Hijri calendar

Hijri calendar
Name	Hijri calendar
Alt	Islamic calendar
Type	Lunar calendar
Origin	7th century CE
Epoch	Hijra (622 CE)
Months	12
Days	354–355

Hijri calendar is a lunar calendar used to determine the timing of religious observances in Islam and to record dates in many Muslim-majority societies. It traces its epoch to the Hijra, the migration associated with Prophet Muhammad and the early Rashidun Caliphate, and is employed alongside solar systems such as the Gregorian calendar and the Julian calendar. The calendar's cycles inform festivals like Ramadan, Eid al-Fitr, and Eid al-Adha, and intersect with civic institutions from the Ottoman Empire to modern states such as Saudi Arabia and Pakistan.

Overview and definitions

The Hijri system defines years by the synodic lunar month, producing a year of 12 months totaling about 354 or 355 days, in contrast to the 365-day Gregorian calendar year and the 365/366-day Julian calendar. Its epoch is the Hijra in 622 CE, an event centered on Medina and involving figures like Abu Bakr and Umar ibn al-Khattab. Common terminology includes Arabic month names such as Muharram, Safar, Rabi' al-awwal, and Dhu al-Hijjah, terms found in medieval sources from the Abbasid Caliphate, Umayyad Caliphate, and documents preserved in archives of the Mamluk Sultanate.

History and origins

Origins trace to pre-Islamic Arabian lunar reckoning used in trade between cities like Mecca and Yathrib and in regional polities such as the Ghassanids and Lakhmids. The formal selection of the Hijra as epoch was made under the second caliph Umar ibn al-Khattab during administrative reforms connecting to fiscal practices in the Rashidun Caliphate and later bureaucracies of the Umayyad Caliphate and Abbasid Caliphate. Scholars such as Al-Biruni, Ibn al-Shatir, and Al-Battani contributed astronomical and calendrical observations that influenced Islamic timekeeping, while contacts with Byzantine Empire and Sassanian Empire astronomy transmitted methods for intercalation, which Islamic jurists debated in councils influenced by figures like Al-Shafi'i and Al-Ghazali.

Types and variants

Several variants exist: the tabular or calculated form used for administrative purposes, the observational form based on local moon sightings practiced in communities influenced by Sunni Islam and Shia Islam, and national adaptations adopted by states such as Saudi Arabia, Iran, and Turkey. The tabular Islamic calendar was formalized in medieval treatises and used in the Timurid Empire and Mughal Empire for court chronologies. The civil or astronomical Hijri forms—employed in civil affairs in countries like Libya and Mauritania—can differ from religious observance as practiced in cities such as Cairo, Karachi, Istanbul, and Riyadh.

Structure and calculation

A Hijri year comprises 12 lunar months—Muharram, Safar, Rabi' al-awwal, Rabi' al-thani, Jumada al-ula, Jumada al-akhirah, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qadah, and Dhu al-Hijjah—each beginning with the sighting or calculation of the new crescent. Calculations rely on lunar cycles studied by astronomers like Ibn Yunus and techniques stemming from Ptolemy's tradition transmitted via House of Wisdom scholarship in Baghdad. The purely observational method references hadiths associated with Prophet Muhammad and legal rulings from schools such as the Hanafi school, Maliki school, Shafi'i school, and Hanbali school. Astronomical algorithms, used in modern astronomical organizations like the International Astronomical Union and national observatories, compute conjunctions and visibility employing parameters from Kepler and Newtonian mechanics adapted to lunar theory.

Religious and cultural significance

The calendar structures core Islamic rituals: Sawm (Ramadan) fasting, Hajj pilgrimage rites concluding in Dhu al-Hijjah, and observances linked to dates revered by denominations such as Twelver Shia and Ismaili communities. Festivals like Eid al-Fitr and Eid al-Adha anchor communal life in cities such as Baghdad, Cordoba, Delhi, Cairo, and Marrakesh and are celebrated in institutions including mosques like Masjid al-Nabawi and Al-Aqsa Mosque. Scholarship on calendrical law intersects with jurists from the Ottoman ulema to contemporary councils like the Al-Azhar University and national fatwa bodies in countries like Malaysia, Indonesia, and Egypt.

Modern use and civil adoption

Modern states vary in adopting the Hijri calendar for civil or religious purposes: Saudi Arabia uses a lunar Hijri year for official documents and public holidays, while nations such as Jordan, Morocco, Tunisia, and Algeria incorporate Gregorian dating for civic administration, sometimes alongside Hijri dates. Debates over dual dating touched governments from the Ottoman Empire's reformers like Tanzimat figures to 20th-century reformers in Turkey and Iran. Contemporary digital systems, archives like the British Library and Bibliothèque nationale de France, and software by corporations such as Microsoft and Google implement conversion algorithms between lunar and solar calendars, raising issues addressed by international bodies including the United Nations and regional organizations such as the Organisation of Islamic Cooperation.

Category:Calendars