Seeing the world on a globe
have been slow to accept the concept of a spherical world, yet the
ancient Greeks knew Earth was round. The Greek historian, Strabo, wrote
of a world globe ten feet in diameter made by Crates of Mallus and
exhibited in 150 B.C. Thus, for centuries, men have known the shape of
Earth, but most visualized it only as the small, flat area that
embraced their everyday lives. Today, however, we live in a global
community, and the globe has become the map of our modern world. Jet
travel and modern communication have overcome natural barriers, reduced
distances between all nations. And man's exploration in outer space
with manned and unmanned satellites has brought home graphically the
roundness of our Earth and its place in the universe.
of the basic uses of your globe is to find places--cities, nations,
land and water areas-- just as easily as you can find the busiest
street in your home town. Finding a place is not enough, however,
unless you see it in its true geographical relationship to the rest of
the world or, in other words, see those countries which are its
neighbors and the true distances and directions between them. The
question, "Where is it?" is answered best by using a globe, for only on
a globe are distances, directions, sizes and shapes of countries, and
their relationship to each other---all correct! Seeing the true
geographical relationships of all nations on this round replica of our
world increases our understanding of their economic, social, and
political status, as well as their interdependence.
has been said that wider use of the globe among all peoples of Earth
could be a powerful instrument for peace. Your globe will dispel any
misconceptions about distances and directions obtained from studying
flat maps. Looking straight down at the north pole, you see that ours
is largely a northern world. Many great nations form a circle around
the pole--Japan, China, the Soviet Union, the Scandinavian countries, the United Kingdom, Canada, the
United States. Today, the
Arctic has become a busy intersection for planes following the shortest routes between major cities of the world.
only is your globe a true guide to our modern world; its usefulness
extends to many other areas of learning. It illuminates the pages of
history, makes events in today's world more significant, enriches our
understanding of the sciences including the exciting new sciences of
inner and outer space. Learning the uses of your globe from the pages
that follow will assist you toward its fullest enjoyment.
Finding places on your globe
a globe is round, with no beginning or end, there are two main
reference lines from which all distances and locations are calculated.
One is the equator running east and west around the middle of the
globe, dividing it into two equal halves. The other is the prime
meridian, an imaginary line running from pole to pole and cutting
through Greenwich, a section of
London, England. Both of these lines are 0º and the globe numbering system starts at the point where they intersect.
lines running east and west, parallel to the equator, are called
latitude lines. They are sometimes referred to as parallels because
they are parallel to each other. Latitude lines are shown at 15º
intervals north and south of the equator. Look at
New Orleans on your globe and you will find it located at 30º. Since it is north of the equator, we say it is 30º north latitude, or 30N.
lines running north and south from pole to pole are called longitude
lines, or sometimes referred to as meridians. Longitude lines are
numbered along the equator on your globe at 15º intervals east and west
of the prime meridian at
Greenwich. Again using
New Orleans as an example, we find it located at 90º, or 90º west of 0º longitude. Thus,
New Orleans is located at 30N latitude and 90W longitude.
latitude lines go from 0º at the equator to 90º at the poles. Longitude
lines go from 0º at the prime meridian to 180º, a point on the exact
opposite side of the globe. In giving a position, latitude is always
stated first. Lines of latitude and longitude appear on your globe only
at certain intervals; otherwise, they would cover up all other map
The international date line
You will find the international date line along the 180º meridian in the
Pacific Ocean on your globe. It is half way around the world from
Greenwich. When it is noon in
it is midnight on the International Date Line, and it is there that a
new day is born. Since we gain or lose an hour ever 15º we travel east
or west of
if we were to travel completely around the world, we would lose or gain
an entire day. The International Date Line is the place internationally
agreed upon at which the loss or gain of a day takes place.
are a few jogs in the date line. In order that the eastern tip of
Siberia may have the same date as the rest of the Soviet Union and the
Aleutian Islands may have the same date as
Alaska, the date line jogs away from the 180º meridian to avoid these points.
On a flight from Tokyo to
a traveler who had started his dinner on Sunday would finish it across
the date line on Saturday--the day preceding! When it is noon, Sunday,
January 1, on the west side of the line, it is noon, Saturday, December
31 on the east side. Going west you advance a day: going east you go
back a day.
at the stroke of midnight on the International Date Line is a day the
same all over the world. A moment later, there are two days going on,
on Earth at the same time. When Tuesday has arrived at the
International Date Line, it is still Monday over the rest of the world.
The new day moves westward. When a day is six hours old, it has
traveled one-quarter of the way around the world. Then one-quarter of
the world is having Tuesday and the other three-quarters are having
Monday. Six hours later, the new day is half way around the world, and
in another six hours, three-quarters of the way. Finally, it approaches
the date line again and another new day, Wednesday, is born.
Measuring in degrees
of years ago, the Babylonians invented the system of dividing up a
circle that cartographers use today. The distance around your globe, or
any sphere or circle regardless of its size, is measured by dividing it
into 360 sections called degrees, and each degree represents a fraction of the complete globe. Angular distance is a term sometimes used in describing the location of a place on the globe.
the preceding page, we located New Orleans at 30ºN latitude because, as
shown in the illustration, a radius or line drawn from new Orleans to
the center of Earth forms a 30º angle with one drawn from the equator
to the center. Similarly, a radius drawn from the prime meridian at the
equator to Earths center forms a 90º angle with one drawn from the
New Orleans meridian to the center. This locates the city 90º west of the 0º meridian.
