The calendar system according to The Quran

The traditional Islamic calendar (also known as Hijri calendar) is based on a lunar (moon) calendar consisting of 354/355 days. Since this is not aligned with the complete revolution of the earth around the sun of 365.25 days (which is what the commonly used Gregorian solar calendar is based on) it means that the seasons will often be out of sync in the Islamic calendar, e.g. "ramadan" (which means intense heat) can occur in the coldest season, or the Traditional month called "raabi al awwal" (which means "the first spring") can occur in winter. This naming makes little sense and seems to make the calendar impractical. [background]

Is the year according to The Quran lunar or solar?
10:5 He is the One who made the sun a radiance and the moon a light and determined for it* phases that you would know the number of the years and the account...
*singular masculine, to my knowledge this could refer to both the sun and moon or just moon. Sun/shams is a feminine.
17:12 We have made the night and the day as two signs: the sign of the night We have obscured while the sign of the day we have made visible so that you may seek favors from your Lord and that you may know the number of years and the account and every thing We have explained it distinguished.

Since the night and day are determined by the sun and not the moon 17:12 strongly suggests that the year is solar. But 10:5 does hint at both sun and moon being used in a calendar/timing system.
If we were to try and reconcile these verses to make them work together we can use:
9:36 Indeed the count of the months/moons with God is twelve months/moons in God's decree the day He created the heavens and the earth; four of them are inviolable/restricted - that is the upright system; so do not wrong yourselves therein and fight those who set up partners collectively as they fight you collectively. Know that God is with the righteous
9:37 Indeed the nasiu/intercalation is an increase in rejection, those who have rejected are led astray by it. They make it lawful one year and they make it inviolable/restricted one year to adjust the count that God has made inviolable; so making lawful what The God made unlawful. Their evil works are fair-seeming to them...
"nasiu/intercalation" means arbitrary adjustment in order to change the count (of either 12 months/moons or 4 being inviolable or both or perhaps their order). This is also mentioned in Classical Arabic dictionaries albeit there is no consensus on what it means. It just so happens that in some solar years of 365.25 days the number of moons/months could be 13 which would allow for such manipulation and this is likely what these verses refer to. It doesn't really matter what type of adjustment was occurring as it can be eliminated by sticking to the "count" (Arabic: 3idat) as per Quran. The word count/3idat is different to number/3adad. We are only concerned with counting 12 so if there happens to be 13 in one solar year we don't count the 13th one, thus allowing the seasons to remain in sync with the months/moons every year. The seasons being in sync is also alluded to in 12:47 which says "you will sow seven years/sinin as usual/custom" - farmers only work according to the seasons which don't change from one year to the next.
It stands to reason that this intercalation would only be done once it was known whether there was 12 or 13 months/moons that year. In other words it would be done at the end of the year to adjust the following year. The Quran implies and the dictionaries discuss this manipulation was about altering the inviolable months/moons for one's advantage.

According to The Quran "al ashar al haram" (the 4 inviolable months/moons, see 9:36) MUST be consecutive (i.e. 4 in a row). For explanation please see this thread or these specific posts:
https://free-minds.org/forum/index.php?topic=9610235.msg416993#msg416993
https://free-minds.org/forum/index.php?topic=9610235.msg417228#msg417228
https://free-minds.org/forum/index.php?topic=9610235.msg432823#msg432823
The above also refutes the Traditional Islamic calendar (in which they are not consecutive).

Other minor evidence "al ashar al haram" are a quartet (i.e. consecutive, a group of 4):
https://free-minds.org/forum/index.php?topic=9610235.msg417095#msg417095
https://free-minds.org/forum/index.php?topic=9610235.msg417137#msg417137

