Time Zone
Maps
Day 13
Early Timekeeping
Before the invention of clocks, people marked the
time of day using the sun. Many used a sundial to
tell what time it was.
The sun is not at the same place in the sky at various
locations around the world at the same time, so a
sundial was not really practical.
Greenwich Mean Time
When well-regulated mechanical clocks became
widespread in the early 19th century each city began to
use some form of solar time on which to base clock
settings.
Solar time still meant that time differed from place to
place.
In 1675, Greenwich Mean Time (GMT) was established at
the Royal Observatory in England to aid English sailors in
planning sea travel and routes.
It also provided a standard reference time for all of the
cities in England which, up until them, each had a
different local time.
How Time Zones Came About
Local “solar” time became even less reliable when
railroads and telecommunications improved—clocks
were set at different times from one place to the
next. The use of time zones smoothed out these
differences.
The first time zone in the world was established in
Great Britain using GMT. This quickly became
known as Railway Time.
In 1852, the Royal Observatory in Greenwich began
to transmit the first “time” signals so that clocks
could all be set to the same time (synchronized).
America’s Time Zones
Timekeeping on by American railroads in the mid-19th
century was somewhat confused.
Each railroad company used its own standard time,
usually based on the local time of its headquarters or most
important train station.
Some major railroad junctions (place where two or more
railroad routes crossed) were served by several different
railroad companies. In which case, the trainmaster had a
separate clock for each railroad company. Very
confusing!!!!!
The main station in Pittsburgh, Pennsylvania had SIX
different clocks to watch for the six different railroad
companies that used its station.
Time Zones Become Official
By the 1880s, railroads in the U.S. and Canada agreed on
time zones that were one hour apart. It was inaugurated
on Sunday, November 18, 1883, also called "The Day of
Two Noons",[4] when each railroad station clock was reset
as standard-time noon was reached within each time
zone.
Within one year, 85% of all cities with populations over
10,000, about 200 cities, were using standard time.
By 1918, the U.S. Congress passed the Standard Time Act
and it brought the confusion of times to an end when all
regions of the U.S. were part of one of the established
time zones.
Time Zones
A time zone is a region on
Earth which has a
consistent, legally
authorized standard time
throughout that region.
The U.S. now has 9 standard time zones. The
Continental United States has 4. From east to west
they are Eastern Standard Time , Central Standard
Time, Mountain Standard Time, Pacific Standard
Time.
As you move from East to West through the
time zones, the time changes by one hour.
When it is 8 a.m. in New York, for example,
it is 7 a.m. in New Orleans, 6 a.m. in Denver,
and 5 a.m. in Los Angeles.
Use the time zone converter below
to see what time it is in various
cities around the world.
http://www.timeanddate.com/worldclock/converter.html
Enter the current time for Shreveport.
Select a city…..like Tokyo, Japan
See the time difference between the two. Check
out the date too.
It may already be tomorrow in some locations!!!!