While discussing the month (and the monthlong fast) of Ramadan in my previous blog post, I briefly touched upon the subject of the Islamic calendar. It subsequently occurred to me that many non-Muslims may not be aware that such a thing as an “Islamic calendar” even exists. Likewise, many non-Jews may not be aware that there is also such a thing as a “Jewish calendar.”

So, I thought a few words about various religious calendars might be in order.

The official “civil” calendar currently in use by most of the world for general purposes is the familiar Gregorian calendar. This calendar, of course, has specifically Christian origins, but it has been widely adopted by most countries as the default international standard.

The Gregorian (or “Christian”) calendar is the broadly accepted “general use” calendar according to which there are 365 days per year, divided into 12 months of fixed and unchanging lengths (with one exception during leap years). This is also, of course, the calendar that divides human history into two eras: “B.C.” and “A.D.”

That particular convention reflects the specifically Christian roots of the Gregorian calendar, since “B.C.” is an abbreviation for Before Christ and “A.D.” is short for Anno Domini (which is Latin for “In the Year of our Lord”). This calendar views the birth of Christ as the central pivot point of history, and so its years are numbered or counted either forward (A.D.) or backward (B.C.) from that central moment in time.

It’s worth noting, since the question comes up sometimes, that there is no such thing as a “year zero” in this context. One minute after the presumed time of Christ’s birth is “one minute A.D.”, and one minute prior to Christ’s birth is “one minute B.C.” Likewise, the 12 months immediately prior to Christ’s birth constitute the year 1 B.C., while the 12 months immediately following Christ’s birth constitute the year 1 A.D.

Also, I said “the presumed time” of Christ’s birth, because it has now come to light that the historical Jesus was probably not, after all, born at the precise point in history that this entire calendar was constructed and structured around. Most modern biblical scholars today place the actual date of the birth of Jesus of Nazareth at what would be closer to somewhere between 6 B.C. and 4 B.C.

Be that as it may, the bottom line is that the Gregorian or Christian calendar takes the presumed or traditional time of the birth of Christ as its central organizing feature, and as the “start date” for at least its “A.D. portion” of history. According to this widely accepted practical convention, as I write we are currently living in the year 2012 A.D. (or, more properly, in the year A.D. 2012 — the “A.D.” part technically comes first, given the total phrase’s  literal meaning of “In the Year of our Lord 2012”).

However, other religions and cultures have calendars of their own, which have quite different “start dates” or central organizing features. Accordingly, they count or number the years very differently.

For example, the traditional Jewish (or Hebrew) calendar, which is currently used as the official civil calendar in Israel and relied upon by Jews worldwide as a reference for Jewish holidays and other religious observances, takes as its own central organizing principle or “start date” the presumed time of Creation. According to rabbinic tradition, and based upon pertinent calculations relying upon scriptural data, the date of biblical Creation was figured as being what corresponds in the Gregorian calendar to 3760 B.C.

For Jews, of course, the birth of Christ holds no special relevance, so for them “B.C.” is simply not even a factor in play. Instead, Judaism starts counting the years of its own calendar from what the Christian or Gregorian counter reckons as 3760 B.C., but which for Jews is simply “the year one” — the time of the divine Creation of the world.

If you take 3760 years B.C., and you add to that the additional 2012 years A.D., then the number of years that have elapsed since the Creation amount to a grand total of some 5772 years. And that, therefore, is the actual number of the year we’re currently living in. As I write this blog entry (during what the Gregorian calendar regards as July 2012), according to the Jewish or Hebrew calendar it is now the year 5772 A.M. (“A.M.” here is short for Anno Mundi, which is Latin for “In the Year of the World” [e.g., since the creation of the world].)

(To be even more precise: as I write, it is currently the year 5772 A.M.; it will remain so until sunset on Sept 16, 2012, which is the date of the Jewish New Year. For Judaism, as also for Islam, each new day is reckoned to begin at sunset [rather than at sunrise, or at 12:01 in the morning]; therefore, the Jewish New Year will begin at sunset on 09/16/2012, at which point we will then be living in the year 5773 A.M.)

Likewise, the Islamic calendar revolves around yet another entirely different “start date” or central organizing feature of its own. Accordingly, the Islamic calendar — widely in use, naturally, throughout the Islamic world — also counts or numbers its years quite differently from the approaches used by both the Jewish/Hebrew and Christian/Gregorian calendars.

The Islamic calendar starts counting its years neither from a presumed date of Creation (as the Jewish calendar does) nor from the presumed birth of Christ (as the Christian calendar does), but instead from the time of Muhammad. However, it does not begin numbering the years from the date of Muhammad’s birth, as a non-Muslim might expect. Rather, the Islamic calendar starts its counting from the date of a monumentally important event during his lifetime — the Hijra (Arabic for “flight,” “migration”) of Muhammad and his companions from his hometown of Mecca to the nearby town of Medina.

Pagan and polytheistic Mecca had become hostile to Muhammad and his earliest followers, whose countercultural proclamation of uncompromising monotheism put them at increasingly dangerous odds with the Meccan establishment. Forced to flee from Mecca for their safety, Muhammad and his companions found refuge in the welcoming sanctuary of Medina, where the small young community of Muslims were able not only to survive, but to flourish and grow — even eventually returning to Mecca in triumph.

The Hijra was thus a critical emigration that proved to be a vital turning point in the origins of the Islamic community; it is considered so essential a point in the birth of Islam that in retrospect it came to be seen as the central “hinge point” in Islamic history. The Hijra therefore came to be the starting point of the Islamic calendar.

Using the Gregorian calendar, the Hijra occurred in what non-Muslims reckon as the year 622 A.D. For Muslims, however, the occasion of the Hijra marked the beginning of what the Islamic calendar regards simply as “the year one” (of the Islamic era).

Now, if you take the current Gregorian calendar year (2012 A.D.) and you subtract from it 622 years (corresponding to 622 A.D. being the Gregorian date for the Hijra), then the result you get is 1390 years. And if we take the date of the Hijra as being, somewhat roughly and loosely speaking, more or less equivalent to “the birth of Islam” — or at least pretty close to whatever Islam’s actual exact birthdate might be — then we can affirm that Islam, as a religion, is now right about 14 centuries old, or so.

However, contrary to what one might expect, the Islamic calendar does not say that we are currently “in the year 1390.”

There is an additional complicating factor: Islamic calendar years are 10 to 11 days shorter than Gregorian calendar years. This means that as the years — and centuries — accumulate, the shorter Islamic calendar years pile up in slightly greater numbers than the corresponding Gregorian calendar years do.

Over the course of 1390 years (as measured by the Gregorian calendar), the Islamic calendar has by now fallen further behind the Gregorian one by roughly another 40 years, or so (give or take a few).

The upshot of all of that simply comes down to this: according to the Islamic calendar — with its shorter-length years, and its own much later “start date” (equivalent to 622 A.D.) — we are currently living in the year 1433 A.H. (“A.H.” is short for Anno Hegirae, Latin for “In the Year of the Hijra.”)

(It will remain 1433 A.H. until sunset on November 14, 2012, when the Islamic New Year begins; at that point, the Islamic calendar will roll over, kicking off the year 1434 A.H.)

So, what year is this? The answer depends upon whom you ask.

For Jews, this is the year 5772 AM (“In the Year of the World”).

For Christians, it’s the year 2012 AD (“In the Year of the Lord”).

For Muslims this is the year 1433 AH (“In the Year of the Hijra”).

And, of course, they’re all correct — from their own perspectives, that is.