (constellation)|Sagittarius]] in December.

{| class="wikitable" 
|+Names of the equinoxes and solstices
![[Celestial longitude|Ls]]
!By date
([[Gregorian calendar]])
!By sun position
([[subsolar point]])
!By season
([[Northern Hemisphere]])
!By season
([[Southern Hemisphere]])
|-
| style="text-align: right;" | 0°
|[[March equinox]]
|Northward equinox
|Vernal (spring) equinox
|Autumnal (fall) equinox
|-
| style="text-align: right;" | 90°
|[[June solstice]]
|Northern solstice
|[[Summer solstice|Estival (summer) solstice]]
|[[Winter solstice|Hibernal (winter) solstice]]
|-
| style="text-align: right;" | 180°
|[[September equinox]]
|Southward equinox
|Autumnal (fall) equinox
|Vernal (spring) equinox
|-
| style="text-align: right;" | 270°
|[[December solstice]]
|Southern solstice
|[[Winter solstice|Hibernal (winter) solstice]]
|[[Summer solstice|Estival (summer) solstice]]
|}

===Solstice terms in East Asia===
{{Main|Xiazhi|Dongzhi (solar term)}}

The traditional East Asian calendars divide a year into 24 [[solar term]]s (節氣). '''Xiàzhì''' <small>([[Pinyin|pīnyīn]])</small> or '''Geshi''' <small>([[Romanization of Japanese|rōmaji]])</small> ({{CJKV|t=夏至|s=夏至|j=夏至|k=하지(Haji)|Tibetan=དབྱར་ཉི་ལྡོག|v=Hạ chí|l=''summer's extreme''}}) is the 10th solar term, and marks the '''summer solstice'''. It begins when the Sun reaches the [[celestial longitude]] of 90° (around 21 June) and ends when the Sun reaches the longitude of 105° (around 7 July). Xiàzhì more often refers in particular to the day when the Sun is exactly at the celestial longitude of 90°.

'''Dōngzhì''' <small>([[Pinyin|pīnyīn]])</small> or '''Tōji''' <small>([[Romanization of Japanese|rōmaji]])</small> ({{CJKV|t=冬至|s=冬至|j=冬至|k=동지(Dongji)|Tibetan= དགུན་ཉི་ལྡོག|v=Đông chí|l=''winter's extreme''}}) is the 22nd solar term, and marks the '''winter solstice'''. It begins when the Sun reaches the [[celestial longitude]] of 270° (around 23 December) and ends when the Sun reaches the longitude of 285° (around 5 January). Dōngzhì more often refers in particular to the day when the Sun is exactly at the celestial longitude of 270°.

The solstices (as well as the [[equinox]]es) mark the middle of the seasons in East Asian calendars. Here, the Chinese character [[wikt:至|至]] means "extreme", so the terms for the solstices directly signify the summits of summer and winter.

===Solstice celebrations===
{{See also|Fête St-Jean-Baptiste|Festival of San Juan|Saint Jonas Day|St John's Day (Estonia)|Ivan Kupala Day|Golowan|Wheel of the Year}}
{{unreferenced section|date=June 2012}}
[[File:Summer Solstice Sunrise over Stonehenge 2005.jpg|2005 Summer solstice sunrise over [[Stonehenge]]|thumb]]
The term ''solstice'' can also be used in a wider sense, as the date (day) that such a passage happens. The solstices, together with the equinoxes, are connected with the seasons. In some languages they are considered to start or separate the seasons; in others they are considered to be centre points (in [[England]], in the Northern Hemisphere, for example, the period around the northern solstice is known as midsummer). [[Midsummer's Day]], defined as St. Johns Day by the [[Christian Church]], is 24 June, about three days after the solstice itself). Similarly 25 December is the start of the [[Christmas]] celebration, and is the day the Sun begins to return to the Northern Hemisphere. The traditional British and Irish main rent and meeting days of the year, "the usual [[quarter days]]," were often those of the solstices and equinoxes.

