What is the correct view regarding the start of the Ramadan fast and Eid al-Fitr: is it based on the Sharia-sanctioned sighting according to the Hadith, "Fast when you see it and break your fast when you see it," or by relying on astronomers' calculations?

The decisive factor in the beginning and end of the month of Ramadan is the sighting of the crescent moon (with the naked eye). The Islamic Sharia is suitable for every time and place, and acting upon the sighting is something people in every era and country are capable of. Allah Almighty and His Messenger linked the fasting of Ramadan and breaking it to the sighting of the crescent moon, and did not link it to astronomical calculations. Therefore, Muslims must rely on the sighting of the crescent moon, and whoever deviates from this, their statement is anomalous and cannot be relied upon.