By Duncan Steel 31/12/2018

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New Year is coming in a few hours (as I write), at least on the calendar used as the global standard. Not everyone counts years in quite the same way, though.  


It takes most of us a week or two to get used to the number of the year having changed. In the days when we still wrote cheques, the first few such slips of paper each year would often carry the signs of hasty corrections in the very last digit at upper right. But imagine what it is like if you also use a different dating system to that which has become the world standard.

In my preceding post I wrote about how our common dating system uses a radix defined by the traditional day of the circumcision and naming of Jesus Christ: 1st January in AD 1. ‘Common’ is a good word to use there, and it is notable that rather than the AD (Anno Domini) and BC (Before Christ) notations, many now use instead CE (Common Era) and BCE (Before Common Era) in order to introduce a distinction from the religious meaning. For example, if you peruse Wikipedia’s pages you will find that CE and BCE tend to be used.

The simplest distinction in dating is between the Gregorian system which provides the basis for the world standard, and the Julian calendar that is still used by various Christian denominations, in particular the Eastern Orthodox churches. I am writing on AD 2018 December 31st (the ‘proper’ way to state a date, I’d say: the AD should come first, followed by the most significant digit; after all, we do not say that some item costs 95 cents and two dollars). Tomorrow it will be 2019, but on the Julian calendar it will still be 2018 for another 13 days. Indeed, Christmas is yet to come for the Orthodox churches, because December 25th (Julian) is January 7th (Gregorian).


The Orthodox churches (and some other cultures) still use the Julian calendar, meaning that their celebration of the Nativity occurs 13 days after the event was marked on the Gregorian calendar.


In case you should think that I am picking on the Orthodox churches, let me note that modern astronomers still use a vestige of the Julian calendar. The ‘year’ we use in calculating things like light-years is defined by the mean Julian year of 365.25 days. A convention often used by astronomers to number days for ease of international coordination is the Julian Date (JD) framework, which is the number of days (plus the fraction of a day) since 1st January in 4713 BC on the proleptic Julian calendar. I am quite fond of that because ‘my’ asteroid is number 4713, although on the proleptic Gregorian calendar the equivalent date is 24th November 4714 BC. The start date was chosen because it precedes any recorded history (along with some technical astronomical reasons), so there are no negative JDs to consider.

It happens that a number of different, separated cultures have developed calendars that have initial eras (year-zeroes, if you like) that are several millennia BC. Some of these have been labelled AM (Anno Mundi: the year of the world).

The best-known perhaps, and often cited in gleeful ignorance, is the 4004 BC of James Ussher, 17th-century Archbishop of Armagh and Primate of All Ireland. His modern detractors make fun of the apparent preciseness of his stipulated time (at nightfall on 22nd October 4004 BC, proleptic Julian) without realising that his identification was based on the time of the autumnal equinox in that year. By the standards of the scholarship of the day Ussher was no fool.

At the time that Ussher published his determination of the start of the world – in 1654 – it happens that Britain and Ireland were using an entirely different calendar: between the execution of Charles I in 1649 and the restoration of King Charles II eleven years later, the Roundheads imposed a Puritan calendar, counting off the “the first year of freedom” and so on. This sort of new era definition has occurred frequently, as we will see.

Returning to calendars with assumed starting eras several millennia ago, the Meso-American/ Mayan Long-Count with a creation date in 3114 BC was much in the news a few years back due to the delusion that it predicted a global cataclysm that would occur on December 21st in 2012. In case you didn’t notice, this didn’t happen.

In Christianity various Anno Mundi eras have been adopted. The Byzantine Empire – which developed from the Eastern Roman Empire after Constantine the Great moved the capital to Byzantium/ Constantinople/ Istanbul in the early 4th century, and legalised Christianity – initially used an AM chronology counting from 5493 BC, but by the 10th century the first day of September in 5509 BC had gained ascendancy for reasons we might regard as being esoteric. Such dating systems continued in widespread use in the East until the 19th century.

In the Judaic faith, the Hebrew or Jewish calendar counts its Anno Mundi from 3761 BC. This leads to different year numbers appearing on newspaper front pages and in official documents.


From the online Jerusalem Post for AD 2018 December 28th (Gregorian); on the Hebrew calendar that day was the 20th in the month of Tevet in AM 5779, the Jewish new year festival of Rosh Hashanah  occurring on different dates in September based on the lunar phase.