Many cultures celebrate various combinations of the winter and summer solstices, the equinoxes, and the midpoints between them, leading to various holidays arising around these events. During the southern or [[winter solstice]], Christmas is the most widespread contemporary holiday, while [[Yaldā Night|Yalda]], [[Saturnalia]], [[Karachun]], [[Hanukkah]], [[Kwanzaa]], and [[Yule]] are also celebrated around this time. In East Asian cultures, the [[Dongzhi Festival]] is celebrated on the winter solstice. For the northern or [[summer solstice]], Christian cultures celebrate the feast of [[John the Baptist|St. John]] from June 23 to 24 (see [[St. John's Eve]], [[Ivan Kupala Day]]), while [[Modern Paganism|Modern Pagans]] observe Midsummer, known as [[Wheel of the Year|Litha]] among [[Wicca]]ns. For the vernal (spring) equinox, several springtime festivals are celebrated, such as the [[Persia]]n [[Nowruz]], the observance in [[Judaism]] of [[Passover]], the rites of [[Easter]] in most Christian churches, as well as the Wiccan [[Ostara (Wicca)|Ostara]]. The autumnal equinox is associated with the Jewish holiday of [[Sukkot]] and the Wiccan [[Wheel of the Year|Mabon]]. 

In the southern tip of [[South America]], the [[Mapuche people]] celebrate [[We Tripantu]] (the New Year) a few days after the northern solstice, on 24 June. Further north, the [[Atacama people]] formerly celebrated this date with a noise festival, to call the Sun back. Further east, the [[Aymara people]] celebrate their New Year on 21 June. A celebration occurs at sunrise, when the sun shines directly through the [[Gate of the Sun]] in [[Tiwanaku]]. Other Aymara New Year feasts occur throughout [[Bolivia]], including at the site of [[El Fuerte de Samaipata]].

<!--In many cultures, the solstices and equinoxes traditionally determine the midpoint of the seasons, which can be seen in the celebrations called midsummer and [[Winter solstice|midwinter]]. In this vein, the [[Japan]]ese celebrate the start of each season with an occurrence known as [[Setsubun]]. The cumulative cooling and warming that result from the tilt of the planet become most pronounced ''after'' the solstices, leading to the more recent custom of using them to mark the ''beginning'' of summer and winter in most countries of [[Central Europe|Central]] and [[Northern Europe]], as well as in [[Canada]], the United States and [[New Zealand]].-->
In the [[Hindu calendar]], two sidereal solstices are named [[Makar Sankranti|Makara Sankranti]] which marks the start of [[Uttarayana]] and Karka [[Sankranti]] which marks the start of [[Dakshinayana]]. The former occurs around 14 January each year, while the latter occurs around 14 July each year. These mark the movement of the Sun along a sidereally fixed [[zodiac]] ([[precession (astronomy)|precession]] is ignored) into Makara, the zodiacal sign which corresponds with [[Capricorn (astrology)|Capricorn]], and into Karka, the zodiacal sign which corresponds with [[Cancer (astrology)|Cancer]], respectively.

The [[Amundsen–Scott South Pole Station]] celebrates every year on 21 June a midwinter party, to celebrate that the Sun is at its lowest point and coming back.

The [[Fremont Solstice Parade]] takes place every summer solstice in [[Fremont, Seattle, Washington]] in the [[United States]].

The reconstructed [[Cahokia Woodhenge]], a large [[timber circle]] located at the [[Mississippian culture]] [[Cahokia]] [[archaeological site]] near [[Collinsville, Illinois]],<ref name=VIS>{{Cite web| title= Visitors Guide to the Woodhenge| url= http://greatriverroad.com/somadco/collins/woodhenge.htm| access-date= December 19, 2017| archive-url= https://web.archive.org/web/20171222051732/http://greatriverroad.com/somadco/collins/woodhenge.htm| archive-date= December 22, 2017| url-status= dead}}</ref> is the site of annual equinox and solstice sunrise observances. Out of respect for [[Native Americans in the United States|Native American]] beliefs these events do not feature ceremonies or rituals of any kind.<ref>{{cite web| title= Welcome the Fall Equinox at Cahokia Mounds | publisher= Illinois Department of Natural Resources | url= https://www.illinois.gov/news/press-release.14832.html | access-date= November 25, 2024 }}</ref><ref>{{Cite web| title= Winter Solstice Sunrise Observance at Cahokia Mounds| publisher = Collinsville Chamber of Commerce| url = http://www.discovercollinsville.com/events/details/winter-solstice-sunrise-observance-at-cahokia-mounds-3895 | access-date= December 20, 2017 }}</ref><ref name=ICT>{{Cite news | title= Cahokia Mounds Mark Spring Equinox : The keepers of Cahokia Mounds will host a spring gathering to celebrate the vernal equinox | url= https://indiancountrymedianetwork.com/travel/destinations/spring-equinox-cahokia-mounds/ | newspaper= Indian Country Today | publisher= [[Indian Country Media Network]] | access-date= December 20, 2017 | archive-url= https://web.archive.org/web/20171222052220/https://indiancountrymedianetwork.com/travel/destinations/spring-equinox-cahokia-mounds/ | archive-date= December 22, 2017 | url-status= dead }}</ref>

===Solstice determination===
Unlike the equinox, the solstice time is not easy to determine. The changes in [[Position of the Sun|solar declination]] become smaller as the Sun gets closer to its maximum/minimum declination. The days before and after the solstice, the declination speed is less than 30 [[arcseconds]] per day which is less than {{frac|60}} of the [[angular size]] of the Sun, or the equivalent to just 2 seconds of [[right ascension]].

