The Criteria for Islamic Calendar
The best way to find out the end of the present month or the start of the new month is to keep watching the moon phases as per 2:189. The moon has waxing and waning phases as it traverses in the sky (10:15) and this movement is accurate and precisely fixed by Allah (55:5). If we keep watching these different phases of the moon, we can easily find out the correct week-day in which the new month starts. We can observe that, at the last stage of the moon in a month, the illuminated part of the moon becomes thinner and thinner and at last it becomes so thin and so close to the Eastern horizon around Fajr time, which Noble Qur’an 36:39 describes as “al Urjoonal qadeem”. Seeing this last visible phase, the observer is assured that moon will not be seen on the next day. This day is the Day of conjunction and it is the last day of the month. This conjunction (new moon/ black moon) is also a phase of the moon.
According to the Sharia as well as Astronomically, the Universal day in which Conjunction takes place has to be considered as the Last day of the month and the new month must start from the fajr of the following day, irrespective of the time of Conjunction and/or the sunset-moonset difference at Makkah or anywhere else.
An Islamic Calendar has to be a global calendar and therefore, a dateline is a mandatory to start a day globally, similar like a Friday starts in New Zealand side of dateline and the day of Friday progresses as we go westward. The same concept should be followed in designing a Global Islamic calendar where the Friday will have one Islamic date in every country.
There are people who say that the day starts at New Zealand side because of the International Dateline (IDL), which is fixed by the British and that IDL has no basis in Islam. There is no substance for such an argument because the existing IDL is universally accepted due to the geographical speciality of the region that makes the dateline to go mainly through the sea. It is also to be noted that, an Islamic calendar is a lunar calendar constituted by a group of “solar days” and as stated above we have an established system of beginning of a solar day from the east of the IDL from where the Muslims start their Friday prayer. Therefore, there is no harm to accept the current dateline as the dateline for an Islamic calendar also.
In lunar calendar, when it is said that a new month starts the next day immediately after the day of conjunction, some hypothetical questions could be asked concerning the possibility of people in the eastern region close to IDL has to enter a new month even before conjunction happens in the world. Similarly, the people on the western region close to IDL have to wait one more day even after observing the conjunction on a particular day.
Here we must note one point. The ‘day’ and ‘date’ of conjunction is always recorded similar to the birth of a person in the world. For instance, the Prophet (ﷺ) was born in Mekkah on a Monday; however, this particular moment may be a different day for people in another part of the world like USA. But, we know that the day of birth is recorded as Monday everywhere in the world with reference to day (Monday) in relation to the place of birth.
Based on the above, as an example, if moon birth (conjunction/ new moon) occurs over New Zeeland side of IDL on a Friday, and then the day of conjunction will be Friday even though the people across the IDL on Canadian side observe the same event on Thursday. We must keep in mind that the time of conjunction is not the one that determines the beginning of new month, but the day of conjunction with reference to the place of conjunction which should determine the first day of new month. In the above case, the new month begins on Saturday for all as the day of conjunction is Friday with reference to the place (Geographical Position – GP.) of conjunction.
If moon birth (conjunction/ new moon) occurs over Canadian side IDL on a Friday, and then the day of conjunction will be Friday even though the people across the IDL on New Zeeland side observe the same event on Saturday. Here also, the actual day of conjunction is Friday with reference to the place of conjunction. Therefore, people in the eastern side of IDL (New Zeeland) has to enter new month even before the actual conjunction takes place on the other side of the IDL.
In all cases, it is to be clearly noted that, everyone enters into the new month only on the next day after the “day of conjunction” with reference to the place (GP) of conjunction.
It is admitted that the current IDL was altered certain times in the past by certain countries/ islands by jumping across to the other side of the IDL. This was done by individual countries/ islands for commercial and political benefits. Any country/ island that are close to the IDL, renaming their days and dates cannot go against the concept of IDL and their individual decision has no bearing on other countries.