[LEAPSECS] Cheating means more planning, not less

Rob Seaman seaman at noao.edu
Sat Dec 27 03:04:41 EST 2008

I wrote:

>> Whatever the preferences of the ITU, they will discover that it is

>> simply unacceptable to allow local dates to vary secularly from

>> civil timekeeping dates.

Tony Finch replies:

> Civil time *is* a form of local time.

The question isn't about haggling over terminology. We've had that
discussion before.

Rather, a clock can be deposited at any meridian on any planet, set to
any time, running at any rate. The question is whether a particular
choice of parameters is useful and sustainable. Additionally if a
planet has populations scattered at wide longitudes, the more basic
requirement is to organize a coherent system to manage the whole.

Identifying the length of the civil day with the length of the mean
solar day is the key to providing that coherence. (True now on Mars
as well as Earth.) The mean solar day is just the sidereal day plus
the synodic correction for lapping the sun once a year. The mean
solar day is a global phenomenon. The eccentricity of the Earth's
orbit and the tilt of its axis (etc) add periodic terms that average
out. Latitude and politics overlay local variations that are a
distraction from the central issue. Tidal slowing, on the other hand,
represents a global long term secular trend. A trend with global
implications demands a global solution.

The trend just happens to be slow enough to permit cheating.
Consensus based planning is necessary *especially* if we decide to
cheat. Cheating is ultimately fruitless over the long term, no matter

The ITU has a responsibility to consider options with a long term
future. A permanent embargo on leap seconds does not have one.
Whatever action the ITU takes, it should be fully and carefully
planned and not obligate our descendants to clean up an embarrassing

>> Only one - standard time based on mean solar time - has ever been

>> shown to be *practically* workable.


> Two: standard time plus daylight saving time is the other

DST is a trivial gimmick layered on standard time. Standard time is a
global system layered on the mean solar day.

Ideally we will come out of this exercise with an improvement to
standard timekeeping. Wouldn't it be more fun to pursue that project
rather than playing an endless game of whack-a-mole with ITU politics?


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