Xref: utzoo comp.misc:2102 rec.aviation:6106
Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!plx!slvblc!dick
From: dick@slvblc.UUCP (Dick Flanagan)
Newsgroups: comp.misc,rec.aviation
Subject: Re: Timezones
Message-ID: <1090@slvblc.UUCP>
Date: 13 Mar 88 03:22:02 GMT
References: <1083@ektools.UUCP> <325@jc3b21.UUCP> <1988Mar11.014836.4816@sq.uucp>
Sender: uupc@slvblc.UUCP
Reply-To: slvblc!dick@ucscc.UCSC.EDU (Dick Flanagan)
Followup-To: rec.aviation
Organization: SLV Systems Group, Ben Lomond, California
Lines: 37
Summary: There are actually 25 of them
Disclaimer: none


In article <1988Mar11.014836.4816@sq.uucp> msb@sq.uucp (Mark Brader) writes:
> > All the time zones in the world have a one-letter
> > identifier.  The one for Greenwich happens to be "Z".
>
> This would be a neat trick, since there are about 35 time zones in the world.

Well, there are really only 25 "official" time zones around the world.
Generally one for each hour of the earth's rotation each day.  With two
exceptions, each is 15 degrees of longitude (or one hour) wide.  Each
is given a letter designation.  'J' is omitted (I've often wondered who
decides such things) and 'Z' straddles the Prime Meridian through Green-
wich, England.

The two exceptions are the 'M' and 'Y' zones which are only 7-1/2 degrees
wide and which are on either side of the International Date Line.  Whereas
the time difference in both zones is the same--12 hours--one is a positive
difference and the other is negative.

> Even when you exclude the ones that are on half hours and odder amounts,
> there are still at least 26, because the International Date Line wanders
> east and west.  Does the single-letter system cover all of these?

Obviously not (see below).

> What does it do about daylight saving time, which creates an additional
> "zone" just west of the line when in effect?

Daylight saving times, wandering date/time lines, and the like are social
phenomena, not physical ones.

Dick

--
Dick Flanagan, W6OLD                         GEnie: FLANAGAN
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