The Islamic calendar started in the year 622 AD. This Algerian stamp of 1979 commemorates the start of the 15th Century of Islamic Calendar. The start of the 15th Hijri century corresponds to the November 20, 1979 AD.
Establishment of the Hijri Calendar
The islamic calendar named (Hijri Calendar) was adopted during the era of the second caliphate of Islam, Omar Ibn Al-Khattab in the year 16 Hijri. The Hijri calendar calculates the years from the year of the Prophet Muhammad’s migration from Mecca to Medina.
The first day of the first month of the first year in the islamic calendar corresponds to the 14th of July 622 AD.
Details of the Hijri Calendar
Islamic Calendar is a lunar calendar. This means that it depends on the movement of the moon. For comparison, the Gregorian Calendar is based on the sun’s revolution.
The observance of a new moon seen for the first time marks the beginning of each month in the Hijri calendar. Like the Gregorian calendar, the islamic calendar has 12 months of 29 or 30 days. As the Hijri year contains approximately 354 days, it has an annual difference of 10 days with the Gregorian calendar.
In most Islamic countries, specialized officials try to observe the new moon of each lunar month. The process of observing begins immediately after sunset of the twenty-ninth day of the lunar month. The observing is limited to a short time, sometimes not exceeding 45 minutes, and then the new crescent disappears. The observation is usually directed to the west, near the sunset location. The proximity of the sun makes it difficult to see the new moon. Because of the proximity to the sun, its light overwhelms the small new moon’s illumination.
In case it is not possible to observe the moon because of the weather condition, the month is completes 30 days.
Catalogue reference: YT 708