Quran 9:1-2 mentions an acquittal/release from a treaty with some polytheists and tells them they have amnesty/ceasefire for 4 months/moons and then in 9:3 it mentions this announcement on the greatest day of the hajj or day of the greatest hajj (doesn't seem to matter which interpretation is chosen) but follows in 9:5 by saying when the plural inviolable months/moons have peeled/stripped-off/passed (see PRL or this post for further evidence of the consecutive nature of this word "inSaLaKHha") then those who broke the treaty can be fought. Note the Arabic plural means 3 or more.
I initially thought The Quran was repeating the same acquittal/release in 9:1 in 9:3 again but I should have realised Quran's word precision is there for a reason. The 1st time it mentions 4 months, 2nd time it mentions when 3 or more inviolable months have peeled away. Also note how the beginning of each verse 9:3, 9:4 and 9:5 are linked to each other.
Thus the wording from 9:1-5 suggests the clear possibility that the 4 inviolable months/moons begin - then on the 2nd inviolable moon/month the hajj/homage periods can begin. This aligns with 2:197 which states "hajj are the months (plural: ashurun) well known". Remember the Arabic plural is 3 or more thus a minimum of 3 months/moons are allowed for hajj. If so this would match with 9:1-5.
The question then becomes what could be the first month/moon of the inviolable months/moons (if the last 3 are for the hajj)? The only other "named/described" month/moon given in Quran is "shahr ramadan" so this becomes the obvious candidate. The meaning of "ramadan" is intense heat. In the Northern hemisphere the hottest period begins after the summer solstice (which is around June 21st) and it just so happens the first moon after the summer solstice appears larger and somewhat orange, making it somewhat distinct. Some cultures have called it the rose moon or hot moon [source].

Interestingly when The Quran introduces "shahr ramadan" and then "al hajj" in chapter 2 it is in this order, i.e. ramadan first then discusses hajj immediately after.

We can prove from Quran that "al hajj" and "ramadan" do not coincide (i.e. same moon/month) because in the nights of abstinence one is allowed sexual relations with one's spouse (2:187) but when one is undertaking "al hajj" this is not allowed (2:197) and is only allowed after one fulfills/completes their hajj (which is a minimum of 2 days) see 2:203. Also see 2:196 in which abstinence is given as an option for expiation but this would make little sense if one was already abstaining/fasting in ramadan. And lastly exemption is given for abstinence if traveling but undertaking the hajj would likely involve traveling so seems a mixed message.

If the above is correct it means ramadan and the months/moons that follow would be in a hot period during the year. This seems to be supported by 9:81 which implies during this time a group declined to go with the messenger having said "do not mobilize* in the heat".
*this word is used as early as 9:38 in this chapter.

We can also show the Traditional Islamic calendar clashes with Quran 106:2 which says the so-called tribe of Quraysh journeyed in the shitaa/winter and the sayf/spring. Muhammad Asad notes in his explanation of this verse "i.e. the two annual trade caravans - to the Yemen in "shitaa" and to Syria in "sayf"- on which the prosperity of Mecca depended".
The word "sayf" is often mistranslated as summer because this is the Modern Arabic meaning. In Classical Arabic dictionaries such as Lane's Lexicon and Lisan al Aarab the word "sayf" can mean "spring" or "late spring" (depending on whether the 4 or 6 season calendar is being referred to from ancient Arabia) e.g.
4 season calendar: shitaa/winter, sayf/spring, qayz/summer, kharif/fall/autumn
6 season calendar: shitaa/winter, rabi Awal/early spring, sayf/late spring, qayz/summer, rabi thany/early fall, kharif/late fall.
It may be interesting to note in the 6 season calendar some seasons are split into two which is similar to the naming of some months in the Traditional Islamic calendar suggesting a remnant of the past remains.
No matter which translation of "sayf" is chosen it still poses a critical problem for the Traditional Islamic lunar calendar because ramadan and the inviolable months/moons would sometimes occur in their journey times of "sayf" and "shitaa" meaning they would not be around when masses of people were allegedly congregating for the hajj (e.g. in Mecca, according to traditions). The event of hajj, which has elements of an annual fair, would be a prime opportunity for trade thus traveling elsewhere during this period seems very odd. Monetary/worldly benefits of hajj are alluded to in Quran (2:195-198, 9:18-20, 9:28, 22:27-29). Also it would mean ramadan occurs during their journey periods which seems odd.
In our analysis it would make sense that Quraysh would travel in "sayf/spring" BEFORE the start of the inviolable months/moons to buy goods to sell at the annual event of the hajj. Then AFTER the inviolable months/moons it would also make sense that they use the money they earned during trading and travel to buy goods and/or trade.
Thus 106:2 clearly suggests the inviolable months/moons would occur within a regular pattern of seasons in the year.

