On the Gregorian calendar at 0° longitude, the northward equinox usually occurs on March 20. However, it can occur as early as March 19 (which happened most recently in 1796, and will happen next in 2044), and it can occur as late as March 21 (which happened most recently in 2007, and will happen next in 2102). For a common year the computed time slippage is about 5 hours 49 minutes later than the previous year, and for a leap year about 18 hours 11 minutes earlier than the previous year. Balancing the increases of the common years against the losses of the leap years keeps the calendar date of the March equinox from drifting more than one day from March 20 each year.
The March equinox may be taken to mark the beginning of astronomicalspring and the end of astronomical winter in the Northern Hemisphere but marks the beginning of astronomical autumn and the end of astronomical summer in the Southern Hemisphere.[11]
The point where the Sun crosses the celestial equator northwards is called the First Point of Aries. However, due to the precession of the equinoxes, this point is no longer in the constellationAries, but rather in Pisces.[13] By the year 2600 it will be in Aquarius. The Earth's axis causes the First Point of Aries to travel westwards across the sky at a rate of roughly one degree every 72 years. Based on the modern constellation boundaries, the northward equinox passed from Taurus into Aries in the year −1865 (1866 BC), passed into Pisces in the year −67 (68 BC), will pass into Aquarius in the year 2597, and will pass into Capricornus in the year 4312. It passed by (but not into) a 'corner' of Cetus at 0°10′ distance in the year 1489.[citation needed]
In its apparent motion on the day of an equinox, the Sun's disk crosses the Earth's horizon directly to the east at sunrise; and again, some 12 hours later, directly to the west at sunset. The March equinox, like all equinoxes, is characterized by having an almost exactly equal amount of daylight and night across most latitudes on Earth.[14]
The ancient Babylonian calendar began around the spring equinox, in the month of Nissānu, at which time they recited their creation myth, the Enūma Eliš.[15][16] Due to Babylonian influence, the beginning of the religious year in the Hebrew calendar shifted to the spring equinox, with Nisan being the first month.[17][18]
The Indian national calendar starts the year on the day after the spring equinox on March 22 (March 21 during leap years) with a 30-day month (31 days in leap years), then has 5 months of 31 days followed by 6 months of 30 days.[19]
The Julian calendar had a flaw in that the solstices and equinoxes gradually fell on earlier dates. At the First Council of Nicaea (325), the Christian Church set the date of the spring equinox to 21 March on the Julian calendar, for the purpose of calculating Easter.[22] However, the effect continued to accumulate, and by the 16th century, the spring equinox fell on March 10 or 11 in the Julian calendar.[23] It was for this reason that the Gregorian calendar reform was introduced in 1582, to reinstate the date to about 21 March and to minimise any further drifting.
Commemorations
Bas-relief in Persepolis, a symbol of IranianNowruz: a bull (symbolizing the Earth) and lion (the Sun) in eternal combat are equal in power on the equinox.Chichen Itza during the spring equinox—Kukulkan, the famous descent of the snake
Abrahamic tradition
The Jewish Passover usually falls on the first full moon after the Northern Hemisphere vernal equinox,[24] although occasionally (due to accumulated error strictly following the Meton approximation, currently three times every 19 years[citation needed]) it will occur on the second full moon.[25]
The Christian ChurchescalculateEaster as the first Sunday after the first full moon on or after the March equinox. The official church definition for the equinox is March 21. The Eastern Orthodox Churches use the older Julian calendar, while the western churches use the Gregorian calendar, and the western full moons currently fall four, five or 34 days before the eastern ones. The result is that the two Easters generally fall on different days but they sometimes coincide. The earliest possible western Easter date in any year is March 22 on each calendar. The latest possible western Easter date in any year is April 25.[26]
The northward equinox marks the first day of various calendars including the Iranian calendar. The ancient Iranian peoples' new year's festival of Nowruz can be celebrated March 20 or March 21. According to the ancient Persian mythology Jamshid, the mythological king of Persia, ascended to the throne on this day and each year this is commemorated with festivities for two weeks. Along with Iranian peoples, it is also a holiday celebrated by Turkic people, the North Caucasus and in Albania. It is also a holiday for Zoroastrians, adherents of the Baháʼí Faith and NizariIsmaili Muslims irrespective of ethnicity.[29]
According to the sidereal solar calendar, celebrations which originally coincided with the March equinox now take place throughout South Asia and parts of Southeast Asia on the day when the Sun enters the sidereal Aries, generally around April 14.
The traditional East Asian calendars divide a year into 24 solar terms (节气, literally "climatic segments"), and the vernal equinox (Chūnfēn, Chinese and Japanese: 春分;Korean: 춘분;Vietnamese: Xuân phân) marks the middle of the spring. In this context, the Chinese character 分 means "(equal) division" (within a season).
In Japan, Vernal Equinox Day (春分の日 Shunbun no hi) is an official national holiday, and is spent visiting family graves and holding family reunions.[30][31]Higan (お彼岸) is a Buddhist holiday exclusively celebrated by Japanese sects during both the Spring and Autumnal Equinox.[30]
World Storytelling Day is a global celebration of the art of oral storytelling, celebrated every year on the day of the northward equinox.[citation needed]
The Baháʼí calendar year starts at the sunset preceding the March equinox calculated for Tehran.[38]
In Annapolis, Maryland, United States, boatyard employees and sailboat owners celebrate the spring equinox with the "Burning of the Socks" festival. Traditionally, the boating community wears socks only during the winter. These are burned at the approach of warmer weather, which brings more customers and work to the area. Officially, nobody then wears socks until the next equinox.[39][40]
↑Krupp, Edwin (2012). Echoes of the Ancient Skies: The Astronomy of Lost Civilizations. Dover Publications. p.203.
↑Ristvet, Lauren (2015). Ritual, Performance, and Politics in the Ancient Near East. Cambridge University Press. p.153.
↑Kelley, David (2011). Exploring Ancient Skies A Survey of Ancient and Cultural Astronomy. Springer. p.219. for a time, the Jews adopted the Babylonian beginning point of the year near the March equinox with the month Nisan/Nissanu
↑O'Neill, William Matthew (1976). Time and the Calendars. Manchester University Press. p.85.
↑Forsythe, Gary (2012). Time in Roman Religion: One Thousand Years of Religious History. Routledge. pp.123, 182. Varro places the equinoxes and solstices at the midpoints of the seasons ... His dating for the beginnings of the four seasons are as follows: February 7 for spring, May 9 for summer, August 11 for autumn, and November 10 for winter.
↑Ó Carragáin, Éamonn (2005). Ritual and the Rood: Liturgical Images and the Old English Poems of the Dream of the Rood Tradition. University of Toronto Press. pp.106–107.
