1. Conjunction (New Moon)
2. Age: Youngest Moon
3. Big Moon (must be second day moon?)
4. Why not with Saudi Arabia
5. Moon in Qur'an, Sunnah, & Fiqh
6. Month is 29 or 30 Days
7. Astronomy Questions
8. Eclipses Questions
9. Sighting Questions
10. Sighting Criteria
In South East Asia there's Mohammed Ilyas, currently residing in Pulau Pinang, Malaysia. I assumed you already knew him. I've read some of his books. His method in the determination of the new visible moon is highly complex. From what I gathered the criteria used by South East Asian countries to determine the hilal is, at sunset, at least 2° altitude for the moon, 8 hr. after conjunction and 3° hypotenuse difference between the sun and the moon. That criterion is used if the hilal is hidden behind the clouds. Can you please tell me if this method is feasible? (Oct 19,1997)
I, Khalid Shaukat know Dr. Ilyas personally. I have spent some days with him, attending conventions for moon-Sighting and Islamic calendar. His criteria are very approximate, and have failed many times since 1996, that I have monitored regarding actual moon-sighting. The criteria described by you are not his criteria. They are the criteria adpopted in South East Asian countries, and will not yield a visible crescent.
Your model for predicting the new moon and the confirmation of the model by verification of moonsighting has demonstrated that we are on the right path. The problem is that many Middle Eastern countries and some of the U.S. & Canadian communities led by Middle Eastern immigrants assume Saudi decision on new moon as having sighted the new moon.
Your observations may be correct that the Saudi months start with the new moon and not observing the new crescent moon. This status will never change unless the source of the problem is corrected, which is the criterion used in decision making process in Saudi Arabia. You should increase your efforts to contact the right people. They will not listen to the Pakistanis or Indians (Rafiq's). The only way is to educate and convince influential Saudis visiting here. You need one right Royal family individual or a religious leader, who can understand your system. They may be able to make a difference, otherwise present chaos will continue. GOOD LUCK
If that can be done, I can foresee Muslim Ummah united in at least their observation of Ramadan and Eids. (Jan 1, 1998)
We are trying to educate Muslims all over the world as well as Saudi Arabia. In-sha-Allah with our sincere efforts something good will come out with the help of Allah. May Allah bless you for your concern, and show guidance to all of us including the decision makers all around the world.
I compared your predicted moon dates with the US Naval Observatory data, unfortunately there are differences between these two. I am not an astronomer (I am Chem. Engineer) and don't know how you calculated those dates. Is there any reason that yours is not compatible with theirs?
It looks to me that you are confusing "New moon" reported by US Naval Obs. with a visible crescent. "New moon" reported by US Naval Obs. is totally invisible. Any Islamic dates based on that would be 1 or 2 days ahead. We calculated dates based on a crescent that could be seen.
What is the minimum angular separation required to see the new crescent? How can I calculate it for a particular place and date for a new born moon? (Dec 21, 1998)
Minimum separation (elongation) for visibility, statistically known, is about 10.5 to 11° for naked eye, and about 7.5 to 8 for powerful telescopes. Remember, these are for perfect atmospheric conditions, which do not exist most of the times and places. To calculate this separation is not easy. It requires a lot of mathematical terms to calculate the positions of sun and moon based on local horizon in question, and then their separation angle is calculated using spherical trigonometry. The more accurate lunar theory and calculation methods you use, the better the results would be.
How much time is required for the 1st hilal to remain in the sky after sunset for visibility according to your findings? Why it is invisible if it remains above the horizon for more than 40 minutes after sun set? (Jan 20, 1999)
Time varies for locations and months. On one particular evening a crescent may be thinnest in Japan but the same crescent will be 15 hours to 18 hours thicker in USA, and would remain in the sky above horizon at different latitudes for different duration.
