Science: Moon Sighting Prospects in 10 Sentences or Less

The Eid-ul-Fitr in Pakistan is likely to fall on this Friday as per the Ruet-e-Hilal’s decision to sight the Moon on Thursday, creating a 2 DAYS difference (!!) with Saudi Arabia. Read on; and I am continuing from this article: (+ check the comments for a pre-requisite of why I wrote this blog post…)

This website shows the New Moon’s birth for the city of Islamabad, Pakistan for August:

1121 7 Aug 02:51

Okay – the decision by the Ruet Hilal Committee and Met Department’s to look for the Moon on Thursday is actually correct and set in concrete science. Let me explain:

There are several conditions that have to be fulfilled first before the prospect of Lunar visibility occurs. Scientifically, birth of the Moon is when the the Moon crosses the plane of Sun from old (month) to new. At this time the Moon is not yet “thick” enough to be visible as a crescent as it is too close to the Sun. As it moves further away, the sun light falls on it’s rims and this is what makes the “crescent” shape and allows us to see it (You can illustrate this by holding a sphere/ball in your hand blocking a light source in front of you, then slowly moving the sphere to left/right). For the Moon crescent to actually become thick enough to be visible, you have to wait a while till it moves away in it’s orbit. This takes anywhere from 18-22 hours – minimum. And then you have another basic condition; the new Moon is only visible at most, half an hour after sunset.

According to the website above, the birth of the Moon occurs on 7th August 2:51 (AM). If you add 20 hours, this gives you 22:51 or 10:51 PM on the 7th August. This violates several conditions of visibility: the 18-22 hours visibility period and the post-sunset visibility condition (to name just two- there is another condition violated in this case which I call the “ecliptic” condition and isn’t easy to explain).

Hence the only possibility of Moon sighting is on the next day, that is 8th. Which is a Thursday.

(Source: Doing observational astronomy for past 14 years)

For further arguments regarding how the issue is handled in Pakistan/KPK/S.Arabia, read my other blogpost: The Luna(cy) of the Moon Sighting.

Thank you, and have a joyous Eid.


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