I have an idea to make a lunar calendar that is as definite as solar calendar so that it can be used globally in day-to-day life. I have heard that Saudi Arabia use lunar calendar. This calendar will be based on calculating the birth of moon in different parts of the world. My questions are:

  1. Does something like this already exist?
  2. Should I use the current time-zone or will I make make new time-zones for it?
  3. Usually the next islamic day changes after the setting of the sun. Should I change the date at 0000 hrs or when the sun sets?
  4. Is there any work that is already done in this area?
  5. Is there any resource for calculating moon-birth at different locations?
  6. If two different location within a same time-zone has different output for moon visibility, then what will be the date in that timezone?

Reference to any of question will be useful.

  • Check this. Might help.
    – user2350
    Commented Jul 26, 2013 at 19:47

2 Answers 2


I'm not sure if the following links would help, but they are source code for what seem to be similar projects:

  1. Code Project: Convert bet3. ween Hijri Calendar and Gregorian Calendar
  2. PHP based Open Source Hijri Calendar
  3. A Stack-Overflow question that links to Hijri Calendar source

Note that several apps and utilities exist on pretty much all the major platforms which show you the Hijri Calendar. I use iPray on iOS, which shows prayer times in addition to the Hijri Calendar, the lunar phase, the location of the sun and the moon, and the direction of the Quibla.

The time zone affects the time of day, not the date. I don't think the Hijri Calendar would be affected by this. I'd say go ahead with existing time zones - you can't 'create' them and expect mass-adoption.

If your purpose is to create an islamic calendar, then to the best of my knowledge, dates should change at Sun set, not at midnight.

As for calculating the moon's phase (thereby calculating the 'moon birth', you can check out resources here. And a ready-made java source is here.

I don't think Time Zone has anything to do with this... if two locations have the same time zone but different lunar phases, then that doesn't affect anything at all. The date you calculate is based on the lunar phase, not the time zone.

Hope I was of help.

  • Whoops... my bad... you're right. Makes it easier then...
    – Omaer
    Commented Jul 30, 2013 at 9:30

Quran talks about the calendar for mankind based on moon. Three criteria are mentioned to identify the date by:

  1. "ahillah" in 2:189. Most of the commentators had translated as "new moons" or "new crescents". The context in which the verse was revealed can be understood by referring to thafseer ib abbas(ra). Appropriate meaning of ahillah is : phases of moon.
  2. "Manaazil" stage/position of moon and "adassineena val hisaab" meaning no: of years and calculation in 10:5.
  3. Urjoonul qadeem, the withered date stalk appearance of moon in 36:39. Urjoonul qadeem is the last visible phase of a lunar month. Next day the moon will not be visible to the naked eye though new moon is already born (after conjunction) marking the last day of the month. Next day is the first day of the new month.

Few points to be noted regarding the present erroneous unislamic unscientific way of fixing date:

  1. moon sighting is a misnomer. Appropriate term is moon observation.
  2. day and date should be uniform to mankind.
  3. day and date does not change separately.
  4. Islamic date/day begins at sunset is wrong as fajar salaah is the first prayer and isha the last concluded with withr prayer.
  5. Islam is a universal religion and rules applied for the calendar should be universal according to quran hadeeth and science.
  6. Earth is spherical and a day consist of approx 24 hrs.
  7. IDL is the place at which day and date starts and this rule should be applicable to Islamic calendar.
  8. day does not end with sunset to mecca. hence reference to mecca is an error.
  9. is it logic to have two or three dates for friday? we say islam is perfect, and it is deen if allah.
  10. hadeeth and quran never contradicts. Therefore prophet will never tell that sighting is compulsory, but it is a means to know that new month has begun. prophet did not order to go and search the moon on 29th of the month. This moon is invisible for naked eye.

Muslims stick on to sighting as they have misunderstood as sunna of prophet and by going against quran we actually encroach the lordship of allah. 9:36,37. Intercalation is kufr. some lunar months are 29 and some 30, but they are fixed. We cannot fix it according to our will. It is against the quran 9:36,37

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