Sometimes the crescent may remain above horizon for more than 1 hour but it may not be seen, because it does not have any light of its own; it merely reflects sunlight, which it can only reflect if moon is at least a certain angle from the sun. Even when it meets minimum angle requirement, in some cases, the crescent is invisible because of being too low on the horizon, such that the background light of the setting sun on the horizon is brighter than the crescent.
If you understand that moon does not have its own light, then its presence on the sky does not mean it is visible. You should realize that on 28th or 29th evening of a lunar month the moon disappears from sight; this is mainly for the same reason that it is not at sufficient angle to reflect sunlight.
How long it takes for the moon to get a separation of 7° from the sun, which is considered as the limit for which the sun light falling on moon cannot come to the earth, and moon remains invisible? (Nov 20, 2000)
It takes a minimum of approximately 8.5 hours to 15.5 hours for the moon to move 7° away from the sun. 8.5 hours is the case when the moon is closest to earth and is 5° from the ecliptic plane at the time of moon birth (example: Dec 14, 1955). 15.5 hours is the case when moon is farthest from the earth and is 0° from the ecliptic plane at the time of moon birth (example: Dec 10, 1977). The crescent will be visible to the high powered telescopes about 2.5 hours after it has attained 7° angle from sun, i.e., at 11 to 18 hours of age. To the naked eye it would be visible at 16 to 23 hours of age.
The US Naval Observatory's site can provide the percentage of the moon's illuminated area for a given place and time. My question is, approximately, how much area (in terms of percentage) should be illuminated for the crescent to be seen?
Surface illumination is not the only factor that will make it visible. If that moon is too low on the horizon, such that the background sky illumination from the setting sun is more than moon's surface illumination then the moon will not be visible. Sky background illummination also depends on many other factors, like pressure temperature, humidity, particulates in the atmosphere, the distance the rays from moon travel in the atmospheric layer, the distance between moon and earth, the distance between sun and earth etc.
What could be the safe lower limit on the age of the moon, so that any claim before that limit can be safely disregarded?
Safe limit would mean that any claim before this should certainly be rejected but it does not mean that a claim after this should be accepted either.
What would such safe limit be for naked eye and what would it be for telescope? (Feb 2003)
11. Ittihad-ul-Matali' or Ikhtilaf-ul-Matali'
12. Eid-ul-Fitr and Yaumul-Arafah
The crescent for the new moon of Shawwal was not sighted (with the eye) by Muslims anywhere across the world today, Tuesday, Jan 27, 1998. Therefore we continue to fast tomorrow (Wednesday) to complete the 30 days. Why we cannot have Eid, when 30 days are completed? (Jan 27,1998)
This 30 day complete argument is wrong. If you start fasting before new moon was even born, then you did not start the month on the right day. 30 day complete argument is only good when the previous month began with the correct sighting of the moon, and not by mistaken claims.
All experts of the world about moonsighting are unanimous that moon can not be seen in Asia, Europe, Africa, South America, and East coast of North America on Jan 28, 1998 (Wednesday). Non-sighting of the moon after 30 days is a clear proof that the month did not begin correctly, otherwise moon is always visible on 30th day, given clear skies.
I have noticed that the moon was visible more than two hours after sunset, and it seems to be big. Some people may ask me about this, and I want to have an answer. Does this mean anything. Does it favor the fact that Eid is supposed to be on Friday, Jan 7, 2000 instead of Saturday. (Feb 13, 2000)
No, certainly not. It does not favor the Eid of Friday. Khalid Shaukat and many other tried to see the moon in Washington DC area even on Friday, Jan 7, 2000 and the finding was that despite very clear horizon (no clouds) and moon setting 1 hour after sunset, we could not see the moon even on Friday. That means the moon was impossible to see the day before.
The moon is visible all over the world within about 36 hours of the time it becomes visible first, except the polar regions. So, non-visibility in clear horizon on Jan 7, was a clear proof that it was not visible in that area the day before. Now moon was sighted in Texas, Arizona, and westward on January 7. So, even though it was not visible in Washington DC area we celebrated Eid on Jan 8, based on (Ittihadul-Matali) one horizon.
