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    Re: What time is it, really?
    From: Gary LaPook
    Date: 2008 Jul 18, 14:21 -0700

    Addendum:
    
    97/100 = .2425 so the Gregorian year is 365.2425 days which closely
    approximates the actual solar year of 365.2422 (rounded to the same
    precision) a difference of only .0003 days.
    
    gl
    
    On Jul 18, 1:35 pm, glap...@pacbell.net wrote:
    > The Gregorian calendar was promulgated by Pope Gregory in 1582 to
    > correct the deficiency in the then current Julian calendar which had
    > caused the equinox to slip by 11 days. (England did not adopt the new
    > calendar until 1752.) The Julian calendar applied a leap day every
    > four years making the average solar year 365.25 days and this had
    > caused too much of a correction since the average year is not quite
    > that long which caused the 11 day slip over the centuries. Gregory's
    > calendar eliminated 3 leap days every four hundred years, (100 leap
    > days under the Julian calendar and only 97 leap days under the
    > Gregorian calendar in every 400 year period.) This was accomplished by
    > eliminating leap days in century years unless the century was
    > divisible by 400 (2000 was a leap year while 1700, 1800 and 1900 were
    > not) while the Julian calendar makes every century year a leap year
    > since century years are all divisible by 4. This fraction, 97/100
    > (making a year 365.24 days), closely approximates the actual length of
    > a solar year which is actually 365.24219878 days, so the current
    > calendar accumulates one day of error with respect to the solar year
    > about every 3300 years.
    >
    > gl
    > On Jul 18, 10:32 am, Bill  wrote:
    >
    > > Greg R. Wrote
    >
    > > > K, that's one "extra" day than the annual allotment of 365, so I go
    > > > back to my original question about why we don't need leap-days every
    > > > year instead of every 4 years or so (something sticks in my mind about
    > > > it being 365 1/4 rotations/year(?) - which would jibe with 1 leap-day
    > > > every 4 years or so).
    >
    > > Correct.  It takes almost 365.25 days for the earth to make one complete
    > > revolution around the sun.  The extra 0.25 day would be a bit much to handle
    > > time wise, so we stop at 365.  Which leaves us a bit more shy of completing
    > > a full revolution each year after leap year.  The extra day in a leap year
    > > every 4 years gets us back on track (mostly).  Since the time to orbit the
    > > sun is not precisely 365.25 days, we have have the exceptions where there is
    > > no leap year to even things out.
    >
    > > Bill B.
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