In astronomy, equinox can have two meanings:

• Either of the two events when the Sun is positioned directly over the Earth's equator and, by extension, the apparent position of the Sun at that moment, or the time that it happens. Solstices occur twice a year when the tilt of the Earth's axis is most oriented toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes
• The time at which the vernal point, celestial equator, and other such elements are taken to be used in the definition of a celestial coordinate system—see Equinox (celestial coordinates). In Astronomy, a celestial coordinate system is a Coordinate system for mapping positions in the sky In Astronomy, equinox is a moment in time at which the vernal point Celestial equator, and other such elements are taken to be used in the definition of a

An equinox in astronomy is that moment in time (not a whole day) when the centre of the Sun can be observed to be directly above the Earth's equator, occurring around March 20 and September 23 each year. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study The Sun (Sol is the Star at the center of the Solar System. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden. Events 1122 - Concordat of Worms. 1459 - Battle of Blore Heath, the first major battle of the English

More technically, at an equinox, the Sun is at one of two opposite points on the celestial sphere where the celestial equator (i. In Astronomy and Navigation, the celestial sphere is an imaginary rotating Sphere of "gigantic Radius " The celestial equator is a Great circle on the imaginary Celestial sphere, in the same plane as the Earth 's Equator. e. declination 0) and ecliptic intersect. The ecliptic is the apparent path that the Sun traces out in the sky during the year These points of intersection are called equinoctial points—the vernal point and the autumnal point. By extension, the term equinox may be used to denote an equinoctial point.

There is either an equinox (autumn and spring) or a solstice (summer and winter) on approximately the 21st day of the last month of every quarter of the calendar year. Solstices occur twice a year when the tilt of the Earth's axis is most oriented toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes On a day which has an equinox, the centre of the Sun will spend a nearly equal amount of time above and below the horizon at every location on Earth and night and day will be of nearly the same length. The word equinox derives from the Latin words aequus (equal) and nox (night). In reality, the day is longer than the night at an equinox. Commonly the day is defined as the period that sunlight reaches the ground in the absence of local obstacles. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the From Earth, the Sun appears as a disc and not a single point of light; so, when the centre of the Sun is below the horizon, the upper edge is visible. Furthermore, the atmosphere refracts light; so, even when the upper limb of the Sun is below the horizon, its rays reach over the horizon to the ground. In sunrise/sunset tables, the assumed semidiameter (apparent radius) of the sun is 16 minutes of arc and the atmospheric refraction is assumed to be 34 minutes of arc. Sunrise is the instant at which the upper edge of the Sun appears above the Horizon in the East. Sunset, also called sundown in some American English Dialects is the instant when the trailing edge of the Sun 's disk disappears below Remote Authentication Dial In User Service ( RADIUS) is a networking protocol that provides centralized access authorization and accounting management for people or computers A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60 of one degree. Atmospheric Refraction is the deviation of Light or other Electromagnetic wave from a straight line as it passes through the atmosphere due to the Their combination means that when the upper limb of Sun is on the visible horizon its centre is 50 minutes of arc below the geometric horizon, which is the intersection with the celestial sphere of a horizontal plane through the eye of the observer. These effects together make the day about 14 minutes longer than the night at the equator, and longer still at sites toward the poles. The real equality of day and night only happens at places far enough from the equator to have at least a seasonal difference in daylength of 7 minutes, and occurs a few days towards the winter side of each equinox.

Illumination of the Earth by the Sun on the day of equinox, (ignoring twilight).

The Earth in its orbit around the Sun causes the Sun to appear on the celestial sphere moving over the ecliptic (red), which is tilted on the equator (blue).

