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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
>
> 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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