Solstice

For locations not too close to the equator or the poles, the dates with the longest and shortest periods of daylight are the summer and winter solstices, respectively.Similarly, for an observer on the South Pole, the Sun reaches the highest position on the December solstice day.At maximum or minimum elevation, the relative yearly motion of the Sun perpendicular to the horizon stops and reverses direction.[11] Because of the variation in the rate at which the sun's right ascension changes, the days of longest and shortest daylight do not coincide with the solstices for locations very close to the equator.The warmest and coldest periods of the year in temperate regions are offset by about one month from the solstices, delayed by the earth's thermal inertia.Xiàzhì (pīnyīn) or Geshi (rōmaji) (Chinese and Japanese: 夏至; Korean: 하지(Haji); Vietnamese: Hạ chí; lit.Dōngzhì (pīnyīn) or Tōji (rōmaji) (Chinese and Japanese: 冬至; Korean: 동지(Dongji); Vietnamese: Đông chí; lit.Here, the Chinese character 至 means "extreme", so the terms for the solstices directly signify the summits of summer and winter.Similarly 25 December is the start of the Christmas celebration, and is the day the Sun begins to return to the Northern Hemisphere.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 Yalda, Saturnalia, Karachun, Hanukkah, Kwanzaa, and Yule are also celebrated around this time.For the vernal (spring) equinox, several springtime festivals are celebrated, such as the Persian Nowruz, the observance in Judaism of Passover, the rites of Easter in most Christian churches, as well as the Wiccan Ostara.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.Other Aymara New Year feasts occur throughout Bolivia, including at the site of El Fuerte de Samaipata.This difference is hardly detectable with indirect viewing based devices like sextant equipped with a vernier, and impossible with more traditional tools like a gnomon[26] or an astrolabe.[28] In 2012, the journal DIO 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.
The seasons (with the transition points of the June solstice , September equinox , December solstice , and March equinox ) and Earth's orbit characteristics.
A solargraph taken from the Atacama Pathfinder Experiment at the Llano de Chajnantor Observatory in the southern hemisphere. This is a long-exposure photograph, with the image exposed for six months in a direction facing east of north, from mid-December 2009 until the southern winter solstice in June 2010. [ 10 ] The Sun's path each day can be seen from right to left in this image across the sky; the path of the following day runs slightly lower until the day of the winter solstice, whose path is the lowest one in the image.
Derivative of −Δt, the so-called Equation of time . The axis on the right shows the length of the solar day , also called the synodic day.
Sun Triangle in New York points at Sun upon equinox and solstices
2005 Summer solstice sunrise over Stonehenge
Solstice (disambiguation)equinoxesequinoxsolsticeexcursioncelestial equatorcelestial sphereseasonsdaylightJune solsticeDecember solsticedeclinationdaily pathSeptember equinoxMarch equinoxEarth's orbitNorth PoleSouth Polesummer solsticewinter solsticeRoman RepublicNatural Historyrelative velocityframe of referenceinertial frame of referenceplanet Earth is seen to rotateellipticaltiltedplane of Earth's orbitsolargraphAtacama Pathfinder ExperimentLlano de Chajnantor ObservatoryelevationhorizoneclipticequatorEquation of timesolar dayright ascensionSeasonplane of the eclipticobliquity of the eclipticsubsolar pointTropic of CancerTropic of CapricornLahaina NoonHonoluluArctic Circlemidnight sunmidsummerAntarctic Circlepolar nightsea iceterminatorsouthern solsticenorthern solsticeequirectangular projectioncelestial navigationspherecircumferencescirclesparallelperpendicularplanetsCleomedesZodiaceclipsesNorthern HemisphereSouthern HemisphereLatinateIslamic calendarHebrew