Grade 9 Academic Geography – Strand A Mapping Skills
Time Zones
The Earth rotates 15 degrees every hour. The idea behind multiple time zones is to divide the world into
24 15-degree slices and set the clocks accordingly in each zone. All of the people in a given zone set their
clocks the same way, and each zone is one hour different from the next.
In Canada, there are six time zones: Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific.
When it is 12:30 p.m. in Newfoundland, it is
 noon in the Atlantic time zone
 11 a.m. in the Eastern time zone
 10 a.m. in the Central time zone
 9 a.m. in the Mountain time zone
 8 a.m. in the Pacific time zone.
Note: Saskatchewan uses Mountain Standard in the summer and Central Standard in the winter. That
is, Saskatchewan does not use Daylight Savings Time.
All time zones are measured from a starting point centered at England's Greenwich Observatory. This
point is known as the Greenwich Meridian or the Prime Meridian. Time at the Greenwich Meridian is
known as Greenwich Mean Time (GMT) or Universal Time. The International Date Line (IDL) is located
on the opposite side of the planet from the Greenwich Observatory.
Time Zones - Overview
Canadian Sir Sandford Fleming invented time zones in 1884 to address concerns about intercontinental
railway transportation.
Theory behind Time Zones
 Since the earth rotates around its axis once every 24 hours, there are 24 time zones around the
earth, with 1-hour difference between them. Since the earth rotates through 360O in 24 hours, it
rotates through 15O of longitude in 1 hour (360O / 24 = 15O). Thus, each time zone is 15 degrees
wide. Every place within a time zone has the same time, referred to as its standard time.
 The Prime Meridian is the centre of a time zone that extends 7.5O on either side. Time in this
zone is called Universal Time (UT).
 The Earth rotates from west to east. Time zones east of the Prime Meridian have local times
ahead of UT. Time zones west of the Prime Meridian have local times behind UT. For example if
the sun is directly above the Prime Meridian, the local time in the city of Berlin, which is one
time zone east of UT, is 1 p.m. In Ottawa, which is five time zones west of the Prime Meridian,
the time is 7 a.m. It will be five more hours before the sun appears directly over the 75OW
meridian which is the centre of the time zone where Ottawa is located.
 Time zone shapes have been modified worldwide. China has one standard time for the whole
country despite the fact that it covers more than 60O of longitude. Canada has six standard time
zones, although the boundaries do not follow the meridians of longitude.
 Some places are located where time zones meet. St. John's, Newfoundland, at 52.5OW, is
located between the third and fourth time zones west of the prime meridian. Its time is 3.5
hours behind UT.
International Date Line
When sailors first sailed around the world, they returned home either a day ahead or a day behind those
people who stayed. To correct this situation, the International Date Line was established. It runs
between the North and South Pole, and generally follows the 180 line of longitude through the Pacific
Ocean. It zigzags to avoid dividing land masses or island groups belonging to the same country. If you
cross the date line moving westward, you add a day. If you cross the date line moving eastward, you lose
a day. The time does not change unless the date line corresponds to a time zone boundary.
Daylight-Saving Time
Many parts of the world change their time according to the season. During the summer, daylight-saving
time is used to extend daylight hours into the evening when most people are awake. That is, the sun
would set at 9 p.m. instead of 8 p.m. Theoretically, this time adjustment should reduce energy use since
lights don't have to be turned on until later in the day. In Canada and the United States, daylight-saving
time begins on the first Sunday in April and ends on the last Sunday in October. Other countries use
different dates.
Longitude and Time
Early sailors determined their latitude by the angle of the sun above the horizon or by the position of the
North Star (Polaris), but they had no practical way to find their longitude. In theory, longitude could be
calculated if sailors knew their local time and the time in Greenwich. However, the pendulum clocks that
were in use at the time did not work on a ship being tossed about by waves. In 1791, Englishman John
Harrison developed the marine chronometer - spring-loaded clock that could keep time on a moving
ship. Longitude was calculated in the following manner:
 Exact local time: 7:00 am
 Greenwich time: 12:00 noon
 Since local time was five hours behind Greenwich, the location was west of the prime meridian.
 5 hours = 75 degrees (5 x 15o)
 Current longitude: 75o W of the prime meridian. Possible locations: Ottawa, Canada;
Philadelphia. U.S.A.
Time Zones of Canada – Unique Zones
Newfoundland
Many people wonder why the Province of Newfoundland has a time zone that varies by the half hour
rather than the standard one hour. While the system of Standard Time employs 24 meridians, and each
are theoretically the centres of 24 Standard Time Zones, some adjustments have been made to the time
zones for the convenience of inhabitants that lie within the zones. Newfoundland, (but not Labrador),
lies squarely in the eastern half of its time zone, exactly three and a half hours from Greenwich. In 1963,
the Newfoundland government attempted to bring the province into conformity with the other Atlantic
provinces but withdrew in the face of stiff public opposition. Other countries that operate on the half
hour time difference are Suriname, Iran, India, Sri Lanka, and Central Australia.
Summary -- Eight Time Zone Facts
1. The Earth rotates about once every 24 hours. There are 24 hours in a day.
2. The circumference of the Earth is 360°.
3. Most time zones have a one hour time difference. The exception is Newfoundland Standard
Time.
4. Canada has six time zones: Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific.
When it is 12:30 p.m. in Newfoundland, it is
 noon in the Atlantic time zone
 11 a.m. in the Eastern time zone
 10 a.m. in the Central time zone
 9 a.m. in the Mountain time zone
 8 a.m. in the Pacific time zone.
Note: Saskatchewan uses Mountain Standard in the summer and Central Standard in the
winter.
5. Time Zones have approximately 15° of longitude from east to west.
6. The world has 24 time zones (15° x 24 hours = 360°).
7. Standard times starts at 0° longitude running through Greenwich, England. This is called the
Greenwich Meridian or the Prime Meridian.
8. Standard time was developed by Canadian Sir Sandford Fleming.