All the scholars of the Ummah Muhammadiyyah ﷺ agree that the Muslim community should attempt to perceive the crescent on the 29th and if it is not seen then complete the full 30 days. To date, no one has said to find the crescent even after completing 30 days because the last month's moon is sure to be complete, and the new moon has started. But if 29 days are completed, and the moon is perceived, the 7 methods of proof of its visibility are listed within Islamic Jurisprudence. But why are so many restrictions imposed on the procedure of the announcement of the crescent on the passing of the 29 days? This is so to ensure certainty of the passing of the previous Islamic month and the beginning of the next one, without any hinderance or doubt.

 

ھُوَ الَّذِیۡ جَعَلَ الشَّمۡسَ ضِیَآءً وَّ الۡقَمَرَ نُوۡرًا وَّ قَدَّرَہٗ مَنَازِلَ لِتَعۡلَمُوۡا عَدَدَ السِّنِیۡنَ وَ الۡحِسَابَ

 

The holy Quran states: He (Allah) gave the sun (its) radiant glow and the moon its light, He determined their phases precisely, so you might (calculate) the passing years and keep time.
The movements and stages of the moon are mentioned in the Holy Quran. After mentioning the stages, the phrase لِتَعۡلَمُوۡا عَدَدَ السِّنِیۡنَ وَ الۡحِسَابَ directly indicates that the knowledge of the positions and stages of the moon aids in setting the date and calendar. Before Islam, people attributed superstitious theories to the moon and stars. Islam denied it; there were supposed theories about the lunar eclipse, but Islam abolished them and condemned the soothsayers (astrologers) because they were against monotheism. There is no other opinion that the classical Muslim scholars forbade the announcement of the crescent with astronomical calculation. But what is the reason for this? Here is a quote from Imam Ahle Sunnah, Imam Ahmad Raza Khan Rehmatullah Alaihi. He writes while describing the Jantris.

According to the correct ruling of jurisprudence, the opinion of astronomy experts is not valid in announcing the crescent, even if they are just. Then, after that, he wrote that today's calendars (almanac), which are generally published by Hindus etc., infidels, Materialistic Muslims, or Muslims, are based on the Hindu almanac. How can those (almanac) calendars be accepted? I have examined many famous (almanac) calendars for the last twenty years. First, Egyptian astronomy is imperfect and confusing, and these compilers of calendars (almanac) don't fully understand it either. Those obscene mistakes were seen in the horoscopes, which even a sane child would not do. (Fatawa Rizwiyyah Volume 10).

Astronomical research has developed over the past century. The science of astrophysics presents and proposes experimental and precise theories rather than hypotheses. Currently, the movement of the moon and its data are entirely error-free and like how scientific information about the sun's rising and setting is not wrong, in the same way, the information about the moon; its time of rising and setting; its movements in the orbits; eclipses and its phases are correct. An easy example to understand the vital role of modern science in Islam is given here. Four witnesses are a prerequisite for proof of adultery; the discovery of DNA has provided more authentic evidence than witnesses. The same situation is in the dilemma of the moon, where, there is no possibility of error in information based on astrophysics. After the development of science over the last 100 years, Islamic scholars accepted the crescent announcement based on astrophysics and wrote books on its importance and necessity. On this issue, a complete paper by the great Sunni scholar of Syria, Dr. Mustafa al-Zarqa, in the book Al-Aql wa Fiqh fi Fahm al-Hadith, answers all these questions. The importance of the crescent's announcement on astrophysics knowledge has been elucidated in the Urdu translation of this website.