On the
Gregorian calendar, the northward equinox can occur as early as 19 March or as late as 21 March at
0° longitude. 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 20 March 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
Babylonian calendar began with the first new moon after the March equinox, the day after the return of the Sumerian goddess
Inanna (later known as
Ishtar) from the underworld, in the
Akitu ceremony, with parades through the
Ishtar Gate to the
Eanna temple and the ritual re-enactment of the marriage to
Tammuz, or Sumerian
Dummuzi.[citation needed]
The
Persian calendar begins each year at the northward equinox, observationally determined at
Tehran.[15]
The
Indian national calendar starts the year on the day next to the vernal equinox on 22 March (21 March in 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.[15]
Julian calendar
The
Julian calendar reform lengthened seven months and replaced the intercalary month with an intercalary day to be added every four years to February. It was based on a length for the year of 365 days and 6 hours (365.25 d), while the mean tropical year is about 11 minutes and 15 seconds less than that. This had the effect of adding about three quarters of an hour every four years. The effect accumulated from inception in 45 BC until the 16th century, when the northern vernal equinox fell on 10 or 11 March.[16]
The date in 1452 was 11 March, 11:52 (Julian).[17]
In 2547 it will be 20 March, 21:18 (Gregorian) and 3 March, 21:18 (Julian).[18]
Commemorations
Abrahamic tradition
The Jewish
Passover usually falls on the first
full moon after the Northern Hemisphere vernal equinox,[19] although occasionally (currently three times every 19 years[citation needed]) it will occur on the second full moon.[20]
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 21 March. 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 22 March on each calendar. The latest possible western Easter date in any year is 25 April.[21]
Iranian tradition
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 20 March or 21 March. 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.[22]
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 14 April.
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.[23][24]Higan (お彼岸) is a Buddhist holiday exclusively celebrated by Japanese sects during both the Spring and Autumnal Equinox.[23]
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.[31]
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.[32][33]