TheMarch equinox^[7][8] ornorthward equinox^[9] is theequinox on theEarth when thesubsolar point appears to leave theSouthern Hemisphere and cross thecelestial equator, heading northward as seen from Earth. The March equinox is known as the vernal equinox (or spring equinox) in theNorthern Hemisphere and as the autumnal equinox (or fall equinox) in the Southern Hemisphere.^[8][7][10]

On theGregorian calendar at0° longitude, the northward equinox can occur as early as 19 March (which happened most recently in 1796, and will happen next in 2044), and it can occur as late as 21 March (which happened most recently in 2007, and will happen next in 2102). For acommon year thecomputed time slippage is about 5 hours 49 minuteslater than the previous year, and for a leap year about 18 hours 11 minutesearlier 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 ofastronomicalspring and the end of astronomicalwinter in the Northern Hemisphere but marks the beginning of astronomicalautumn and the end of astronomicalsummer in the Southern Hemisphere.^[11]

Inastronomy, the March equinox is the zero point ofsidereal time and, consequently, theright ascension andecliptic longitude.^[12] It also serves as a reference for calendars and celebrations in many cultures and religions.

The point where the Sun crosses the celestial equator northwards is called theFirst Point of Aries. However, due to theprecession of the equinoxes, this point is no longer in theconstellationAries, but rather inPisces.^[13] By the year 2600 it will be inAquarius. 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 themodern constellation boundaries, the northward equinox passed fromTaurus 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 intoCapricornus in the year 4312. It passed by (but not into) a 'corner' ofCetus 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 atsunrise; and again, some 12 hours later, directly to the west atsunset. 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]

TheBabylonian calendar began with the first new moon after the March equinox, the day after the return of the Sumerian goddessInanna (later known asIshtar) from the underworld, in theAkitu ceremony, with parades through theIshtar Gate to theEanna temple and the ritual re-enactment of the marriage toTammuz, or SumerianDummuzi.^{[citation needed]}

ThePersian calendar begins each year at the northward equinox, observationally determined atTehran.^[15]

TheIndian 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]

TheJulian 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]

• The JewishPassover usually falls on the firstfull 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]
• TheChristian 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. TheEastern Orthodox Churches use the olderJulian calendar, while the western churches use theGregorian calendar, and the western full moons currently fall four, five or 34 days before the eastern ones. The result is that the twoEasters 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]

• The northward equinox marks the first day of various calendars including theIranian calendar. The ancient Iranian peoples' new year's festival ofNowruz 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 withIranian peoples, it is also a holiday celebrated byTurkic people, theNorth Caucasus and inAlbania. It is also a holiday forZoroastrians, adherents of theBaháʼí Faith andNizariIsmaili Muslims irrespective of ethnicity.^[22]

• In manyArab countries,Mother's Day is celebrated on the northward equinox.^{[citation needed]}
• Sham el-Nessim is a modern celebration which is claimed by some to have been celebrated inancient Egypt but with little evidence. It is one of thepublic holidays in Egypt. It is assumed by some that sometime during Egypt'sChristian period (c. 200–639) the date moved toEaster Monday, but before then it coincided with the vernal equinox.^{[citation needed]}

According to thesidereal 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 thesidereal Aries, generally around 14 April.

• In Cambodia, theAngkor Wat Equinox is a solar phenomenon which dates back to the reign ofSuryavarman II.

• The traditional East Asian calendars divide a year into 24solar terms (节气, literally "climatic segments"), and the vernal equinox (Chūnfēn,Chinese andJapanese: 春分;Korean:춘분;Vietnamese:Xuân phân) marks themiddle of the spring. In this context, theChinese character 分 means"(equal) division" (within a season).
• In Japan,Vernal Equinox Day (春分の日Shunbun no hi) is an officialnational 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]

• Dita e Verës or Verëza is theAlbanian pagan feast that celebrates the spring equinox: the beginning of thespring-summer period. It is traditionally celebrated throughoutAlbanian inhabited territories, also officially inAlbania.
• Hilaria was anancient Roman festival commemorating the death and resurrection ofAttis.
• Lieldienas
• inNorse paganism, aDísablót was celebrated on the vernal equinox.^[25]
• Drowning of Marzanna

• Spring equinox in Teotihuacán
• The reconstructedCahokia Woodhenge, a largetimber circle located at theMississippian cultureCahokiaarchaeological site nearCollinsville, Illinois,^[26] is the site of annual equinox and solstice sunrise observances. Out of respect forNative American beliefs these events do not feature ceremonies or rituals of any kind.^[27][28][29]

• 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]}
• World Citizen Day occurs on the northward equinox.^[30]
• TheBaháʼí calendar year starts at the sunset preceding the March equinox calculated for Tehran.^[31]
• InAnnapolis, 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]
• Neopagans observe the March equinox (referred to asOstara) as a cardinal point on theWheel of the Year. In the northern hemisphere some varieties of paganism adaptvernal equinox celebrations, while in the southern hemisphere pagans adaptautumnal traditions.^{[citation needed]}
• International Astrology Day^{[citation needed]}
• On 20 March 2014 and 20 March 2018, the March equinox was commemorated by an animatedGoogle Doodle.^[34]

• "Ancient Equinox Alignment".Loughcrew, Ireland.
• Dates and times of the Northward equinox at theWayback Machine (archived 10 June 2019)
• Spring Starts Today All Over America, Which Is Weird (19 March 2020)