During this Ramadan, as in some previous years, there have been many questions about the criteria for determining the start of the Islamic month and the role of science and the moon sighting in this regard.  The following article sheds some light on these and related issues, and we hope it will help educate the community on this important subject. This was originally written a few years ago in response to questions many community members had. It is being posted again for general benefit.

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            The sole purpose of this article is to answer the various questions that are frequently raised in this regard, and we hope this positive academic approach will help diffuse some of the tensions and the confusion that have arisen within the community.

            Allah says in the Qur’an:

They ask you about the crescents.  Say: They are times appointed for the people and for the hajj… (al-Qur’an, 2:189)

            In this verse the Qur’an sets the new crescent as the standard for the beginning of the Islamic month. In this way, Islam introduced a purely lunar calendar that was distinct from the different calendars in use at the time in Arabia and elsewhere.  Along with verses 36 and 37 of Surah al-Tawbah, which prohibit any sort of modification or tampering with the calendar, this verse introduced a uniquely observational calendar that was directly accessible to the people without making them dependent on calculations, astrologers, or any central coercive authority.

            For the Islamic calendar to fulfill its proper and intended function in society and in order to avoid doubt, confusion, and disunity, it is necessary for Muslims to have a basic understanding of the criteria for determining the beginning of the month.  The first question to arise is why there isn’t complete unity on this issue in the first place.

The Role of Ijtihad

            To answer that question, it is important to understand the nature and importance of the process of ijtihad within Islam, especially in the school of Ahl al-Bayt (as).  When there are different fatwas or religious rulings about an issue, it is common for people to ask questions along the lines of, “Why don’t the scholars just get together, solve the issue, and give a single answer?”

            This question reflects the natural tension that exists between free scholarly debate and conformity of action.  In any field of human endeavor, there is a tradeoff involved in allowing academic disagreement: it permits scholarship to progress and develop, but it also leads to less conformity and agreement in practice.  Two doctors may reach different conclusions about the best way to treat an illness, economists may offer different models and suggestions to prevent a recession, and jurists may differ in their interpretation of secular or religious law.  On the other hand, imposing a specific solution or answer to a problem prevents confusion and disunity in practice, but it stifles the advancement of knowledge.

            Within the Sunni world, the introduction of the four schools of fiqh—Hanafi, Maliki, Shafi`i, and Hanbali—was just such an attempt to impose conformity on people’s religious practice by the Abbasid government of the time, who “closed the gates of ijtihad” and required people to follow the rulings of one of the above schools.

            However, within the school of Ahl al-Bayt (as) the practice of ijtihad has remained a continuous and unencumbered one from the time of the Imams until the present day, and the minor differences in religious rulings that do sometimes come about are far outweighed by the benefits of the dynamic process of religious scholarship.

The Role of Taqlid in Religious Practice

             There is a misconception among many people that taqlid means following a faqih (Islamic jurist) in all matters pertaining to religious practice, though this in fact is not true.  Instead, taqlid entails abiding by the religious verdicts and rulings of a faqih, commonly known as fatwa in Arabic.  However, the application of those rulings in daily life depends on determining the subject to which a particular ruling applies, and that is neither the role of a faqih, nor necessarily his area of expertise.

            For example, the faqih will give us the standard by which to determine what constitutes wine, which is najis and haram to ingest.  That standard—his religious ruling—is binding on those who follow him.  But if we take a particular liquid to him and ask, “Is this wine?” the answer is not binding.  Even if he says with certainty that it is wine, if we know he is wrong or even if we are uncertain, we are no more bound by his pronouncement than that of someone else.  Instead, we have to refer to our own certainty or to experts who can make that determination.

            The moon sighting is one such issue where some people assume they should simply follow their faqih in his declaration, but like the example given above, that is not the case.  We refer to the faqih to determine what standard to apply in starting the new Islamic month, but this is not an area for taqlid.

Declaration of the First of the Month by a Faqih

            Although the start of the Islamic month is not subject to taqlid, there are some jurists who say that a faqih can make a ruling declaring the beginning of the month.  This is known as a hukm and not a fatwa, because it has nothing to do with taqlid.  For the followers of jurists who consider such a declaration valid, it is binding if it is made by any faqih—not just the faqih a person follows in taqlid.

