From Time to Time

 From Time to Time

By Bobby Neal Winters

From time to time, it is good to think of some of the good things that were done for us by those who came before us.  Some of them saw problems and came up with simple, long-term solutions to those problems.  Consider the calendar.

The year--and by year I mean Solar year--is 365.24217 days long.  The Solar year is the length of time it takes to pass from the first day of spring in one year to the next. (It is to be compared to the Sidereal year, but just let it go.)  We lay out our calendar to try to fit the calendar year, but we’ve got a problem, that fraction.  

We have to divide the calendar into an integral number of years and that fraction gets in the way.  We like to have the first day of spring to hit around March 20, but if we set the calendar year as having 365 days, the first day of spring starts moving away from that.  In about four years, it’ll be March 21.  In forty years it will be March 30.  In 80 years, it will be April 10.  

Do you begin to see the problem?  You’d have to start tracking spring in a way separate from the calendar, and it’s quite reasonable to think that knowing when the first day of spring is was the original purpose of the calendar.

This problem was fiddled with for a while, but someone, and I will say Julius Caesar--and I know people who will correct me--decided to add a “leap day” to the calendar every four years and call those years leap years.  If you do the math--or even if you don’t--that works out to having a calendar year that is 365.25 days long.  This is closer to 365.24217, but it’s not dead on.  You are off by 0.00783 of a day in the other direction.

That difference is a lot smaller.  That should solve the problem, but--as the Steve Miller Band said, “Time keeps on slipping, slipping, slipping into the future....” After 15 hundred years, you are off by 11 days. Spring is starting much earlier in the year.

This time the powers that be fiddled with more sophistication.  They noticed that if you skipped adding a leap year every 100 year you would get a calendar year that was 365.24 years long on the average.  This is a little better but not all that much.  After 1500 years, you will still be 3 days off. This particular reform was being promoted by Pope Gregory of the Roman Catholic Church, and they believe in eternity.  Someone figured out that if you skipped adding a leap year in years divisible by 100 unless that year was divisible by 400 then you got a year that was 365.2425 days long.  This differs from the true value by 0.00033.

In 1500 years, you will be off by less than 12 hours. In 10,000 years you will be off by 3 days.  This is what we like to call someone else’s problem.

And all we have to do is follow a rule that says add a year to the calendar in years divisible by 4. However, when the century turns, you can skip adding the day. Unless the year is divisible by 400 hundred, then add it anyway. Most of us remember the “divisible by 4” part.  The fact that we have a presidential election that year helps.

We only have to remember not to add the day every 100 years.  Although I’ve never had to deal with that because, the only turn of the century I’ve experienced was the year 2000 which was divisible by 400, so it was a leap year as usual. 

One of the beautiful things about this solution is that it requires only a tiny amount of effort and even that small amount of effort is spread across years, centuries, or nearly a half a millennium. Very few of you reading this will have to remember that we get to skip a leap year in 2100, and we’re clear on remembering not to skip it until 2400.

Actually, “we” don’t have to remember.  The people who make the calendars do.  If we had to do anything, there would be people against it just as there are people against the time change. 

Maybe I shouldn’t’ve said anything. 

Bobby Winters, a native of Harden City, Oklahoma, blogs at redneckmath.blogspot.com and okieinexile.blogspot.com. He invites you to “like'' the National Association of Lawn Mowers on Facebook. Search for him by name on YouTube. )