Al-Hilal: The first visible moon on Earth

The moon in a full phase

Introduction :

This is a research document that gives some light on the Al-Hilal mentioned in the Quran and gives suggestions about the scientific method for an Islamic Calendar.

“As for the moon, We have ordained ˹precise˺ phases for it, until it ends up like an old, curved palm stalk.” – Yaseen 36:39

[The moon begins from the astronomical new moon to the full moon and then back to the astronomical new moon to complete a cycle. The visible phase begins from the crescent moon (Al-Hilal) and ends in the last visible crescent (like an old, curved palm stalk)]

Expected properties for a Calendar

1. A given day for a date

If July 31 is a Friday in Saudi Arabia, then July 31 in the United States will be Friday, although there is a time difference;


If the date of Dhū al-Ḥijjah 10 is Yawm al Jumu’ah in Saudi Arabia, then Dhū al-Ḥijjah 10 will be Yawm al-Jumu‘ah in the United States, despite the time difference. This means that even though Americans fall asleep during Friday prayers in Saudi Arabia, they still pray the Friday prayers on the same day.

Only one day can be marked against a date in the calendar, and it would be unreasonable and impractical to use a calendar that shows one day in the US and another day in Saudi Arabia towards a date.

[The picture shows an example, where Muslims observe Eid (Dhu al-Hijjah 10) on Yawm-al-Ithnayn, Yawm-al-Thalatha, and Yawm-al-Arba from different countries, it is not possible for a proper calendar]

The question that many ask is, whether to fast on the day of Arafat or the 9th day of Dhū al-Ḥijjah. The question itself is unfounded because the day of Dhū al-Ḥijjah 9 in the US should not be different from the day of Dhū al-Ḥijjah 9 in Saudi Arabia. If Dhū al-Ḥijjah 9 in Saudi Arabia is on Yawm al-Jumu‘ah, the Dhū al-Ḥijjah 9 will be on Yawm al-Jumu‘ah in US as well.

2. A date will not change when a man-made border change

The city, state, or country are man-made borders, they can be changed at any time. Eg: India and Pakistan were not separate countries before.

“The sun and the moon run on their fixed courses”. (Al-Quran 55: 5)

So the moon courses have nothing to do with the man-made borders or ruling area of a King.

The Quran says

They ask you about the Al-Ahilla. Say, “These are signs for the people to reckon dates and fix the periods for hajj. ……..” (Al-Baqarah,  2: 189)

Abu Hurairah narrated that: the Prophet (S) said: “The fast is the day the people fast, the breaking of the fast is the day the people break their fast, and the sacrifice is the day the people sacrifice.” At-Tirmidhi, Book 8, Hadith 16

People’ / ‘Annas’ mentioned in the above Quran verse and the hadith, refers to the whole of mankind on earth and it doesn’t segregate into any country or Kingdom. So, the hilal is the date for mankind. Not only for the people in the US, for the people in Saudi Arabia, or the people in any other country.

We can understand that it is a matter of delay to reach the news in a place before the day starts if we are specifically looking for the first visible moon. Now the world has become a global village and we are living in the era of the information superhighway. So, the Quran or hadith did not advise us to split the celebration within the borders, since they have only political importance.

See Appendix E, for more discussions regarding this including Quraib’s hadees.

3. The number of days available in a month will be equal to all

The number of days available to all natives in a month in a particular year will be equal. The month of Ramadan in a year will not be 30 in the US and 29 in Oman.

