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« Return to Thread: Joining list. Calendar reforms.
Re: Joining list. Calendar reforms.
by Irv Bromberg
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On 2009 May 20, at 15:38 , MIKE OSSIPOFF wrote:
I've just joined this mailing list.
Welcome!
The Gregorian leapyear system is accurate enough. Its drift, with respect to equinoxes and solstices, awar from its average position (I'll call that "drift-from-center" if I refer to it again) isn't a problem.
The Gregorian calendar reform stated objective was to keep the vernal (northward) equinox on March 21st. Therefore the timing of the other equinox and the solstices are irrelevant to it, and so is the "tropical" year. The Gregorian mean year is almost 12 seconds too long, relative to the mean northward equinoctial year in the present era, and its leap years are non-uniformly spread, increasing the medium-term "equinox wobble". A fixed cycle with a slightly shorter mean year and a leap rule that spreads the leap years as uniformly as possible would reduce the long-term equinox drift as well as reducing the medium term wobble. Distributing the leap years in a symmetrical pattern simplifies choice of epoch with respect to the astronomy and simplifies astronomical evaluations of the leap cycle, because the first year of each cycle will always fall at the average for the cycle. It is possible to do all this with a simple leap rule (single step) than the Gregorian calendar employs (3 steps: if divisible by 100 then check if divisible by 400 otherwise check if divisible by 4).
Please see the general discussion and especially the symmetrical leap rules discussion at <http://www.sym454.org/leap/> as well as the discussion of the lengths of the seasons at <http://www.sym454.org/seasons/> and discussion of the equinox and March 21st at <http://www.sym454.org/mar21/>.
Of course the other way to have a fixed calendar is via a "leap-week". That's acceptable to me. It would cause a drift-from-center of about half a week.
Though, personally, I feel that a fixed calendar is an unnecessary complication, and though I'd rather pursue the perfectinist quest for the lowest drift-from-center possible, I understand that most calendar reform advocates want a fixed calendar, and so I would help promote a fixed calendar that uses a "leap-week".
One thing: If you're going to go to all the trouble of a fixed calendar, then I claim that you should make the months (or whatever year-divisions you use) have a whole number of weeks, so that each can start on the same day of the week that the year always starts on. That would make it easier to determine the day of the week for any particular date.
OK, Mike, it sounds like my Symmetry454 calendar is just what you want, if I dare say so myself!
Please see <http://www.sym454.org/symmetry/>.
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