Now moon was visible more than 2 hours on Jan 8. Yes, of course; same thing happenend in Washington DC area. Even on Jan 7, it was setting 1 hour after sunset, but it was still not visible. So, do not look at a big moon of Jan 8, and estimate when could it have been visible. On Jan 6, in Washington DC area it was 4 hours old; on Jan 7, it was 28 hours old still not visible, and on January 8, it was 52 hours old. Age is very misleading factor for visibility. Moonset after sunset also is misleading for visibility. Also remember that moon sets about 50 minutes later every day, so on the third day you can expect it to set after two hours.
What is the definition of "YAWM ARAFAH" and how are we going to fast "YAWM ARAFAH" for example Monday, March 5, 2001 is 9th Dhul-Hijjah in North America and it is day of EID for Hujjaj.
Hujjaj do not have a day of Eid. They never pray Salatul-Eid. According to all four school of thoughts, fasting is on the 9th of Dhul-Hijjah based on local sighting. This has been the way for over 1300 years. Just 50 years ago, people in Iran, Afghanistan, and Far East did not know when YAWM ARAFAH was in Makkah. How were those Muslims fasting on YAWM ARAFAH, or was their fast invalid? Also remember, that Hajj was prescribed seven years after Eid-al-Adha was prescribed. so, saying that Eid-al-Adha has always been on the day after hajj is not right.
Based on authentic moonsighting, when was Eid-al-Fitr 1423 AH?
On 4th Dec 2002, the crescent was invisible from almost all areas of the world. There was a remote chance of seeing it off the west coast of South America / Polynesian Islands on 4th Dec 2002 with optical aid but no reports were received. Reports from Hawaii say that moon was not seen in clear skies.
ISNA's methodology for determining the beginning of Ramadan and Shawwal for North America has been consistent since 1993. ISNA keeps telephone lines open to receive any witness of sighting on the relevant evenings. After receving the witness ISNA asks its astronomer consultants to evaulate it by talking to the witness. If the witness of sighting contradicts with indisputable scientific evidence then only it is rejected. This time for Shawwal 1423, not a single claim came to ISNA on Dec 4. ISNA waited until 6:30pm PST which was 90 minutes after sunset on west coast giving ample time to receive any witness of sighting. It was past 10:30pm on East coast of Canada and was getting too late in the night. Finally ISNA and Shura Council made their decision to call Dec 5 as 30th day of Ramadan, and Dec 6 to be Eid.
Based on authentic and correct moonsighting, Ramadan started in North America on Nov 6, 2002, while it started in India, Pakistan, & Bangladesh on Nov 7. Eid was celebrated on Friday Dec 6, in all the following countries:
(1) Japan (2) Indonesia (3) Malaysia (4) Singapore (5) Brunei (6) Bangladesh (7) India (8) Pakistan (9) Afghanistan (10) Iran (11) Oman (12) Mauritius (13) Kenya (14) Tanzania (15) South Africa (16) Morocco (17) UK (18) Trinidad and Tobago (19) USA (20) Canada
The problem is that when Saudi Arabia or any other country announced that Eid is on Thursday, Dec 5, 2002, people translated it as if the moon has been sighted there. In fact, about a week before moonsighting day, on Nov 27, Saudi Arabia declared Dec 5 as Eid day, as evident from a fax received by a prominent ISNA Shura member who mentioned it in the Shura Conference Call on Nov 27. How did Saudi Arabia see the moon a week before the 29th day of Ramadan?
