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The Muslim Lunar Calendar - Overview

There are often many questions and queries regarding the differences between the gregorian calendar (solar) and the muslim calendar (lunar). Aspects of the lunar calendar are explained below.

 
The Islamic calendar or Muslim calendar (also called the Hijri calendar) is the calendar used to date events in many predominantly Muslim countries, and used by Muslims everywhere to determine the proper day on which to celebrate Islamic holy days. It is a lunar calendar having 12 lunar months in a year of about 354 days. Because this lunar year is about 11 days shorter than the solar year, Islamic holy days, although celebrated on fixed dates in their own calendar, usually shift 11 days earlier each successive solar year, such as a year of the Gregorian calendar. Islamic years are also called Hijra years because the first year was the year during which the Hijra occurred— prophet Muhammad's emigration from Mecca to Medinah. Thus each numbered year is designated either H or AH, the latter being the initials of the Latin anno Hegirae (in the year of the Hijra).

The current Islamic Year is 1427.

Pre-Islamic Calendar
The predecessor to the Islamic calendar was a lunisolar calendar which used lunar months, but was also synchronized with the seasons by the insertion of an additional, intercalary month, when required. Whether the intercalary month (nasi) was added in the spring like that of the Hebrew calendar or in autumn is debated. It is assumed that the intercalary month was added between the twelfth month (the month of the pre-Islamic Hajj) and the first month (Muharram) of this pre-Islamic year. The two Rabi' months denote grazing and the modern Meccan rainy season (only slightly less arid than normal), which would promote the growth of grasses for grazing, occurs during autumn. These imply a pre-Islamic year beginning near the autumnal equinox. However, the rainy season after which these months are named may have been different when the names originated (before prophet Muhammad's time) or the calendar may have been imported from another region which did have such a rainy season. On the other hand, prophet Muhammad forbade the intercalary month (released the calendar from the seasons) near the end of his life (as recorded in Sura 9, verse 36), which implies a pre-Islamic year beginning near the vernal equinox because that is when the modern lunar year began during his last year.

Numbering The Years
According to Islamic tradition, Abraha, governor of Yemen, then a province of the Christian Kingdom of Aksum (Ethiopia), attempted to destroy the Kaaba with an army which included several elephants. Although the raid was unsuccessful, because it was customary to name a year after a major event which occurred during it, that year became known as the Year of the Elephant, which was also the year that prophet Muhammad was born. (See surat al-Fil.) Although most Muslims equate it with the Western year 570, a minority equate it with 571. Later years were numbered from the Year of the Elephant, whether for the years of the pre-Islamic lunisolar calendar, the lunisolar calendar used by prophet Muhammad before he forbade the intercalary month, or the first few years of the lunar calendar thus created. In 638 (AH 17), the second Caliph Umar began numbering the years of the Islamic calendar from the year of the Hijra, which was postdated AH 1. The first day of the first month (1 Muharram) of that proleptic Islamic year, that is, after the removal of all intercalary months between the Hijra and prophet Muhammad's prohibition of them nine years later, corresponded to July 16, 622 (the actual emigration took place in September). The first surviving attested use of the Hijri calendar is on a papyrus from Egypt in 22 AH, PERF 558.

Months
Each month has either 29 or 30 days, but usually in no discernible order. Traditionally, the first day of each month was the day (beginning at sunset) of the first sighting of the lunar crescent (the hilal) shortly after sunset. If the hilal was not observed immediately after the 29th day of a month, either because clouds blocked its view or because the western sky was still too bright when the moon set, then the day that began at that sunset was the 30th. Such a sighting had to be made by one or more trustworthy men testifying before a committee of Muslim leaders. Determining the most likely day that the hilal could be observed was a motivation for Muslim interest in astronomy, which put Islam in the forefront of that science for many centuries. This traditional practice is still followed in a few parts of the world, like Pakistan and Jordan. However, in most Muslim countries astronomical rules are followed which allow the calendar to be determined in advance, which is not the case using the traditional method. Malaysia, Indonesia, and a few others begin each month at sunset on the first day that the moon sets after the sun (moonset after sunset). In Egypt, the month begins at sunset on the first day that the moon sets at least five minutes after the sun.