Diagram of the Earth's seasons as seen from the north. Far right: December solstice

Diagram of the Earth's seasons as seen from the south. Far left: June solstice

Day arc at 0° latitude, equator

Day arc at 20° latitude

Day arc at 50° latitude

Day arc at 70° latitude

Day arc at 90° latitude, pole

Names

• Spring equinox^[2] and autumn or fall equinox. Spring is one of the four Temperate Seasons Spring marks the transition from Winter into Summer. Autumn (also known as fall in North American English) is one of the four Temperate Seasons Autumn marks the transition from Summer These names can be used when one wants to relate the equinox to a season. The seasons of the Northern Hemisphere and Southern Hemisphere are opposites (the spring equinox of one hemisphere is the autumn equinox of the other) so these names can be ambiguous. Northern Hemisphere is the half of a Planet that is North of the Equator —the word hemisphere literally means 'half ball' Southern Hemisphere is the half of a Planet that is South of the Equator —the word hemisphere literally means 'half ball'
• March equinox and September equinox. An alternative to the previous set, but without the ambiguity for which hemisphere they are intended. These names are still not universal, however, as not all people on Earth use a solar-based calendar where the equinoxes occur every year in the same month (they differ in the Hebrew calendar, for example). The Hebrew calendar (הלוח העברי ha'luach ha'ivri) or Jewish calendar is a Lunisolar calendar used by Jews for predominantly religious The names are also not useful for other planets (Mars, for example), even though they have seasons.
• Vernal equinox and autumnal equinox. These names are direct derivatives of Latin (ver = spring, autumnus = autumn), and as such more apt to be found in writings. Although in principle they are subject to the same problem as the spring/autumn names, their use over the centuries has fixed them to the viewpoint of the northern hemisphere. As such the vernal equinox is the equinox where the Sun passes from south to north, and is a zeropoint in some celestial coordinate systems. In Astronomy, a celestial coordinate system is a Coordinate system for mapping positions in the sky The name of the other equinox is used less often.
• Vernal point and autumnal point. They are the points on the celestial sphere where the Sun is located on the vernal equinox and, respectively, on the autumnal equinox.
• First point of Aries and first point of Libra. Aries, the ram, is the first Astrological sign in the Zodiac. Libra is the seventh Astrological sign in the Zodiac, originating from the constellation of Libra. Alternative names for the previous set, but removing the problem that the vernal equinox may be dependent on a specific hemisphere. One disadvantage is that due to the precession of the equinoxes the astrological signs where these equinoxes are located, do not correspond any longer with the actual constellations. In Astronomy, Precession refers to the movement of the rotational axis of a body such as a planet with respect to Inertial space. Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic In common usage a constellation is a group of celestial bodies that are connected together in some arrangement typically stars to form a visible figure or picture
• Pisces equinox and Virgo equinox. Pisces (ˈpaɪsiːz Fish (plural symbol, Unicode ♓ is a Zodiac Constellation which lies between Aquarius to the west and Aries Virgo ( Virgin, symbol, Unicode ♍ is a Constellation of the Zodiac. Names to indicate in which constellations the two equinoxes are currently located. These terms are rarely used.
• Northward equinox and southward equinox. Names referring to the apparent motion of the Sun at the times of the equinox.

Heliocentric view of the seasons

The Earth's seasons are caused by the rotation axis of the Earth not being perpendicular to its orbital plane. A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather. The Earth's axis is tilted at an angle of approximately 23. 44° from the orbital plane. This tilt is called the axial tilt. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. As a consequence, for half a year (from around 20 March to around 22 September) the northern hemisphere tips toward the Sun, with the maximum around 21 June, while for the other half year the southern hemisphere has this honour, with the maximum around 21 December. Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden. Events 66 - Emperor Nero creates the Legion I Italica. 1236 - The Lithuanians Events 524 - Godomar, King of the Burgundians defeats the Franks at the Battle of Vézeronce. Events 69 - The end of the Year of the four emperors: Following Galba, Otho and Vitellius, Vespasian The two instances when the Sun is directly overhead at the equator are the equinoxes. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the Also at that moment both the north pole and south pole of the Earth are just on the terminator, and day and night are divided equally between the hemispheres. The terminator is a fictive line that delimits the illuminated day side and dark Night side of a planetary body (also known as the "grey line" or

The table above gives the dates and times of equinoxes and solstices over several years. Solstices occur twice a year when the tilt of the Earth's axis is most oriented toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes A few remarks can be made about the equinoxes:

