Notes

Mapping the Earth: Latitude and Longitude
Vocabulary
equator an imaginary circle that divides the earth into northern and southern hemispheres
geography the study of the earth that deals with its plants, animals, and climate
globe a sphere with a map of the earth on it
international date line imaginary line agreed upon as the place where each calendar day begins
latitude the measurement of distance in degrees north or south of the equator
longitude the measurement of distance in degrees east or west of the prime meridian
prime meridian meridian from which the longitude east and west is measured.It passes through Greenwich, England, and its longitude is 0 degrees.








The world contains wonders that still baffle the most brilliant minds today. It seems as if scientists make new natural discoveries every year. An old saying in the educational world is "the more we learn, the more we realize what we don't know." In other words, the wise scientist realizes that he has not even scratched the surface of knowledge about the world's geography and history. From the Matterhorn of Switzerland to the Great Barrier Reef off the coast of Australia, there are numerous wonders for man to explore. Geography is the study of the earth: its surface, climate, continents, countries, peoples, industries, and products. In this study of world geography, you will look at the physical and climatic characteristics of continents and the development of the people in those regions. First, you will learn longitude and latitude. Then you will study the different maps of the earth and the hemispheres. A hemisphere is an imaginary division of the earth into halves. Finally, you will look into the political and cultural regions of our world.



Geography is the study of the earth. The word comes from a Greek word geographia, which means writings about the earth. Researchers study everything from the mountains to the coastlines of every continent and island around the globe. In order to study the earth, geographers have created a system of imaginary lines to locate different places on the planet.

The earth you live on is a sphere that rotates daily on its axis. The axis is an imaginary line that runs through the center of the earth from top to bottom. It passes through both the North Pole and the South Pole. The poles are imaginary points marking the "top" and "bottom" of our earth. If the earth were a basketball spinning on someone's finger, the finger would be the bottom of the axis at the South Pole.

Another important imaginary line is the equator. It circles the center of the earth halfway between the two poles. The equator divides the earth into two halves, the Northern Hemisphere and the Southern Hemisphere (half-spheres). The area around the equator is the warmest on earth; the areas around the poles are the coldest.

That is a lot of imaginary lines!

The Shape of the Earth

The earth is not perfectly round. Well, it is not flat, either, but if you were to say that the earth is a perfect spehere, you would be wrong. You see, the force of our planet's rotation causes the earth to flatten out just slightly on the top and bottom. It also bulges just slightly in the middle. Thus, the circumference of the earth is slightly greater around the equator than it is running through the poles.

Just like every house on your street has an address, every single spot on earth has an address. Any place on earth can be located by longitude and latitude. These are imaginary lines used to create an address for any point on earth.
LONGITUDE AND LATITUDE

Lines of longitude run from the North Pole to the South Pole. These lines, called meridians, have a beginning and an end at the poles. Meridians divide the earth into 360° (° is the symbol that means degrees). This is the number of degrees in any circle. Even though these lines run north to south, they are used to measure distances east or west of the prime meridian.

One of the lines of longitude had to be chosen as a starting point for counting purposes. The geographers chose the meridian that runs through the town of Greenwich, England, as the prime, or first, meridian. The prime meridian is 0° longitude. Every place on earth is located by the number of degrees east or west of the prime meridian, up to 180°, which is half of the total 360° in a circle. Halfway around the world the lines of east and west meridian meet at the international date line. The international date line is 180° both east and west longitude.
Latitude Runs from East to West

Latitude lines are circles that run around the earth from east to west. Unlike meridians, they do not meet at any point. Lines of latitude are therefore called parallels, because they are parallel to each other. Parallels also divide the earth into 360°. The equator is 0° latitude. All points on earth are a number of degrees north or south of the equator. A single degree of latitude is approximately 69 miles (111 km).

The North Pole is 90° north latitude, or 90° north of the equator. The South Pole is 90° south latitude, or 90° south of the equator. Since the poles are only one-fourth of the way around the globe from the equator, 90° (or one-fourth of the 360° in a full circle) is the largest number of degrees latitude can have.

Look at the map above. It shows some of the countries in northern Europe near the prime meridian. The country of Denmark is located at about 10° east longitude because it is that far east of the prime meridian. Iceland is located at about 70° north latitude because it is that far north of the equator. The location 60° north latitude, 10° east longitude pinpoints the exact spot where those two lines cross in Norway.

Degrees of latitude and longitude can be divided even further if more accuracy is needed. Each degree is divided into sixty minutes ( ' ) and each minute into sixty seconds( " ). Thus, using latitude and longitude, any point on earth can be accurately numbered. For example, a spot near New Orleans, Louisiana might be 30° north latitude, 89° 55' 15" (89 degrees, 55 minutes, 15 seconds) west longitude.
PRACTICING LONGITUDE AND LATITUDE

Every location on earth has an "address." This address is in the form of longitude and latitude lines. You can use longitude and latitude measurements to locate countries or cities. As you learned in the beginning of the lesson, longitude and latitude lines form a grid. Where the lines intersect tells you the specific location of a place. If you are locating a country using longitude and latitude on a flat map, you can use a ruler to follow the lines to find the intersection. If you are using a globe, you can trace the longitude and latitude lines with your finger while turning the globe to locate the specific place.

Look at the map below and see if you can find the country that is located at approximately 45° North, 75° West.

You will see that this country is Canada.

You can also use longitude and latitude lines to locate cities. Look at the following map and determine which major city is located at approximately 35° North, 140° East.

Tokyo, Japan is located at approximately 35° North, 140° East.

If a country or city does not fall directly on a longitude or latitude line, you can estimate the number of degrees. Make sure to look at the map scale and the surrounding lines of longitude and latitude to help you determine your estimate. Then, make a reasonable estimate of the country's or city's location.

For example, Cape Town, South Africa is located at approximately 33° South, 18° East.

Using longitude and latitude is like using an address to locate a friend's house. With these two numbers, you will be able to find the exact location of any place on the earth.