HISAB is an Arabic word, which means accounting or arithmetic. And arithmetic is the fundamental of mathematics that includes the operations of numbers that lays the foundation of the subject for students.
So it isn’t a surprise that astronomy has a lot of maths in it, including the calculation method of determining the presence of hilal (crescent moon) in Islamic astronomy (ilmu falak).
Rukyah, on the other hand, refers to the simple method of seeing the hilal with our own eyes, with or without the aid of sighting instruments such as binocular or telescope after the sun sets at the end of a Hijri (Islamic calendar) month for the purpose of determining the beginning of the next month.
But don’t be deceived by the word rukyah in imkanur rukyah because there is nothing rukyah about it at all, as it is basically another form of hisab.
Only when the hisab methodology, which can determine the presence of hilal much earlier, is followed up with rukyah on the appointed day, then the rukyah term in imkanur rukyah makes perfect sense.
Imkanur rukyah is the preferred method of Mabims countries (Brunei, Indonesia, Malaysia and Singapore) in determining a new Islamic month.
For the uninitiated, in the Islamic calendar, the new crescent moon marks the start of a new month. Although it takes 29.5 days for the moon to go through all of its phases, it isn’t practical for a month to have half a day.
Hence, an Islamic month can have either 29 or 30 days. The number of days in each month depends on when the new crescent moon is first sighted.
On the 29th of each Islamic month, Muslims go out after sunset looking for the moon. If you can see it on the 29th, then that month has 29 days. If you cannot, it means that month has 30 days.
The hisab methodology is the most scientific, accurate and objective way of knowing in advance whether on the appointed day (Ramadan 29), hilal can be sighted.
However, it is just merely a predictive tool, albeit a useful one – a theoretical construct of pure science, which will show objectively the existence of hilal. However, whether the hilal could be seen by all inhabitants of the earth, as predicted by the hisab is another matter.
And this becomes subjective because the moon does not produce its own light. The only way we can see it on earth is because it reflects light from the sun.
The eight phases of the moon
In astronomy, there are eight phases of the moon, beginning with the new moon where the side of the moon facing the earth is not lit up by the sun at all – and so the new moon is invisible at this phase.
The next phase is the waxing crescent, where a small portion of the moon’s surface is lit. This is the phase, which marks the new Islamic month.
This is followed by the first quarter, the waxing gibbous and finally the full moon.
After this phase, the moon appears to get smaller (waning), going through the reverse process of a waning gibbous, last quarter and waning crescent, before the cycle is repeated.
Thus, the relevant hilal to be sighted is the waxing (growing) one, that is, the first to appear immediately after the new moon phase.
So in essence, hilal visibility varies internationally, just like the sunset and sunrise times throughout the globe.
This has led to some countries marking religious holidays on different dates, which is not peculiar to the festivals of Islam only especially if a lunar calendar is used.
If this is all there is to it, the matter can be settled by hisab rather quickly. But things are not so straightforward because in astronomy, there are certain conditions for the hilal to be visible, namely:
1. The sun must be below the horizon, as it needs to be dark enough to spot the small slither of the new crescent;
2. The moon needs to be above the horizon (a moonrise); and
3. The moon and the sun need to be far enough apart in the sky. This is known as the Danjon limit, which is an estimate of the smallest angular separation (centre to centre) between the sun and the moon at which a lunar crescent can be seen.
French astronomer André-Louis Danjon (1890-1967) set the value at about 7º based on the crescent observations available to him in the early 1930s.
No one questions condition 1 but there are disagreement among Muslim astronomers on condition 2 pertaining to how high must the moon be above the horizon, giving rise to differences in variables like the angle of elevation in relation to the azimuth and the sun, and so on for the hilal to be seen.
In the case of condition 3, disagreement also arises on how far apart in the sky the moon and the sun need to be because if the moon is too near the sun at sunset, it would be almost impossible to see the hilal in the form of a very thin curved line.
So the issue is no longer a simple one between the proponents of rukyah versus hisab, which was so pronounced in the 1960s-70s.
Now even among the proponents of hisab, including imkanur rukyah, they disagree among themselves precisely because each has a different idea of what values to put in the variables mentioned above.
Even among the conventional astronomers, they disagree about the value of the Danjon limit.
So what is the resolution? Back to basics to see what the Prophet said on the matter. According to a hadith narrated by Muslim:
“Kurayb said: Umm Fadl, daughter of Harith, sent him (Fadl, that is, her son) to Mu’awiyah in Syria. I (Fadl) arrived in Syria… It was there in Syria, Ramadan commenced. I saw the new moon (of Ramadan) on Friday. I then came back to Medina… Abdullah ibn Abbas asked me… When did you see it? I said: We saw it on Friday night. He said: (Did) you see it yourself? I said: Yes, and the people also saw it so they observed fast and Mu’awiyah also observed fast. Thereupon he said: But we saw it on Saturday night. So we shall continue to observe the fast until we complete 30 (fasts) or we see it… I said: Is the sighting of the moon by Mu’awiyah not valid for you? He said: No; this is how the Messenger of Allah has commanded us.”
We can see the above hadith as a “depiction” of the argument between two proponents of the rukyah as the science of astronomy, which is the basis of hisab wasn’t fully developed in the world then.
So when in another hadith, the Prophet advised when the actual position of the month is concealed on account of cloudy sky, then count 30 days, the context of his saying is after we have tried to sight the hilal with the naked eye.
So what this means is imkanur rukyah is the best methodology to be used, especially in a region with cloudy sky, but if and only if, this is followed up by rukyah on the appointed day of Ramadan 29 because we just have to go through the motion of sighting the hilal physically even when hisab says with “certainty” we cannot sight it.
If this is done, 99.9% of the time the finding of imkanur rukyah will gel perfectly well with the follow-up of sighting the hilal physically.
So Malaysia is right in using imkanur rukyah to determine the new month of Syawal and then followed it up with the obligation of physical sighting on Ramadan 29, which is a Thursday.
This physical sighting resulted in the absence of visible hilal, just as predicted by hisab, and hence Syawal 1 falls on April 22.
But what about the event of last year dubbed as the shocking Raya?
Malaysia is still in the right as it went through the motion of sighting the moon (obligatory) on Ramadan 29 and the crescent moon was sighted in Labuan despite hisab saying it cannot be sighted at all.
What about the criticism Labuan is the only one out of the so many places gazetted as moon sighting locations in Malaysia that sighted the hilal?
The answer is, in Islam, truth is not subject to a democracy of the majority.
Even if the hilal is sighted in one location, that is good enough for the country to declare the next day as Syawal 1, even if other Mabims countries had it two days later because they did not see the hilal on Ramadan 29.
The other countries are within their right to do this as celebrating Hari Raya on a different day is an indication that differences of opinion are celebrated in Islam.
For this year, there is total unity as most Mabims countries celebrated Hari Raya on the same day, but the big question is, do other Mabims countries follow Malaysia’s lead in the obligation of sighting the hilal physically? Hopefully. – April 21, 2023.
* Jamari Mohtar reads The Malaysian Insight.
* This is the opinion of the writer or publication and does not necessarily represent the views of The Malaysian Insight. Article may be edited for brevity and clarity.