Ruling on Using Astronomical Calculation to Confirm the Month of Ramadan
Is it permissible to rely solely on astronomical calculations to confirm the entry of Ramadan, or is visual sighting required?
Astronomical calculation is not relied upon to confirm crescents; rather, the standard is visual sighting based on the Prophet's saying: "Fast upon seeing it and break fast upon seeing it," and the words of astronomers are disregarded.
The statements of calculators are ignored, and astronomical calculations are not used to establish Ramadan; legal demands are linked to visual sighting or completing the count.
Ramadan is not established for people at large by astronomical calculation or by an astrologer's word, but by sighting or by completing Shaʿbān as thirty days; the calculator himself, however, may act on his own calculation, and it counts for his obligatory fast.
Astronomical calculation is not relied upon to establish the entry of Ramadan; fasting becomes obligatory by sighting the crescent, or by completing Shaʿbān as thirty days when the sky is clear. If clouds or haze obscure the crescent on the night of the thirtieth, fasting that day is obligatory.