4. The starting position of a Month on Earth / Starting position of a day on Earth

A month comprises multiple days (29 or 30). Therefore, a month (eg: Dhū al-Ḥijjah) on earth should start where the first day of that month on earth starts. That place is, on a named day (eg: Yawm al-Jumu‘ah), where the Adhan of a day is heard for the first time on earth. (See Appendix A & B for more details)

Different methods currently used

  • Local calculation: Some people look for moonsets after sunset. This is not a definite calculation method for the revelation of the Hilal, and it cannot be considered globally. All the local methods will break the ‘expected calendar properties’ explained above in this document.
  • Hijri Committee of India(HCI): HCI considers the next day of the astronomical new moon (conjunction) to be the start day of the new month. I don’t think it is Islamic since Islamic month starts after the Al-Hilal process on Earth. If it is early conjunction, the first crescent moon may be spotted a day earlier in some places and the last visible crescent (Called waning crescents/ like Urjunul Khadeem) of the month may disappear a day earlier. The last visible crescent of the month will have all the traits of the first visible crescent of the month. If it is late conjunction, the dark moon day may also experience a day late in some places. In other words, it is not possible to determine the ceiling/flooring round of the Moon’s rotation between day 29 and 30 around Earth using the point of conjunction.
  • Fiqh Council of North America(FCNA): After conjunction somewhere on the globe, at local sunset, the angle between the sun and the moon should be at least 8° and the moon should be at least 5° above the horizon. If these conditions are met, the month starts the next day, otherwise, the month starts on the day following the next day.  This method is even better, but we will not get any hints from the Quran or Hadiths about these degrees, looking at the elongation and altitude of the moon, which is not accurate or natural and it is not a definite calculation method for the revelation of the Hilal.
  • Ummul Qura: On the new moon day, if the moon is born before sunset at Makkah and the moonset is after sunset then the month starts on that night. The first day of the month falls on the next day, otherwise, wait for another day. The disadvantages of this method are i) if the moon is born just before the sunset of Makkah, it does not mean the moon turned to the Al-Hilal stage ii) The first Adan or Juma on earth for a day (eg: Al-Yawmul Juma) is not starting from Makkah. Saudi is not following this for announcing Islamic Sacred days (eg: Ramadan 1 1443 is on April 2 according to Ummul Qura, but Saudi Started it on April 1st)

So, what is the real solution?

Suggestions before you proceed

A word to ordinary people: Islam always stands for the unity of Umma, so, always follow your local Masjid or local community and try to celebrate Eid on a common day. You will not be punished for following your leaders, instead, you will be rewarded for your unity.

A word to Islamic Leaders: The ordinary people trust you, so try to always follow the best method. If you are really against calculation, at least follow Mecca, it is the best way to unite Ummah or accept the earliest sighting report anywhere in the world.

The Solution

The Al-Hilal process: The appearance of the moon to mankind after its birth.

Invisible birth Vs actual birth

When a human zygote forms in the womb of a mother,  nobody says it is an actual birth, but after different stages, the fetus comes out of the mother’s womb as a baby, so that all can see, we call it the actual birth. Similarly, after the astronomical new moon, the actual birth (Al-Hilal process) of the moon happens when the moon appears to mankind.

The Moon to orbit around the earth takes between 29 and 30 days. At the end of every rotation, the earth, moon, and the sun come to the same plane ( New moon / Conjunction),  astronomically, one can say that the invisible birth of the Moon takes place during this time. It will be noon wherever this birth takes place on earth. The first condition for seeing the moon after this phenomenon, which takes place at noon, is the setting of the sun.

So, if the new moon is born before the sunset of a day starts on earth (see, section: “Starting position of a day on Earth”.)  the moon will set after the sun sets globally for a day, and from the next morning, the moon will rise after the sun rises globally.

This is the ‘Al-Hilal’, the first visible Hilal on Earth.

“By the sun and its brightness, and the moon as it follows it(when the moon is visible after sunset.), and the day as it unveils it, and the night as it conceals it!”  (Al-Shams, 1 – 4)

Abbas – Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs:

“when it follows the sun, on the first night when the new moon is seen”

Jalal – Al-Jalalayn:

“And [by] the moon when it follows her, rising after she has set

Kathir – Ibn Al Kathir:

Qatadah said, “`as it, Talaha (follows it)’ is referring to the night of the Hilal (the new crescent moon). When the sun goes down, the Hilal is visible.”