• Because the Sun is a sphere and not a point source of light, the actual crossing of the Sun over the equator takes approximately 33 hours.
• At the equinoxes, the rate of change for the length of daylight and nighttime is the greatest. At the poles, the equinox marks the transition from 24 hours of nighttime to 24 hours of daylight. High in the Arctic Circle, Longyearbyen, Svalbard, Norway has an additional 15 minutes more daylight every day around the time of the Spring equinox. Longyearbyen is the Administrative centre of Svalbard and is located on Spitsbergen, the largest island of the Svalbard Archipelago. Svalbard is an Archipelago in the Arctic Ocean north of mainland Europe, about midway between Norway and the North Pole. Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional Whereas, in Singapore, which lies virtually on the equator, the amount of daylight each day varies by just seconds. Singapore
• It is 94 days from the June solstice to the September equinox, but only 89 days from the December solstice to the March equinox. The seasons are not of equal length because of the variable speed the Earth has in its orbit around the Sun.
• The instances of the equinoxes are not fixed but fall about six hours later every year, amounting to one full day in four years, but then they are reset by the occurrence of a leap year. The Gregorian calendar is designed to follow the seasons as accurately as is practical. It is good, but not perfect. Also see: Gregorian calendar#Calendar seasonal error. The Gregorian calendar is the most widely used Calendar in the world today
• Smaller irregularities in the times are caused by perturbations of the Moon and the other planets.
• Currently the most common equinox and solstice dates are 20 March, 21 June, 22 September and 21 December, the four year average will slowly shift to earlier times in the years to come. Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden. Events 524 - Godomar, King of the Burgundians defeats the Franks at the Battle of Vézeronce. Events 66 - Emperor Nero creates the Legion I Italica. 1236 - The Lithuanians Events 69 - The end of the Year of the four emperors: Following Galba, Otho and Vitellius, Vespasian This shift is a full day in about 70 years (largely to be compensated by the century leap year rules of the Gregorian calendar). But that also means that in many years of the twentieth century the dates of 21 March, 22 June, 23 September and 22 December were much more common, so older books teach, and older people still remember, these dates as the main ones. Events 630 - Byzantine emperor Heraclius restores the True Cross to Jerusalem. Events 217 BC - Battle of Raphia: Ptolemy IV of Egypt defeats Antiochus III the Great of the Seleucid kingdom. Events 1122 - Concordat of Worms. 1459 - Battle of Blore Heath, the first major battle of the English Events 1790 - The Turkish fortress of Izmail is stormed and captured by Suvorov and his Russian armies
• Note that the times are given in UTC, roughly speaking, the time at Greenwich (ignoring British Summer Time). Greenwich ( ˈɡrɛnɪtʃ GREN-itch /ˈɡrɛnɪdʒ/ GREN-idge or /ˈɡrɪnɪdʒ/ GRIN-idge is a district in south-east London, People living farther to the east (Asia, Australia) whose local times are in advance, will see the seasons apparently start later, for example in Tonga (UTC+13) an equinox occurred on 24 September 1999; a date which will not happen again until 2103. The Kingdom of Tonga is an Archipelago in the south Pacific Ocean comprising 169 islands 36 of them inhabited stretching over a distance of about 800 kilometres (500 miles Events 622 - Prophet Muhammad completes his hegira from Mecca to Medina. Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) On the other hand people living far to the west (America) have clocks running behind in time, and may experience an equinox occurring as early as 19 March. Events 1279 - A Mongolian victory in the Battle of Yamen ends the Song Dynasty in China.

Geocentric view of the seasons

The explanation given in the previous section would be useful for an observer in outer space. As seen by an observer on Earth, it may appear to the casual observer that the Sun revolves around the Earth once a year. As such, in the half year centred around June it rises and sets more towards the north, which means longer days and shorter nights for the northern hemisphere and shorter days and longer nights for the southern hemisphere. In the half year centred around December the Sun rises and sets more towards the south, and the day and night durations are reversed.

Also on the equinox day, the Sun rises, for every place on Earth (except at the poles), at 6:00 in the morning and sets at 18:00 in the evening local time. But these times are not exact for several reasons.