Earth's area is so great that 1º can equal as much as 69.17 miles, the
degree is broken down into smaller parts for more exact measurements
such as those required for navigation. Each degree can be divided into
60 equal parts called minutes ( ' ), and each minute can be further divided into 60 parts called seconds
( " ). Even the tiny second can be divided into decimals for greater
accuracy, making it possible to pinpoint any place on the face of
Earth, no matter how small. A single house in
New Orleans, for instance, might be located at 30º 27' 14.085" N and 90º 43' 31.535" W.
Miles in a degree
length of a degree of latitude on Earth's surface is about 69 miles,
and is fairly constant because lines of latitude are all parallel and
equally distant. It is a different story with longitude lines, as they
gradually converge toward the poles. One degree of longitude at the
equator equals 69.17 miles, but as you move toward the poles, the
distance between longitude lines diminishes. At 40º latitude, a degree
of longitude equals 53 miles, at 60º the length of a degree of
longitude is about 35 miles or approximately one half of the equatorial
length and, at 90º where all lines meet, it is 0 miles.
the morning, your city is turning toward the sun. It passes under the
sun at noon and turns away from it at night. Noon is the time when the
sun is highest in the sky above you. It takes twenty-four hours for
Earth to make one complete rotation. Therefore, each of the twenty-four
meridians on your globe, or a space of 15º, represents one hour of
The word meridian is from the Latin and means mid-day. All places located on the same meridian have noon at the same time. When a place is having noon, the sun is on the meridian.
Before noon is known as A.M (ante meridian) and after noon is P.M.
(post meridian). Because of Earths rotation from west to east, when the
sun is on the Greenwich meridian, all places west of
Greenwich are before noon as they approach the sun. All places east of
Greenwich are after noon as they have already passed under the sun.
Traveling great circle routes and measuring distances
We frequently hear the term great circle or great circle route used in connection with air travel and, more recently, space flights. Great circles
are the greatest circles that can be drawn on a globe or on the face of
Earth. They divide the sphere exactly in half. The equator is a great
circle, and so is every meridian.
we live on a round world, the shortest route between any two points
lies along a great circle. You will see this for yourself when you
measure distances on your globe and discover that the arc of a great
circle between any two points always creates a direct line. Looking at
a flat map, one would assume that to travel from Chicago (42N latitude) to
Tokyo (36N latitude), one would head west and even a little south.
But the shorter route is the great circle route, which can be simulated
by stretching a piece of string tautly between the two cities. This
route, hundreds of miles shorter, heads northwest, past the 60º parallel and southern Alaska, almost missing the
Pacific Ocean entirely.
To compute the distance from Chicago to
mark each city on your string, then place it on the equator line and
count the number of degrees between marks. You will find there are
about 89º. Multiplying by 69.17 (miles per degree at the equator), the
answer is 6,156 miles. Tracing great circle routes on your globe will
give you a new idea of distances and directions. It may come as a
surprise to those who have always studied flat maps, to find that the
great circle route from Toronto to Bangkok is directly over the North Pole; that the route from Melbourne, Australia to Rio de Janeiro, Brazil lies over Antarctica; that you head northeast from Seattle for the most direct route to
Time equals space on your globe
the sun appears to rise in the east and set in the west, it is the
Earth that is moving, constantly rotating from west to east. It is this
continuous turning toward the sun and away from it that causes day and
Using the time dial
You can tell the time of any place on Earth by counting the number of meridians and figuring one hour later for each one east of you or one hour earlier
for each one west of you. Your globe has a time dial, loosely capped
over the North Pole, and you will see that it is divided into
twenty-four equal parts, each representing one hour (or one meridian).
Numbering is from noon to midnight and from midnight to noon. Half the
dial is dark to indicate the darkness hours from sunset to sunrise and
half is light for daylight hours.
Let us suppose you are in
New Orleans, sighting along the 90ºW meridian. Now rotate the globe (the time dial turns with it) until you find
Paris. Sighting up along the nearest meridian you find it is 4:00 P.M. Turn the globe to
Cairo and repeat the procedure. It is 6:00 P.M. there. Now, rotating the globe all the way to
Tokyo, you find the day is over and it is 1:00 A.M. the next morning.
Why we have standard time zones
we did not have a system of standard time zones throughout the world,
every spot on earth would have a different time. Travelers would have
the almost impossible task of trying to keep their watches set
accurately. At the equator, the earth rotates 1,038 miles per hour, or
17 ¼ miles per minute. Going westward, to keep accurate time, one would
have to set his watch back one minute every 17 ¼ miles traveled. Traveling eastward, one would set his watch ahead in the same proportions.
avoid such difficulties, Earth was divided into twenty-four time zones
by international agreement. A traveler, then, has only to set his watch
ahead by one hour as he enters a new time zone going east, or back one
hour if he is traveling in a westerly direction. Each of the
twenty-four time zones is centered on the 15º meridian and all time
within any zone is the same. The boundaries of the zones are irregular
in many places to suit local convenience. Obviously it would be
impractical for a city to have two different times because it happened
to straddle a time zone boundary.
Source Cited: Replogle Globes Inc.
Used with permission, Interface Network Inc.