This clustering of imagined dates for the creation of the world preoccupied Western thinkers quite apart from Ussher. Isaac Newton turned his attention to this some decades after Ussher, and decided that the world may have been formed around 4000 BC. Late in the 18th century the Freemasons adopted a chronology based on an Anno Lucis (the year of light, AL) defined simply as the Gregorian date plus 4,000. This means that the effective Masonic year-zero was 4001 BC.



The Masonic Lodge in Cromwell, Central Otago. On the front portal the year given for its construction – shown in more detail at the head of this blog post – is AL 5900 or AD 1900, where “AL” means Anno Lucis.





Another dating system that is similar, but I might suggest to be based more on science, is that used by some geologists and palaeontologists. This is the Holocene Epoch (HE): simply add 10,000 years onto the AD/CE date, which means a leading digit one. As I write we are about to enter HE 12019. Of course the Holocene epoch did not begin overnight at the start of HE 1, but it did start around 12,000 years ago.


In passing I note that archaeologists who perform dating by various techniques use a BP (Before Present) scale, where the ‘present’ is 1950. This cannot be shifted, in essence, to 2000 or 2020 or whenever because the advent of atmospheric nuclear bomb testing means that the amount of carbon-14 in the atmosphere has been artificially altered, upsetting radiocarbon dating. Nevertheless a scale to be termed ‘b2k’ has been suggested for use with dating methodologies independent of radiocarbon, such as counting annual layers in polar ice deposits.

Quite apart from the difference in 13 days between the dating systems used by most Western churches (the Gregorian calendar) and some Eastern Orthodox churches (the Julian calendar), there are some Christian denominations that use quite distinct dating eras. In my previous post I explained how the AD system is based on the traditional dates of the Annunciation, Nativity and Circumcision (25th March 1 BC, 25th December 1 BC, and AD 1 January 1st respectively) due to an error made by a monk in Rome in the sixth century, with the actual birth of Jesus having occurred more than four years earlier, perhaps in mid-April of 5 BC.

In the Ethiopean Church the era definition is based on an assumed date of the Annunciation or Incarnation that was some years later, on AD 9 March 25th (on the Julian calendar, the leap-year cycle of which continues to be used in the Ethiopean Calendar) and a civil year beginning seven months earlier, on AD 8 August 29th. With the 13-day slippage between Julian and Gregorian calendars this means that, in Ethiopia and Eritrea, New Year occurs on September 10th or 11th, depending on whether it is a leap year. To look at it another way, the Ethiopean calendar is seven years, eight months and ten days behind the commonly-used world dating system. Currently it is 2011 there, for another eight months or so. Thankfully there is an app available to do an easy conversion (as above right).

Further north, the Coptic Orthodox Church uses a related calendar. Like the Ethiopean, the Coptic Calendar stems from the ancient Egyptian calendar and uses similar months. However, it uses as its radix AD 284 August 29th (rather than that same date in AD 8), 284 being the year that Diocletian became Roman Emperor, marking a period of intense persecution of Christians, especially in Egypt. The Coptic Calendar therefore counts from the Era of Martyrs, and can be confusing because it may be denoted either as AM (Anno Martyrum) or AD (Anno Diocletiani).


The Coptic Church uses a calendar that counts from the year 284, with New Year occurring in what we would term ‘September’. This graphic shows two equivalent dates.


Above I have been addressing mostly Christian or Judaic dating systems which have year lengths defined fundamentally by the time it takes Earth to orbit the Sun, although the phases of the Moon affect such events as Easter and Rosh Hashanah. In Islam the ‘year’ instead counts off twelve lunations, and so lasts for 354 or 355 days; that is, it is a lunar year. Lasting about eleven days less than a solar year means that the various religious observances, such as Ramadhan, slip backwards through the Gregorian calendar.

In terms of the start era, the Islamic calendar is based on when Muhammad and his followers shifted from Mecca to Medina in AD 622, this event being known as the Hijra. Islamic years are sometimes denoted AH (Anno Hegirae), with AH 1440 expected to terminate on 30 August next (though technically the calling of a new month/year depends on the actual sighting of the new crescent moon).

The above is termed the Lunar Hijri calendar. There is also a Solar Hijri calendar, using the year defined by Earth’s orbit but also counting from the era of the Hijra. Abbreviated as SH, this is the official calendar in Iran and Afghanistan (although they use different month names). In terms of astronomy it is more accurate than the Gregorian calendar because it hinges on when the vernal equinox actually occurs in March (for the Tehran meridian), rather than an imprecise numerical model designed for religious purposes (i.e. fixing the date of Easter).