To summarise the information we have so far:
Year is solar (365.25 days)
Both sun and moon are involved in the calendar/timing system.
Count of months/moons is 12 per solar year, 4 of which are consecutive inviolable months/moons
The first inviolable month/moon is likely "shahr ramadan" and the latter 3 are for the hajj - and all 4 are in a warm period
The hajj period and ramadan do not overlap/coincide
Seasons are in sync (i.e. regular pattern) in the year
The inviolable months/moons are unlikely to be in spring or winter

As you can hopefully see the information is coming together nicely. However the above system would seem to require a starting/reset point, i.e. a point from which to count 365.25 days and from which to count 12 moons/months. The Quran does not seem to be explicit about this.
Interestingly 9:36-37 suggests that the arbitrary inconsistency was the problem, thus as long as the count of months/moons is 12 and 4 of them are inviolable then we must ask ourselves: as long as we are consistent does it really matter at what point the year starts? I do not think it does and if I am correct then this could explain the northern/southern hemisphere issue.
For example in the northern hemisphere the hot/summer months are at a different time of the year to the hot/summer months in the southern hemisphere. In other words the seasons are at different times in the north and south. If God is All-Knowing and the author of The Quran then obviously God would know this to be the case - so does Quran allow for a solution?

All in the above summary are related to cosmic/natural phenomena, e.g. it doesn't matter if you're in the north/south the earth will still take 365.25 days to orbit the sun, there will still be a "shahr ramadan" (albeit at different times of the year), you can still count 12 months/moons in a solar year etc but if we were to adopt a one size fits all approach and fix/start the calendar to begin from a natural phenomena such as summer solstice or "shahr ramadan" for example then the timing of the year would be different in the north and south, making things somewhat difficult/impractical. Thus ideally we should use something that is common to both north/south and from Quran we know the year is solar so this could be a neutral, albeit arbitrarily chosen, point to begin the calendar, e.g. one point/day in the day/night pattern of 365.25 days.
It just so happens that the most commonly used civil calendar today is the Gregorian solar calendar and both north and south have agreed upon January 1st as a starting point for the year and this seems to work well. This allows unity in time cross communication between north/south and each still have their own seasons, likewise each hemisphere would still have its "shahr ramadan" and inviolable months/moons, but they would occur at different times of the year - there is nothing in Quran to suggest it has to be the same for all people around the world and if the reason behind the inviolable months is related to wildlife hunting/conservation (5:1) then it makes sense they would be different for north/south. Wildlife birth/rearing cycles are tuned to seasonal cycles, which of course would be different in north/south, so it makes sense they would be different north/south.
Also if all the world's muslims were to converge on one spot for a few months of the year it may overwhelm the area so this could be another reason for having the timing difference. This difference in timing can be likened to the situation of the regular/timed salat of the mumineen which occurs at different times around the world - and can work anywhere in the world including the North pole [see here]. Interestingly this can be likened to Quran's implication that only those who witness "shahr ramadan" apply what entails - again allowing this timing system to work anywhere in the world. These examples highlight one of many examples of remarkable word precision in Quran. For those that don't know one objection to Quranic timings is that they do not work for extreme locations (e.g. area within Arctic circle).

The arbitrary nature of using different lengths of time could be demonstrated by the following verses ("hijajin" 28:27, "huquban" 18:60, "hawl" in 2:240, "sinin/sanat" as used in 10:5 and 17:12 and various verses, "3am" in various verses). In 29:14 the latter two are used together suggesting a difference. In none of these occurrences is one term critiqued. The Quran simply seems to relate the stories as is, i.e. whatever timing term they used and referred to is included in the information.