calendarCancerCapricornastrological signsprecession of the equinoxesconstellationsTaurusSagittariusGregorian calendarEstival (summer) solsticeHibernal (winter) solsticeXiazhiDongzhi (solar term)solar termspīnyīnrōmajiChineseJapaneseKoreanVietnamesecelestial longitudeFête St-Jean-BaptisteFestival of San JuanSaint Jonas DaySt John's Day (Estonia)Ivan Kupala DayGolowanWheel of the YearStonehengeEnglandMidsummer's DayChristian ChurchChristmasquarter daysSaturnaliaKarachunHanukkahKwanzaaDongzhi FestivalSt. JohnSt. John's EveModern PagansWiccansPersianNowruzJudaismPassoverEasterOstaraSukkotSouth AmericaMapuche peopleWe TripantuAtacama peopleAymara peopleGate of the SunTiwanakuBoliviaEl Fuerte de SamaipataHindu calendarMakara SankrantiUttarayanaSankrantiDakshinayanaprecessionAmundsen–Scott South Pole StationFremont Solstice ParadeFremont, Seattle, WashingtonUnited StatesCahokia Woodhengetimber circleMississippian cultureCahokiaarchaeological siteCollinsville, IllinoisNative Americansolar declinationarcsecondsangular sizesextantverniergnomonastrolabeatmospheric refractionsolstitial coluretime zoneastronomical year numberingGeminiCapricornusOphiuchusScorpiusAnalemmaGeocentric view of the seasonsIranian calendarsPerihelion and aphelionZoroastrian calendarThe American Heritage Dictionary of the English LanguageHoughton Mifflin HarcourtPrinciple of relativityAlbert Einsteinabsolute space and timeIsaac NewtonEuropean Southern ObservatoryBowditch, NathanielStraboUniversity of California PressIndian Country Media NetworkBibcodeMeeus, JeanUnited States Naval ObservatoryTime measurementstandardsChronometryOrders of magnitudeMetrologyCoordinated Universal TimeoffsetInternational Earth Rotation and Reference Systems ServiceISO 31-1ISO 8601International Atomic Time12-hour clock24-hour clockBarycentric Coordinate TimeBarycentric Dynamical TimeCivil timeDaylight saving timeGeocentric Coordinate TimeInternational Date LineIERS Reference MeridianLeap secondSolar timeTerrestrial Time180th meridianEphemeris timeGreenwich Mean TimePrime meridianTime in physicsSpacetimeChrononContinuous signalCoordinate timeCosmological decadeDiscrete time and continuous timeProper timeTheory of relativityTime dilationGravitational time dilationTime domainTime-translation symmetryT-symmetryHorologyAstrariumAtomic clockComplicationHistory of timekeeping devicesHourglassMarine chronometerMarine sandglassRadio clockstopwatchWater clockSundialDialing scalesHistory of sundialsSundial markup schemaCalendarGregorianHebrewHoloceneIslamicJulianSolar HijriAstronomicalDominical letterIntercalationJulian dayLeap yearLunisolarTropical yearWeekday determinationWeekday namesChronological datingGeologic time scaleInternational Commission on StratigraphyAstronomical chronologyGalactic yearNuclear timescaleSidereal timeunits of timeInstantSecondMinuteMomentFortnightOlympiadLustrumDecadeCenturySaeculumMillenniumChronologyDurationMental chronometryDecimal timeMetric timeSystem timeTime metrologyTime value of moneyTimekeeperAncient Greek astronomyAstronomersAglaoniceAgrippaAnaximanderAndronicusApolloniusAratusAristarchusAristyllusAttalusAutolycusCallippusCleostratusEratosthenesEuctemonEudoxusGeminusHeraclidesHicetasHipparchusHippocrates of ChiosHypsiclesMenelausOenopidesPhilip of OpusPhilolausPosidoniusPtolemyPytheasSeleucusSosigenes of AlexandriaSosigenes the PeripateticThalesTheodosiusTheon of AlexandriaTheon of SmyrnaTimocharisAlmagest (Ptolemy)Catasterismi (Eratosthenes)On Sizes and Distances (Hipparchus)On the Sizes and Distances (Aristarchus)On the Heavens (Aristotle)Antikythera mechanismArmillary sphereDioptraEquatorial ringMural instrumentTriquetrumCallippic cycleCelestial spheresCircle of latitudeCounter-EarthDeferent and epicycleEquantGeocentrismHeliocentrismHipparchic cycleInferior and superior planetsMetonic cycleOctaeterisSpherical EarthSublunary sphereBabylonian astronomyEgyptian astronomyMedieval European scienceIndian astronomyMedieval Islamic astronomy