When there is the Al-Hilal process of the moon as it follows the sun (Quran 91:2) from the eastern end, it will become a global phenomenon (See Ibn Taymiyyah’s opinion below) and the Hilal will be visible in different areas of the world overnight.

“The sighting [of the hilal] differs according to the difference in east and west. Undoubtedly, when it is sighted in the East, it MUST be sighted in the West, but not vice versa because the sunset is delayed further in the West than in the East. Thus, when it is sighted, it increases in light and distance from the Sun and its rays during the sunset [of the West]. It is then more likely to be sighted. This is not necessarily the case however if it was sighted in the West, because the reason it was sighted could have been the delay in the sunset in their (the Westerners’) [area], and thus it increased in distance and illumination, whereas during the sunset in the East, it was closer.” (Majmoo’ Fatawa Ibn Taymiyyah, vol. 25, pg. 98)

When we consider the Hilal globally, the probability for the cloud to cover the Hilal all over the world is 0.

Proposed Calendar

We can create a calendar based on the Al-Hilal explained above. Abdul Jaleel Pulikkoden, who came up with this concept initially, created a calendar based on this Al-Hilal process (See Appendix D).   If the new moon is born before the sunset of a day on earth, the next day will be the first day of the next month. If the new moon is born after the sunset of a day on earth, the month starts on the day following the next day.

[The picture shows, that the new moon is born before Yawm-al-Ithnayn’s (Monday’s) sunset on earth, so the next day (Tuesday – al-Thalāthā) will
be the first day of the month]
[The picture shows, that by the time the new moon is born, Yawm-al-Ithnayn’s (Monday’s) sunset was over on earth, so the day following the next day (Wednesday – Yawm-al-Arba’) will be the first day of the month]

Appendix A: Islamic day on earth

A day starting point is not directly related to time but it is related to a place (IDL – International Date Line), where the changing of the day of the earth occurs. There are a lot of discussions going on with this IDL which is another topic.  To understand about a gregorian based astronomical day, you can refer to this link

The above link shows the change of a local day starting at midnight, you can assume the day starts at Maghrib, 3 AM, or Fajr according to your Islamic understanding.

Appendix B: IDL – Importance of International Date Line and its corrections

The international date line is an imaginary line that runs north-south across the Pacific Ocean from the North Pole to the South Pole.

General Importance

Initially, the IDL was discovered by the circumnavigators of the earth, not a man-made line invented by scientists. The area of the IDL is natural, it was there on earth. Antonio and Magellan, first mentioned, on Wednesday, the ninth of July 1522, a peculiar incident that had occurred during the voyage: somewhere along the journey a whole day had been ‘lost’. 

See Ref 2.

Islamic Importance

Islamic Jumua Starts here: The IDL is a line on Earth where Muslim start Juma and End Jumua. The time to reach Jumua from this line back to this line, rotating around the earth is 24 hours. The IDL cannot be replaced entirely, when the sun comes up towards IDL (noon) on one side of people pray Jumah, and on the other side of the people pray Dhuhr on Saturday or Thursday.  If the IDL is not sacred at all, then Muslims have to admit that Friday and Friday prayers are starting wrongly in the world.

Adan of a day starts here: Suppose today is Friday, the first Adan of Friday started from IDL, and the last Adan of Friday will end on the IDL.

Can IDL be in Mecca?

If the IDL is in Mecca, suppose it is crossing through Kaba, when one side of Kaba people is praying Juma the other side of Kaba people should pray Dhuhr on Thursday/Saturday. Other than that, the IDL will split a day, so that, it will split the culture and activities of human life. So the IDL must run through an ocean.

The zig-zag in IDL

               The IDL has some Zig-Zag in it, portions of the line were moved east or west, and those changes were done for political reasons. The zig-zag is not considered when coming to global calculation; It is considered as a straight line.

Appendix C: Two things require further improvement/research.