• Most places on Earth use a time zone which is not equal to the local time, differing sometimes up to an hour or more, and even two hours if daylight saving time (summer time) is included. Daylight saving time ( DST In that case, the Sun can rise for example at 8:00 and set at 20:00, but there would still be 12 hours of daylight.
• Even those people fortunate enough to have their time zone just equal to the local time still will not see sunrise and sunset at 6:00 and 18:00, respectively. This is due to the variable speed of the Earth in its orbit, and is described as the equation of time. The equation of time is the difference over the course of a year between time as read from a Sundial and time as read from a Clock, measured in an ideal situation It has different values for the March and the September equinox (+8 and −8 minutes respectively).
• Sunrise and sunset are commonly defined for the upper limb of the solar disk, and not for its centre. The upper limb is already up for at least one minute before the centre appears, and likewise the upper limb sets one minute later than the centre of the solar disk.
• Due to atmospheric refraction the Sun, when near the horizon, appears a little more than its own diameter above the position than where it is in reality. Atmospheric Refraction is the deviation of Light or other Electromagnetic wave from a straight line as it passes through the atmosphere due to the This makes sunrise more than another two minutes earlier and sunset the equal amount later. The two effects add up to almost seven minutes, making the equinox day 12h 7m long and the night only 11h 53m. In addition to that, the night includes twilight. When dawn and dusk are added to the daytime instead, the day would be almost 13 hours.
• The above numbers are only true for the tropics. For moderate latitudes this discrepancy gets larger (London, for example: 12 minutes), and close to the poles it gets very large. Up to about 100 km from both poles the Sun is up for a full 24 hours on equinox day.
• Height of the horizon on both the sunrise and sunset sides changes the day's length. Going up into the mountains will lengthen the day, while standing in a valley with hilltops on the east and the west can shorten the day significantly. This is why settlements in east-west running valleys are more favourable (daylight-wise) than north-south running valleys.

Day arcs of the Sun

Some of the above statements can be made clearer when picturing the day arc: the path the Sun tracks along the celestial dome in its diurnal movement. Diurnal motion is an astronomical term referring to the apparent daily motion of Stars around the Earth, or more precisely around the two The pictures show this for every hour on equinox day. In addition, also some 'ghost' suns are indicated below the horizon, up to 18° down. The Sun in this area still causes twilight. Twilight is the time before Sunrise, called Dawn, and the time after Sunset, called Dusk. The pictures can be used for both the northern and the southern hemisphere. The observer is supposed to sit near the tree on the island in the middle of the ocean. The green arrows give the cardinal directions.

• On the northern hemisphere, north is to left, the Sun rises in the east (far arrow), culminates in the south (right arrow) while moving to the right and sets in the west (near arrow). In astronomy the culmination, at a given point of a Planet, Star, Constellation, etc
• On the southern hemisphere, south is to the left, the Sun rises in the east (near arrow), culminates in the north (right arrow) while moving to the left and sets in the west (far arrow).

The following special cases are depicted.

• The day arc on the equator, passing through the zenith, has almost no shadows at high noon. In broad terms the zenith is the direction pointing directly above a particular location ( Perpendicular, Orthogonal)
• The day arc on 20° latitude. The Sun culminates at 70° altitude and also its daily path at sunrise and sunset occurs at a steep 70° angle to the horizon. Twilight is still about one hour.
• The day arc on 50° latitude. Twilight is almost two hours now.
• The day arc on 70° latitude. The Sun culminates at no more than 20° altitude and its daily path at sunrise and sunset is at a shallow 20° angle to the horizon. Twilight is more than four hours, in fact there is barely any dark night.
• The day arc at the pole. If it were not for atmospheric refraction, the Sun would be on the horizon all the time.

Celestial coordinate systems

The vernal point (vernal equinox)—the one the Sun passes in March on its way from south to north—is used as the origin of some celestial coordinate systems:

• in the ecliptic coordinate system, the vernal point is the origin of the ecliptic longitude;
• in the equatorial coordinate system, the vernal point is the origin of the right ascension. In Astronomy, a celestial coordinate system is a Coordinate system for mapping positions in the sky The ecliptic coordinate system is a Celestial coordinate system that uses the Ecliptic for its Fundamental plane. Ecliptic longitude ( solar longitude or celestial longitude) is one of the co-ordinates which can be used to define the location of an Astronomical object The equatorial coordinate system is probably the most widely used Celestial coordinate system, whose equatorial coordinates are Declination (\delta Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere

Because of the precession of the Earth's axis, the position of the vernal point changes over time and as a consequence both the equatorial and the ecliptic coordinate systems change over time. In Astronomy, Precession refers to the movement of the rotational axis of a body such as a planet with respect to Inertial space. Therefore, when specifying celestial coordinates for an object, one have to specify at what time the vernal point (and also the celestial equatorial) are taken. That reference time is also called equinox. In Astronomy, equinox is a moment in time at which the vernal point Celestial equator, and other such elements are taken to be used in the definition of a

The autumnal equinox is at ecliptic longitude 180° and at right ascension 12h.

