– By Syeda Qudsia, NUST Science Blog
Eid is an eventful occasion in Pakistan – especially in Pakistan, in fact. And all the credit goes to our very own “moon-sighting controversy”. If you have spent an Eid in Khyber-Pakhtunkhwa, on their first day, you are likely to come across a most confusing situation: the Afghan population has already celebrated theirs with Saudi administration, half of the rest are celebrating it that day, and remaining are on the wait for another day. So, on occasion of “central” Eid of Pakistan, when your relatives are happily going to come to your house for wishing “Eid Mubarak”, chances are that Eid is a thing long past and forgotten in your mohalla.
Who’s to blame? Choose the best option:
- Local Committee at Masjid Qasim Ali Khan
- Meeting presided by Maulana Muneeb ur Rahman
- None – we are just doomed to two Eids when we cannot manage three
- The moon itself is conspiring to break Pakistan
Here are the set of events as happened this year:
Friday, August 17, 2012: People in Waziristan see the crescent. Eid Mubarak!
Saturday, August 18, 2012: The moon is 22 hours old and timed to set 16 minutes after sunset, in Karachi (In Islamabad, moonset was only 8 minutes later)1. Mathematically, the moon is there, so Saudi government declares celebrations to begin that evening. In case of Pakistan, where we make special arrangements to be the lucky ones to see moon at its youth, meteorologists on our media predict that moon-sighting will be impossible as age of moon should be around 30 hours for it to be visible and difference in sunset and moonset must be about 30-40 minutes. People in different parts of KPK manage to see the moon anyway, and Provincial Government gives its approval.
Sunday, August 19, 2012: Many parts of KPK celebrate Eid, along with some regions in Balochistan. The official Eid is declared to be celebrated on Monday, August 20, 2012, in Pakistan.
Not a new story, happens all the time. Now, let us move to our “behind the scenes”… but before we do that, let’s discuss the many factors collectively responsible for sighting of a new moon.
Age of the moon:
Age of the moon is a contributing factor, but it is not a hard and fast criterion – The moon can be generally visible at age 17 to 24 hours. Here are some instances:
- The reported record for youngest moon ever seen with optical aid is held by Mohsen G. Mirasaeed of Tehran, on September 7, 2002, at an age of 11 hours 40 minutes2.
- Youngest moon to be seen with the naked eye stands at 15 hours 32 minutes, and was seen by Stephen James O’Meara in May 19902.
Claims made for crescents above 15 hours of age are considered professionally credible, although other factors, like elongation, altitude, clarity of the sky, etc., are brought into account before stating them as authentic.
This is the most important factor contributing to the visibility of new moons. It is the angle between two celestial bodies. In our case, it’s the angle sun-earth-moon. When we have a complete solar eclipse, this sun-earth-moon angle is 0°. At complete lunar eclipse, this angle is 180°. As age of moon increases, its elongation increases and it becomes more visible at greater elongations. The moon does not always start with 0° elongation; its elongation can be up to 5° at time of its birth. So such a moon that starts at maximum elongation can be sighted at younger ages.
Minimum elongation at which the moon can be sighted is termed as the Danjon’s limit and is about 7°. Below this, the moon is not visible, as accepted generally. It is widely accepted, though, that moon at an elongation of 9° to 10° is visible.
Magnitude and Altitude:
The magnitude of any celestial body is its brightness: the sun has a magnitude of -26.8 whereas the full moon has a magnitude of about -12.7, and it goes backwards from there3 (a moon at magnitude -10 will be less bright than the full moon). Altitude of the moon is its setting in the sky with respect to the horizon. A moon with less altitude appears low set in the sky.
The location and the weather conditions of the observer dramatically affect the moon-sighting phenomena. People at lower latitudes and higher geographical altitudes are well suited to view younger moons. At higher altitudes, the skies are generally darker and less hazy. Very thin crescents can become visible to the trained eye right after sunset, and can be spotted if the observer knows where to look.
Let us go over the events again…
Friday, August 17, 2012: Sunset was timed at 1850 hours, PST. The moon was born 2 hours 4 minutes afterwards.
Saturday, August 18, 2012: At sunset, the age of the moon was about 22 hours, with moon lag time of 16 minutes. Its altitude was 3° in Karachi (1° in Islamabad), so it was pretty low set. The magnitude of the moon was -4.8. The elongation of the moon was 13°.
Her Majesty’s Nautical Almanac Office predicted earliest sightings on this day in the regions of Australasia, Southern Africa, Central and South America.
Sunday, August 19, 2012: The age of the moon at sunset was 46 hours. Its altitude was 12 in Karachi and 8 in Islamabad. Its magnitude was -6.0, so overall quite an easy moon to see.
Predictions were that it would be visible throughout the world, with exceptions still of Northern Asia, Japan, Canada, and Europe (where the moon would be sighted on August 20).
There you go… all the evidence compiled. Did you see the moon? Science says the moon could not have been seen in any area of Pakistan on Saturday. But there have been reports of sightings of moon in other countries as well, where the moon was declared improbable to be sighted (another example is Iran, where the moon could not have been sighted, but was). It turns out that this moon-sighting controversy is not a local problem 😛 .
And who’s to blame?
Well, it’s time we learned to live without that.