InsightJuly August 2006

Astronomy, Moon Sighting and Hijri Calendar

Dr. Dildar Ahmed, Ph.D


Since all of their annual religious festivals and events, such a fasting, Eids, Hajj, etc., are related to it, for the Muslims the Hijri calendar has fundamental importance. It is a pure lunar calendar. In pre-Islamic Arabia, various systems of measuring time were in vogue. Some calendars were lunar, while others were lunisolar- using months based on the phases of the moon but intercalating days outside the lunar cycle to synchronize the calendar with the seasons.

As it is generally known, the Hijri calendar was established by Hazrat Umar (592-644CE), the second Righteous Caliph, during his caliphate, with the consultation of the Companions, in the year 638CE. The Hijrah, or the Migration of the Holy Prophet and his Companions from Makkah to Madinah, was chosen as the starting point for the new calendar. The starting date for the calendar was chosen, counting backwards, to the first day of the first month (i.e., 1 Muharram) of the year of the Hijrah. According to the new calendar, the first day of Muharram 1, corresponds to July 16, 622CE.1

Since it was established by the Muslims according to their own tradition and needs, the Hijri calendar is also called the Islamic calendar. It has been the official calendar of the Islamic Caliphate and other Muslim empires and realms for centuries until the Western colonial powers replaced it with the Gregorian calendar. The Hijri calendar, though locally fixed, is still the official calendar of the Muslim countries of the Middle East. The other Muslim countries, such as Pakistan, where Gregorian calendar is officially followed, also give especial importance to the Hijri Calendar because of its connection to religious festivals and events. The newspapers, annual diaries and calendars also publish Hijri dates along with the Gregorian.

Despite all of its religious, cultural and historical significance, the Muslims could not yet formulate a perpetual Hijri calendar that can be followed by the whole ummah. As the world, thanks to the revolution in fields of communication and transportation, is shrinking day by day, the Muslim scholars and intellectuals are realizing the need for a common calendar more and more seriously.2

The reason being given to the failure is the literalistic fiqhi, or juristic, approach that insists on actual physical sighting of the lunar crescent to mark the start of a Hijri month. As a result, the beginning of a Hijri month, particularly, the months related to religious festivals such as Muharram, Ramadhan, Shawal and dhil-Hajj, is practically marked each year on actual sighting of the lunar crescent and not on the basis of astronomical data. Consequently, different Muslim countries may have different Hijri dates. For instance, when in Pakistan it is the first of Shawal, Saudi Arabia, generally, has the second of Shawal. Sometimes, even within a country different cities have different Hijri dates. Thus, very often the first of Ramadhan, for example, in Karachi and Peshawar occurs at different days. As a result, if a child is born on the first of Ramadhan in Karachi, with respect to Peshawar it will be the second of Ramadhan. This is, indeed, an embarrassing situation that calls for an early solution.

Unless we work out some system or formula to make it universal and perpetual, it is not possible to use the Hijri calendar for any type of advance planning at any level. Moreover, no time-based computer programming can be made with uncertain and unpredictable dates. Therefore, we have to formulate a system so that a perpetual Hijri calendar applicable to the whole globe can be developed.

The Qur’anic conception of the universe is that of an organized and orderly world created by Allah almighty Who is all-Wise, all-Knowing and all-Powerful.3 Moreover, while the Holy Qur’an has vehemently condemned and rejected the divinity, and divination on the basis, of the heavenly bodies, it has strongly encouraged their positive study, i.e., astronomy.4 Furthermore, according to the Qur’an, the sun and the moon, and all other celestial bodies, follow their set courses and measure.5 To calculate time and to have a reckoning of months and years what we have to do is to find out the system that is followed by the moon. After having discovered that system, we will be perfectly able to predict its position at a particular time of a month with respect to a particular locality on the earth.

Astronomy today is a highly advanced science. Therefore, the position of the moon in the sky can be calculated with high precision on the basis of the astronomical data.6 On the other hand, physical sighting has such limitations that insistence on it will never allow to formulate a perpetual calendar. There are numerous visibility problems which may not permit the lunar crescent to be visible for a person from some point of the earth. In addition to physical factors, there are nowadays numerous manmade objects in the space that may also be mistaken for the lunar crescent. Furthermore, there are places on the earth from where physical sighting, at least for some period of time in the year, is not possible due to meteorological or other reasons.

The matter of fact is that physical sighting is not an end in itself; it is just a means to determine the beginning of a lunar month. It was the sole method available to the Muslims at the time of the Holy Prophet, sallallahu alaihi wa sallam. Now, however, authentic, scientific knowledge is available to make in advance a lunar calendar. Under such a circumstance, it is not the intension of the Islamic Shariah to avoid authentic knowledge and go on insisting on physical sighting, which invariably gives rise to controversies and disputes among the Muslims through out the world. There are, thus, only two options open to us: either we declare the Hijri calendar impracticable in the age of computer and global village for any type of advance planning and continue with disputes and controversies on each occasion of religious festivals, or we must take advantage of the authentic science of astronomy to develop a perpetual, global Hijri calendar.

In order to be able to prepare a perpetual Hijri calendar in advance that can be followed throughout the globe, we will have to base it on astronomical calculations. And, secondly, we will have to fix a certain place on the earth as a reference.

