For the lunar Hijri calendar used by mostMuslims to date holidays and events, seeIslamic calendar. For the Late Ottoman-era solar calendar, seeRumi calendar. For a succession of Iranian solar calendars, seeIranian calendars.
A Solar Hijri calendar of year 1383SH showing the second month ofOrdibehesht (thus April–May 2004; see conversion table below). The month's name comes from theAvestan word forAsha.
TheSolar Hijri calendar[a] is the official calendar ofIran. It is asolar calendar, based on the Earth's orbit around the Sun. Each year begins on the day[b] of theMarch equinox and has years of 365 or 366 days. It is sometimes also called theShamsi calendar,Khorshidi calendar orPersian calendar and the most recent of theIranian calendars. It is abbreviated asSH,HS,AP, or, sometimes asAHSh, while thelunar Hijri calendar (commonly known in the West as the 'Islamic calendar') is usually abbreviated asAH.
Theepoch (very first day) of the Solar Hijri calendar was the day of the spring equinox, March 19, 622CE. The calendar is a "Hijri calendar" because that was the year thatMohammed is believed to have left fromMecca toMedina, which event is referred to as theHijrah.
Since the calendar uses astronomical observations and calculations for determining thevernal equinox, it theoretically has no intrinsic error in matching the vernal equinox year.[3][4][5][6] According to Iranian studies, it is older than the lunar Hijri calendar used by the majority ofMuslims (known in the West as theIslamic calendar); though they both count from the year of the Hijrah.[7][8] The solar Hijri calendar usessolar years and is calculated based on the "year of the Hijrah," and the lunar Hijri calendar is based onlunar months, and dates from the presumed actual "day of the Hijrah".
Each of the twelve months of the solar Hijri calendar corresponds with azodiac sign. In Iran before 1925 and inAfghanistan before 2023,[c] the names of the zodiacal signs were used for the months; elsewhere the month names are the same as in theZoroastrian calendar. The first six months have 31 days, the next five have 30 days, and the last month has 29 days in common years, 30 inleap years.
The ancient Iranian New Year's Day, which is calledNowruz, always falls on the March equinox. Nowruz is celebrated by communities in a wide range of countries from theBalkans toCentral Asia. Currently the Solar Hijri calendar is officially used only in Iran.
The calendar'sepoch (first year) corresponds to theHijrah in 622CE, which is the same as the epoch of theLunar Hijri calendar but because it countssolar years rather than (shorter)lunar years, the two calendars' year numbers do not coincide with each other and are slowly drifting apart, being about 43 years apart as of 2023.
The first six months (Farvardin–Shahrivar) have 31 days, the next five (Mehr–Bahman) have 30 days, and the last month (Esfand) has 29 days in common years or 30 days in leap years. This is a simplification of theJalali calendar, in which the commencement of the month is tied to the sun's passage from one zodiacal sign to the next. The sun is travelling fastest through the signs in early January (Dey) and slowest in early July (Tir). The current time between theMarch andSeptember equinoxes is about 186 days and 10 hours, the opposite duration about 178 days, 20 hours, due to theeccentricity of Earth's orbit. (These times will change slowly due toprecession of the Earth'sapsides, becoming inverted after around 11,500 years.)
The Iranian Solar calendar produces a five-year leap year interval after about every seven four-year leap year intervals.[citation needed] It usually follows a 33-year subcycle with occasional interruptions by a single 29-year subcycle. The reason for this behaviour is (as explained above) that it tracks the observed vernal equinox.
Some predictive algorithms had been suggested, but were inaccurate due to confusion between the averagetropical year (365.2422 days) and the mean interval between spring equinoxes (365.2424 days). Thesealgorithms are not generally used (seeAccuracy).
The Iranian Solar calendar year begins at the start of spring in theNorthern Hemisphere: on the midnight in the interval between the two consecutivesolar noons that includes the instant of theMarch equinox.[2] (The solar noon is calculated based on the meridian used forstandard time in Iran.) Hence, the first mid-day is on the last day of one calendar year, and the second mid-day is on the first day (Nowruz) of the next year.
