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Re: What time is it, really?
From: Gary LaPook
Date: 2008 Jul 18, 14:21 -0700
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, Billwrote: > > > 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. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---