            To illustrate this point, let us look at the rulings of some of our present-day jurists.  Sayyid Sistani holds that the faqih does not have the prerogative of declaring the start of a new month, and such a declaration is not binding on others, though it is recommended to observe precaution (for example, by fasting without the intention of Ramadan):

The 1st day of any month will not be proved by the verdict of a Mujtahed and it is better to observe precaution.[1]

            In contrast, both Sayyid Khamenei and Shaykh Makarim Shirazi consider the ruling of a jurist to be authoritative.  In his answers to legal queries, Sayyid Khamenei states:

… and similarly if a religious jurist rules about the crescent, his judgment will be a religious hujjah (authority) for all believers, and it is obligatory on them to obey it.[2]

            It should be noted that this only applies if the religious authority actually issues a ruling regarding the beginning of the month.  If however, he obtains personal satisfaction about the moonsighting without issuing a ruling to that effect, that does not mean others are required to follow the same dates as he is following:

Until a religious authority issues a decree announcing the sighting of the new crescent, the mere ascertaining of it by him is not sufficient for others to follow him, unless they are convinced thereby of the end of Ramadan.[3]

            In addition, even the ruling of a religious authority will not be binding on those who, through whatever means, know that ruling to have been made in error.[4]

            Thus, for followers of Sayyid Sistani, they cannot follow the statement of their own faqih or any other unless they are personally satisfied that it is correct (or, of course, if the crescent has been established by other means.)

            Followers of Sayyid Khamenei or Shaykh Marakim, however, would have to follow the declaration of a religious authority, even if that declaration was not made by the jurist they follow in taqlid.  So a ruling by Sayyid Khamenei would be binding on followers of Shaykh Makarim as well.

Criterion for the Start of the Month

            There is a near consensus among Shi’i jurists that the criterion for the start of the Islamic month is for the new crescent to be visible in the sky; most jurists specify that it must be visible to the unaided eye (and not through a telescope or other instrument).  Contrary to what some people think, this is different from the new moon, which is invisible from earth.  The crescent usually becomes visible one or two days after the new moon.

Using Astronomy to Determine the Start of the Month

            There is also consensus among jurists that using astronomy or calculations to determine the new month is not allowed, unless one derives certainty through those means.  In that case, it is permitted.[5]

            Many people have the misconception that astronomy gives definitive answers and should be able to resolve any disputes.  In reality, the visibility of the crescent is different from calculations of sunrise, sunset, the new moon, and so on—all of which can be calculated with precision.

            The visibility of the new crescent depends on many different factors, including the age of the moon, its angular separation from the sun (which affects how much of the moon’s surface is illuminated), and when the moon sets.  Experts have derived models based on these and other factors that in many cases can rule out the moon’s visibility or say with certainty that the moon will be visible, but not in all cases.

            Thus, even though it cannot be relied on in entirety, there is a clear role for astronomy in moon sighting, especially in ruling out reports of seeing the crescent where such a sighting was not possible.[6]

Eyewitness Testimony of the Moon sighting

            There are several ways to establish the new crescent.  Whether a jurist’s declaration is binding or not was discussed above.  The other ways are

  1. for a person to see the crescent personally,
  2.  for its sighting to have been established with certainty (for example if a large number of men and women saw the moon),
  3. for thirty days to have passed from the start of the previous month,
  4. or for two adil witnesses to testify that they have seen the crescent.

            With regard to the testimony of two adil witnesses, there are two opinions among Shi’i jurists.  One holds that their testimony is valid as long as:

  1. they do not contradict one another[7]
  2. they are not contradicted by at least two other adil witnesses who say the crescent moon was not visible[8]
  3. a person does not have personal certainty that they are in error.[9]

            This view is held by Sayyid Khamenei and Shaykh Makarim Shirazi.[10]

            Sayyid Sistani, however, expresses the conditions for the testimony of witnesses to be admissible differently:

If two just (Adil) persons say that they have sighted the moon at night. The first day of the month will not be established if they differ about the details of the new moon. This difference can be either explicit or even implied.
For example, when a group of people goes out in search of a new moon and none but two Adils claim to have seen the new moon, though, among those who did not see, there were other Adils equally capable and knowledgeable [in terms of locating the crescent], then the testimony by the first two Adils will not prove the advent of a new month.[11]

            Thus, in the view of Sayyid Sistani, the sighting of the moon should be something that is clearly and unambiguously established.  If the crescent is visible in the sky and many people go out to look for it, it does not make sense for many or most of them not to see it.  In several questions that were asked of him, Sayyid Sistani has specified that this standard applies even if the reported sightings of the crescent were more than two in number:

لو كان هناك اكثر من شاهدین عادلین بالرؤیة (اربعة او ستة او ثمانیة شهود بالرؤیة) فهل هذا یعني وقوعهم بالخطأ والاشتباه علیه تترك شهادتهم؟

الجواب: یمكن الخطأ في العشرة ایضا.

