Are the calculations of astronomers considered for moonsighting?

ⓘ Supported by Al Medina 313.



Islamic Text

No, astronomical calculations are not considered.

ابْنَ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا، عَنِ النَّبِيِّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، أَنَّهُ قَالَ: «إِنَّا أُمَّةٌ أُمِّيَّةٌ، لاَ نَكْتُبُ وَلاَ نَحْسُبُ، الشَّهْرُ هَكَذَا وَهَكَذَا» يَعْنِي مَرَّةً تِسْعَةً وَعِشْرِينَ، وَمَرَّةً ثَلاَثِينَ

Ibn ‘Umar  narrated that the Prophet ﷺ said, ‘We are an unlettered Ummah, we do not write or use (astronomical) calculations. A month is like this, and this.’ Meaning sometimes 29 and sometimes 30 days. (Bukhari , 1913).

The above Hadith has caused Hanafi scholars to conclude that calculations are not considered when it comes to moonsighting. The Hadith is not considered to be general and therefore applicable to all aspects of life, rather it is specific to moonsighting. Therefore, we do use calculations for other matters but not moonsighting since the Hadith is clear regarding this issue.

قَوْلُهُ: وَلَا عِبْرَةَ بِقَوْلِ الْمُوَقِّتَيْنِ
أَيْ فِي وُجُوبِ الصَّوْمِ عَلَى النَّاسِ بَلْ فِي الْمِعْرَاجِ لَا يُعْتَبَرُ قَوْلُهُمْ بِالْإِجْمَاعِ، وَلَا يَجُوزُ لِلْمُنَجِّمِ أَنْ يَعْمَلَ بِحِسَابِ نَفْسِهِ، وَفِي النَّهْرِ فَلَا يَلْزَمُ بِقَوْلِ الْمُؤَقِّتِينَ أَنَّهُ أَيْ الْهِلَالَ يَكُونُ فِي السَّمَاءِ لَيْلَةَ كَذَا وَإِنْ كَانُوا عُدُولًا فِي الصَّحِيحِ

No consideration is given to the opinion of astronomers. Meaning with regards to obliging fasting upon the people. Rather in al-Miraaj (the author said) there is consensus (Ijma) that their (astronomers) opinions are not considered and it is not permitted for a starwatcher to act according to his own calculations. In al-Nahr (the author stated) it is not binding to act upon the opinions of astronomers when they say the crescent will be (visible) in the sky on such a night, even if they (the astronomers) are upright, according to the sound opinion. (Imam Ibn Abideen, Radd al-Muhtaar).  

And Allah (Most High) Knows best.

– Answered by Shaykh Noorud-deen (08.04.2021)

See also:

Is the Hadith about not using calculations for moonsighting Sahih?

Does taking an injection invalidate the fast?

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