While this is the basic condition for identifying Al-Hilal mentioned by the Quran, the area of improvement are

1. Does the straight line of IDL still need further correction?

As mentioned earlier, the zig-zag of IDL is not considered for calculation, instead, it is considered as a straight line.  While the current IDL is considered a straight line, it may need minor corrections because it is not entirely running through the water. The actual IDL is to be at 168° 41′ W   ie.  168.6833333333 degrees.  So when the IDL is moved west (180 – 168.6833333333 = 11.3166666667) degrees =  0.754444 Hour Angle,  the IDL will run mostly through water except in some rare land areas like ‘Mount Vsevidof’.

These corrections are exceptional cases and need further discussion.

[The picture shows the straightened IDL in yellow and the corrected straight line in red, The original (before edit)  Photo Credit:]

2. Exact time of sunset

As mentioned above our criteria is that we are checking whether the new moon is born before the sunset of a day on earth. When we check the sunset, we should consider the Equator for the calculation, and don’t consider places towards the poles. There will always be exceptions for places toward the poles even in the case of prayer time. There is no point in talking about exceptions when talking about a general calculation.

Though we take the equator for calculation, there is a question about the exact time of sunset.

[Picture of a day marked with prayer time, when day and night length equal on earth, ie, equinox at the equator]

The length of day and night for any location on the equator is constant throughout the year at about 12 hours (See Ref:5). Daylight at the equator is always a bit longer than darkness, the result of the refraction of light through the atmosphere that allows us to see the sun a few minutes before it rises and a few minutes after it sets. Conjunction happens at noon, so, if daylight length is 12 hours at the equator, the time difference from noon to sunset will be 6 hours. Also, need to consider Equinox and Solstice.

2.1 Importance of Eve (Night before the day) and start time of day discussion

A month comprises multiple days (29 or 30). So, the starting time of a month is the starting time of the first day of that month. There is a difference of opinion as to whether the beginning of an Islamic calendar day is at Maghrib, 12 AM, 3 AM, or Fajr. Starting time of day is not directly related to the criterion we have described in this document so, it should not be discussed in this connection.

Before the daytime starts, you need to get a hint of the date of the coming day from the moon calendar hanging in the sky at night(Eve) in preparation for the day.

If we follow the proposed criterion, the calendar will better match with moon phases which are observed at Night(Eve) than many other calendars. To align with visible moon phases, the month should start with a visible moon phase.

“It is He who made the Sun a shining light and the Moon a derived light and determined for its phases – that you may know the number of years and account [of time]. Allah has not created this except in truth. He details the signs for people who know. ” ( Quran 10:5)

This Quranic verse indicates moon phases help to account for the time.

[The above picture shows phases of the moon from Al-Hilal to the last visible phase (phase like Urjoonul Qadeem)]

Moreover, the use of the word “lailat” in the hadiths should be understood from the language used by the Arabs, the first narrators, and transmitters of the Qur’an and Hadith. The Laylat-al-Jumu’ah is what the Arabs call the night before Friday(Friday Eve). It has nothing to do with the discussion of what time the day started, rather, it is related to the use of language. The prophet explained the importance of Friday Eve because it is the preparation Night for the Friday congregation and prayer.

2.2 Second importance of sunset time.

Most Islamic scholars believe an Islamic day starts at sunset. It is important to happen the birth of the moon before the Islamic day starts on the earth.

The end time of Asr before entering Magrib is important, it is considered the declining time of the day.

Quran pledge with the ‘Asr’ in 103:1

By the declining day  – Pickthal

I swear by the passage of time – Wahihuddin Khan

By (the Token of) Time (through the ages) – Yusuf Ali

Jalal – Al-Jalalayn :

By Time! — or [it ‘asr can mean the period] from the decline of the sun to sunset, or [it may denote] the afternoon prayer.

After the end time of the Asr , before Sunset, any prayer is haram. Timing of Asr ends when the Sun turns yellow before setting. It can be explained as the ‘no man’s land’ at the border between two countries. Suppose countries A and B give citizenship by birth, If X is born just before crossing the ‘no man’s land’ from Country A to Country B (ie before the security check of Country A), X will get citizenship of Country A otherwise not.