            This was part of a question regarding a case in which more than two adil witnesses report seeing the moon even though it is not astronomically possible:

What if there are more than two adil witnesses to the sighting (four, six, or eight witnesses to the sighting)?  Does this mean that they are in error and their testimony will be rejected?

Answer: Even ten people can be in error.

            Another question and answer deal specifically with the issue of a crescent that was seen by some people but not others:

في بعض الشهور يعلن عن ثبوت الهلال عند بعض العلماء في بعض بلاد الشرق استناداً الى أقوال بعض من شهدوا برؤيته فيها، ولكن يقترن ذلك ببعض الأمور:
أـ كون الشهود وعددهم 30 مثلا ـ موزعين على عدة بلدان، مثلا (2) في أصفهان، (3) في قم، (2) في يزد، (4) في الكويت، (5) في البحرين، (2) في الأحساء، (6) في سوريا، وهكذا.
ب ـ صفاء الافق في عدد من البلاد الغربية واستهلال المؤمنين فيها مع عدم وجود مانع لرؤية.
ج ـ اعلان المرصد الفلكي البريطاني انه يستحيل رؤية الهلال في تلك الليلة في بريطانيا ما لم يستخدم المنظار)التلسكوب( وأن رؤيته بالعين المجردة إنما يتيسر في الليلة اللاحقة.
فما هو الحكم في هذه الحالة؟ افتونا مأجورين.
الجواب: إنّ العبرة باطمئنان المكلف نفسه بتحقق الرؤية أو بقيام البينة عليها من دون معارض، وفي الحالة المذكورة ونظائرها لا يحصل عادة الاطمئان بظهور الهلال على الأفق بنحو قابل للرؤية بالعين المجردة، بل ربما يحصل الإطمئنان بعدمه وكون الشهادات الصادرة مبنية على الوهم والخطأ في الحس، والله العالم.

During certain months, it is declared that the sighting has been proven according to some religious scholars in some Eastern countries. This is based on the testimony of those who have sighted the new moon. Such declarations are usually coupled with the following facts:

a. The witnesses who sighted the moon and who number around thirty, for example, are scattered in various cities such as 2 in Isfahan, 3 in Qum, 2 in Yazd, 4 in Kuwait, 5 in Bahrain, 2 in Ahsã’, and 6 in Syria, etc.

b. The sky was clear in a number of cities in the West, and the believers went out in the attempt to sight the moon; and there was nothing preventing the sighting.

c. The observatories in England announced that it was impossible to sight the new moon that evening in England except by using a telescope; and that its sighting with the naked eye would be possible only in the following night. So, what is the ruling in such a case? Please guide us, may Allãh reward you.

Answer: The criterion is the satisfaction of the individual himself [1] about the actual sighting [of the new moon] or [2] the proof of sighting without any counter claim. In the case mentioned above, satisfaction is not normally achieved concerning the appearance of the new moon on the horizon in such a way that it could have been sighted by the naked eye. On the contrary, one is satisfied that it was not sighted and that the testimony [of sightings in the Eastern cities] is based on illusion and error in sight. And Allãh knows the best.[12]

            In short, the beginning of each Islamic month must be based on certainty, and even the testimony of trustworthy and adil witnesses cannot be utilized unless it fulfills the standard mentioned above.

Evaluating Sighting Reports Scientifically

            As mentioned earlier, astronomical models are still not precise enough to tell us with absolute certainty exactly where the crescent will or will not be visible in all cases.  This is because of the many factors, both astronomical and atmospheric, that affect its visibility.

            At the same time, it is frequently possible to scientifically rule out the prospect of sighting in a particular area, a fact which we can also see reflected in the questions posed to Sayyid Sistani that are quoted above.  Experts have created astronomical models that explain the possibility of seeing the crescent in terms of “visibility curves” that spread westward across the globe.  These curves, plotted on a map or globe, show where the crescent should be visible with ease, where it may be visible under perfect atmospheric conditions, where optical aids may be needed to find or see it, and finally, where the crescent will not be visible at all, even with telescopes.

            The models created in this way are based on astronomical realities and are corroborated by years, or even centuries, of observations, and thus are extremely reliable—especially in ruling out any report of sighting the crescent that originates from outside of even the widest visibility curve (in which the crescent can only be seen with optical aid, not with the naked eye).  So if there is a case where a reported sighting conflicts with conclusive astronomical data, it can be discounted.

