Telescope pointing at the sky, searching for the new moon

Understanding the Islamic Lunar Calendar: A Timeless Guide

Posted by Mariya Collins on

The Islamic Lunar Calendar, also known as the Hijri calendar, is a critical component of Islamic religious practice. Unlike the solar-based Gregorian calendar, the Islamic calendar is based on the phases of the moon. The Islamic lunar calendar not only marks the passage of time but also anchors religious observances and traditions for Muslims around the world.

Ancient Islamic Hijri Calendar

Origins and Structure

The Islamic calendar began in 622 CE: the year of the Hijra (emigration) of the Prophet Muhammad (peace be upon him) from Makkah to Madinah. The calendar was devised during the reign of Khalifa Umar ibn al-Khattab as a formalized means of marking time and standardizing important Islamic dates. After consultation with the revered companions, Uthman ibn Affan and Ali bin Abi Talib, it was decided that the Hijra was so pivotal in Islamic history that the Islamic calendar should start from this year; hence, 622 CE was designated as 1 AH (Anno Hegirae or "in the year of the Hijra") in the Islamic calendar.

Path of the Hijra from Mecca to Madina

The Hijri calendar comprises 12 months, each beginning with the sighting of the new moon. The months in the Islamic calendar are:

  1. Muharram
  2. Safar
  3. Rabi' al-Awwal
  4. Rabi' al-Thani
  5. Jumada al-Awwal
  6. Jumada al-Thani
  7. Rajab
  8. Sha'ban
  9. Ramadan
  10. Shawwal
  11. Dhul-Qadah
  12. Dhul-Hijjah
Names and significance of the Islamic months

Each month is either 29 or 30 days long, depending on the moon's cycle. This results in a lunar year that is approximately 354 or 355 days long: about 10 to 12 days shorter than the solar year used in the Gregorian calendar. As a result, the Islamic months rotate through the seasons over a cycle of about 33 years.

Religious Significance

The Hijri calendar plays a crucial role in the religious life of Muslims. Key Islamic events and observances are based on this calendar:

  • Islamic New Year: Muharram, the first month, is observed as the start of the new Islamic year. The tenth day of Muharram, known as the day of Ashura, holds particular significance.
  • Ramadan: The ninth month, Ramadan, is perhaps the most well-known. It is the month of fasting, where Muslims abstain from food and drink from pre-dawn until sunset.

  • Eid al-Fitr: Marking the end of the month of Ramadan, Eid al-Fitr is a joyous celebration commemorating the end of the month of fasting.

  • Dhul-Hijjah: The twelfth month, Dhul-Hijjah, is when the Hajj pilgrimage takes place. This month also includes Eid al-Adha, the Festival of Sacrifice, which takes place on the tenth day of Dhul-Hijjah.

Muslims using a powerful telescope to site the new crescent moon

The Role of the Moon

The moon's phases are integral to the Islamic calendar, making the sighting of the new moon (hilal) crucial for determining the start of each month. Traditionally, this sighting is done with the naked eye, although modern methods, including powerful telescopes and astronomical calculations, are sometimes used to aid or confirm the sighting.

New moon sighting in the Saudi desert

Practical Implications

For Muslims, understanding the Islamic calendar is essential for the proper observance of religious duties. It also requires an awareness of the variability of Islamic dates in the Gregorian calendar. For example, the exact dates of Ramadan or Hajj change each year in the Gregorian calendar.

Muslim communities often rely on announcements from religious authorities or Islamic organizations to confirm the sighting of the moon and the start of significant months.

New crescent moon sighted near a minaret in the night sky


The Islamic Lunar Calendar is more than a tool for marking time; it is a reflection of our faith. Its rhythm and cycles remind us of our connection to the Creator of the Universe. By following the phases of the moon, the Islamic calendar fosters a unique spiritual discipline and an appreciation for the beauty and order of creation.

Phases of the moon, illustrated

As we continue to navigate the complexities of modern life, the Hijri calendar stands as a testament to the timeless Islamic principles and traditions that continue to guide and inspire Muslims around the globe.

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