Relying on physical sightings of the new moon is the principle in determining the beginning of Ramadan
Dar Al-Ifta` Al-Misriyyah said that like all the other lunar months, the beginning of the month of Ramadan is determined by sighting the new moon with the physical eye. The sighting for the beginning of Ramadan is made at the time of sunset on 29th of the month of Sha’ban. If the new moon is sighted, the beginning of the month of Ramadan is determined and if not, the month of Sha’ban is completed to 30 days.
In a fatwa, Dar Al-Ifta` determined that visual sightings are the principle in conjunction with astronomical calculations. The opinion chosen for fatwa is that astronomical calculations negate [erroneous] physical sightings but do not confirm them. The fatwa added that the testimony of any person who claims to have sighted the new moon with his naked eye while astronomical calculations indicate unequivocally the impossibility of a physical sighting, is rejected. In this manner, the beginning of the month of Ramadan is established through a physical sighting of the new moon with the naked eye in conjunction with implementing science, whether rational or empirical. The resolutions reached by the Islamic Juristic assemblies have determined the same.