[Datetime-SIG] Fwd: Calendar vs timespan calculations...

Alexander Belopolsky alexander.belopolsky at gmail.com
Thu Aug 6 20:21:41 CEST 2015

On Thu, Aug 6, 2015 at 5:46 AM, M.-A. Lemburg <mal at egenix.com> wrote:
[Alexander Belopolsky]
>> ...  "due to the initial choice of the value of the second
>> (1/86400 mean solar day of the year 1820)" sounds like nonsense.
> More details on all this are available at:
> http://tycho.usno.navy.mil/leapsec.html (provided their server is up)

Thanks for the link!  "Modern studies have indicated that the epoch at
which the mean solar day was exactly 86,400 SI seconds was
approximately 1820." makes much more sense: they did not pick the
value for SI second to match 1/86400 mean solar day of the year 1820,
it just so happened that the value they picked for other reasons
matched later estimates of what we now think 1/86400 mean solar day of
the year 1820 was.

I now believe it was all a bad PR.  What they should have done was to
announce that according to the new measurements a "year" is 1 second
longer than people thought, so they would add 1 second at the end of
June *every year*, but since the Earth is wobbling unpredictably, on
some years they will occasionally skip a second in December.  If they
did that, 30 years later leap second support would be as widespread as
support for February 29.

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