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September equinox

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When sun appears directly over equator

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UT date and time of
equinoxes andsolstices on Earth^[1]^[2]
event	equinox		solstice		equinox		solstice
month	March^[3]		June^[4]		September^[5]		December^[6]
year	day	time	day	time	day	time	day	time
2020	20	03:50	20	21:43	22	13:31	21	10:03
2021	20	09:37	21	03:32	22	19:21	21	15:59
2022	20	15:33	21	09:14	23	01:04	21	21:48
2023	20	21:25	21	14:58	23	06:50	22	03:28
2024	20	03:07	20	20:51	22	12:44	21	09:20
2025	20	09:01	21	02:42	22	18:20	21	15:03
2026	20	14:46	21	08:25	23	00:06	21	20:50
2027	20	20:25	21	14:11	23	06:02	22	02:43
2028	20	02:17	20	20:02	22	11:45	21	08:20
2029	20	08:01	21	01:48	22	17:37	21	14:14
2030	20	13:51	21	07:31	22	23:27	21	20:09

Illumination of Earth by theSun on the day of anequinox

TheSeptember equinox (orsouthward equinox) is the moment when theSun appears to cross thecelestial equator, heading southward. Because of differences between thecalendar year and thetropical year, the Septemberequinox may occur from September 21 to 24.

At the equinox, the Sun as viewed from theequator rises due east andsets due west. Before the Southward equinox, the Sun rises and sets more northerly, and afterwards, it rises and sets more southerly.

The equinox may be taken to mark the end ofastronomical summer and the beginning of astronomical autumn (autumnal equinox) in theNorthern Hemisphere, while marking the end of astronomical winter and the start of astronomical spring (vernal equinox) in theSouthern Hemisphere.^[7]

Occurrences

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Sunset at the equinox from the site of Pizzo Vento atFondachelli Fantina, Sicily

Date	time (UTC)
2018-09-23	01:54
2019-09-23	07:50
2020-09-22	13:31
2021-09-22	19:21
2022-09-23	01:04
2023-09-23	06:50
2024-09-22	12:44
2025-09-22	18:19
2026-09-23	00:05
2027-09-23	06:02
2028-09-22	11:45

Constellation

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The point where the Sun crosses thecelestial equator southwards is called the First Point ofLibra. However, because of theprecession of the equinoxes, this point is no longer in theconstellation Libra, but rather inVirgo.

The solar point of the September equinox passed from Libra and into Virgo in −729 (730 BCE) and will enterLeo in 2439.

Apparent movement of the Sun in relation to the horizon

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At the equinox, the Sun rises directly in the east and sets directly in the west. However, because ofrefraction it will usually appear slightly above the horizon at the moment when its "true" middle is rising or setting. For viewers atthe north orsouth poles, it moves virtually horizontally on or above the horizon, not obviously rising or setting apart from the movement in "declination" (and hence altitude) of a little under a half (0.39) degree per day.

For observers in either hemisphere not at the poles, the Sun rises and sets more and more to the south during the 3 months following the September equinox. This period is the second half of a 6-month long southerly movement, beginning with theJune solstice when the Sun rises and sets at its most northern point.

Culture

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Calendars

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The September equinox marked the first day of theFrench Republican Calendar.

Commemorations

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West Asia

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The Southward equinox marks the first day of Mehr or Libra in theIranian calendar. It is one of theIranian festivals called JashneMehregan, or the festival of sharing or love inZoroastrianism.

East Asia

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In JapanAutumnal Equinox Day (秋分の日,Shūbun no hi) is a public holiday.^[9]Higan (お彼岸) is a Buddhist holiday exclusively celebrated by Japanese sects during both the Spring and Autumnal Equinox.
In Korea,Chuseok is a major harvest festival and a three-day holiday celebrated around the Autumn Equinox.
TheMid-Autumn Festival is celebrated on the 15th day of the 8thlunar month, often near the autumnal equinox day, and is an official holiday in mainland China, Hong Kong,Taiwan and in many countries with a significant Chinese minority. As the lunar calendar is not synchronous with the Gregorian calendar, this date could be anywhere from mid-September to early October.
The traditional East Asian calendars divide a year into 24solar terms (节气, literally "climatic segments"), and the autumnal equinox (Qiūfēn,Chinese andJapanese: 秋分; Korean:추분; Vietnamese:Thu phân) marks themiddle of the autumn season. In this context, theChinese character 分 means"(equal) division" (within a season).

Judaism

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The JewishSukkot usually falls on the firstfull moon after the northern hemisphere autumnal equinox, although occasionally (In the modern Jewish calendar, three times every 19 years) it will occur on the second full moon.
Rosh Hashanah falls on anew moon close to this equinox.

Europe

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Dożynki is a Slavic harvest festival. In pre-Christian times the feast usually fell on the autumn equinox.
The Southward equinox was "New Year's Day" in theFrench Republican Calendar, which was in use from 1793 to 1805. TheFrench First Republic was proclaimed and theFrench monarchy was abolished on September 21, 1792, making the following day (the equinox day that year) the first day of the "Republican Era" in France. The start of every year was to be determined by astronomical calculations following the real Sun and not the mean Sun.
The traditionalharvest festival in the United Kingdom was celebrated on the Sunday of the full moon closest to the September equinox.

Neopaganism

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Neopagans observe the September equinox as a cardinal point on theWheel of the Year. In the Northern Hemisphere some varieties of paganism adaptAutumn Equinox traditions. In the Southern Hemisphere, the vernal equinox corresponds withOstara.

Americas

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The reconstructedCahokia Woodhenge, a largetimber circle located at theMississippian culture Cahokia archaeological site nearCollinsville, Illinois,^[10] is the site of annual equinox and solstice sunrise observances. An announcement for the 2017 observance said "Out of respect for Native American beliefs, no rituals or ceremonies will be held at the free event. But visitors will stand in the same place where the Mississippian people once gathered to watch the sun rise."^[11]^[12]^[13]