The crux of the year for the Thellid Calendar is the winter solstice of the northern hemisphere1. This is called "Old Year's Day" and is ALWAYS the last day of the year. It is a special day and falls outside the normal days of the week and outside the normal months. It has NO day of the week!
All other days of the year are assigned a day of the week, (except the Leap Day).
The day following Old Year's Day is called "New Year's Day" and it is always the first day of the week2 and of the year.
NOTE: A given solstice occurs at a different time for each longitude and it will often occur that two places have that solstice on a different DAY! For this reason the Thellid Calendar is tied to the solstice at one place only, otherwise half the world would have a calendar that differs by one day from the other half. It is convenient to use the Greenwich Observatory in London as that place, since it has been the time standard for centuries.
In Leap Years, (years when the Greenwich Winter Solstice, (GWS), would have otherwise have moved on to New Year's Day), an additional day is added immediately before Old Year's Day. It is called "Leap Day" and it too falls outside the normal week.
I am well aware that inserting a leap day BEFORE Old Year's Day creates problems that would be obviated by inserting it AFTER Old Year's Day. These problems relate to the fact that you can't tell if the 365th day of the year is a Leap Day just by looking at it, 3 out of 4 times it will be an Old Year's Day. If the Leap Day came AFTER Old Year's Day then the 366th day would ALWAYS be a Leap Day and the 365th day would ALWAYS be Old Year's Day. This is wonderful mathematically, but semantically and socially it is unacceptable!
The New Year must immediately follow the old: you can't have an extra day between the two! What would that mean? A day with no year? And socially, the night between the two days is CRITICAL! We all get together to ring out the old and see in the new. To insert a day between the two would throw the whole celebration out of whack. For these reasons I consider a little mathematical inconvenience to be an acceptable price to pay for a system that makes sense socially.
NOTE: Thellid Leap Years DO NOT generally coincide with Gregorian Leap Years! Nor do they always occur 4 years apart. It all depends on how the natural procession of the seasons at Greenwich coincides with the rotation of the Earth. Because the Thellid Calendar is DRIVEN by the GWS instead of trying to predict it, it is self correcting, however, this also means that you need an ephemeris or almanac to establish whether a year will be a Leap Year, you cannot tell just be looking at it. I regret the inconvenience but I believe the benefits more than outweigh the price. You can find a list of modern Thellid Leap Years here.
There are 13 months of 28 days each year. Rather than perpetuate the inconsistent, unimaginative and culturally loaded current system of names, where some are the names of Gods and others just translate as "eighth month" and "ninth month" etc, I have created a new set of names of neutral meaning3. In order the names are:
Since there are 13 months, they do not fit neatly into 4 seasons. This is perhaps not such a problem as some might at first think, for the following reasons:
It is sad to lose the divisibility of 12 months but more important to us now is the unit of the week, and that is preserved and enhanced!
There are 7 days in the week. For the same reasons I cited in changing the names of the months I have changed the names of the days of the week. It is sad for many of us to lose our linguistic connection with the pre-Christian Gods but it is time to move on. In order their names4 are:
In the current Western culture Teijal and Vaira form the weekend; a period where most do not have to work.
The idea of 5 days work and 2 days off is a reasonable model and should never be allowed to be pushed back to a greater work/relax ratio. Indeed a more civilised ratio would be 4:3.
Rather than assigning the year zero to some dubious point in time, arrived at by some religious organisation, based on interpreting some archaic piece of writing, of doubtful provenance, of significance only to a minority of the global population, it would be far better to assign it to something we can ALL share in, such as: the beginning of human civilisation! Apart from providing a start for counting the years it provides a humbling and salutary reminder of just how short our history really is!
Of course we don't know exactly what year human civilisation began, but archaeological evidence of the first permanent human-built settlements and agriculture are all within the last 12,000 years. For this reason the Thellid Calendar adopts the Human Era (HE) starting point, as proposed by Cesare Emiliani in 1993.
To convert our current system of "Common Era" dates to Human Era we need only add 10,000, (often simply prefixing a 1), to all positive CE years, (all AD years), and subtract all negative CE years, (all BC years), from 10,0015. So:
Note that strictly speaking Emiliani's HE format only works with Gregorian years. The Thellid year normally begins 9 or 10 days before the Gregorian one, meaning that Gregorian HE dates between 21 and 31 December, will have a Thellid HE date ONE YEAR LATER. For this reason, where there is any doubt, all Thellid dates should be followed by the designation "T". Eg 8,075 T, 12,012 T.
Date notation is simple enough for the most part: eg 13th of Duvadda, 12,005 becomes 13/3/12005 T or 3/13/12005 T (depending on what country you are from6) or simply 69/12005 T (getting rid of the redundant month classification).
The designation "T" should be applied when there is any doubt as to whether it is a Thellid or Gregorian Date. In a page that is clearly exclusively full of Thellid dates it is not necessary.
A difficulty occurs with Leap Day and Old Year's Day. If you get rid of the month there is no problem, eg 365/12005 T or 366/12004 T, although you can't tell just from the number 365 whether it was a Leap Day or not. (You may need to consult your almanac for this.) This problem is best fixed by naming the day, eg Leap Day 12004 T, Old Year's Day 12005 T.
This problem is worst however, when you use a notation that requires a month for a day that has no month! The solution is to create 2 extra months, each of one day, simply for the benefit of numeric notation. Leap Day is the first day of Nabbakan, (the 14th month), and Old Year's Day is the first day of Werrimul, (the 15th month). So Leap Day 12,062 T may be written as 1st Nabbakan, 12062, or 1/14/12062 T. Old Year's Day 12,031 T becomes 1st Werrimul, 12031 or 1/15/12031 T. Old Year's Day will be recorded as the 15th month whether or not there was a 14th month that year7.