Is it permissible for a Muslim to rely on astronomical calculations for the beginning and end of fasting, or is it necessary to sight the moon?

Islamic Sharia (definition) has made sighting the crescent moon a sign of the beginning of the lunar month and the commencement of acts of worship such as fasting, breaking fast, and Hajj, as stated in the Quran and Sunnah (definition). Allah has not burdened Muslims with knowing the beginning of the month through precise astronomical calculations, which only a few possess knowledge of. Referring to the science of stars to determine the beginning of acts of worship without sighting is considered an innovation that has no basis in Islamic law.