Another strict-astronomy calendar that uses the vernal equinox on the Tehran meridian to define the start of the year is that of the Bahá’i religion. Their count (the Bahá’i Era or BE) starts in AD 1844 so we are currently in BE 175.

As one might anticipate, the multiplicity of religious sects in India has led to a phenomenal number of rival calendars being used from one place or temple to another. In Sikhism the Nanakshahi Calendar is used, but there is ongoing debate over its definition; it counts from within AD 1469. In Hinduism there are similarly many regional differences, with the Bikrami, Tamil, Bengali and Malayalam and other calendars all being distinct but mostly having start eras in the first millennium BC.

In consequence, soon after independence in 1947 the Indian Government decided that a national calendar would be needed, and a Calendar Reform Committee reported in 1955 on a system based on astronomical considerations. The Shalivahana Shaka calendar was introduced on AD 1957 March 22nd (Gregorian), that becoming 1 Chaitra 1879 of the Shaka Era (i.e. its radix is in AD 78, at the vernal equinox), and we are currently in SE 1940.

The Gazette of India, showing equivalent dates on the Gregorian and
the Indian National/Shalivahana Shaka calendars.


In Taiwan an era starting in AD 1912 is still used, based on the foundation of the Republic. In the People’s Republic of China that system was dropped from 1949. It happens that 1912 also contains the start epoch for the Juche era used in North Korea.

In recent centuries in the Western world various new era schemes have been introduced, some of them being short-lived. The Puritan calendar mentioned earlier is one example, another being the French Republican calendar that lasted from 1793 until 1805. A longer-lived convention is the convention of the U.S. Government in counting years since the Declaration of Independence on 1776 July 4th:


Part of the fourth and final page of the original manuscript of the U.S. Constitution, showing the dating as being the 17th day of September in the year 1787 and also the twelfth year of “the Independance [sic] of the United States of America”.


Elsewhere regnal years may still be used for official purposes, for example in Japan. We are currently in the Heisei era, which began on 1989 January 8th, the day after the death of the previous Emperor, and so the year H30 will terminate with that date in 2019; the Heisei era itself will end when Emperor Akihito abdicates on April 30th.

This may seem anachronistic to us, but perhaps we could take a look at our own recent practice. It turns out that both regnal years and Gregorian year dating have been used in official documentation in New Zealand and the United Kingdom.







At left: New Zealand Acts of Parliament from the mid-19th century. The upper two bills are both from the year 1856, but one is denoted as being from the 19th year of the reign of Queen Victoria, the other from the 20th year of her reign: one was passed before her accession date of June 20th (in 1837), the other after that date. The lowest of the three bills shown has the initial rubric in Latin: Anno Vicesimo Sexto Victoriae Reginae (“The Twenty-Sixth Year of Queen Victoria”), from which one can deduce that ‘The Gold Fields Act 1862’ must have been passed after June 20th.
















This potential confusion over which-year-is-which is circumvented if both regnal years are given (as they are on some NZ legislation I have examined). Here is an example from the UK. Queen Elizabeth II acceded to the throne on the death of her father, King George VI, on February 6th in 1952; she was in NZ at the time, and it was Waitangi Day, which means that her regnal years perennially begin on that date. The bill shown at right is dated March 29th, 1955, which technically was in the fourth year of her reign, but the dating shows “3 & 4 ELIZ. 2”, 1955 being the calendar year which contains parts of both the 3rd and 4th years of her reign.


At right: A UK Act of Parliament from 1955, showing the double-regnal-year dating deployed so as to avoid confusion (!)


What have I tried to tell you in this blog post? Essentially, my core subject here is that our years are numbered in many different ways. What system you might use in particular situations may depend upon your nationality, location, religion, and other factors.

Which is the best dating system? Well, it all depends… As I have pointed out, the Gregorian system is second-rate, in terms of astronomy (and that has some knock-on effects for other areas of science, as I will outline in a future blog post), and it also uses a radix (its effective year-zero) that is fundamentally wrong. However, before someone asks, no I am not suggesting it should be changed. It provides a useful framework for usage globally.

I had intended to end all my posts with the words “out of space”, but the truth is that if I am to get this blog up on the SMC website before the end of 2018 (at least in New Zealand) then I will need to end things here. In fact, I am almost out of time.