Saudi Arabia Declared New Crescent “Sighted” – But Is This Scientifically Possible?

The declaration of the start of 1 Dhul-Hijjah 1439 AH by Saudi Arabia stirred some controversies around muslim world. In its announcement, the Supreme Judicial Council of Saudi Arabia said that new crescent moon (hilaal) was sighted on the evening of Saturday, 11 August 2018. This ‘moon sighting’ report was used to declare that 1 Dhul-Hijjah 1439 AH starts on Sunday, 12 August 2018.

However, no other valid sighting reports were made by members of crescent moon sighting committee all around the world on Saturday. There was no single crescent moon photos from Saturday, 11 August 2018. In contrast, earliest report of valid moon sighting accompanied by photographs came from Sydney, Australia the next day, Sunday, 12 August 2018.

Below is a statement from UK-based Crescent Moon Society that assessed the Saudi Arabia decision.

Statement from The New Crescent Society
Saturday 11 August 2018


We have been inundated with messages with regards to the start of Dhull Hijjah, and the exact date of Eid ul Adha 1439 / 2018. Today Saudi Arabia have announced that they have “sighted” the crescent moon, and the month of Dhul Hijjah starts on Sunday 12 August. This news is being shared on various media outlets.

To clarify, it is scientifically impossible for Saudi Arabia to have sighted the moon this evening. Please take a look at the data in the attached visibility charts (we have used two independent sources), which clearly demonstrate that Saudi Arabia was not in the visible range tonight. It was in fact not possible to have seen the new crescent moon anywhere in the inhabitable world tonight.

This declaration is all the more remarkable given that there was a partial solar eclipse today (August 11th). A new crescent, by definition, cannot be visible during a solar eclipse as the sun and moon are in conjunction. For Saudi Arabia to have seen the new crescent within 7 hours of conjunction would represent something not only scientifically deemed hitherto impossible, it would set a new world record for the earliest ever new crescent sighting.

Far more likely, of course, is that this is an incorrectly reported sighting. This is not the first time Saudi Arabia have produced a sighting claim which is plainly contradicted by scientific data and experienced astronomers.

As for the UK, and in the rest of the world, astronomers will be going out to look for the moon tomorrow when it will be visible. Countries who have already announced that they will follow local moon sighting reports, and therefore will not be following this announcement from Saudi Arabia, include: Morocco, Indonesia, Malaysia, Singapore, Brunei, Pakistan and Bangladesh. Thus the month of Dhul Hijjah will start on Monday 13 August for those who follow local sighting reports.

As a result, is likely we will have two separate Eid dates for various communities in the UK. They are as follows:

 Tue 21 August (Mosques who following Saudi announcements)
Wed 22 August (Mosques who follow local visibility / local calendars)

Whenever you are celebrating, and wherever you are – have a blessed month, and Eid Mubarak!

The New Crescent Society


The New Crescent Society is an organisation dedicated to the revival of the traditional practice of observing celestial bodies, and celebrating the historic relationship between Muslims, astronomy and faith.

Within the UK, The New Crescent Society advocates for an Islamic calendar for UK Muslims that is based on UK lunar-visibility, rather than relying on sighting reports from abroad.

Sources for data: HM Nautical Almanac Office, UK; Faculty of Science, Utrecht University; ]

Habib bin Hilal

Habib bin Hilal is Editor in Chief of this blog and manager of the website: Alhabib - Coloring with Islam.


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