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Towards the Unity of the Muslim Ummah

Astronomical Lunar Date Line (ALDL)

 Islamic Jurisprudence (shari'ah) and Scientific Perspective


Determination of the lunar calendar should not constitute a reason for conflict amongst Muslims. Since there is no dispute with regard to the practical implementations associated with this issue, such as the rituals of fasting the month of Ramadan, paying the zakah upon completion of the year, or performing Hajj during specific months. The determination of the month’s beginning with certainty is a scientific issue. The capacity of people to determine it will vary according to the level of their knowledge, which in turn, will vary from one group of people to another, and generation to the next. Nevertheless, this case is similar to the determination of the qiblah direction at a specific location on earth. There is no dispute with regard facing al-Masjid al-Haram during our prayers. The methods associated with calculating the position relevant to a geographical location, is clearly a scientific issue left to be determined by the professionals, such as geographers, navigators, and astronomers. As long as an individual has done their best to know the location of the qiblah, their prayer will be valid, even if they have faced a wrong direction; since Allah (swt) will not burden a soul beyond it’s own limits. Similarly, a person’s fasting will be valid even if we failed to realize the accuracy of the existence of the moon.


A consensus should exist among Muslims, at least for those who are living at the same town or country, concerning adopting a specific rule to unite their view about the beginning of the new month. Whether they reach the reality or they miss it, their rituals are valid. Unity itself is a shar’iah objective, since the day of fasting is the day on which the Muslims collectively should begin their fasting, and the day of Eid is the day on which they collectively break their fast. The unity is explicitly stated in hadith of Prophet Muhammad alayhi-al-salato-wa-al-salam, and the rituals are accurate without dispute, even for those who are certain of the error of the decision taken by the people of authority among them. Nevertheless, even for those who have accurate scientific knowledge, they should be ready to give up the results of their knowledge and sacrifice their personal opinions for the sake of unity of the Muslim ummah if can be accrued through other opinion.


The shari’ah passages (Qur’an and Sunnah) direct us, as Muslims, to consider the calculations in order to realize the positions of the sun and the moon to determine such rituals as the time of prayer and fasting among others. In the event that calculation methods are not available, we are then directed to consider the sighting of the sun and its shades and sighting the new moon for the appropriate time determinations. However, such permission is negated now due to our certain knowledge of astronomical calculations regarding both the sun and the moon. Additionally, with the advent of telecommunications, it makes the spread of information easier between scientists, Islamic scholars and the ummah, thus unifying us more.


It was clearly pointed out by the earlier Muslim scholars, starting from the time of tabi’in, that the astronomical calculations is the speech of the shari’ah (taklif) for those who are possessing the astronomical knowledge and that the observation of the moon sighting or completion of the month thirty days is for those who do not possess the required knowledge.  


A group of the early scholars, the salaf, had decreed that those who know and understand the astronomical calculations are obligated to follow this method even if they are certain that the visibility of the moon is impossible due to the early age of the moon or due to atmospheric conditions. Others have said that the entire Muslim ummah should follow the astronomical calculation either in the case of affirmation or negation of the moon visibility. Others have said, it is permissible only, not as an obligation.

Sheikh Ahmad Shakir’s (a well known Egyptian scholar of the mid-20th century AD) view is that the determination of the lunar calendar depends solely on the astronomical calculation, while the moon sighting is permissible for those who lack the knowledge of astronomical calculation. Sheik Shakir was free of the condition that the moon should last enough time after sunset to enable the observer for the moon sighting. 


Dr. Yusuf al-Qaradawi, (a contemprary Egyptian scholar in Qatar), emphasizes that the astronomical calculation is a scientific and practical method to achieve the objectives of the shari’ah. Today, it is readily available, accurate, and distant from the possibilities of error which exist with the observation of the moon sighting. Additionally, he considered that astronomical calculations have reached a level of certainty to the point of reliability as a condition for the unity of the entire ummah, therefore removing the continuous disputes regarding days of fasting, breaking of the fast, and the days of celebrating, Eid. The astronomical calculations should be considered and accepted according to the rule of Qiyas al-Awla. 


