Is it permissible to rely on astronomical observatories' calculations for establishing the beginning and end of the month? Is it permissible for a Muslim to use modern instruments to sight the crescent, or must the sighting be with the naked eye?
Source: FtawySummary from Ftawy's records · added here Sep 2, 2026
The legitimate method for establishing the new month is by sighting the crescent moon, and this must be done by someone trustworthy in their religiosity and sharpness of sight. Relying solely on astronomical calculations is not permissible; rather, visual sighting must occur. Using binoculars (a magnifying scope) to sight the crescent moon is permissible but not obligatory. Whenever its sighting is confirmed by any reliable means, it becomes obligatory to act upon it, as the Prophet (peace be upon him) said: "When you see it, fast, and when you see it, break your fast."
Summary from Ftawy's records · added here
Reviewed by El Fatwa's sharia committee.
Read the full answer on Ftawyhttps://ftawy.com/en/questions/13729
Where this answer came from
- Source platform
- Ftawy
- Original fatwa ID
- 13729
- Added here
- . This is when the answer was added to El Fatwa, not the fatwa's date.
- Text
- Summary from Ftawy's records, reviewed by El Fatwa's sharia committee.
- Read the full ruling
- Read the full answer on Ftawy