Dr. Saleh AlSaab, former head of the Astronomy Department at the King Abdul Aziz City for Science and Technology in Riyadh, currently teaching at the Institute for Gifted and Talented in Riyadh, reported that NONE of the 6 official Hilaal sighting committees saw the Hilaal on Wednesday evening. Yet the offical Saudi announcement was for Eid ul Fitr on Thursday, Dec 5! Jordanian Astronomical Society sent an airplane with expert observers with instruments to try to see the moon from above clouds, and they did not see anything on Dec 4.
Just because some cities or countries are celebrating Eid on Dec 5, 2002 does not mean they have seen the moon. They may be basing their decision on some calculations. A pious Muslim's testimony of spotting some other object for a moon does not fulfill Shari'ah requirement when he is clearly mistaken by scientific evidence as Allah (SWT) says, "Ashshamsu wal-qamaru bi-husbaan".
Abdul-Rashid Abdullah from Oahu Hawaii reported: "On Dec 4, five teams of at least 3 brothers each went to sight the Hilal all around the Leeward (west) side of Oahu and 1 team on Kauai. The skies were reasonably clear but there was no sighting of the Hilal." Remember, the most West has the best chances of visibility on any given day.
The conclusion is that moon was not sighted anywhere in North America nor any place East of it on Dec 4 2002.
Any sighting claim has to be rjected because the moon was invisible, and people make mistakes in taking other objects (jet smoke, thin piece of cloud, helicopters, etc.) for the moon.
I heard that Saudis have hilal sighting committees. Those committees did not see the moon on February 1, 2003. Hajj date, however, was announced by Saudi authorities as February 10. You say sighting was not possible. Was it based on Ummul-Qura calendar? (Feb 4, 2003)
Answer: Dr. Saleh Al Saab (Previous head of Astronomy and Geophysics Institute at KACST), (Consultant and Member of the 6 Official Saudi Hilal Sighting Committees of Saudi Arabia established by the Crown Prince/Shura Council in 1419 AH) reported: "The 6 Official Saudi Hilal Sighting Committees from Makkah, Riyadh, Qassim, Hail, Tabuk and Asir; attempted Hilal observation on the evening of Friday, January 31st, 2003 and on Saturday, February 1st, 2003. The Hilal was not seen by individuals and collective members of the 6 Committees under clear skies using naked eyes, telescopes and binoculars." This means that Saudi Hajj announcement is either based on Ummul-Qura calendar or false sighting claims.
13. Dates in Islamic History
The Prophet (Peace be upon him) went to Arafat on Friday the 9th Dhul-Hijjah of 10 AH which was on March 6, 632 CE. Is it correct according to calculation? Give detailed answer with exact time? (Dec 30, 1998)
Very correct. The calculation confirms that new moon occurred at 21:07 GMT on February 25, 632 CE (Tuesday). On the following day, February 26, 632 CE in Medinah, the calculations for the moon show the following results:
Sunset at 6:25 pm, moonset at 7:04 pm. At sunset, the elongation is 10.1, Age of moon 18.3 hours, and Altitude above horizon 7.6°. Moreover, in those days there were no city light and the sky was definitely darker than these days. This is a greater factor in visibility at that time.
This crescent was visible on February 26, 632 CE (Wednesday), and the 1st of Dhul-Hijjah was on February 27, 632 CE (Thursday). Therefore the day of Arafat, 9th Dhul-Hijjah was on March 6, 632 CE (Friday).
What was the date for sun eclipse when our Prophet's son Ibrahim died?
Sun Eclipse occurred at Prophet's time when (his son) Ibrahim died. It was recorded in history that it was Jan 27, 632 CE (Monday), See the details of this eclipse. It was the 29th of Shawwal, while Dhul-Qi'dah 1, 10AH was on Jan 29, 632 CE (Wednesday). Dhul-Qi'dah was of 29 days also and Dhul-Hijjah 1, 10AH was on Feb 27, 632 CE (Thursday), such that Hajj-e-Nabavi fell on Friday, March 6, 632 CE.
