Introduction to World Religions by Felix Just, S.J., Ph.D.
Islamic Calendar and Feasts
The Islamic Lunar Calendar:
The Islamic calendar is strictly lunar, in contrast to the Gregorian/Western calendar (which is mainly solar), or the Hebrew calendar (a luni-solar hybrid).
The Islamic year consists of 12 months, each of which can have either 29 or 30 days, with a total of either 354 or 355 days per year:
According to long-standing Islamic tradition, each month begins on the day when the first sliver of the new moon is first observed (looking West, just after sunset); thus, the full moon is always on the 14th or 15th day of each month.
In contrast, the Gregorian/Western "months" are not tied to the moon's phases; a new moon or full moon might fall on any day of the "month."
An issue hotly debated among Muslims today is whether the new moon must literally be observed with the naked eye, or whether one can use astronomical calculations to determine the beginning of each month, and thus the entire calendar, far in advance:
Most Muslims believe that the traditional methods should be maintained, that the crescent moon must literally be observed for a new month to begin after 29 days (or else a 30th day is added to the old month), because that is what the Qur'an commands and/or ancient Muslim traditions have always done.
Other Muslims propose that it would not be against Islamic beliefs to calculate the beginning of each new month in advance mathematically/astronomically.
Since the moon requires about 29½ days to orbit the earth, each month on the Islamic calendar could be either 29 or 30 days long.
In contrast, the length of each month on the Gregorian/Western calendar is fixed: April, June, Sept, and Nov always have 30 days; Jan, March, May, July, Aug, Oct, and Dec always have 31 days; only February varies, having 28 days most years, but 29 days in leap years.
Since 12 lunar rotations require exactly 354 and 11/30 days, each Islamic year (12 months) has a total of either 354 or 355 days;
In contrast, the Gregorian/Western year normally has 365 days, but is lengthened to 366 days in leap years (every fourth year, with a few exceptions).
With either 354 or 355 days, each Islamic calendar year is 10 or 11 days shorter than the 365¼-day solar year of the Gregorian/Western calendar;
thus, every 32 years on the Gregorian/Western calendar corresponds to 33 years on the Islamic calendar.
Unlike the Hebrew "luni-solar" calendar, the Islamic lunar calendar does not add a "leap month" every few years to keep the lunar and solar calendars in sync.
As a consequence, the four seasons rotate through the various months of the Islamic year; each month eventually occurs in all four seasons within a cycle of 32 Western or 33 Islamic years; in other words; the Islamic "New Year" may be in October one year, but in July eight years later, in April eight years after that, already in January in another eight years, but occurs again in October either years later, at the end of the full 32/33 cycle.
Year and Dates on the Islamic Calendar:
Year One on the Islamic calendar was fixed as the year of the Hijrah, when Mohammad and his followers moved from Makka to Madinah, in 622 AD.
More precisely, the first day of the first month of the Islamic year one corresponds to July 26, 622, the very day they left Makka.
Due to the strictly lunar nature of the Islamic calendar (as explained in the first section above), all fixed dates on this calendar occur 10 or 11 days earlier in subsequent years on the Western calendar. For example, the following table shows how the first day of Ramadan has shifted in recent years:
Islamic dates are often indicated with AH, an abbreviation for the Latin anno hegirae ("Year of the Hegira").
This is similar to how Gregorian/Western years are traditionally designated AD, which comes from the Latin anno Domini ("Year of the Lord").
To roughly convert an Islamic year (AH) to the equivalent Gregorian year (AD), or vice versa, one can use the following formulas:
AD = 622 + (32/33 x AH)
AH = 33/32 x (AD – 622)
The Twelve Islamic Months:
Ramadan, the ninth month, is considered the most important or holiest month, a time of fasting (see the "Pillars of Islamic Practice").
The Hajj, the annual pilgrimage to Makka, takes place from the 8th to 10th days of the twelfth month, Dhu al-Hijjah.
The Arabic names of the twelve months of the Islamic calendar:
3) Rabi' al-awwal
4) Rabi' al-thani
5) Jumada al-awwal
6) Jumada al-thani
11) Dhu al-Qi'dah
12) Dhu al-Hijjah
Islamic Feasts and Commemorations:
Some Muslims believe that they should celebrate only two festivals annually:
Eid al-Fitr and
The strictest Muslims do not even celebrate their own birthdays, or the anniversaries of any other events.
Other Muslims (esp. Shi'ites) add several more feasts and commemorations, as detailed below.
Eid al-Fitr, the "Feast of Breaking the Fast" (1st of Shawwal)
It is celebrated immediately after the end of the annual month of fasting (Ramadan, the ninth month); thus it falls on the first day of the tenth month.
Festivities include special meals and the exchange of gifts among family and friends.
Eid al-Adha, the "Feast of the Sacrifice" (10th of Dhu al-Hijjah)
It commemorates the sacrifice of Abraham, when he nearly sacrificed his son (Ishmael in Islamic tradition, in contrast to Isaac in the Hebrew Bible), but killed a ram instead.
It is celebrated at the end of the Hajj, the annual pilgrimage to Makka; Muslims who are attending the Hajj perform certain rituals on this day.
Muslims throughout the rest of the world also celebrate with special meals and exchanging gifts among family and friends.
Other Feasts and Holidays - celebrated or commemorated by some Muslims (esp. Shi'ites), but not all:
Islamic New Year (1st day of Muharram)
Day of Ashura (10th day of Muharram) - Muslim "Day of Atonement"; for Sunnis, a voluntary fast; for Shi'is, the most important holy day, commemorating the martyrdom of Imam Husayn ibn Ali (Hussein, son of Ali, grandson of the prophet Muhammad).
Mawlid or Milad al-nabi (12th day of Rabi' al-awwal, the third month) - commemorates the "Birthday of the Prophet" Muhammad.
Laylat al-mi'raj (27th night of Rajab, the seventh month) - commemorates the miraculous "Night Journey" of the Prophet from Makka to Jerusalem, and his ascension into heaven (see Qur'an 17.1).
Laylat al-bara'a (14th night of Sha'ban, the eighth month) - Muslim "Day of the Dead" in South and SE Asia; also the eve of the birthday of the Twelfth Imam of the Twelver Shi'is.
Laylat al-qadr, the "Night of Power" (between the 26th and 27th of Ramadan) - commemorates the night in which Muslims believe the Qur'an was first revealed to Muhammad.