Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

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

    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.
    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.
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site