The ruling on sighting the crescent of Ramadan with the naked eye or through observatories

Question:
The questioner asks: Is it necessary to see the crescent of Ramadan with the naked eye? What is the evidence for this? Or do modern inventions suffice in its place?

Answer:
The Prophet (peace and blessings be upon him) said: . When the people saw the crescent during the time of the Prophet (peace and blessings be upon him), Ibn 'Umar (may Allah be pleased with him) came to him and informed him that he had seen the crescent, so he ordered the people to fast. In another hadith, a Bedouin came and informed the Prophet (peace and blessings be upon him) that he had seen the crescent. He said: "Do you testify that there is no god but Allah and that Muhammad is the Messenger of Allah?"
He said: "Yes." So the Prophet (peace and blessings be upon him) ordered Bilal to inform the people and to announce the fast to them. If the sighting is established by the testimony of one Muslim, it is obligatory for them to fast, based on the saying of the Prophet (peace and blessings be upon him): Whether the sighting is with the naked eye or through astronomical observatories or telescopes used to enhance vision, there is no harm in that. It is not necessary to use the naked eye; if there are means by which the sighting can be achieved and the location of the crescent determined, this is what helps in obeying Allah, and there is no harm in using them. Yes.