So, the no-man area of a day starts a few minutes before sunset, when the sun turns yellow. We can refer to this time as ‘Wusta’ end time since the Asr prayer is called Salatul-Wusta.

The exact time of sunset and IDL correction delta factor comes into consideration only when the new moon is born just before/after the sunset of a day on earth. These are very rare cases. In most cases, we will get a clear distinction to decide whether the Al-hilal process happened or not.

Appendix D: Previous Hijri Calendar 1440

Appendix E: Global Vs Local Moonsighting

Ittihad-al-mathla’ vs Ikhtilaf-al-mathla’

The Quran and Sunnah give light to Ittihad-al-mathla’, and our criterion is based on Ithihad-al-mathla’.

Abu Umayr reported on the authority of some of his paternal uncles who were Companions of the Prophet (s): Some men came riding to the Prophet (S) and testified that they had sighted the new moon the previous day. He (the Holy Prophet), therefore, commanded the people to break the fast and to go out to their place of prayer in the morning. (Abu Dawud, Hadith#1153)

In the above hadith, Prophet accepted one day earlier moonsighting report from the riders without ego even after he started fasting. The fastest way of communication at prophet’s time was horse riding. Nowadays there is no limit to get a moonsighting report from a different locality.

“If the sighting of the New Moon is confirmed in any quarter of the Earth then Saum becomes obligatory for the Muslims in all other parts. Differences in the Matla’ (rising of the moon) shall not be considered. This is the uniform judgment of the three Imams. Only the Shafi path differs (Madahibul Arba’ Vol.1, Page:550)

“Muslim Scholars agree that if the natives in one place, in general, observe the new moon, fasting becomes obligatory on all the inhabitants on this earth” (Rahmathul Umma Page: 118)

There is no consideration for the differences in the rising of the moon. This is the interpretation of the report from Abu Hanifa (Fatawa Almagiriya : Vol 1 Page 198)

Concern 1: The prophet asked us to complete 30 if it is cloudy.

When we consider the Hilal globally, the probability for the cloud to cover the Hilal all over the world is 0. Even locally we are accepting moonsighting reports from other places if our backyard or our city is cloudy. This means at the prophet’s time communication was limited, within that limited distance, if it is cloudy, and if there is no way to know the presence of the moon either by news reports from other areas or by calculation, there is no other option except 30-day completion.

Concern 2: If the Fajr is over in an east side country by the time moon is sighted in a west side country, how can we fast?

  • If we follow the Al-Hilal criteria (explained in this document), this issue will no longer exist. We can spot the Hilal from the eastern end of the earth.
  • If you follow only global sighting without calculation, you need to start fast only from the next Fajr after you get to know the moon was sighted in another locality, and if you get to know people of certain other locality could complete 30 days of fasting while you only had 29 days of fasting, the Fatwa is below

“People of the certain locality observed 30 days of fast based on the sighting of the moon and people of a certain other locality observe 29 days fasting based on their sighting of the moon, then those who observed fast for 29 days are obliged to compensate fasting by one more day. The difference in the rising of the moon will not be considered.  (Fatawa Qaadee khan 1:198)

The followers of Abu Haneefa have the above same opinion (Tafsir Qurtubi 2:295)

‘Proof’ against global moonsighting

The Quraib’s Hadith (Sahih Muslim Book 006, Hadith # 2391):