It is essential that we should make distinction between two methods of moon calculations. One is associated with the determination of the astronomical new moon. The astronomical new moon is defined to occur when the sun and moon have the same geocentric ecliptic longitude. The results of this method are definite and certain. There is no dispute between any of the astronomers regarding the accuracy of this method. The second type of calculation is associated with the possibility of the moon visibility at a specific geographical location at a specific time – after sunset on the given day by sighting, which begins with the thin crescent. The moon is actually sighted in the western sky after sunset within a day or so after the new moon. The scientific base is agreed upon, but the results vary with a margin of error since it is not only depending on mathematical calculations but on the atmospheric conditions which are beyond our control or prediction in addition to other astronomical factors affecting the possibility of visibility. 

The method of mathematical calculations, concluded at this study, as supported by the passages of the shari’ah, is the first type, which it is called the ‘astronomical conjunction’.


The new moon (the beginning of the new month) begins at the same moment for all inhabitants on earth. Yet it falls in two consecutive days due to the spherical shape of the earth and the conventional system of time people proposed and agreed upon. According to the conventional system the reference point of time being with Greenwich Mean Time, the time zone differences from GMT should be considered/adjusted. Thus, the moment of the new moon is logically going to be daytime for some locations while beings nighttime for other locations, depending on the geographical location. Nothing in the shari’ah, let alone science, can tell you that the new moon would only being at night. Nor should it be considered as a new crescent if it had existed before sunset and should last on the horizon until it’s visibility through the naked eye after sunset.


The conclusion of this study, ALDL, is characterized by its clarity and ease of implementation. At a specific location (longitude) on earth, the time of the new moon begins before dawn either during daytime or nighttime. The rituals will begin from the dawn of that day for fasting or Eid and night time for tarawih. Towards the Western Hemisphere, the age of the moon is maturing and in the Eastern Hemisphere, people will start their day after the completion of the circle around the globe. In other words, the rituals of the new month begin at the same moment for everyone, no matter where their location is on Earth. The name of the day may vary due to the time zone differences around the world. The very nearby two islands, Alaska’s Little Diomede and Russia’s Big Diomede, have a distance of a few miles from each other, but they have 24 hours time zone difference since they are separated by the International Date Line. For example, when it is Thursday in Little Diomede, it is technically, Friday in Big Diomede, which is just a few miles away. The agreement of the name of the day will result in one day different between them. If you miss your Friday prayer at Big Island, you can perform it on the next day at the nearby island.


As a result of this method, we will have a clear lunar calendar which would be similar to the Gregorian calendar. This will bring unity to Muslims and help them publish information about their holidays for years in advance assisting with holiday planning. This will also facilitate business transactions and international relations at the global level.


Implementing of such a system will also remove the perceived notion of ignorance and the failure to comprehend simple astronomical facts made towards the Muslim ummah and their fuqaha’ and their lack in applying accurate scientific information that is readily available to all.


The early Muslim generations had achieved a superior level in scientific fields such as, astronomy, physics and mathematics. The Islamic scientific achievements in the past are the basis of the modern world development today. Among the most important causes for their advancement at that time was the implementation of the shari’ah passages. If we as Muslims are to advance past the previous achievements of the Tabi’in and the Salaf, it is time to implement the calculation of the astronomical new moon which the scholars had instructed us to follow as early as the end of the first hijri century.


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While the Foundation is sure of the accuracy of ANM as the shari'ah method (ruling derived from the Qur’an and Sunnah) to be followed; we also upheld the maslahah (significant benefit) of unity, at least among those who live in the Philadelphia area. We did this through a call for unity for the second time among the major mosques of the area, to adopt one agreed upon method, instead of the seven different methods that exist in the our region. It was explicitly stated, that the agreed upon method should not be necessarily the method that we consider as most accurate (ANM).  Unfortunately, no responses were received to support such a call for unity, and few show their willingness to discuss this issue. However, we agree with the Fiqhi Council of North America in their following advice:

A Call for Understanding and Harmony     
The Fiqh Council is encouraging all Muslims throughout North America to consider using the new methodology for the sake of unity and to avoid the confusion and disputes that have occurred in the past. However, the Fiqh Council does not intend to force its decision on anyone or any Muslim community.

You should follow the decision of your Imam and your Masjid. Moreover, you should do so with great respect and avoiding unnecessary disputes and discussion. It is not expected that everyone will embrace this decision immediately. As with all changes, it will take time for people to understand the new method. But, Insha’Allah, once people see the new methodology as a more objective and accurate standard, it will serve to unite us in the near future. 




The letters and documents that have been sent to 34 Islamic Centers or Mosques are available at these links: 


For more information, please contact Dr. Mustafa A. Ahmed.

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