All the solar eclipses that could be noticeable in Arabia during the prophethood of Muhammad (peace be upon him) are listed below (For details of any eclipse, click on it):
Sun-Eclipse visible while Prophet was in Makkah:
(Islamic date unknown because of undocumented practice of Nasi')
- July 23, 613 CE (Monday) - Around 10 am Local Time
- May 21, 616 CE (Friday) - Around 10 am Local Time
- November 4, 617 CE (Friday) - Around 11 am Local Time
- September 2, 620 CE (Tuesday) - Around 10 am Local Time
Sun-Eclipse visible while Prophet was in Medinah:
- April 21, 627 CE (Tuesday) - Dhul-Qi'dah 29, 5 AH - Around 11 am Local Time
- January 27, 632 CE (Monday) - Shawwal 29, 10 AH - Around 10 am Local Time
What was the date when our Prophet (Peace be upon him) died? Some people say, "It was 28th Safar;" others say, "It was 12th Rabi-al-Awwal;" yet others say, "It was 9th Rabi-al-Awwal." Can you throw some light on it?
Hadith books report that it was Monday when our Prophet (Peace be upon him) died, and it was about 3 months after the Hajj-e-Nabavi. 12th Rabi-al-Awwal date was considered based on a Hadith (book by Baihaqi), which reports, "The Prophet's death occurred after passing 12 nights of Rabi-al-Awwal, and it was Monday." So, after passing 12 nights, the day of 12th Rabi-al-Awwal starts and that was considered as the death date of our Peophet (Peace be upon him).
Moomsighting calculations for the month of Safar, 11 AH reveal that moon was visible in Medinah on Sunday, April 26, 632 CE. This means that 28th Safar was on Sunday, May 24, 632 CE. 28th Safar started on the evening of Saturday, May 23, 632 CE. So that date cannot be correct.
Moomsighting calculations for the month of Rabi-al-Awwal, 11 AH, reveal that moon was difficult to see in Medinah on Monday, May 25, 632 CE. So, if the moon was seen on May 26 (Tuesday) evening, then first of Rabi-al-Awwal was on May 27 (Wednesday), 8th Rabi-al-Awwal was on June 3 (Wednesday), 9th Rabi-al-Awwal was on Thursday, 12th Rabi-al-Awwal was on Sunday, 13th Rabi-al-Awwal was on Monday, June 8, 632 CE (Julian Calendar).
History says, that on 10th Muharram 61 Hijri (Friday), Hazrat Imam Husain (Alihis salam) was martyred. But if I calculate by the software I find the day was Wednesday, Oct 10, 680 CE instead of Friday. What could be the reasons for this discrepancy?
How accurate is new moon time calculation. Does software need any correction (after any time interval) to get accurate result when new moon occurs? If we go 1400 years back to calculate, will we get accurate new moon time and accurate visibility area?
The calculations for new moon need some correction because of long passage of time (like 1400 years). The new moon calculations by U.S. Naval Observatory is fairly accurate for this passage of time. However, visibility calculations softwares I have seen do not account for corrections needed for old times. I have written my own program, to apply such correction.
The new moon for Muharram 61 Hijri was on Sep 28, 680 CE (Friday) [This is the date according to Julian Calendar as the Gregorian Calendar took effect in 1582 CE], but the moon age on that day at Maghrib time of Karbala was less than 2 hours. So it can only be visible the next day, Saturday, Sep 29, and the 10th Muharram 61 Hijri would be Tuesday, Oct 9, 680 CE. I have been a student of Islamic history, and I have not seen the day of 10th muharram 61 Hijra being mentioned as Friday.
What was the solar date on 1st Muharram 1st Hijri?
The practice of Nasi' was abolished in Zul-Hijjah of 9 Hijri (See Surah Tauba in Qur'an 9:37), when Hajj was made obligatory. If we calculate pure lunar months back from that month, it comes out to be 8 full lunar years and 11 lunar months before the month of Zul-Hijja 9 Hijri. That makes it 107 lunar months before Zul-Hijja 9 Hijri.
