The Lunar Calendar
The moon is the earth's dark satellite, visible only by reflecting the light
of the sun. The visible area of the moon changes daily according to the angle
formed by line between the sun, the earth and the moon, which results in the
cycle of lunar phases.
The Islamic calendar is based on this natural phenomenon, which is used to
determine the beginning of each lunar month in compliance with the Qur'an (Surat
Al-Baqarah 2:189), ''They ask thee about the new moons. Say, 'they are but
signs to mark fixed points of time for people [to manage their affairs], and
[to identify the time of] hajj.''' Of particular concern to Muslims are the
beginnings of the fasting month of Ramadan and the month of hajj, the
pilgrimage season. The first day of the lunar month is identified by the
sighting of the waxing crescent, after sunset on the twenty-ninth or the
thirtieth day of the foregoing month.
Everywhere in the Muslim world, sighting the waxing crescent is important. In
addition to setting the calendar, it also determines the dates of important
religious occasions. But sighting the crescent has always been a controversial
issue in the Islamic world. In some places, it can be spotted easily whereas
in others it may not be. There have been incidents of inaccurate sighting
reports. Such incongruities call for more efforts on the part of Muslim
astronomers to put an end to differences in this regard.
The moon, like the planets, has a slightly elliptical orbit. To determine its
apparent position, particularly as a waxing crescent, several measurements
have to be made including its distance from the sun, its position in relation
to a specific observer on earth, and the exact time of its rising and setting.
Detailed tabular calculations of the motion of the moon were produced in the
nineteenth century by the British-born American mathematician and astronomer,
Ernest William Brown. These tables were later improved by twentieth century
astronomers who developed equations to determine the exact position of the
Muslim astronomers, proceeding from Kepler's laws, have developed computer
software to identify the position of the earth in its orbital movement round
the sun. The point is to determine accurately the time of sunset and,
consequently, the exact position of the crescent using the equations derived
from Brown's lunar tables.
Muslim astronomers known for their work on calculating the lunar months
include, most notably, Al-Battani (850-929), Al-Bayrouni (973-1048) and Nassir
al-Din Al-Tousi (1258-1274). In the nineteenth century, an Egyptian army
general, Mohamed Mokhtar Pasha (1846-1897), produced a valuable work on
tabular correlations of the Muslim calendar, the Gregorian calendar and the
ancient Middle Eastern luni-solar system of time reckoning.
The tables cover the Muslim calendar from years 1 through 1500 and the
matching dates under the other two systems. According to Islamic Shari'a, to
establish the beginning of the new lunar month, the crescent must be sighted
by the naked eye under specific conditions. The sighting may, however, be
influenced by a number of factors including:
the life-length of the crescent, and the angle it forms with the sun;
the height of the crescent relative to the horizon line at the time of sunset;
the distance between the earth and the moon;
weather conditions and the degree of visibility.
The first two factors are essential. The third is partially important, since
the distance between the earth and the moon changes by approximately ± 4%,
which has a negligible effect on visibility. The fourth factor depends on
variable local conditions at the time of sighting the crescent.
The following two conditions for sighting the crescent were set by the Fiqh
(Muslim jurisprudence) committee of the Islamic Conference held in Istanbul in
The angle of the crescent's position above the horizon at sunset must be at
least 5 arc degrees;
The angle formed by the moon and the sun must be at least 8 arc degrees.
When these two most essential conditions are fulfilled, the following day
shall be the first day of the new month.
The motion of the moon can now be calculated with great precision, but the
beginning of every new lunar month remains a problem. Surveys will have to be
conducted in various places in the Islamic world for several years to allow
for sufficient statistical analysis. If this is done, differences between
Muslim countries in marking religious occasions may be finally overcome.
Whenever faced with two or more options, Prophet Muhammad (SAW) always chose
the one that was most accessible to his faithful followers. The Qur'an (Surat
At-Tawbah 9:128) describes him as being extremely commiserating and willing to
spare the Muslims suffering and hardship. The Qur'an (Surat Al-Baqarah 2:185)
also tells us that God intends every facility for the faithful, and does not
will that they be put to unaffordable tasks in life. Islamic Shari'a was
therefore satisfied with what was within the means of the Prophet's
companions. This, however, does not mean that recently developed scientific
methods are to be excluded. This seemingly contradiction of views calls for a
Early Muslim scholars were almost unanimous on rejecting astronomical methods
during their time because, to them, there was no clear line of demarcation
between astronomy and astrology. However, modern astronomy is different. It
draws on spherical geometry and celestial mechanics, two modern branches of
science that enabled man to land on the moon over a quarter of a century ago.
According to Dr. Mostafa Al-Zarqa, a leading Muslim scholar, the debate on the
legitimacy of astronomical calculation is the greatest oddity in modern
jurisprudence, remaining hot at a time when man has navigated the vast
expanses of the universe, and landed on the moon. At the present time, landing
on the moon is no longer considered a great feat.
All relevant Hadith suggest that sighting the moon with the naked eye was the
only method available back then because the majority of the Muslim population
was illiterate. This by no means excluded verifiable scientific methods that
are capable of yielding extremely accurate results. The naked-eye method is
perfectly acceptable when conditions of clear visibility are available.
Otherwise, there is no reason why scientific calculations should not be relied
upon. It is a shame that there is sometimes a three-day discrepancy between
Muslim countries in deciding the beginning and the end of Ramadan.
The position of early Muslim jurisprudents to reject guessing and intuition as
sources of reliable knowledge on this particular issue is understandable.
Astronomy was far from developed at that early stage of Islam, Al-Zarqa
The Fatwa (Muslim religious opinion) House in Egypt decided decades ago that
the naked-eye sighting method is the standard method of establishing the
beginning and the end of lunar months. Astronomical measurements, the House
says, may be used only as a supportive tool, not as an alternative. But
sighting reports that contradict accurate measurements must be rejected
because Islam exhorts its followers to resort to the proper channels of
learning and knowledge.
Meanwhile, with the approach of every new Ramadan, the same controversy around
deciding its first and last days is renewed. Muslim countries continue to
begin and end Ramadan on different days, and to celebrate other important
religious occasions on different days because of a lack of coordination and