This difference is hardly detectable with indirect viewing based devices like [[sextant]] equipped with a [[Vernier scale|vernier]], and impossible with more traditional tools like a [[gnomon]]<ref>{{cite web
|title=Solstice Determination based on Observations
|last=Mollerup
|first=Asger
|date=January 12, 2008
|url=http://sundial.thai-isan-lao.com/solstice-determination.html
|access-date=September 27, 2010
|archive-url=https://web.archive.org/web/20090211044959/http://sundial.thai-isan-lao.com/solstice-determination.html
|archive-date=February 11, 2009}}</ref> or an [[astrolabe]]. It is also hard to detect the changes in sunrise/sunset azimuth due to the [[atmospheric refraction]]<ref>{{cite journal
|last = Exton
|first = Harold
|title = A Fresh Analysis of Some Recent Data on Atmospheric Refraction Near the Horizon with Implications in Archaeoastronomy
|journal = Journal of History of Astronomy, Archaeoastronomy Supplement
|volume = 23
|page = S57
|date = 1992
|issue = 17
|bibcode = 1992JHAS...23...57E
|doi = 10.1177/002182869202301707|s2cid = 118484271
}}</ref> changes. Those accuracy issues render it impossible to determine the solstice day based on observations made within the 3 (or even 5) days surrounding the solstice without the use of more complex tools.

Accounts do not survive but Greek astronomers must have used an approximation method based on interpolation, which is still used by some amateurs. This method consists of recording the declination angle at noon during some days before and after the solstice, trying to find two separate days with the same declination. When those two days are found, the halfway time between both noons is estimated solstice time. An interval of 45 days has been postulated as the best one to achieve up to a quarter-day precision, in the solstice determination.<ref>{{cite journal
|last = Hugh
|first = Thurston
|title = Early Greek Solstices and Equinoxes
|journal = Journal for the History of Astronomy
|volume = 32, Part 2
|issue = 107
|pages = 154–156
|date = 2001
|doi = 10.1177/002182860103200208
|bibcode = 2001JHA....32..154T
|s2cid = 118464897
|issn = 0021-8286|doi-access = 
}}</ref>
In 2012, the journal DIO [http://www.dioi.org/cot.htm#ngmw found] that accuracy of one or two hours with balanced errors can be attained by observing the Sun's equal altitudes about S = twenty degrees (or d = about 20 days) before and after the summer solstice because the average of the two times will be early by q arc minutes where q is (πe cosA)/3 times the square of S in degrees (e = earth orbit eccentricity, A = earth's perihelion or Sun's apogee), and the noise in the result will be about 41 hours divided by d if the eye's sharpness is taken as one arc minute.

Astronomical almanacs define the solstices as the moments when the Sun passes through the [[colure|solstitial colure]], i.e. the times when the apparent geocentric [[celestial longitude]] of the Sun is equal to 90° (June solstice) or 270° (December solstice).<ref>{{cite book
|last=Meeus
|first=Jean
|author-link1=Jean Meeus
|date=1998
|title=Astronomical Algorithms
|edition=Second English
|url=https://archive.org/details/astronomicalalgo00meeu
|url-access=limited
|location=Richmond
|publisher=Willmann-Bell, Inc.
|pages=[https://archive.org/details/astronomicalalgo00meeu/page/n184 177]–182
|isbn=0-943396-61-1}}</ref> The dates of the solstice varies each year and may occur a day earlier or later depending on the [[time zone]]. Because the earth's orbit takes slightly longer than a calendar year of 365 days, the solstices occur slightly later each calendar year, until a leap day re-aligns the calendar with the orbit. Thus the solstices always occur between June 20 and 22 and between December 20 and 23 <ref>{{cite web|title=December solstice|url=https://www.timeanddate.com/calendar/december-solstice.html|access-date=March 21, 2018}}</ref><ref>{{cite web|title=June solstice|url=https://www.timeanddate.com/calendar/june-solstice.html|access-date=March 21, 2018}}</ref> in a four-year-long cycle with the 21st and 22nd being the most common dates, as can be seen in the schedule at the start of the article.