Looking at the moon birth 107 months before Zul-Hijja of 10 hijri, the moon was born on July 14, 622 CE (Wednesday). The moon age on that day at sunset of Makkah was 10.5 hours and moonset was 17 minutes after sunset.
The moon was 2.8 degrees above the horizon. These parameters are not sufficient to make the moon visible. The visibility of moon in Makkah or Medinah was only possible on July 15 and not before that. Therefore, the 1st of Muharram would have been on July 16, 622 CE (Friday).
Does anyone know exact date (in Gregorian Calendar) of the Prophet's (pbuh) birthday, 12th Rabi' al Awwal? (Dec 15, 2012)
Back in those days, the Chritian calendar was Julian Calendar, not the Gregorian Calendar. Gregorian Calendar started in 1582 CE in USA, 1752 CE in UK, and in many countries as late as 1911 CE.
It was certain that the Prophet was born on Monday, the 12th Rabi al-Awwal. Different historians give the year of birth as 569, 570, 571 based on their understanding of the calendar problem. Different reported dates include the following:
|Nov. 4, 569 (Monday)||It cannot be correct because most tradition report that the Prophet was born in spring season|
|April 21, 570 (Monday)|| |
|April 20, 571 (Monday)|| |
|April 22, 571 (Monday)||It cannot be Monday. The correct date for Monday was on April 20, 571|
So, the two dates remaining to be deciphered are April 21, 570 and April 20, 571, whether they were on the 12th Rabi al-Awwal.
To solve this puzzle, I took an independent approach. Since we know that a practice of intercalation (Nasi') of inserting a 13th month was going on in Arabia by Jews as well as by Arabs, I looked at the Jewish calendar in great depth. Jewish calendar has a cycle of 19 years, beacuse after every 19 years the moon phases repeat on the same solar dates. This is called Metonic Cycle in astronomy. Also Jewish calendar always starts from 1st of Tishri, which always comes close to Autumnal Equnox (September 22).
Looking for Jewish calendar of 568 CE to 571 CE, I found the start of Jewish year as shown in the following table:
|Metonic Cycle||Jewish Year||Days in year||1st Tishri|
|16 ||4329 ||355 ||Sep 8, 568 Saturday|
|17 ||4330 ||383 ||Aug 29, 569 Thursday|
|18 ||4331 ||354 ||Sep 16, 570 Tuesday|
|19 ||4332 ||385 ||Sep 5, 571 Saturday|
In those days, Nasi' month, Adar I, lined up with Arab's Nasi' month of Zhul-Hijja. So, corresponding months in each of the three calendars (Jewish, Arab, and Christian) were as follows:
| ||Jewish Calendar||Arab Calendar||Christian Calendar|
|1 ||Tishri ||Sha'ban||September/October|
|3 ||Kislev ||Shawwal||November/December|
|4 ||Tevet ||Zhul-Qi'da||December/January|
|5 ||Shevat ||Zhul-Hijja||January/February|
|6 ||Adar I (only in leap year)||Nasi' Zhul-Hijja||February/March|
|6a ||Adar (Adar II in leap year)||Muharram||March/April|
|7 ||Nissan ||Safar||April/May|
|8 ||Iyar ||Rabi al-Awwal||May/June|
|9 ||Sivan ||Rabi al-Thani||June/July|
|10 ||Tammuz ||Jumada al-Oola||July/August|
|11 ||Av ||Jumada al-Ukhra||August/September|
|12 ||Elul ||Rajab||September/October|
Knowing that Rabi al-Awwal lined up with Iyar of Jewish calendar I calculate dates for Monday near 12th Rabi-al-Awwal based on possible sighting of the new moon in Makkah. The results are as follows:
|Year ||Jewish Date||Arab Date for Monday||Julian Date|
|569 ||Iyar 12, 4329 ||12th Rabi al-Awwal||April 15, 569 Mon|
|570 ||Iyar 14, 4330 ||13th Rabi al-Awwal||May 5, 570 Mon|
|571 ||Iyar 10, 4331 ||9th Rabi al-Awwal||Apr 20, 571 Mon|
Monday, 12th Rabi al-Awwal falls on April 15, 569 CE, matching spring season. Year 569 is 53 years before Hijra (year 622 CE) and 63 years before Prophet's return from this world (year 632 CE). So this must be the birth date of the Prophet.
