The Ruling on Relying on Astronomical Calculations for the Beginning and End of Fasting

Question:
This questioner says: Is it permissible for a Muslim to rely on astronomical calculations for the beginning and end of fasting, or is it necessary to see the crescent moon?

Answer:
This issue is settled, praise be to Allah. In this matter, one refers to the rulers and the scholars. The Muslim is with the Muslims; if they fast, he fasts with them, and if they break the fast, he breaks the fast with them. A Muslim does not ask such a question; he fasts with the Muslims and breaks the fast with them. However, for the sake of benefit, the Prophet (peace and blessings be upon him) tied fasting and breaking the fast to the sighting of the crescent moon. He said: "Fast when you see it, and break your fast when you see it. If it is obscured from you, then complete the number of days for the month, thirty days." So he tied breaking the fast to the sighting of the crescent moon and fasting to the sighting of the crescent moon. The sighting is sufficient if one Muslim sees it; if one Muslim sees it and his testimony is established before the ruler, then the Muslims all fast because they are one community. It is not befitting to display such doubt, asking: "Do we fast based on the calculation or based on the crescent moon?" The Messenger (peace and blessings be upon him) said: "Fast based on the crescent moon." No one has a word to say against the word of the Messenger (peace and blessings be upon him). Yes.

The presenter:
May Allah reward you,