The upper culmination of the vernal point is considered the start of the sidereal day for the observer. In astronomy the culmination, at a given point of a Planet, Star, Constellation, etc Sidereal time is a measure of the position of the Earth in its rotation around its axis or time measured by the apparent Diurnal motion of the Vernal equinox The hour angle of the vernal point is, by definition, the observer's sidereal time. In Astronomy, the hour angle is one of the coordinates used in the Equatorial coordinate system for describing the position of a point on the Celestial sphere Sidereal time is a measure of the position of the Earth in its rotation around its axis or time measured by the apparent Diurnal motion of the Vernal equinox

For Western tropical astrology, the same thing holds true; the vernal equinox is the first point (i. Western astrology is the system of Astrology most popular in Western countries e. the start) of the sign of Aries. Aries, the ram, is the first Astrological sign in the Zodiac. In this system, it is of no significance that the fixed stars and equinox shift compared to each other due to the precession of the equinoxes. In Astronomy, Precession refers to the movement of the rotational axis of a body such as a planet with respect to Inertial space.

In Jyotiṣa on the other hand, their 'vernal equinox' was fixed to the stars about 17 centuries ago, and has been drifting away from the seasons since then, now amounting to 22 days. Jyotiṣa ( Sanskrit jyotiṣa, from jyótis- "light heavenly body" also spelled Jyotish and Jyotisha in English

Cultural aspects

In the list below the terms March and September equinoxes are used when the celebration is fixed in time, while the terms spring and autumn equinoxes refer to those which are different in the two hemispheres.

• The Persian new year, Nowruz, is held annually on the vernal equinox, as the beginning of spring. The Iranian calendar or Solar Hejri (تقویم هجری شمسی؛ سالنمای هجری خورشیدی Taqwim Hejri Shamsi Salanmay Hejri Khurshidi) is an astronomical Nowrūz ( /noruz/ ↔, (English New Day various local pronunciations and spellings) is the traditional Iranian New year Holiday celebrated

• Sham El Nessim was an ancient Egyptian holiday which can be traced back as far as 2700 B. Sham el-Nessim ( Coptic: shom en nisim) (شم النسيم literally "sniffing the air" or "breathing the air" is an Egyptian holiday which Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now C. It is still one of the public holidays in Egypt. Holidays in Egypt have many classifications There are a set of national holidays celebrated by the entire population Sometime during Egypt's Christian period (c. 200-639 CE) the date moved to Easter Monday, but before then it coincided with the vernal equinox. Easter Monday is the day after Easter Sunday and is celebrated as a Holiday in some largely Christian cultures especially Roman Catholic

• The Jewish Passover always falls on the full moon following the northern hemisphere vernal equinox. PLEASE TAKE NOTE************ Passover ( Hebrew, Yiddish: פֶּסַח Pesach, Tiberian: pɛsaħ Israeli: Pesah, Pesakh, Yiddish Full moon is a Lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun.

• The Christian churches calculate Easter as the first Sunday after the first full moon on or after the March equinox. Church (disambiguation Christian Church and the word church are used to denote both a Christian association of people and a Place of worship Computus ( Latin for Computation) is the Calculation of the date of Easter in the Christian calendar. Easter ( Greek: Πάσχα Pascha or Pasxa) is the most important religious feast in the Christian Liturgical year. The official definition for the equinox is on March 21. Events 630 - Byzantine emperor Heraclius restores the True Cross to Jerusalem. However, as the Eastern Orthodox Churches use the older Julian calendar, while the Western Churches use the Gregorian calendar, both of which designate March 21 as the equinox, the actual date of Easter differs. The Eastern Orthodox Church is the second largest single Christian Communion in the world The Julian calendar, a reform of the Roman calendar, was introduced by Julius Caesar in 46 BC and came into force in 45 BC (709 Ab urbe condita The Gregorian calendar is the most widely used Calendar in the world today The earliest possible Easter date in any year is therefore March 22, on each calendar. Events 238 - Gordian I and his son Gordian II are proclaimed Roman emperor.

