[LEAPSECS] Calendars count days - clocks divide them up

Rob Seaman seaman at noao.edu
Tue Jul 2 17:36:04 EDT 2013

On Jul 2, 2013, at 1:10 PM, "Poul-Henning Kamp" <phk at phk.freebsd.dk> wrote:

> All languages I know about, have a word for "day" and one for "night"

English has daytime and nighttime as well.

> A small minority of languages also have a word for a 24 hour period

> starting and ending at midnight.

Or meaning something more like "the period of time from one diurnal marker to the next", where this could be sunrise, sunset, noon, etc.

> I don't think any nordic person would agree that "a day has 24 hours".

However many hours a day is deemed to have, it does not have a quadratically accelerating secular error introduced by fiat.

> In Ancient egypt the day had 10 hours, no matter how long the day was due to the seasons.

Reference? Perhaps this is confounding a count of hours of daytime with what you describe above as both a 24-hour period and not 24 hours?

>> And it seems there is impatience about working through these consequences.


> Or maybe some people correctly recognize that standardization is done

> for the benefit of the future, not for the clarification of the past ?

The benefit of the future is layered on system engineering best practices, not political whims.

In the future there will be one fewer day per year than sidereal rotations just as there is today, as there was in ancient Egypt, and as is true elsewhere in the Solar System.

The sidereal rotation period of the Earth will continue to vary in weird and wonderful ways. Attempts to eliminate leap seconds have engineering implications.


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