[LEAPSECS] Solar time: From mean solar days, to mean solar years

[Keith Winstein]

To be a pedant [but if you can't be one on the leapsecs mailing
list...], the SI second is *9192631770* periods of the radiation etc.
Your figure is high by 1000.

On Wed, Aug 20, 2014 at 9:22 AM, Preben Nørager <samp5087 at gmail.com> wrote:
>
> In the discussion about whether or not to drop the leap second, I think it
> is not a question about solar time or not solar time. It is in other words
> not a question about either solar time or atomic time.
>
>
>
> If we drop the leap second it will be in favour of another timescale, which
> uses only atomic clocks to tell the time, but the time in that other
> timescale will still be based upon a kind of solar time.
>
>
>
> About a hundred years ago it was decided, that the mean solar year, and not
> the mean solar day, should be the unit of international time.
>
>
>
> In 1960 the second was defined as 1/31556925,9747 of the mean solar year,
> and in 1967 the second was redefined [equally in length to the previously
> defined second] as the duration of 9192632770 periods of radiation.
>
>
>
> When the second was defined in 1960 it was defined as a fraction of the
> so-called tropical year. That was a mistake of wording. The tropical year is
> a measurement of the solar longitude on the ecliptic, but the international
> definition of the second is not based upon measurement of the solar
> longitude on the ecliptic.
>
>
>
> The definition of the second is based upon Newcomb's theory of the solar
> system, and in that theory it is the barycenter of the solar system, and not
> the center of the sun, which defines the length of the solar year.
>
>
>
> The length of the solar year, according to Newcomb’s theory, is the time for
> the longitude of the barycenter of the solar system to increase 360 decrees.
>
>
>
> The solar year, thus defined, can be measured either for one year, or for an
> average of years.
>
>
> But the 1960 and the 1967 definition of the second can also be used as an
> international definition of the mean solar year.
>
>
>
> I think we should drop the leap second, and continue UTC without leap
> seconds as TI [International Time], so that 1 mean solar year is the
> duration of 290091231835491000 [31556925,9747x9192632770] periods of
> radiation in the caesium atom.
>
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