Messages in this thread | | | Subject | Re: February 30th 2000 | Date | Thu, 13 Jan 2000 12:50:20 +0100 (MET) | From | (Rogier Wolff) |
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J. Scott Kasten wrote: > Sorry, but no, we're not. The exact time measurement for a year > is 365.24219878... days. We round that off to 365.25 for conveininece > to get a leap day every four years. However, the decimal is less > than .25, so after 100 years, we end up ahead. Thus centuries > are not supposed to be leap years normally, in order to "down correct" > for the .25 estimate. Now, the part .00219878... remaining, works > out to be an extra day every 400 years.
Not quite.
Our current (gregorian) rules come to
365 + 1/4 - 1/100 + 1/400 = 365.2425
The difference with 365.24219878 is: .00030122, which means that every 3320 years or so, we're having one too many leap years. So, I would suggest that we make the year 3300 a leap year. And 6600, 9900, 13300 and so on.... (*)
However, the global temperature of the earth influences the turning of the earth enough that we can't predict the exact number of turns around its axis that long head.... So, it doesn't make sense to try and fix a rule right now that will be wrong by the time it first comes into action...
By the way, my encyclopedia says there are 365.2428933 days in a year, which would require us to have to one -=less=- leapyear every 2500 years.
Some quick websearching gives:
http://www.50megs.com/aalembert/y2kco.html that mentions: 365.2422454...
For a quick laugh check out: http://www.europa.com/edge/pyramid.html which mentions that the exact length of the year is 365.24 days. (And implies that the egyptians who built the pyramids used tenths of an inch as a measure of length.)
http://www.johnpratt.com/items/calendar/cal_intro.html mentions 365.242 as the "TRUE" value.
http://www.mathematik.uni-bielefeld.de/~sillke/ALGORITHMS/calendar/ancient-time-formular mentions: 365,24219878 and 365,2422 , which are actually pretty close to each other. The extra leap year shifts only by 13 years or so, which wouldn't make a difference for a good 20000 years......
Roger.
(*) The century closest to n*3320, that isn't already a leap year....
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 ** *-- BitWizard writes Linux device drivers for any device you may have! --* "I didn't say it was your fault. I said I was going to blame it on you."
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