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Ending the moon-sighting controversy through science

Updated June 17, 2015

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Astronomy can accurately establish the time of birth of the new moon with the accuracy of seconds, and its likelihood of being visible. —Reuters/file
Astronomy can accurately establish the time of birth of the new moon with the accuracy of seconds, and its likelihood of being visible. —Reuters/file

This article was originally published on June 17, 2015.


As Pakistanis prepare for the holy month, filling their refrigerators with Seher and Iftar essentials, and go lengths to ensure that their Eid dresses are ready on time, they are all fixated on one question:

“Yaar, chaand kab hai?” (When will the moon be sighted?)

Thanks to the ill-informed reporting of our media and the myth-believing nature of Pakistanis, we grow up blaming the Central Ruet-i-Hilal Committee (the official body for moon sighting and the authority which declares the official start of Islamic months) for its inability to see the moon.

To further fuel the controversy, there is Masjid Qasim Ali Khan in Peshawar, which dissents every other year (save last year), and announces the start and end of Ramazan asynchronously with the rest of the country.

Some blame the Masjid, some blame the Ruet-i-Hilal Committee, and most live in ignorance of the matter at hand. If one takes out the time to understand this moon business, they will learn that modern scientific tools can help us resolve the issue, which is not an issue at all, if you ask me.

The Sun-Earth-Moon geometry

The rotation of the moon around the Earth drives the Lunar Calendar, which is also the Islamic or Hijri Calendar. The time between two full moons is 29.5 days. When the moon comes exactly between the Sun and the Earth, it is called the “Conjunction” and it is said that a new moon is “born”.

At the conjunction point, all of the Sun’s radiation is reflected back by the moon and none reaches the Earth. Therefore, the moon is completely black to us earthlings and is thus invisible.

The time passed after the moment of conjunction is called the age of the moon.

Image: Creative Commons
Image: Creative Commons

After the conjunction, the moon continues proceeding in its orbit and the angle between the moon and Sun as seen by an observer on Earth (elongation) increases. It happens at different rates during different months, because its orbit is elliptical, and hence, its speed varies. As the angle increases gradually from 0 degrees, the crescent moon starts to form.

Image: Creative Commons.
Image: Creative Commons.

According to Syed Khalid Shaukat, an expert on moon sighting who has decades of experience at his disposal, the minimum angle between the Sun and moon for the moon to be visible through naked eye is 10.5 degrees. Reaching this elongation can take anywhere from 17 to 24 hours after conjunction. Thus, age is not the primary factor for moon’s visibility – the elongation is.

The conflict

A section of Islamic scholars believe that seeing the moon with the naked eye should be the criterion for declaring the start of a new month. A smaller section advocates that we can rely solely on the calculations, and there is no need to visually see the moon.

Without endorsing one view over the other, I will simply point out that as far as sighting the moon goes, we could acquire great deal of help from science.

We could use calculations and modern simulations for knowing where and when to look for the moon, how high it will be in the sky, and what are the chances of its visibility. It is now possible to calculate the exact window of the moon’s visibility after sunset and even generate simulated images of the moon beforehand.

The official and unofficial moon sighting committees ask people to testify if they have seen the moon. This is where these simulated images can be used: anyone who claims to have seen the moon can be asked questions like what time they saw it, how high it was, whether it was near or close to the sun, whether the cusps were upward or sideways, whether it was on the left side or right side of the moon, etc.

These questions are enough to filter out false claims of sighting.

This rejection is attributed to genuine misjudgment, which does not diminish the person’s uprightness and acceptability as a witness. Numerous renowned as well as recent and contemporary scholars support this view.

That is how the Central Ruet-i-Hilal Committee filters out testimonies, but the Masjid Qasim Ali Khan gives no value to these calculations, and relies solely on the piousness of a person as evidence of correct sighting.

The Ruet-i-Hilal Committee has borne the brunt of a history of misconceptions and badmouthing, but in fact, the committee makes very scientific decisions, give or take occasional errors, which are very rare.

Their decision is almost always in accordance with scientific calculations, while those by Masjid Qasim Ali Khan are often found mathematically impossible. Outside of science, it is indeed very hard to establish the sighting of the moon to a credible degree, and so Masjid Qasim's claims will be doubtful at best.

In 2011, the Masjid announced that the moon had been sighted and that Ramazan would commence from August 1, whereas the visibility wasn’t possible from Peshawar and surrounding areas at all.

Image courtesy: Moonsighting.com
Image courtesy: Moonsighting.com

On the other hand, the Central Ruet-i-Hilal Committee made the correct decision.

Image courtesy: Moonsighting.com
Image courtesy: Moonsighting.com

Explaining the 'fat' crescent

Another misconception of Pakistanis is that if the crescent is fat, it could not possibly be the first sighting of the lunar month.

Wrong. It may not be the first date of the lunar month, but it can certainly be the first sighting.

The reason for that is, if the moon's 'age' is less than 17 hours on a given day, it will set without becoming visible to the naked eye. So technically, there was a crescent, it just never got the chance to be seen from Earth. The next day at the same time, it will be 17+24=41 hours of age, and will definitely look fatter and more visible.

Blaming the Ruet-i-Hilal Committee for not spotting the young crescent on its first day is foolish – blame nature, rather.

Today, astronomy can accurately establish the time of birth of the new moon with the accuracy of seconds, and its likelihood of being visible. So, what is the harm in using this astronomical basis to reject a claimed sighting which could not possibly be correct?