A New Calendar

The 13-month "Sol" Calendar

Sol calendar 2007


  • The Sol Calendar has twelve contiguous, identical months - January through November - which have exactly 28 days each
  • All months are identical for their first 28 days
  • A new month, Sol, appears between June and July, which minimizes the seasonal displacement of the traditional months a 13-month calendar would otherwise create
  • The last month, December, has 29 days each year
  • Leap years are every four years (in the same years we currently have leap years) and they add a 366th day to December (a Dec. 30), the same number of days the Gregorian calendar adds during a leap year
  • While itís not perpetual - 2007 begins on a Monday, not on a Sunday, as in 2006 - the Sol Calendar nonetheless avoids the nightmare solution of adding "null" or "off-calendar" days to make it perpetual
  • It preserves the standard, seven-day week and all the current monthís traditional names
  • Almost all professional accounting systems offer a 13-period reporting option. Computer accounting programs will likely be easily adjusted to 13 months

Criteria Assessed
Does this calendar effectively address current concerns with the Gregorian Calendar? 
Yes, it does. Unlike our current jumble of month sizes, the Sol Calendar's 28-day months can easily be remembered, and the leap year is more rationally located at the end of the year, rather than tucked after February (which hasn't been considered the end of the year for centuries.)

Since each month's calendar is the same for the first 11 months (and identical through the 28th day every month) it's easy to remember that the 27th day of every month in 2006 is a Friday.

Does it present any problems of its own?
The issue of uneven business quarters is not addressed with this calendar. In fact, it destroys the quarters altogether, since 13 is not evenly divisible. Other than in 2006, the year's sum total of workdays aren't even divisible into two equal parts. In 2006, it can be cut into two 130-day halves. That won't happen again until 2011, then 2017. Still, all months but December can be compared equally, whereas now, they cannot be.

Since the calendar's first day "floats" from day to day each year, as in the Gregorian calendar, it's not perpetual, which could be seen as a flaw because it doesn't address that concern. Adding "null" days would correct this, but that would add other, more serious, flaws (see below.)

Unlike other calendars, which keep 30- and/or 31-day months, the Sol Calendar eliminates 37 numbered days from the Gregorian calendar, all from the end of months. Even though one, Dec. 30, comes back again like Feb. 29 does now - every four years, this destroys a LOT of birthdays, and might be a big problem for advocates of its adoption among people who care about exact commemorations of their birth on the exact date.

A less serious flaw is that when the first day of the month is a Sunday, as it is in 2006, 13 Friday the 13ths appear on the calendar. Those who are spooked out by this fact will likely shy away from this particular calendar.

The "New Calendar Rhyme" Test:
"Twelve months have 28 days, December 29.
Every four years, December gets 30 at leap year time."

How easy would it be for this calendar to be adopted?
Resistance to adding a month to the traditional 12-month calendar would be strong, perhaps overwhelming in its intensity. However, a case can be made that it would lead to a more logical calendar arrangement. Like the current calendar, there are no off-calendar days, and a leap year is simply added to the end of the year.

The fact that it doesn't solve the current calendar's uneven quarters - this calendar actually destroys them altogether - is a point advocates of this calendar would have to address.

On the plus side, this calendar could be adopted in place of any Gregorian year, since there's no requirement that the year start on a certain date, as is required by some reform proposals.

Also going for it is the fact that the Sol 13-month Calendar, as outlined above, is elegant, simple and very attractive. This and the sheer symmetry of the months may help overcome some of the objections listed here in the eyes of the public.

Important notes:
It should be mentioned here that this calendar (by Jim Eikner of Austin, Texas) is a latter-day descendant of the International Fixed Calendar, which in turn has its roots in the Positivist Calendar created by French philosopher August Comte in 1849. Comte based his calendar on Polynesian calendars, and named months for famous people and also named each day. Needless to say, using his names for months - which included Homer, Shakespeare, Caesar, St. Paul and Dante - would entrench opposition to the change, and perhaps bring out interest groups who wished to name months in their own fashion. Fights over proposed month names such as King, Reagan, Thatcher, Kennedy or Christ would be unending, making this impractical in light of modern politics.

The modern International Fixed calendar also has a 13-month year, each with 28 days. It also adds a "null" day at the end of the year not belonging to any month. The added month, named either Sol or Midi, is located in the same place as the Sol Calendar proposal above, between June and July. In leap years, another off-calendar day, "leap day," would be inserted between June and Sol/Midi.

From a practical point of view, as discussed with the World Calendar, any off-calendar days present a nightmare for record keeping, and would tend to doom any calendar proposal.

As for the Sol Calendar proposal above, these null-day issues do not exist, and would not be an impediment to adopting that version of the 13-month calendar.

It should also be mentioned that a 13 Moon Change Peace Calendar - a variant of the International Fixed Calendar - has been proposed by a New Age religious group, with overtones of universal harmonic convergence and peace. Like Comte before them, they rename the weeks and months and even the days of the week, using the ancient Mayans for inspiration instead of the names of Western scientists. 

It even names the cycles of the centuries in the manner of the Mayans, and totem animals are attached to the calendar as well. While some would certainly be attracted to these aspects, most others would be repulsed or even amused by them, and in any case would not want to adopt one unknown (dare I say, "fringe"?) religion's calendar for all of civilization.

NEW 11/06:pdflogo.gif - 297 BytesDownload two attractive Sol Calendars for 2007 (.pdf format)

Web Links
Official Site of the 13-Month Sol Calendar

The International Fixed Calendar
The "13-moon Change Peace Calendar"

The World Calendar      The 30x11 Calendar       

The Symmetry454 Calendar       Common-Civil-and-Time Calendar

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