1. HISTORY AND MOTIVATION

The Islamic Calendar, which is based purely on lunar cycles, was first

introduced in 638 C.E. by the close companion of the Prophet and the second

Caliph, `Umar ibn Al-KHaTTab (592-644 C.E.). He did it in an attempt to

rationalize the various, at times conflicting, dating systems used during

his time. `Umar consulted with his advisors on the starting date of the

new Muslim chronology. It was finally agreed that the most appropriate

reference point for the Islamic calendar was the _Hijrah_. The actual

starting date for the Calendar was chosen (on the basis of purely lunar

years, counting backwards) to be the first day of the first month

(1 MuHarram) of the year of the Hijrah. The Islamic (Hijri) calendar

(with dates that fall within the Muslim Era) is usually abbreviated

A.H. in Western languages from the latinized _Anno Hegirae_. MuHarram 1,

1 A.H. corresponds to July 16, 622 C.E.

The Hijrah, which chronicles the migration of the Prophet Muhammad

(PBUH) from Makkah to Madinah in September 622 C.E., is the central

historical event of early Islam. It led to the foundation of the first

Muslim city-state, a turning point in Islamic and world history.

To Muslims, the Hijri calendar is not just a sentimental system of time

reckoning and dating important religious events (e.g., Siyaam (fasting)

and Hajj (pilgrimage to Makkah)). It has a much deeper religious and

historical significance.

Muhammad Ilyes [Ilyes84] quotes Nadvi who wrote:

``It (the advent of the 15th century) is indeed, a unique

occasion to ponder that the Islamic Era did not start

with the victories of Islamic wars, nor with the birth

or death of the prophet (PBUH), nor with the Revelation

itself. It starts with Hijra, or the sacrifice for the

cause of Truth and for the preservation of the Revelation.

It was a divinely inspired selection. God wanted to teach

man that struggle between Truth and Evil is eternal. The

Islamic year reminds Muslims every year not of the pomp

and glory of Islam but of its sacrifice and prepares them

to do the same.''

From a historical angle, Ilyes quotes Samiullah who writes:

``All the events of Islamic history, especially those which

took place during the life of the Holy Prophet and afterwards

are quoted in the Hijra calendar era. But our calculations

in the Gregorian calendar keep us away from those events and

happenings, which are pregnant of admonitory lessons and guiding

instructions.

...And this chronological study is possible only by adopting the

Hijri calendar to indicate the year and the lunar month in line

with our cherished traditions.''

2. SPECIFICATION AND METHOD

The Islamic (Hijri) year consists of twelve (purely lunar) months.

They are: (1) MuHarram; (2) Safar; (3) Raby` al-awal; (4) Raby` al-THaany;

(5) Jumaada al-awal; (6) Jumaada al-THaany; (7) Rajab; (8) SHa`baan;

(9) RamaDHaan; (10) SHawwal; (11) Thw al-Qi`dah; and (12) Thw al-Hijjah.

The most important dates in the Islamic (Hijri) year are:

1 MuHarram (Islamic new year); 27 Rajab (Isra & Miraj); 1 RamaDHaan

(first day of fasting); 17 RamaDHan (Nuzul Al-Qur'an); Last 10

days of RamaDHaan which include Laylatu al-Qadar; 1 SHawwal

(`iyd al-FiTr); 8-10 Thw al-Hijjah (the Hajj to Makkah); and

10 Thw al-Hijjah (`iyd al-'aDHHae).

It is considered a divine command to use a (Hijra) calendar with 12 (purely)

lunar months without intercalation [Ilyes84], as evident from the following

verses of the Holy Qur`an (Trans: A. Yusuf Ali):

They ask thee

the New Moons

Say: They are but signs

To mark fixed periods of time

In (the affairs of) men

And for Pilgrimage. (II:189)

The number of months

In the sight of Allah

Is twelve (in a year)

So ordained by Him

The day He created

The heavens and the earth;

Of them four are scared;

That is the straight usage

So wrong not yourselves

Therein, and fight the Pagans. (IX: 36)

Verily the transposing

(Of a prohibited month)

Is an addition to Unbelief:

The Unbelievers are led

To wrong thereby: for they make

it lawful one year,

And forbidden another year,

Of months forbidden by Allah

And make such forbidden ones

Lawful. The evil of their course

Seems pleasing to them.

But Allah guideth not

Those who reject Faith. (IX: 37)

Since the Islamic calendar is purely lunar, as apposed to solar or luni-solar,

the Muslim (Hijri) year is shorter than the Gregorian year by about 11 days,

and months in the Islamic (Hijri) year are not related to seasons, which

are fundamentally related to the solar cycle. This means that important

Muslim festivals, which always fall in the same Hijri month, may occur

in different seasons. For example, the Hajj and RamDHaan can take place in

the summer as well as the winter. It is only over a 33 year cycle that lunar

months take a complete turn and fall during the same season.

For religious reasons, the beginning of a Hijri month is marked not by

the start of a new moon, but by a physical (i.e., an actual human) sighting

of the crescent moon at a given locale. From the Fiqhi standpoint, one may

begin the fast in RamDHaan, for example, based on "local" sighting (IKHTILAF

AL-MATALE') or based on sighting anywhere in the Muslim World (ITTEHAD

AL-MATALE'). Although different, both of these positions are valid Fiqhi

positions.

Astronomically, some data are definitive and conclusive (i.e. the time of the

BIRTH of a new moon). However, determining the VISIBILITY of the crescent

is not as definitive or conclusive; rather it is dependent upon several

factors, mostly optical in nature. This makes it difficult to produce

(in advance) Islamic calendars that are reliable (in the sense that they

are consistent with actual crescent visibility).

Efforts for obtaining an astronomical criterion for predicting the time of

first lunar visibility go back the the Babylonian era, with significant

improvements and work done later by Muslim and other scientists. These

efforts have resulted in the development in a number of criteria for

predicting first possible sighting of a crescent. However, there remains

a measure of uncertainty associated with all criteria developed thus far.

Moreover, there has been little work in the area of estimating crescent

visibility on global (as apposed to local) scale. Until this happens, no

Hijri calendar software can be 100% reliable, and actual crescent sighting

remains essential especially for fixing important dates such as the beginning

of RamaDHaan and the two `iyds.

The slight differences in printed Islamic calendars, worldwide, can therefore

be traced to two primary factors: (1) the absence of a global criterion for

first visibility; and (2) the use of different visibility criterion (or

method of calculation). Weather conditions and differences in the observer's

location also explain why there are sometimes differences in the

observances of Islamic dates, worldwide.

Readers interested in further information should consult Mohammad

Ilyas' excellent book ``A Modern Guide to Astronomical Calculations of Islamic

Calendar, Times & Qibla,'' Berita Publishing, 1984, (ISBN: 967-969-009-1).

The book contains a thorough discussion of the Islamic calendrical system

and related historical and scientific developments. It also presents a sound

proposal for a universal Islamic Calendar based on a global visibility

criterion and the concept of a Lunar Day (or International Lunar Date Line).

Waleed Muhanna

Tuesday 13 Jumaada al-THaany 1413 A.H.

December 8, 1992