The first day of the calendar year, Nowruz ("New Day"), is the greatest festival of the year in Iran, Afghanistan, and some surrounding historicallyPersian-influenced regions. The celebration is filled with many festivities and runs a course of 13 days, the last day of which is calledsiz-dah bedar (سیزدهبدر; "outdoor 13th"), or formally Nature Day (روز طبیعت).
TheDari (Afghan Persian) month names are the signs of Zodiac. They were used in Iran in the early 20th century when the solar calendar was being used.
In the Iranian calendar, every week begins on Saturday and ends on Friday. The names of the days of the week are as follows:shanbeh,yekshanbeh,doshanbeh,seshanbeh,chahārshanbeh,panjshanbeh andjom'eh.Yek,do,se,chahār, andpanj are the Persian words for the numbers one to five. The name for Friday,jom'eh, comes fromArabic (جمعة).Jom'eh is sometimes referred to by the native Persian name,ādineh[ɒːdiːne] (آدینه). In some Islamic countries, including Iran and Afghanistan, Friday is the weekly holiday.
On 21 February 1911, the secondIranian parliament adopted as the official calendar of Iran a sidereal calendar with months bearing the names of the twelve constellations of the zodiac and month lengths varying based on the astronomical events; it remained in use until March 1925.[1] The present Iranian calendar was legally adopted on 31 March 1925, the last year of theQajar era. The law stated that the first day of the year should be the first day of spring in "the true solar year", "as it has been" ever so. It also fixed the number of days in each month, which previously varied by year with thesidereal zodiac. It revived the ancient Persian names, which are still used. It also officially set theepoch to the Hijrah, although that epoch was already in use since the 1911 law. It also deprecated the 12-year cycles of theChinese-Uighur calendar, which were not officially sanctioned but were commonly used.
Afghanistan legally adopted the official Jalali calendar in 1922[1] but with different month names. Afghanistan usesArabic names of the zodiacal signs; for example, theSaur Revolution in 1978 took place in the second month of the Solar Hijri calendar (PersianOrdibehesht;Saur is named afterTaurus). The Solar Hijri calendar has been until recently theofficial calendar of the government of Afghanistan,[10] and all national holidays and administrative issues were fixed according to the Solar Hijri calendar.
However, theTaliban imposed the lunar Hijri calendar in Afghanistan during both periods of their rule. Under the Taliban'sfirst rule from 1996 to 2001, the lunar Hijri calendar was imposed, thus changing the year overnight from 1375 to 1417.[11] With effect from 1Muharram 1444AH (8Mordad1401 SH; 30July 2022 CE) (theIslamic New Year of the lunar Hijri calendar), the Taliban once again imposed the lunar calendar.[9][dubious –discuss] Thus the year number once again leaped forward, this time from 1401 to 1444.
Tajikistan does not use the Solar Hijri calendar and has never done so, despite being part of the Persian-speaking world. The country does, however, celebrate Nowruz, although the official New Year's Day in Tajikistan is 1 January in the Gregorian calendar,[12] which is also the case in other non-Persian speakingIranian orTurkic communities ranging from Eastern Europe to Western China. The name of Tajikistan's capital,Dushanbe, is taken from the Solar Hijri calendar and translates to "Monday" in Persian.[13]
The Solar Hijri year begins about 21 March of each Gregorian year and ends about 20 March of the next year.[d] To convert the Solar Hijri year into the equivalent Gregorian year add 621 or 622 years to the Solar Hijri year depending on whether the Solar Hijri year has or has not begun.