The arbitrary nature of selecting a starting point could, in part, explain the story of how the Traditional Islamic calendar was set by 2nd Caliph Umar. It is also likely there were a few competing calendars at the time and there was a push to differentiate themselves from the common Julian solar calendar (at the time likely associated with the Roman/Christian empire), hence the lunar calendar. This is my speculation of course.

Interestingly Quran does not name/describe any months/moons except one: "shahr ramadan". The inviolable months/moons (al ashar al haram) are a description. This may be because you only need one identifiable point in order to implement this system.

Lastly it has been claimed that the non-possessive singular word "yawm" (day/era) occurs in Quran 365 times and the dual/plural 30 times [source]. The singular word "shahr" occurs 12 times [source]. If true this is an interesting observation and lends support to the above analysis.

The Quranic calendar system described above is simple and could be implemented by any society regardless of what arbitrary calendar they inherited. The cosmic/natural markers are unaffected by the arbitrary decisions (and errors) of people who came before us. Those who wish to follow The Quran can now and in the future make a fresh start and reset the system to this true marker making it a robust timing solution.

Peace.

Feedback welcome, especially corrections (see here).

Miscelaneous and some unanswered questions
The above has presented some formidable arguments against the Traditional Islamic calendar. I personally do not see how they can answer this - hence could be a provable example of a highly significant error in Traditional Islamic practice.

Does "shahr" in relation to timing mean new moon, moon, moon-cycle or full-moon? I can see arguments for each so I still need to think on this. I assume as long as one was consistent it may not matter much.
It is interesting to note that 17:12 uses "know the number/3adad of years" and does not say "know the count/3idat of years". Compare this to use of "count/3idat" in 9:36-37. Firstly from 9:36-37 I can see how a count could be violated but not a number. Secondly the different usage suggests shahr more likely means moon rather than month, albeit they are linked.
2:189 they ask you about the crescent/new moons* say they are timing device for the people and the hajj...
*plural meaning 3 or more. Why are the moons mentioned here not timing for ramadan?
36:39 the moon/qamar We have determined for it phases until it returns like the old date stalk
Can these verses tell us when moon/month period begins according to Quran?

When is the night of measure (97:1)? See first referenced article below for some analysis. I still need to think on this.

We may need to check the above system to see how a leap year would fit in. I haven't calculated this yet.

Further research could be done on the possible reasons behind the inviolable months/moons in the summer period (see 5:1, 5:95 to begin with), likely related to wildlife hunting/conservation/reflection.

Since we can very accurately calculate backwards and forwards in time the moon/sun phases (thus years) using online calculators it might be interesting to look at old inscriptions and alleged timings of historical events according to traditions to see what we find.



Background References:
https://www.free-minds.org/blind_dating (Much of the above was based on this article by brother Ayman)
THE 'YEAR' IN THE QUR'ĀN by F.A. Shamsi
Project Root List by StudyQuran.org
Corpus Quran
https://mypercept.co.uk/articles/meaning-masjid-al-haram-Quran.html
https://mypercept.co.uk/articles/salat-timings-Quran.html
https://mypercept.co.uk/articles/Quran-2196-critical-thinking.html
https://mypercept.co.uk/articles/meaning-hajj-Quran.html



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More articles: https://www.mypercept.co.uk/articles


This work would not have been possible without the many people who have contributed to this topic, and without the resources now available to anyone wishing to study The Quran in detail. For these stepping stones I am indebted and truly thankful.

IMPORTANT DISCLAIMER:

This work reflects my personal understanding, as of 2nd Aug 2024. Seeking knowledge is a continual process and I will try to improve my understanding of the signs within 'the reading' (al quran) and out with it, unless The God wills otherwise. All information is correct to the best of my knowledge only and thus should not be taken as a fact. One should always seek knowledge and verify for themselves when possible: 17:36, 20:114, 35:28, 49:6, 58:11.

And do not follow what you have no knowledge of; surely the hearing, the sight and the heart, all of these, shall be questioned about that. [17:36]