Can some one calculate the exact date for splitting of Moon (Shaqqul-Qamar) reported in Hadith:
Yes, Khalid Shaukat has calculated the exact date of this event with the following detailed explanation:
Muslim historians wrote that the non-Muslim Arabs asked the Prophet if he could show them some miracle or supernatural sign for them to accept him as a Prophet from God. So, he, pointing his finger to the moon, split the full moon (Shaqqul-Qamar) such that each half of the split moon moved away from each other. Historians including Ibn-Sa'd mention that it happened on full moon (14th night of the lunar month) about five years before Hijrah. Search for full moon seen at night in Mecca about 5 years before Hijrah year of 622 CE reveals the following dates:
May 26, 617, Thursday, 7:51 am Mecca time
June 24, 617, Friday, 5:55 pm Mecca time
July 24, 617, Sunday, 2:24 am Mecca time
August 22, 617, Monday, 10:23 am Mecca time
September 20, 617, Tuesday, 6:56 pm Mecca time
October 20, 617, Thursday, 4:50 am Mecca time
November 18, 617, Friday, 4:24 pm Mecca time
December 18, 617, Sunday, 5:33 am Mecca time
January 16, 618, Monday, 8:10 pm Mecca time
February 15, 618, Wednesday, 12:04 pm Mecca time
March 17, 618, Friday, 4:49 am Mecca time
April 15, 618, Saturday, 9:32 pm Mecca time
May 15, 618, Monday, 1:06 pm Mecca time
June 14, 618, Wednesday, 2:48 am Mecca time
July 13, 618, Thursday, 2:34 pm Mecca time
Of these, only the dates shown in bold are full moon at such time of night in Mecca that it was not too late at night and people were usually awake to witness such event. However, only one out of these three dates, September 20, 617, is just exactly 5 years before Hijrah. The other two dates would be 4 years and 3 to 6 months before Hijrah. So, in my opinion, September 20, 617, Tuesday was the date of Shaqqul-Qamar (when it was the full moon on 14th Muharram, 5 years before hijrah. History also reports that a King of Malabar in India also witnessed Shaqqul-Qamar, and reports say that so impressed he was that he traveled to meet the Prophet and pledged his allegiance to Islam. The clock time in India would have been about 9:30 pm, which seems a reasonable time for witnessing such an event, not too late at night and not too early in the day time.
14. Suggested Global Islamic Calendar
I like the proposal of Moonsighting.com for global islamic calendar that takes 12:00 Noon UTC (or GMT) as the cut-off time for the month to begin everywhere in the world. However, Islamic day begins with Maghrib. In the case of Ramadhan, for example, those living close to IDL - theoretically may have to offer Taraweeh Prayer even before conjunction - in case conjunction is to happen close to midnight at IDL locations (which of course is close to 12 Noon UTC). Hence my suggestion is to keep the cut-off time at 6:00 (am) UTC. This - I believe - would take care of the above issue.
Yes, you are right in saying that those who live close to IDL - theoretically may have to offer Tharawih even before conjunction. But this will happen very rarely and only to the areas that are 3 to 4 time zones west of IDL, say, New Zealand, Australia, and Japan. For those rare ocassions, Taraweeh prayer for those areas can be ommitted for the first night as it is not ("Fard") obligatory. This does not pose any problem.