The official Umm al-Qura calendar of Saudi Arabia used a substantially different astronomical method until recent years. Before AH 1420 (before April 18, 1999), if the moon's age at sunset in Riyad was at least 12 hours, then the day ending at that sunset was the first day of the month. This often caused the Saudis to celebrate holy days one or even two days before other predominantly Muslim countries, including the dates for the Hajj, which can only be dated using Saudi dates because it is performed in Mecca. During one memorable year during the AH 1380s (the 1970s), different Muslim countries ended the fast of Ramadan on each of four successive days. The celebrations became more uniform beginning in AH 1420. For AH 1420-22, if moonset occurred after sunset at Mecca, then the day beginning at that sunset was the first day of a Saudi month, essentially the same rule used by Malaysia, Indonesia, and others (except for the location from which the hilal was observed). Since the beginning of AH 1423 (March 16, 2002), the rule has been clarified a little by requiring the geocentric conjunction of the sun and moon to occur before sunset, in addition to requiring moonset to occur after sunset at Mecca. This ensures that the moon has moved past the sun by sunset, even though the sky may still be too bright immediately before moonset to actually see the crescent. Strictly speaking, the Umm al-Qura calendar is intended for civil purposes only. Their makers are well aware of the fact that the first visual sighting of the lunar crescent (hilal) can occur up to two days after the date calculated in the Umm al-Qura calendar. Since AH 1419 (1998/99) several official hilal sighting committees have been set up by the government of Saudi Arabia to determine the first visual sighting of the lunar crescent at the begin of each lunar month. Nevertheless, the religious authorities of Saudi Arabia also allow the testimony of less experienced observers and thus often announces the sighting of the lunar crescent on a date when none of the official committees could see the lunar crescent. In nearly all of these cases, a retrospective analysis indicates that these extremely early reports of the lunar crescent are impossible and are based on false sightings.

The moon sets progressively later than the sun for locations further west, thus western Muslim countries are more likely to celebrate some holy day one day earlier than eastern Muslim countries.

There exists a variation of the Islamic calendar known as the tabular Islamic calendar in which months are worked out by arithmetic rules rather than by observation or astronomical calculation. It has a 30-year cycle with 11 leap years of 355 days and 19 years of 354 days. In the long term, it is accurate to one day in about 2500 years. It also deviates up to about 1 or 2 days in the short term.

Forbidding Intercalary Months
In the ninth year after the Hijra, Allah revealed the prohibition of the intercalary month. This is expressed in the Qur'an (9:36-37):

• The number of months with Allah has been twelve months by Allah's ordinance since the day He created the heavens and the earth. Of these four are known as sacred; That is the straight usage, so do not wrong yourselves therein, and fight those who go astray.

This prohibition was repeated by prophet Muhammad during his last sermon on Mount Arafat which was delivered during his farewell pilgrimage to Mecca on 9 Dhu al-Hijja AH 10. The three successive holy months mentioned by prophet Muhammad are Dhu al-Qada, Dhu al-Hijja, and Muharram, thus excluding an intercalary month before Muharram. The single holy month is Rajab.

Islamic dates are determined by the actual visibility of the moon as the Prophet (SAW) said:  “Fast by seeing it (the moon) and end the fast by seeing it”.  Muslim scholars have interpreted this Prophetic saying in two different ways.  Some scholars have held the view that each location has its  own sighting of the moon (Ikhtilaf al-Mutali‘).  But most scholars have taken the words “fast by seeing it” (sumu li ru’yatihi) as a general command to all Muslims and not individual sectors of the community.  Hence they regard the sighting of the moon in one region as valid for people of another region, provided the news of sighting the moon reaches them through authentic means. 

Names of The Islamic Months

• Muharram
• Safar
• Rabi' al-awwal
• Rabi' al-thani
• Jumada al-awwal
• Jumada al-thani
• Rajab
• Sha'aban
• Ramadhan
• Shawwal
• Dhu al-Qi'dah
• Dhu al-Hijjah 

Names of the Days of the Week
The Islamic week is derived from the Jewish week, as was the medieval Christian week, all of which have numbered weekdays in common. All three coincide with the Saturday through Friday planetary week. The Islamic and Jewish weekdays begin at sunset, whereas the medieval Christian and planetary weekdays begin at the following midnight. Muslims gather for worship at a Masjid at noon on "gathering day", which corresponds to the sixth day of the Jewish and medieval Christian weeks, and to Friday of the planetary week.

Important Dates
Important dates in the Islamic (Hijri) year are:

• 1 Muharram (Islamic New Year)
• 10 Muharram (Day of Ashurah, commemorates the anniversary of the martyrdom of Imam Husayn ibn Ali)
• 12 Rabiul Awal (Milad un Nabi)
• 27 Rajab (Isra and Miraj)
• 15 Shabaan (Shab-e-Br'aat)
• 1 Ramadan (first day of fasting)
• 27 Ramadan (Nuzul Al-Qur'an) (17 Ramadan in Malaysia)
• Last 10 days of Ramadhan which may include Laylat al-Qadr
• 1 Shawwal (Eid ul-Fitr)
• 8-10 Dhu al-Hijjah (the Hajj to Makkah)
• 10 Dhu al-Hijjah (Eid ul-Adha).

Current Correlations
For a very rough conversion, multiply the Islamic year number by 0.97, and then add 622 to get the Gregorian year number. The Islamic and Gregorian years will have the same number in 20840. The Islamic calendar year of 1429 will occur entirely within the Gregorian calendar year of 2008. Such years occur once every 33 or 34 Islamic years (32 or 33 Gregorian years).

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