• The March equinox marks the first day of various calendars including the Iranian calendar and the Bahá'í calendar. The Iranian calendar or Solar Hejri (تقویم هجری شمسی؛ سالنمای هجری خورشیدی Taqwim Hejri Shamsi Salanmay Hejri Khurshidi) is an astronomical The Bahá'í calendar, also called the Badí‘ calendar, used by the Bahá'í Faith, is a Solar calendar with regular years of 365 days and Leap ^[3] The Persian (Iranian) festival of Nowruz is celebrated then. layout and formatting it should ensure no clashes with the top of the infobox For a topic outline on this subject see List of basic Iran topics. Nowrūz ( /noruz/ ↔, (English New Day various local pronunciations and spellings) is the traditional Iranian New year Holiday celebrated 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. These festivities recall the story of creation and the ancient cosmology of Iranian and Persian people. It is also a holiday for Azerbaijan, Afghanistan, India, Turkey, Zanzibar, Albania, and various countries of Central Asia, as well as among the Kurds. Azerbaijan ( English; Azərbaycan officially the Republic of Azerbaijan (Azərbaycan Respublikası is the largest and most populous country in the South Afghanistan /æfˈgænɪstæn/ officially the Islamic Republic of Afghanistan ( Pashto: د افغانستان اسلامي جمهوریت, India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches Zanzibar ( is part of the East African republic of Tanzania. It consists of the Zanzibar Archipelago in the This article is about the country in southern Europe For a topic outline on this subject see List of basic Albania topics. Central Asia is a region of Asia from the Caspian Sea in the west to central China in the east and from southern Russia in the north to northern Pakistan in the south As well as being a Zoroastrian holiday, it is also a holy day for adherents of the Bahá'í Faith and the Nizari Ismaili Muslims. Zoroastrianism (ˌzɔroʊˈæstriəˌnɪzəm is the religion and philosophy based on the teachings The Bahá'í Faith is a Religion founded by Bahá'u'lláh in nineteenth-century Persia, emphasizing the spiritual unity of all humankind For the Egyptian city see Ismaïlia. The Ismāʿīlī ( Urdu: إسماعیلی Ismāʿīlī, Arabic: الإسماعيليون ^[4]

• The September equinox marks the first day of Mehr or Libra in the Iranian calendar. The Iranian calendar or Solar Hejri (تقویم هجری شمسی؛ سالنمای هجری خورشیدی Taqwim Hejri Shamsi Salanmay Hejri Khurshidi) is an astronomical It is one of the Iranian festivals called Jashne Mihragan, or the festival of sharing or love in Zoroastrianism. The following is a List of Festivals in Iran Iranian Festivals Nowruz: Celebration of the start of spring ("Rejuvenation" Mehregān (alternatively Mihragān, مهرگان or Jashn-e-Mehregān is a Zoroastrian and Iranian festival celebrated in honor of Mithra Zoroastrianism (ˌzɔroʊˈæstriəˌnɪzəm is the religion and philosophy based on the teachings

• The spring equinox marks the Wiccan Sabbat of Ostara (or Eostar), while at the autumn equinox the Wiccan Sabbat of Mabon is celebrated. Wheel of the Year is a Wiccan and Neopagan term for the annual cycle of the Earth 's Seasons It consists of eight festivals spaced at approximately Ostara is a modern pagan festival Etymology The name Ostara goes back to Jacob Grimm, who in his Deutsche Mythologie This article is about the Neopagan festival Mabon. For the Welsh mythological character see Mabon ap Modron.