Reported Sightings and Astronomical Models

            One might be tempted to say that if the moon sighting is reported by trustworthy and adil witnesses even though the astronomical models show it to be impossible, that should call into question the validity of those models rather than result in the discounting of the witnesses’ testimony.

            To understand why that is not necessarily the case, it is important to understand that it is entirely possible and even common for people to think they have seen the moon when in reality they have not.  Clouds, dust, pollution, and other natural factors can sometimes be confused for the young crescent.  And of course, today there are many manmade objects in the sky as well that can confuse even an experienced observer, including aircraft and satellites of various types.  This type of confusion even existed in the era of the Imams, as evidenced by this hadith from Imam Sadiq (as), in which he was asked how many witnesses are sufficient in sighting the crescent.  The Imam replied:

إن شهر رمضان فريضة من فرائض الله، فلا تؤدوا بالتظني.  وليس رؤية الهلال أن يقوم عدة فيقول واحد: قد رأيته، ويقول الآخرون: لم نره؛ إذا رآه واحد رآه مائة، وإذا رآه مائة رآه ألف.  ولا يجزئ في رؤية الهلال إذا لم يكن في السماء علة أقل من شهادة خمسين، وإذا كانت في السماء علة قبلت شهادة رجلين يدخلان ويخرجان من مصر.

Verily, the month of Ramadan is one of the Divine obligations, so don’t base it on conjecture.  And sighting the crescent is not for a group to go out, and then one says, “I have seen it,” while the others say “We didn’t see it.”  If one sees it, a hundred see it, and if a hundred see it, a thousand see it.  And in sighting the moon, the testimony of less than fifty is not sufficient if there is no obstacle in the sky; and if there is an obstacle, the testimony of two men who enter and leave a city is acceptable.[13]

            There are several other similar hadith from the Imams that demonstrate that mistaken sightings were an issue even in that era, before pollution and the presence of foreign objects in the sky were as much of an issue as they are today.

            Thus, if the astronomical models and data are conclusive in discounting the possibility of sighting, that determination in fact can be relied upon even if there are reports of the moon sighting.  However, if the scientific models are not conclusive, the eyewitness testimony cannot be discounted.


            Numerous Shia and Sunni centers determine different dates for the start of the Islamic month, while others rely on the reported sightings.  Whatever determination an individual may make, it is important to bear in mind that unity does not require conformity, but rather respect and understanding for those who may have come to a different determination.

            May Allah guide all of us to further our understanding of the teachings of Islam.  May He accept our worship and prayers during this sacred month, forgive our sins and overlook our shortcomings, and grant us His blessings and favor.   May He keep us united in service of His religion and dedication to the cause of His prophet and the progeny of His prophet, and may He grant us their intercession and company in this world and the next.

[1] Islamic Laws, Issue 1740.  See also المسائل المنتخبة، المسألة 475.

[2] "وهكذا لو حكم الحاكم الشرعي بالهلال كان حكمه حجة شرعية لعامة المكلفين ووجب عليهم اتباعه."

[3] Practical Laws of Islam, Question 839.

[4] Tawdih al-Masa’il, Shaykh Makarim Shirazi, Issue 1456.

[5] Tawdih al-Masa’il, Shaykh Makarim Shirazi, Issue 1457.  See also Islamic Laws, Sayyid Sistani, Issue 1741.

[6] “On the Crescent’s Visibility,” S. Kamal Abdali, Ph.D. (http://patriot.net/~abdali/ftp/moon.pdf)

[7] For example, if one says the moon was in one direction and the other says it was in another direction, their testimony will not be valid.

[8] In this case, if two adil witnesses say, “We saw the crescent,” and two others say, “We did not see it,” the testimony of the first group will be admissible.  But if the second group actually denies and the sighting of the crescent itself, for example, by saying, “We looked, and the crescent wasn’t there,” then the two conflicting testimonies cancel each other and neither is admissible.

[9] For example, if two adil witnesses testify to seeing the moon but a person is satisfied by scientific or other means that their sighting is mistaken or in error.

[10] Practical Laws of Islam, Issue 837; Tawdih al-Masa’il, Issue 1456.  Shaykh Makarim adds that if the two witnesses mention attributes of the crescent that indicate they made a mistake, their testimony does not prove the new month—even if they don’t contradict one another.

[11] Islamic Laws, Issue 1739.

[13] Wasa’il al-Shi`ah, vol. 10, p. 289

[14] This is especially true if the sky is clear.  If it is partly cloudy, the cloud cover may block out enough sunlight to allow the crescent to be visible earlier than otherwise predicted, in which case it may be seen through a clear patch in the sky.