The Ruling on Relying on Astronomical Calculations to Establish the New Moons

The Shaykh : Therefore, we say: It is not permissible to rely on astronomical calculations to establish the new moons, even if these proofs were to become a true science with no doubt or ambiguity. However, this cannot be the case as long as the matter rests on a human being who is prone to error just as he is prone to correctness. For this reason, the Prophet (peace and blessings be upon him) said in the aforementioned hadith: This does not mean that there were no one in the time of the Prophet (peace and blessings be upon him) who wrote or calculated. Rather, it means that the Arab nation, during the Prophet’s (peace and blessings be upon him) mission, was predominantly illiterate. However, there were among them cultured people who read and wrote. But the Prophet (peace and blessings be upon him) stamped this nation, regarding the establishment of the new moons, with the stamp of illiteracy. This is because the Shari'ah is built upon apparent matters that are easy for all Muslims, whether they are illiterate or cultured. Islam is known for prohibiting excessive depth and difficulty, and this includes astronomical calculations. In my opinion, one of the effects of relying on astronomical calculations is two terrible phenomena. The first is what was mentioned previously in the question of the noble brother: the disagreement among Muslims in foreign lands regarding the establishment of the Ramadan moon, between those who rely on the moon as per the sighting of the moon, as prescribed by the explicit text of the Book of Allah and the hadith of the Messenger of Allah (peace and blessings be upon him), as explained previously, and those who rely on astronomical calculations without having any absolute text from the Book, the Sunnah, or the statement of any of the Imams who are qualified for independent legal reasoning. In fact, Shaykh al-Islam Ibn Taymiyyah and al-Hafiz Ibn Hajar mentioned the consensus of the Muslims on not considering astronomical calculations in establishing the Ramadan moon, and indeed in establishing the other months. Therefore, we advise every Muslim who has been given some knowledge of astronomical calculations not to be deceived by this knowledge, because this knowledge has no place. It is not permissible in any way for a Muslim brother who is knowledgeable in this science to contradict the guidance of the Prophet (peace and blessings be upon him) in his actions and words, as explained previously, and not to contradict what the Muslims have followed, both the earliest and the later generations, lest the saying of Allah (Blessed and Exalted is He) be true of him: Therefore, we warn every Muslim brother who relies on his astronomical calculations not to include these calculations in the establishment of the Shari'ah new moons.
As for what was mentioned regarding that astronomer’s doubt about the sighting of those who saw the moon, because there were people who did not see the moon, this indicates, with great regret, that this speaker has no knowledge of the Shari'ah principles. Among these principles is the statement of the scholars: "The one who affirms is given precedence over the one who denies," and "The one who knows is an argument over the one who does not know." If a person, or even one just Muslim, upright and truthful, about whom no open sinfulness is known, comes to testify and says: "I saw the moon," it is not permissible to reject his testimony by saying that people, no matter how many, did not see the moon.