[LEAPSECS] sunrise time is the solution!
dot at dotat.at
Tue Dec 23 09:10:46 EST 2008
It occurs to me that my proposal for a rational replacement for daylight
saving time also provides an answer to the leap second question.
The essence of sunrise time is that we reset our clocks each day to a
fixed time when the sun rises at a benchmark location. For the UK, the
benchmark location would be where the Greenwich meridian crosses the
Tropic of Cancer. The fixed time is 06:44, which is the time of the latest
sunrise at that location according to mean solar time (UT1). The reset is
accomplished by adjusting your timezone offset, which you'd do a few hours
earlier than sunrise to avoid disrupting early risers, and you'd round the
offset to the nearest minute to avoid breaking things like ISO 8601.
If you are setting civil time according to these rules, then civil time is
by definition coupled to the rotation of the Earth, and there can be no
accelerating secular difference between the two. This is true whatever
time scale you use as the basis from which timezone offsets are
calculated. You have a pretty free choice of basis timescale long as
its length of day is not too far from the Earth's LOD.
The resulting system has several useful properties:
* You can use atomic time as your basis timescale, with a LOD of 86400
* The only other time(s) you need to worry about are local time(s), just
like the current situation.
* Both basis time and local time have fixed-length minutes and hours,
which is much simpler than the current situation.
* Basis time has fixed-length days, which is also a simplification.
* Local time has variable-length days, just like the current situation.
* Small timezone adjustments are less disruptive than large ones.
* Frequent timezone adjustments make timezone-related bugs more obvious
and therefore easier to fix.
* It preserves the role of Earth location scientists in time keeping.
f.anthony.n.finch <dot at dotat.at> http://dotat.at/
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