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

[Preben Nørager]

There exist, in use, two differing definitions of the dynamical equinox.
The one is called the rotational equinox, and the other is called the
inertial equinox (Standish 1981, [
http://adsabs.harvard.edu/full/1981A%26A...101L..17S]). The IERS uses the
inertial equinox.


I differentiate between the solar year, where the dynamical inertial
equinox determines the length of the year and, and the tropical year, where
the dynamical rotational equinox determines the length of the year. I have
not seen any comments on this aspect of my post. There has so far mostly
been the usual comments, for or against the mean solar day as the ”natural”
unit of time.


I think there is a lot of resistance against dropping the leap second
because the SI second builds upon a new understanding of the solar year,
where the inertial equinox, and not the rotational equinox, determines the
length of the year. Religion has always used the rotational equinox to
determine time, and never used the barycenter of the solar system, because
measurement of the barycenter belongs to modern time. Therefore I think a
lot of resistance comes from religion.


Modern society shall use the barycenter of the solar system, and the
inertial equinox, to determine time (with help from atomic clocks). But the
tropical year, and the rotational equinox, will always be part of for
instance the dating of Easter.


2014-08-21 9:06 GMT+02:00 Clive D.W. Feather <clive at davros.org>:

> Warner Losh said:
> > Absolutely. We get leap days right because we don?t have to hear from
> the pope?s astronomers every year to know if it will be a leap year or not.
> We know for thousands of years.
>
> And note that it was exactly that problem that led Caius Julius to reform
> the calendar in the first place.
>
> [...]
> > Another thing we could do is [...]
>
> Or we could decouple UTC from GMT and allow each country to decide when to
> change its offset. That subsumes the whole problem into the summer/winter
> time switch, or the "move past the International Date Line" switch, that
> the whole world knows how to handle, even if they don't all do it.
>
> --
> Clive D.W. Feather          | If you lie to the compiler,
> Email: clive at davros.org     | it will get its revenge.
> Web: http://www.davros.org  |   - Henry Spencer
> Mobile: +44 7973 377646
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