• The traditional East Asian calendars divide a year into 24 solar terms (節氣, literally "climatic segments"), and the vernal equinox (Chūnfēn, Chinese and Japanese: 春分; Korean: 춘분; Vietnamese: Xuân phân) and the autumnal equinox (Qiūfēn, Chinese and Japanese: 秋分; Korean: 추분; Vietnamese: Thu phân) mark the middle of the spring and autumn seasons, respectively. A solar term is one of 24 points in traditional East Asian Lunisolar calendars that matches a particular astronomical event or signifies some natural phenomenon See also Vernal equinox The traditional East Asian calendars divide a year into 24 Solar terms (節氣 is a language spoken by over 130 million people in Japan and in Japanese emigrant communities This article is mainly about the spoken Korean language See Hangul for details on the native Korean writing system Vietnamese ( tiếng Việt, or less commonly Việt ngữ) formerly known under French colonization as Annamese ( see Annam) See also Autumnal equinox The traditional East Asian calendars divide a year into 24 Solar is a language spoken by over 130 million people in Japan and in Japanese emigrant communities This article is mainly about the spoken Korean language See Hangul for details on the native Korean writing system Vietnamese ( tiếng Việt, or less commonly Việt ngữ) formerly known under French colonization as Annamese ( see Annam) A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather. In this context, the Chinese character 分 means "division" (of the seasons). A Chinese character, also known as a Han character ( is a Logogram used in writing Chinese (hanzi Japanese (

• In Japan, (March) 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. For a topic outline on this subject see List of basic Japan topics. The of 1948 (as amended establishes the occasions on which Japan has a legal Holiday. Similarly, in September, there is an Autumnal Equinox Day (秋分の日 Shūbun no hi).

• The Mid-Autumn Festival is celebrated on the 15th day of the 8th lunar month, and is an official holiday in many East Asian countries. The Mid-Autumn Festival, also known as the Moon Festival, or in Chinese Zhongqiu Jie ( is a popular harvest festival celebrated by Chinese In Lunar calendars a lunar month is the time between two identical syzygies ( New moons or Full moons. As the lunar calendar is not synchronous with the Gregorian calendar, this date could be anywhere from mid-September to early October.

• Tamil and Bengali New Years follow the Hindu zodiac and are celebrated according to the sidereal vernal equinox (14 April). Tamil people (also called Tamils or Tamilians) ( are an Ethnic group native to Tamil Nadu, a state in India, and the north-eastern Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic Events 43 BC - Battle of Forum Gallorum: Mark Antony, besieging Julius Caesar 's assassin Decimus Junius Brutus in The former is celebrated in the South Indian state of Tamil Nadu, and the latter in Bangladesh and the East Indian state of West Bengal. Tamil Nadu ( Tamil:, Country of the Tamils, t̪ɐmɨɻ n̪aːɽɯ is one of the 28 states of India. The Bengali calendar ( বঙ্গাব্দ Bônggabdo or বাংলা সন Bangla Shôn) or Bangla calendar is a traditional solar Calendar West Bengal ( Bengali: পশ্চিমবঙ্গ Poshchim Bônggo poʃtʃim bɔŋgo is a state in eastern India.

• Earth Day was initially celebrated on March 21, 1970, the equinox day. Earth Day is one of two Observances both held annually during spring in the Northern hemisphere, and autumn in the Southern hemisphere. Events 630 - Byzantine emperor Heraclius restores the True Cross to Jerusalem. Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. It is currently celebrated in various countries on April 22. Events 1500 - Portuguese Navigator Pedro Álvares Cabral becomes the first European to sight Brazil.

• In many Arab countries, Mother's Day is celebrated on the March equinox. The araB gene Promoter is a bacterial promoter activated by e L-arabinose binding Mother's Day is a day honoring Mothers celebrated on various days in many places around the world

• The September equinox was "New Year's Day" in the French Republican Calendar, which was in use from 1793 to 1805. New Year's Day is the first day of the Year. On the modern Gregorian calendar, it is celebrated on January 1, as it was also in ancient Rome (though The French Republican Calendar or French Revolutionary Calendar was a Calendar proposed during the French Revolution, and used by the French government The French First Republic was proclaimed and the French 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 First Republic in France, officially the French Republic (République française was proclaimed on 21 September 1792 during the French Revolution. List of Queens and Empresses of France Wikipedia_talkFeatured_lists#Proposed_change_to_all_featured_lists for an explanation of this and other inclusion tags below Events 1217 - The Estonian tribal leader Lembitu of Lehola was killed in a battle against Teutonic Knights. Year 1792 ( MDCCXCII) was a Leap year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Leap year The start of every year was to be determined by astronomical calculation, (that is: following the real Sun and not the mean Sun as all other calendars).