The problem in your suggestion is that if we take 6:00 am UTC, cutoff time then if the conjunction occurs at 6:01 am UTC (0:01 at 90W longitude), the moon would be 18 hours old at local Maghrib time and it could be visible, and we would be asking them not to start the month. At 90W longitude, there are large areas of Central America and North America where people could see the moon. This situation in my suggestion would occur at IDL, where there is no big land mass, and hardly any Muslims to see the moon. This is the very specific reason to choose 12:00 Noon UTC.
What is the accuracy of calculated Islamic calendar, such as adopted by ISNA, and what is the probability of the calculated calendar being wrong? How the issue of different longitude and latitude is handled with one calendar for whole world?
The calculated Islamic calendar adopted by Fiqh Council of North America (FCNA) and ISNA is based on very exact calculations. Its position is that Ittihadul-Mataali' should be adopted for the sake of global unity. To exercize this Ittihadul-Mataali' Ulamaa' of FCNA decided to follow The European Council for Fatwa and Research (ECFR), headed by Dr. Yusuf Qaradawi states that the sighting was not a requirement but just the means of ascertaining the beginning of lunar cycle for a new month, and that is now attained by exact calculations.
The criteria are that after conjunction somewhere on the globe, at local sunset, the angle between sun and moon should be at least 8 degrees and moon should be at least 5 degrees above horizon. The presence of moon above horizon at sunset somewhere on the globe results in the possibility of sighting, whether by naked eye or by telescope. If these conditions are met, the month starts the next day, otherwise the month starts on the day following next day.
To see the details of ECFR criteria, please see the answer to Question No. 10.10 on this web page. (2009)
15. Visibility Maps
Why do you not provide time stamps for the various maps (showing lunar visibility across the planet)? Or even show several hourly maps (or animation) that showcase how the lunar visibility changes in the course of 24-48 hours of interest. As it is; the map is incomplete as it provides the lunar visibility area, but at what time?
The visibility maps are not for any specific time. They are composit maps, showing the visibility after local sunset at every point (latitude and longitude) on the globe for a specific date shown on top left.
Your visibility maps (showing lunar visibility across the planet) many times show that Saudi Arabia is out of visibility zone, yet Saudi announcement comes they have seen the moon. Is there a possibility that your calculation have some error?
SAUDI DATES: We recently found out that many a times Saudi sightings were before sunset. Saudi desert areas have been known to be without any city lights, or city pollution. It is well known that Saudi Bedouins (Baddoos) see stars in the day time. So, it is very possible that they see the new crescent moon before sunset (sometimes several hours before sunset). Please note that our visibility maps are calculated for visibility at local sunset time at every point on the globe for a specific date. All those calculations are based on the collected observation data after sunset (from 1860 AD to the present) from different locations on the globe. The data of observations we have were all from cities which have city lights, city pollution and after sunset. We do not have any data for sighting before sunset. New evidence show that Saudi claims of sighting comes from desert areas and many times the sightings were before sunset. We, at moonsighting.com started calculating the possibility of sighting before sunset, and our finding for sighting possibility before sunset (under consideraion of Saudi desert areas) was a big surprise. The moon being few degrees above the horizon before sunset may have been seen, which would set in a short time and would not be visible if people try to see it after sunset. It should also be noted that the new crescent moon in desert areas with dry climate and no city lights and no city pollution would have very different refraction effects.
My scientific basis to believe such sightings are three things; elongation being more than Danjon limit, thickness of the crescent more than 0.11 arcminutes and human optics of desert dwellers. Human optics cannot be put in calculations. On this scientific basis I think sightings before sunset may be possible. Such moon may not be seen if the observer waits to see after sunset because many a times, it sets while Muslims still are praying Maghrib prayer, thus making it invisible after sunset.
You can see a Table for actual Saudi dates on www.moonsighting.com/actual-saudi-dates.pdf from 1389 AH (1969 AD) to the present.
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Updated May 3, 2022
16. Full Moon