Correspondence of Solar Hijri and Gregorian calendars (Solar Hijri leap years are marked*)[15]
Its determination of the start of each year is astronomically-determined year-to-year as opposed to the more fixedGregorian orCommon Era calendar which, averaged out, has the same year length, achieving the same accuracy (a differently patterned calendar of 365 days for three consecutive years plus an extra day in the next year, save for three exceptions to the latter in a 400-year cycle). The start of the year and its number of days remain fixed to one of the two equinoxes, the astronomically important days when day and night each have the same duration. It results in less variability of all celestial bodies when comparing a specific calendar date from one year to others.[17]
Iranian mathematicianAhmad Birashk (1907–2002) proposed an alternative means of determining leap years. Birashk's book came out in 1993, and his algorithm was based on the same apparently erroneous presumptions as used byZabih Behruz in his book from 1952.[17] Birashk's technique avoids the need to determine the moment of the astronomical equinox, replacing it with a very complex leap year structure. Years are grouped into cycles which begin with four normal years, after which every fourth subsequent year in the cycle is a leap year. Cycles are grouped into grand cycles of either 128 years (composed of cycles of 29, 33, 33, and 33 years) or 132 years, containing cycles of 29, 33, 33, and 37 years. A great grand cycle is composed of 21 consecutive 128-year grand cycles and a final 132 grand cycle, for a total of 2820 years. The pattern of normal and leap years which began in 1925, will not repeat until the year 4745.
The accuracy of the system proposed by Birashk and other recent authors, such as Zabih Behruz, has been thoroughly refuted and shown to be less precise than the traditional 33-year cycle.[17]
Each 2820-year great grand cycle proposed by Birashk contains 2137 normal years of 365 days and 683 leap years of 366 days, with the average year length over the great grand cycle of 365.24219852. This average is just 0.00000026 (2.6×10−7) of a day shorter thanNewcomb's value for the meantropical year of 365.24219878 days, but differs considerably more from the meanvernal equinox year of 365.242362 days, which means that the new year, intended to fall on the vernal equinox, would drift by half a day over the course of a cycle.[17]
Temporary change of epoch and calendar name in Iran
On 14 March 1975 CE, during thePahlavi era, the Majlis and Senate of Iran, in a joint session, changed theepoch of the calendar to be the supposed first year of the reign ofCyrus the Great[1] (rather than the Hijrah of Muhammad), a change that thus established the "Shahanshahi Calendar".[e] This was done not as a new law, but a joint declaration (قطعنامه). The epoch was carefully chosen so that the ascension ofMohammad Reza Pahlavi to the throne would have happened in the "round" year 2500. Overnight, the year number changed from 1354 to 2534, a difference of 1180 years.
The change lasted until 27 August 1978 CE,[f] at which time the epoch was reverted back to the Hijrah and the original year numbering was reinstated.[1] The reversion was announced on the first day of the government of Prime MinisterJafar Sharif-Emami, and declared that the 1925 law (that introduced the Solar Hijri calendar) was still in effect.
^Persian:گاهشماری هجری شمسی,romanized: Gâhšomâri-ye Hejri-ye Šamsi;Pashto:لمريز لېږدیز کلیز,romanized: lmaríz legdíz kalíz;Kurdish:ڕۆژژمێری کۆچیی ھەتاوی,romanized: Salnameya Koçberiyê; also called in some English sources as theIranian Solar calendar[1]
^If the exact moment of astronomicalMarch equinox occurs before noon (Tehran time), that day is considered the first day of Farvardin. If the equinox occurs after noon, the following day is designated as the first day of Farvardin.[2]
^Since 1 Muharam 1444AH (30 July 2022CE), this calendar is no longer used by the government ofAfghanistan, after its switch to the Lunar Hijri calendar.[9][dubious –discuss]
^Yallop, B.D.; Hohenkerk, C.Y.; Bell, S.A. (2013). "Astronomical Phenomena". In Urban, S.E.; Seidelmann, P. K. (eds.).Explanatory supplement to the astronomical almanac (3rd ed.). Mill Valley, CA: University Science Books. pp. 506–507.ISBN978-1-891389-85-6.