  • It is an event that happened years after the prophet’s wafat; it is not that powerful to overtake the events that happened during the prophet’s lifetime.
  • There are opinions that
    • Abdullah ibn Abbas did not accept it because there was only one witness.(Sharah Muslim 4:212, Tuhfathul Ahwadiyya vol 3 page 379, Sharahu Fatahul Qadeer 2-314, Areedathul Advadi Vol.30 page 211, Ibn Qudama, al-Mughni, 4, 324)
    • It was only Abdullah ibn Abbas’s supposition about the prophet’s instruction – ‘sumoo li-ruyathihi’ (Addarari 1:143, Nailul Authar 4-268)
    • There were political differences between Mu’awiyah in Syria and Medina.
  • The distance between Syria and Medina is about 1000 miles, those who argue for local moon sighting with this Hadith cannot even unite a country, since the countries are wider than 1000 miles, even though all areas fall under the same/different horizon.
  • Those who argue that the prophet didn’t unite Medina and Mecca, cannot even unite a state most of the time, since the distance between Mecca and Medina is about 290 miles.
  • Overall it is against the fact  “a given day for a date”.

Appendix F: Moon observation or Calculation?

During the time of the prophet (s), there were no other methods to understand the presence of the moon, except moon observation, which is why he suggested the natural method, observing the moon to find the starting day of the month. The practice to understand the prayer time was measuring the shadow, nowadays nobody is doing it, since the technology improved a lot. Islam didn’t discourage astronomy but Islam discouraged astrology. Some of the earlier scholars thought both are the same and discouraged both.

The scientific methods are more accurate when compared to methods like measuring the shadow, observing the moon, etc. 

Even, during the prophet’s time there were some incidents reported like i) they broke the fasting early due to fake sunset, ii) Prophet asked to break fasting when he get to know the moon sighting reports from the caravan travelers (caravan travelers were not fasting already) and commanded his followers to come to Eid-gah on the next day.

Imam Al-Subki (Fatawa al-subki Vol 1: 210) recommended calculation years ago “Calculation provides certain and confirmed information, while testimony based on sighting provides only probable information. What is probable cannot counterbalance what is certain”. Sighting the new moon is not `ibadah (an act of worship) in itself. It is a means to achieve the goal of certainty. Now if the goal of certainty can be achieved by a different and more accurate method, then, following such a method will be as Islamic as sighting the moon with the naked eyes.

The Quran says ‘Faman shahida minkum’ (Quran 2:185) :

The general meaning of this verse is

“ …and whosoever of you is present, let him fast the month….” (Pickthal)

Someone translates it as “whoever witnessed the new crescent, let him fast”, and claims local sighting is necessary. This verse does not demand every person, in every city should see the moon, if the sighting is required by all, then whoever witnessed the moon with the naked eye only need to fast. No scholars have that opinion. So, the knowledge about the Hillal or the knowledge about the beginning of the month is important. Even ‘shahadathul kalima’ is all about strong understanding (Ilmul Yaqeen) about Allah and his Rasool.

“Ali bin Abi Talib, Ibn Abbas, Suwayd bin Ghafalah and A’isha, four of the Companions, and Successors such as Abu Mijlaz, Lahiq bin Humayd and U’baydah al- Salmani have said, “Shahida” means whosoever was present when the month started and was resident in his city and among his family, let him complete his fasting…Whosoever was present in the month of Ramadan let him fast.” (Al-Qurtubi, Abu Abdullah, Tafseer al-Qurtubi, Dar al-Kutub al-I’lmiyyah , 2, 290 )

Jalal al-Din al-Suyuti says: Shahida means being “present”. (Al-Suyuti, Jala’l al-Din, Tafseer Jala’layn, Dar Ihya’ al-Tura’th, 37, Al-Razi, Tafseer, 2, 250 )

Also, many explain , that knowing the month (Ibid, 1, 456,  Ibid, 1, 496,)

Also refer Tuhfa 3.381, Minhah 119, Mugni 1-42, Nihaya 1-156, Mahalli 2.50


A global Islamic calendar can be published by precalculating the presence of the Al-Hilal ( the first visible crescent moon on earth). Allah knows the best.

Written by : Shihabudheen Kozhikkoden / [email protected], Concept: Abdul Jaleel Pulikkodan / [email protected], Date: 1st July 2022**
Other references: –
1. Fiqh about calculation
2. IDL Discovery and pictures .3

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