Solar Hijri Calendar
The solar hijri calendar is based on the number of full rotations of the earth around the sun (around 365 days) since the migration of the Prophet Muhammad from Mecca to Medina (aka. Hijra). It is most commonly used in Iran and Afghanistan.
This calendar became the official calendar of Iran in the year 1304 AH/1925 CE, when the Parliament passed a law to replace it for the lunar hijri calendar in all of the public offices and organizations.
It is believed that 'Abd al-Ghaffār Khān Najm al-Dawlah first made the solar hijri calendar. He mentioned the phrase "1246 shamsī" (i.e. 1246 solar hijri year) in the margins of the calendar of the year 807 Jalālī/ 1302-3 AH. He thus calculated a solar calendar from the migration of the Prophet Muhammad from Mecca to Medina. His version of the calendar was known as "Zodiac, solar, hijri calendar".
The Origin of the Year
The solar hijri year starts on the first of Farvardin of the solar year in which the Prophet Muhammad migrated from Mecca to Medina. The day falls on 19 March 622 CE, which was 119 days before Muharram (the first month) of the lunar hijri year.
Every year starts when the sun passes the point of the vernal equinox, that is when the sun enters the northern hemisphere from the southern hemisphere. This moment which is known as the beginning of Aries, is called Nowruz, the first day of the spring.
The Duration of the Year
The solar hijri year is an actual solar year. That is, it lasts from one transition of the center of the sun from the point of the vernal equinox to another transition. The avarge duration is 365 days and 5 hours and 48 minutes 45.2 seconds. But the duration of the actual solar year is not the same all the time, and it may change according to the changes in some astronomical parameters.
In a period of 50 years (1335-1385 SH/ 1956-2007 CE), the duration of the actual solar year changes from 365 days and 5 hours and 42 minutes to 365 days and 6 hours and 4 minutes. It should be recalled that this is different from the duration of the astronomical year, in which the earth revolves around the sun and lasts for 365.2564 days, i.e. 365 days and 6 hours and 9 minutes and 10 seconds.
This calendar is made of twelve actual months, called burj, as they are called after the twelve zodiac constellations. There is a classical division of the celestial sphere from around twenty centuries ago, so that there are twelve zodiac months, according to the twelve zodiac constellations. These months are usually different from the zones in which the sun stays. Besides, because of the rotation of the earth, its axis changes once in 25,800 years. During this period all of the months pass once from the respective zodiac constellation.(This is why the actual and astronomical years are different).
Furthermore, because of the changing apparent movement of the center of the sun in the sky, the duration of every burj changes from 29 to 32 days. Therefore, the length of every solar month could change from one year to another. Once in every four or five years, the year lasts for 366 days. These years are called leap years.
i==Solar Hijri Year as the Official Calendar in Iran== The hijri solar calendar was not official in Iran, and was only used in customs and finances. It only started to be used in the year 1328 lunar AH/1288 SH, when the Member of the Parliament Mirza 'Abd al-Husayn Khan Shaybani Wahid al-Mulk proposed a law on dating the public transactions according to solar hijri year, rather than the lunar hijri year. The Iranian Parliament passed this law on 21 Safar 1329 lunar AH/ 2 Pisces 1289 SH as the third article of the Law of Public Finances.
There is also a story to the effect that the solar hijri calendar (also known as the jalālī calendar) was invented by 'Umar b. Khayyām al-Nīshābūrī. Upon a request from King Malekshāh the Seljuk, Khayyām made the Malekshāhī Observatory and reformed the calendar. The Jalālī Calendar, which was popular among Iranians, is so valid that it has hardly been criticized. It has also been said that it is more accurate than the Gregorian Calendar. Malekshāh established the Jalālī Calendar in Iran. The lunar year is 10 days and 6 hours and 11 seconds shorter than the solar year. With the arrangement of the Jalālī Calendar, it was decided that every four years, one day should be added to the days of the year so that this year lasts for 366 days.
Final Establishment of the Solar Hijri Calendar
Towards the end of the year 1303 solar AH, a group of representatives in the fifth period of the Iranian Parliament, proposed a law to change the Arabic names of the months (after the zodiac signs) to Persian names. After many debates, finally in the 148th meeting of the Parliament on 11 Farvardin 1304 SH, it was decided that Persian names be used for months from the year 1304 AH. From this point the solar hijri calendar was established as the official Iranian calendar. The law runs as follows:
"The law of changing the Arabic burj to Persian months from the Nowruz of 1304 AH -- passed on 11 Farvardin 1304 SH
"Article one -- National Parliament passes the law to establish the Iranian claendar from Noruz 1304 SH, as follows. (The government if obliged to execute this law in all governmental offices.)
a) The origin of the calendar: the Prophet’s migration from Mecca to Medina
b) The beginning of the year: the first day of the spring
c) The duration of the year: actual solar year
d) The names and durations of the months:
- Farvardīn 31 days
- Ordībehesht 31 days
- Khordād 31 days
- Tīr 31 days
- Amordād 31 days
- Shahrīvar 31 days
- Mehr 30 days
- Ābān 30 days
- Āzar 30 days
- Dey 30 days
- Bahman 30 days
- Esfand 29 days
"Provision: In leap years, Esfand lasts for 30 days.
"The calendar calculations according to Khatā and Uyghur, common in previous calendars, will be abrogated with this law. This law was passed on 11 Farvardin 1304 SH in the Iranian Parliament. Signed by the Head of the Parliament, Mu’tamin ul-Mulk"
The Royal Calendar
In the year 1354 SH/ 1975 CE, the Parliament and the Senate held a communal meeting to change the origin of the calendar from the migration of the Prophet to the begining of the Persian monarchy. The goverment was obliged to use the royal calendar instead of the hijri calendar. The coronation of Cyrus the Great in the year 599 BCE became the origin of the solar year, as well as the beginning of Iranian social and political history. Therefore, 1 Farvardīn 1355 SH was announced as the beginning of the 2535th royal year.
In Shahrīvar 1357 SH/ ca. September 1978 CE, the royal calendar was abolished and replaced by the solar hijri calendar.
- The content of this article is mainly taken from تقویم هجری خورشیدی in Farsi WikiShia.