Islamic calendar

Islamic calendar
Name	Islamic calendar
Other names	Hijri calendar, Arabic calendar
Type	Lunar calendar
Origin	7th century CE
Epoch	Hijra (622 CE)
Months	12
Days year	354–355
Region	Widely used across Middle East, North Africa, South Asia, Southeast Asia

Islamic calendar The Islamic calendar is a purely lunar timekeeping system originating in the 7th century CE tied to the Hijra of Muhammad from Mecca to Medina in 622 CE. It underpins observance of major Islamic rites associated with Ramadan, Hajj, Eid al-Fitr, and Eid al-Adha, and it has been adapted by states and communities such as the Ottoman Empire, Safavid dynasty, Mughal Empire, Al-Andalus, and modern nation-states including Saudi Arabia, Indonesia, and Pakistan.

History

Early Muslim communities in Medina used multiple calendrical references including regnal years of the Byzantine Empire and the Sassanian Empire; disputes at a council under the second caliph, Umar ibn al-Khattab, led to adoption of the Hijra epoch. Islamic chronography was shaped by scholars in Basra, Kufa, and later in Baghdad under the Abbasid Caliphate, where astronomers associated with the House of Wisdom such as Al-Khwarizmi and Al-Battani refined calendrical observation. Transmission to Al-Andalus and North Africa involved figures linked to the Umayyad Caliphate of Córdoba, while Ottoman reformers in the 19th century confronted the calendar alongside the Tanzimat reforms and interactions with the French Republic and British Empire. Colonial encounters with the Dutch East Indies and the British Raj influenced how calendrical practice persisted in Java, Sumatra, and the Indian subcontinent.

Structure and rules

The calendar consists of 12 lunar months based on the synodic month as observed in locales such as Mecca, Cairo, Baghdad, Istanbul, and Jakarta. A common year has 354 days and a leap year has 355 days following intercalation rules standardized in medieval jurisprudence by scholars from schools like the Hanafi madhhab, Shafi'i madhhab, Maliki madhhab, and Hanbali madhhab. The epoch is the Hijra in 622 CE, which aligns with the reigns of Byzantine Emperor Heraclius and the final phase of the Sassanid Empire. Month beginnings may be declared by sighting the crescent in observatories associated with institutions such as the Royal Astronomical Society-style bodies in Cairo or national ministries like the Saudi General Authority of Astronomy and Geophysics. Coding systems in modern civil administrations interface the calendar with Gregorian-based bureaucracies like those of the United Nations and European Union.

Months and important dates

The 12 months—including Muharram, Safar, Rabi' al-awwal, Rabi' al-thani, Jumada al-ula, Jumada al-akhirah, Rajab, Sha'ban, Ramadan, Shawwal, Dhu al-Qi'dah, and Dhu al-Hijjah—govern festivals and legal deadlines observed by communities in Karachi, Cairo, Istanbul, Riyadh, and Kuala Lumpur. Key dates like the start of Ramadan and the day of Arafa preceding Eid al-Adha trace back to practices in Medina and rituals described in the Hadith collections attributed to narrators such as Bukhari and Muslim. Commemorative days such as the Islamic New Year and the day of Ashura in Muharram carry historical associations with events like battles involving the Umayyad Caliphate and figures connected to the Battle of Karbala.

Variants and regional use

Several variants exist: the civil lunar calendar used by the Kingdom of Saudi Arabia contrasts with the astronomical tabular system employed historically in the Ottoman Empire and in Ottoman successor states such as Turkey until Mustafa Kemal Atatürk's reforms. The tabular Islamic calendar built on a 30-year cycle influenced practice in Iran and among Ismaili communities, while Sunni communities often emphasize local crescent sighting in places like Makkah, Medina, Cairo, and Damascus. In Indonesia and among the Malays, state religious authorities such as the Ministery of Religious Affairs (Indonesia) coordinate announcements with regional observatories and consultative bodies linked to the Organization of Islamic Cooperation and local ulama councils.

Conversion and calculation methods

Conversion between the Islamic and Gregorian calendar uses arithmetic algorithms such as the tabular 30-year cycle, the Kuwaiti algorithm, and astronomical calculations employed by observatories like those in Greenwich and Cairo. Algorithms developed in medieval houses of learning and improved by mathematicians such as Al-Biruni and Ibn al-Shatir underpin modern calculations. Software libraries used by institutions in London, New York, Jakarta, and Riyadh implement these methods, while judicial bodies in countries like Saudi Arabia, Pakistan, and Egypt may prefer local visual sighting protocols consistent with rulings from legal councils and jurists.

Cultural and religious significance

The calendar structures worship, fasting, pilgrimage, charity, and communal memory across locales from Fez and Cairo to Delhi and Aceh. It frames Islamic liturgy practiced in mosques associated with institutions such as Al-Azhar University, Al-Masjid an-Nabawi, and Masjid al-Haram, and informs holiday planning in national contexts like Egypt, Jordan, Malaysia, and Morocco. Debates over astronomical calculation versus visible crescent sighting involve religious authorities including grand muftis, jurists from the Dar al-Ifta apparatus, and international organizations such as the International Astronomical Union where astronomers collaborate with scholars of Islamic jurisprudence.

Category:Calendars