THE 13 MONTH SOL CALENDAR
Configuration:
* Twelve contiguous and identical months of exactly 28 days.
* The last, thirteenth month of the year (December) has 29 days
normally and 30 days in a leap year.
* The new month (Sol) occurs between June and July.
Features:
* Avoids the use of intercalary days and the disruption of the
standard week.
* Implementations of 13 period financial calendars are already in
wide use in business and accounting.
* Placing the new month (Sol) at mid-year minimizes the seasonal
displacement of the traditional months.
* Placing the extra day(s) year-end allows all months to be identical
for their first 28 days in any given year.
Peculiarities:
* Any year beginning on a Sunday will feature thirteen Friday the 13ths.
* Blue moons (a second full moon in a calendar month) will become even
more rare since they can only occur in December.
* More birthdays will be celebrated on the 28th over the next century, but
in declining numbers.
Although not perpetual, the calendar does offer an easy method for
date/day calculations:
To calculate any day or date in a given year you only need three bits of
information. First, what day of the week did January 1st fall on?
Secondly, is this a leap year? Lastly, remember the numbers 1, 8, 15 and
22 (1, 1+7, 1+14, 1+21).
Assume January 1st was a Friday and it's a leap year. That means that
the first, eighth, fifteenth and twenty-second day of every month is a
Friday. The twenty-ninth day of December (1+28) is also a Friday and,
since it's a leap year, Saturday the 30th is the last day of the year.
What is the third Monday in May? Again assuming January 1st was a
Friday, the third Friday in any month is the 15th so, with a bit of
addition, the third Monday is the 18th.
What day of the week is August 13th? August 8th is a Friday (as is
August 15th) so either adding or subtracting, one deduces the date is a
Wednesday.
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