Geography
in the
News™
Neal G.
Lineback
WORLD TIME
DIFFERENCES
wich, England. Each successive time zone,
east and west, was centered on the next 15
degrees of longitude, or 0, 15, 30, 45, 60
and so on. Since the earth rotates toward
the east relative to the sun, high noon
moves westward. As high noon passes
over the central meridian of a time zone,
its entire time zone (7.5 degrees east and
west of the central meridian) has noon.
Although most of the world adopted
standard time zones, some adjustments
were necessary. For example, when a state
or county was divided into two different
time zones, the boundaries between the
time zones were often gerrymandered, or
arbitrarily moved, to solve the problem.
A few countries, such as Saudi Arabia,
Iran, Afghanistan, India, and Myanmar
(Burma), declined the use of time zones in
favor of some form of local time. The
former Soviet Union and Alaska adopted
the time zones to the east to provide an
extra hour of daylight in the afternoon,
giving them permanent “daylight savings time.” China chose to have all of its
territory in a single time zone, although
its breadth is about the same as the United
States, excluding Alaska and Hawaii.
The United States, including Alaska
IDL
Since the beginning of 2000, we have
been repeatedly and dramatically reminded that new transportation and communication technologies make the world
seem smaller and smaller. Business people
who communicate overseas by email, fax
or telephone quickly realize that the world
does not operate only on American time.
Understanding world time zones is essential to maintaining our increasing international contacts.
Until 1884 most of the world used its
own local time. Each place set its clocks
based on high noon, or
WORLD TIME ZONES
when the sun appeared
highest in the sky on each 12 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5
day. For instance, two
towns located a few miles
east or west of one another had local times a
few minutes apart. Local
time was adequate until
the railroad and the telegraph came along. Printing understandable train
schedules based on local
time at every stop made
no sense.
Because of increasing problems with local
time, an international Geography in the News 06/07/02
congress was assembled
in 1884 to establish stanand Hawaii, has six time zones. From east
dard world time zones. The world is dito west, they are based on the central
vided into 360 degrees of longitude, 180
meridians of 75, 90, 105, 120, 135, and 150
degrees east and 180 degrees west of the
degrees west. These time zones are given
Prime Meridian, which passes through
geographic names: Eastern, Central,
Greenwich, England. Longitude lines, or
Rocky Mountain, Pacific (or West Coast),
meridians, extend from pole to pole and
Alaskan, and Hawaiian time zones.
measure distances east and west. Since
Because the U.S. Eastern Time Zone
each day has 24 hours, the congress diis centered on 75 degrees west, or five
vided the earth into 24 time zones, each
time zones west of the Prime Meridian,
containing 15 degrees of longitude.
Washington’s time is five hours earlier
The first 15-degree time zone was
than London’s (Greenwich Time). In other
centered on the Prime Meridian (0 dewords, if a business call must be made
grees longitude), running through Greenfrom Washington to London during work© 2002 maps.com
ing hours, it must be made before noon, or
it won’t reach London before 5 p.m. Since
almost all of Western Europe is one additional time zone east of the Prime Meridian, there is a six-hour difference between
Washington and Paris, Rome or Berlin.
Afghanistan time does not quite conform to International Time Zones, as it is
4 hours and 30 minutes later than Greenwich time. This means that it is 9 hr. 30
minutes later in Afghanistan than in the
U.S. Eastern Time Zone, not considering
Daylight Savings Time. In other words, a
phone call to Kabul from Washington,
DC, at 11.00 p.m. would be received at
9:30 a.m. the following day.
Although the ancient Greek and Roman scholars understood earth-sun relationships, it was not until Magellan’s crew
returned from their circumnavigation of
the earth in 1522 that graphic evidence
materialized of an impending problem.
The ships’ logs (faithfully recorded ships’
diaries) were one day behind. This, of
course, occurred because the ships had
sailed westward around the earth. Little
by little over the three-year-long voyage,
traveling in the direction that high noon
moves, the ships “lost” a day.
The solution to
the lost day was for
6
7
8
9 10
the congress to estab11
lish the International
Date Line, conveniently located on the
180th meridian in the
middle of the Pacific
Ocean. The Date Line
is the line where new
dates on the calendar
begin. For example,
while it may be Sunday at 2:45 p.m. immediately to the east
of the line, it will be
Monday at 2:45 p.m.
©2001
to the west. All of the
earth to the west of
the Date Line will have already experienced 2:45 p.m. Sunday.
Understanding world time is essential to carrying on international relations and the knowledge demonstrates a
level of sophistication absolutely necessary in today’s international communications.
And that is Geography in the News.
June 7, 2002. #627.
(This is a revised version of GITN 229,
written in 1992. The author is a geography
professor at Appalachian State University,
Boone, NC)