Introduction
Welcome to EarthClock, a 13 month calendar that incorporates geometry (in the literal sense; the measure of the Earth), and natural mathematical patterns. The result is a calendar that behaves as a calendar truly should - in a predictable, intuitive, and cyclical manner.
EarthClock is a free concept, completely devoid of any intellectual property claims, and available for anyone's use or adaption as it is itself a borrowed idea. It was developed by Cody Jassman, originally as Calendar 13 published online on 2011.12.17 ECD (11/11/2011 on the Gregorian Calendar). It is based on the 13 month, 28 day diagram created by John Michell in his book “The Dimensions of Paradise”. The rebranding to EarthClock occurred on 2016.3.14 ECD (02/29/2016 leap day on theGregorian Calendar).
13 months. 28 days each. Simple.
EarthClock evenly divides the months into 28 days consistently which the Gregorian calendar fails to do. 13 months of exactly 4 weeks each equals 364 days. Then, day zero is placed at the beginning of the year (example: 2016.0.0) which occurs on the Gregorian calendar translation of December 21. This date was chosen to mark the average winter solstice, as it was logical to choose an astronomically significant day of the year for day zero. This also means that January 1 on the Gregorian calendar syncs up nicely with 1.11 ECD and the Gregorian leap day of February 29 is easily remembered as it is the “pi day”: 2016.3.14. Both of these date translations, while just happy coincidences, Both of these dates (and I'm sure many more) make for good, easy-to-remember points of reference.
ECD stands for EarthClock Date. The standard ECD notation is year.month.day with no leading zeroes. There are no names for the months; everything is numerical and displayed from greatest (year) to least (day).
What about the leap day?
There are numerous ways alternative calendars attempt to solve the problem of the Earth's year not being an exact number of full days. EarthClock makes no attempt to revise the Gregorian system's solution of the leap day every 4 years*, which means that date conversion between the two is easy - they stay synced up year to year. Leap years will be one day offset from the Gregorian calendar on February 29 forward for translation because the extra day added to a leap year in EarthClock occurs at the end of the year rather than the illogical placement of the end of the second month. In ECD format, the leap day is given the notation xxxx.0.1. This means that a leap year will begin on 0.0 (as do all others) and end on 0.1. You may refer to the example date of 2016.0.1 to see it displayed on the calendar.
The four year leap day cycle can also be tracked visually on EarthClock. The years are shown on each of the 4 sides and progress in counter-clockwise fashion from red in the lower left to purple in the upper left. The purple year is the year that the leap day (in most cases, please see asterisk below for clarification) will fall on.
*Leap days occur once every four years except on years that are multiples of 100 but are not multiples of 400 (1700, 1800, and 1900 were not leap years but 2000 was)
Is there really a need for calendar reform?
I will let you be the judge on this one. Sure, the Gregorian calendar is widely used all over the world and reasonably solves the problem of tracking the duration of the year. But does it achieve its goal elegantly and intuitively? The months have different lengths, and the names of the months that are based on numbers are all offset by 2 (September = sept = 7, but is the 9th month, October = oct = 8, but is the 10th month, etc.). A calendar, ideally, should be organized in a rational, predictable manner and follow a circular pattern as this is the symbolic depiction of the concept which it seeks to measure – namely, the measurement of the Earth's annual journey around the sun.
If you are one of those that take seriously appeals to tradition, you will likely not be persuaded that EarthClock is a better system than the Gregorian calendar. In one way it isn't; we're all well acquainted with the Gregorian system. However, if you believe that we should reform and improve systems – even very longstanding, ubiquitous systems like the calendar – you may find reason to adopt EarthClock into your own life, even if just partially.
Can I use EarthClock and its associated graphics?
The answer to this is a clear, unequivocal yes. As mentioned above, there are no intellectual property claims to EarthClock, nor can you claim any. The work is declared public domain and is free for all people for all uses. No credit is necessary. Even the JavaScript for EarthClock is considered open-source and quite well-organized.