Call for the Uniting of Moon Sightings everywhere with that of Makkah? – Shaykh Ibn Uthaymeen
Q. 393. There are some people who call for the uniting of moon sightings everywhere with that of Makkah, in order to unite the Muslim community over the start of the blessed month of Ramadan and other months. What is Your Eminence’s opinion on this?
A. From the point of view of astronomy, this is impossible, because the appearance of the new crescent, as Shaikhul-Islam Ibn Tairniyyah, may Allah have mercy on him, said, differs (from place to place) according to the consensus of those who are knowledge- able in this field. Since it differs, then what is necessitated by the evidence from the Qur’an and the Sunnah, and scientific evidence, is that every country must have its own ruling.
As for the evidence from the Qur’an and the Sunnah, Allah, the Most High says:
“So whoever of you sights (the crescent on the first night of) the month (of Ramadan, i.e. is present at his home), he must observe Scrum (fasts) that month” [Al-Baqarah 2:185]
So, if it happened that a people in the farthest part of the earth did not witness the month, i.e. the new crescent, while the people of Makkah had seen the new crescent, how could the address in this Verse be applied to those who had not witnessed the new crescent?! The Prophet صلى الله عليه وسلم said:
“Fast when you see it and break the fast when you see it” 
So if the people of Makkah see it, how can we oblige the people of Pakistan and those Asians who live beyond it to fast, when we know that the new crescent has not appeared in their region, and the Prophet صلى الله عليه وسلم: made fasting conditional upon the sighting of the new crescent?
The scientific evidence is the correct analogy, which it is not possible to refute, for we know that the dawn appears in the eastern corner of the earth before the western side. So if the dawn appears on the eastern side, is it incumbent upon us to fast while we are still in the night? The answer is no. If the sun sets in the east, while were still in daylight, is it permissible for us to break our fast? The answer is no. Therefore, the new crescent is exactly like the sun, except that the timing of the new crescent is monthly and the timing of the sun is daily, and He Who said:
“It is made lawful for you to have sexual relations with your wives on the night of As-Saum (the fasts). They are Lihas [i.e. body- cover, or screen, or Sakan (i.e. you enjoy the pleasure of living with them) for you and you are the same for them. Allah knows that you used to deceive yourselves, so He turned to you (accepted your repentance) and forgave you. So now have sexual relations with them and seek that which Allah has ordained for you (offspring), and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Saum (fast) till the nightfall. And do not have sexual relations with them (your wives) while you are in I ’tikaf (i.e. confining oneself in a mosque for prayers and invocations leaving the worldly activities) in the mosques. These are the limits (set) by Allah, so approach them not. Thus does Allah make clear His Ayat (proofs, evidences, lessons, signs, revelations, verses, laws, legal and illegal things, Allah’s set limits, orders, etc.) to mankind that they may become Al-Muttaqun.” [Al-Baqarah 2:187]
is the One Who said:
“whoever of you sights (the crescent on the first night of) the month (of Ramadan, i.e. is present at his home), he must observe Saum (fasts) that month” [Al-Baqarah 2:185]
So, What is necessitated by the evidence from the Qur’an and the Sunnah, as well as scientific evidence, is to make a special judgement for each place regarding fasting and breaking the fast, and to link them on the base of the perceptible sign which Allah has declared in His Book, and His Prophet, Muhammad fig has declared in his Sunnah, and that is the sighting of the moon and the sighting of the sun or the dawn.
 Reported by Al-Bukhari in the Book of Fasting, in the Chapter: The Words of the Prophet صلى الله عليه وسلم: When you see the new crescent (1909); and by Muslim in the Book of Fasting, in the Chapter: The Obligation to Fast the Month of Ramadan Upon Sighting the New crescent (1081).
Source: Fatwa Arkanul Islam, Volume 2 – Shaykh Uthaymeen, Dar-us-Salam English Publication