The easiest and the surest method to devise a perpetual lunar calendar is to mark the beginning of the lunar month from the time of the conjunction 7 of moon since this can be calculated with exact accuracy. This system can be used for all civil and non-religious purposes. If a global body of decision-makers and religious scholars representing all schools of thought agrees to do so, it can also be used for religious purposes. If, however, the Muslim jurists continue to insist to mark the beginning of the religiously significant lunar months by physical sighting, then we will have to fix a place of reference on the earth and to evolve a consensus on the time from conjunction when, astronomically, the lunar crescent will be visible with respective to our place of reference on the earth. Accordingly, the agreed ‘visibility time” from conjunction can be used to develop the calendar. Such a calendar may be called the Global Hijri Calendar abbreviated as GHC (on the pattern of GMT). This calendar will be perpetual and applicable for the whole globe.

As regards the reference place, Makkah al-Mukarramah should be the best choice since it is the spiritual centre of the Muslims all over the world. Accordingly, a Hijri calendar based on Makkah as a place of reference and calculated on the basis of a fixed visibility time from conjunction can be prepared. Until our jurists agree to any of the abovementioned alternatives they may continue with the local sighting for religious festivals and for all other purposes the proposed GHC can be used. This, however, will be the least recommended choice.

The GHC will be perpetual as well as universal just like the Gregorian calendar, and the Muslims of the whole world will be able to use it for all purposes like reckoning of date, future planning and computer programming, etc. We will also be able to adopt it as an official calendar for all the Muslim countries. Moreover, the GHC will also give a practical system for the unity of the Muslim ummah, as the whole ummah will be using the same calendar at least for civil purposes. A serious effort as well as open-mindedness on the part of our scholars and decision-makers can liberate the ummah from prevalent controversies, disputes and expressions of disunity that we witness each year on the occasions of the beginning of Ramadhan, Eids, and on other festivals and days of religious importance.


A perpetual and universal Hijri calendar, GHC, can be developed on the basis of the time of conjunction of the New Moon. Besides the civil and non-religious purposes, such a calendar can equally be used for religious purposes if a global body of Islamic jurists agrees to do so. Alternatively, the beginning of a lunar month can be marked on the basis of an agreed time from conjunction when the lunar crescent should astronomically be visible from a fixed place of reference. A third option, which is not recommended, is that while using local sightings for the religious purposes, the GHC may be used for all other purposes.

Notes and References

1 The Hijri calendar is usually abbreviated as AH in Western languages from the Latinized Anno Hegirae, “year of the Hijrah”. Thus, Muharram 1, 1AH corresponds to July 16, 622CE. The Hijrah, the emigration of the Prophet, sallallahu alaihi wa sallam, took place in September 622CE. The Hijri year is shorter than the Gregorian year by about 11 days, and months in the Hijri year are not related to seasons. This means that important Muslim festivals, which always fall in the same Hijri month, may occur in different seasons. It is only over a 33-year cycle that lunar months take a complete turn and fall during the same season

2 Views and opinions of numerous scholars are available online as well as in the printed form. See, for example, (a) Mohammed Ilyas, A Modern Guide to Astronomical Calculations of Islamic Calendar, Times & Qibla, 2. Berita Publishing Sdn, Bhd. Kuala Lumpur, Malaysia. (b) Ibid, “Lunar Crescent Visibility Criterion and Islamic Calendar”, Quarterly Journal of the Royal Astronomical Society, Vol. 35, 1994, pp. 425-461. (c) Schaefer, B. E., Ahmad, I. A., Doggett, L. E., “Records for Young Moon Sightings”, Quarterly Journal of the Royal Astronomical Society, Vol. 34, 1993, pp. 53-56, (d) Asghar Ali Engineer ( Khalid Shaukat (,
(f) Monzur Ahmed (,
(g) Moulana Shihabuddin Nadvi
3 Numerous Qur’anic verses can be quoted in this respect. See, for example, 36:38-40, 50:6-8, 55:7, and 67:3,4.
4 See, for example, 15:16-18, 37:6-10, and 67:5.
5 See, for example, 6:96, 13:2, 21:33, 55:5.
6 In this regard, visit to the website of US Naval Observatory,, will be helpful.
7 When the earth, the moon, and the sun, are in the same vertical plane but not necessarily in the same line, and the moon is between the earth and the sun. This condition is known as the ‘conjunction’. In scientific or astronomical terms, the ‘conjunction’ is defined as the condition when the sun and the moon have the same ‘right ascension’. At conjunction, the moon is not completely shadowed as viewed from the earth. However, the degree of illumination is so low that for us it is completely invisible. The solar eclipse can also occur at this precise moment when part of the sun appears dark because the sunlight is unable to reach the earth due to the moon being in the middle. However, since the orbit of the moon is tilted by about 5 degrees the moon misses being directly between the sun and earth and, therefore, solar eclipse only occurs a few times during the year rather than at every new moon. Generally, the lunar crescent becomes visible to suitably-located, experienced observers with good sky conditions about one day after conjunction. However, the time that the crescent actually becomes visible varies quite a bit from one month to another.

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