Praise be to Allah.
Firstly: the fact that the moon rises at different times in different places is a well-established fact; no scholar disputes this. However, the scholars differ as to whether this matters or not.
Secondly: the question as to whether different times of moonrise is something that matters is a theoretical question in which ijtihaad is permissible. Those who have knowledge of science and religion differ on this matter, and this difference of opinion is permissible; the one who has the correct opinion will have two rewards, one for being right and one for making ijtihaad; the one whose opinion is wrong will still be rewarded for his ijtihaad.
The scholars’ differences on this matter may be described as one of two: some of them thought that the differences in the times of the moon’s rising was of significance, and others thought that it was not. Both groups cite evidence from the Qur’aan and Sunnah, and maybe even quote the same text, such as the aayah (interpretation of the meaning): “They ask you (O Muhammad) about the new moons. Say: these are signs to mark fixed periods of time for mankind and for the pilgrimage…” [al-Baqarah 2:189] and the hadeeth, “Fast when you see it [the new moon] and stop fasting when you see it…” The difference is one of interpretation of the texts, as each group has its own methods of deriving evidence.
Thirdly: the committee has looked at the issue of confirming the new moon by calculations and what was said on this matter in the Qur’aan and Sunnah, and they have studied the opinions of the scholars on this matter. They decided unanimously that astronomical calculations do not count when it comes to confirming the new moon for shar'i purposes, because the Prophet (peace and blessings of Allaah be upon him) said: “Fast when you see it [the new moon] and stop fasting when you see it…” and also: “Do not fast until you see it [the new moon] and do not stop fasting until you see it…”, and because of the evidence that is derived from these ahaadeeth.
The Standing Committee on Scientific Research and Fatwas (al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah wa’l-Iftaa’) thinks that the Muslim students’ union (or any other group representing the Muslim community) in countries where the government is not Islamic should take the place of an Islamic government in the matter of confirming the new moon for the people living in those non-Islamic countries.
On the basis of the above, this union has the choice of two options: either to consider the differences in times of moonrise to be of significance, or not to do so. Then they should inform all the Muslims in their country what their opinion is, and the Muslims have to follow what they have been told, so as to unite the Muslims in their fasting and to put an end to disputes and confusion. Everyone who lives in those countries should try to sight the moon in the place where they are living, and if one or more trustworthy persons sight the moon, they should fast according to that and tell the union to spread the news. This is at the beginning of Ramadaan; at the end of the month there has to be two witnesses to see the new moon of Shawwaal or the completion of thirty days of Ramadaan, because the Prophet (peace and blessings of Allaah be upon him) said: “Fast when you see it [the new moon] and stop fasting when you see it, and if it is cloudy then complete the month with thirty days.” And Allaah knows best.