• The harvest festival in the United Kingdom is celebrated on the Sunday of the full moon closest to the September equinox. A harvest festival is an annual celebration which occurs around the time of the main harvest of a given region

• World Storytelling Day is a global celebration of the art of oral storytelling, celebrated every year on the spring equinox in the northern hemisphere, the first day of autumn equinox in the southern. World Storytelling Day is a global celebration of the art of oral Storytelling.

Myths, fables and facts

• For a Latin word like nox the plural is noctēs. Although this root is retained in English in the adjective: equinoctial — it is not commonly used for the plural, which is equinoxes, rather than equinoctes. In Grammar, an adjective is a word whose main syntactic role is to modify a Noun or Pronoun, giving more information about the Plural is a Grammatical number, typically referring to more than one of the Referent in the real world
• One effect of equinoctial periods is the temporary disruption of communications satellites. A communications satellite (sometimes abbreviated to comsat) is an artificial Satellite stationed in space for the purposes of Telecommunications. For all geostationary satellites, there are a few days near the equinox when the sun goes directly behind the satellite relative to Earth (ie, within the beamwidth of the groundstation antenna) for a short period each day. A geostationary orbit (GEO is a Geosynchronous orbit directly above the Earth 's Equator (0° Latitude) with a period equal to the Earth's The Sun's immense power and broad radiation spectrum overload the Earth station's reception circuits with noise and, depending on antenna size and other factors, temporarily disrupt or degrade the circuit. The duration of those effects varies but can range from a few minutes to an hour. (For a given frequency band, a larger antenna has a narrower beamwidth, hence experience shorter duration "Sun outage" windows). A sun outage' is an interruption in or Distortion of geostationary satellite signals caused by interference from Solar radiation.
• A folk tale claims that only on the March equinox day (some may add the September equinox day or may explicitly not), one can balance an egg on its point. ^[5][6][7] However one can balance an egg on its point any day of the year if one has the patience. ^[8]
• Although the word "equinox" implies equal length of day and night, as is noted elsewhere, this is not true. For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal. Those days are commonly referred to as the "equiluxes" to distinguish them from the equinoxes. Equinoxes are points in time, but equiluxes are days. By convention, equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart. This way, you can refer to a single date as being the equilux, when, in reality, it spans sunset on one day to sunset the next, or sunrise on one to sunrise the next.
• The equilux counts times when some direct sunlight could be visible, not all hours of usable daylight, which is anytime there is enough natural light to do outdoor activities without artficial light. This is due to twilight, and this part of twilight is officially defined as civil twilight. Twilight is the time before Sunrise, called Dawn, and the time after Sunset, called Dusk. This amount of twilight can make there be more than 12 hours of usable daylight up to a few weeks before the spring equinox, and up to a few weeks after the fall equinox.
• On the contrary, the intensity of light near sunrise and sunset, even with the sun slightly above the horizon, is considerably less than when the sun is high in the sky. The daylight which is useful for illuminating daylit houses and buildings and for producing the full psychological benefit of daylight is shorter than the nominal time between sunrise and sunset, and is present for 12 hours only after the vernal equinox and before the autumnal equinox.
• It is perhaps valuable for people in the Americas and Asia to know that the equinoxes listed as occurring on March 21 that occurred frequently in the twentieth century and that will occur occasionally in the 21st century are presented as such using UTC, which is at least four hours in advance of any clock in the Americas and as much as twelve hours behind Asian clocks. Events 630 - Byzantine emperor Heraclius restores the True Cross to Jerusalem. The twentieth century of the Common Era began on Thus, there will be no spring equinox later than March 20 in the Americas in the coming century. Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden.

References

External links

• Details about the Length of Day and Night at the Equinoxes
• Calculation of Length of Day (Formulas and Graphs)
• Equinoctial Points—The Nuttall Encyclopædia
• Table of times for Equinoxes, Solstices, Perihelion, and Aphelion in 2000-2020
• Table of times of Spring Equinox for a thousand years 1452-2547
• Groundhog Day and the Spring Equinox. The Nuttall Encyclopædia: Being a Concise and Comprehensive Dictionary of General Knowledge is an early-20th-century Encyclopedia, edited by Landscaping. About. com.
• Ancient Equinox Alignment. Loughcrew, Ireland.