HemispheresTo study Earth, geographers divide the globe into equal halves. Each half is called a hemisphere. An imaginary line called the equator divides the globe into north and south halves. The half of Earth north of the equator is called the Northern Hemisphere. The half south of the equator is called the Southern Hemisphere.
Geographers use another imaginary line to divide Earth east from west. This line is called the prime meridian. The half of Earth west of the prime meridian is called the Western Hemisphere. The half east of the prime meridian is called the Eastern Hemisphere. |
Geographic GridThe diagram also shows two globes marked with lines of latitude and longitude. As you have already learned, latitude lines lie to the north and south of the equator. Longitude lines go around Earth over the poles. These lines run east and west of the prime meridian. Geographers use a grid system to find the point where a latitude line and a longitude line cross. This point identifies an absolute location—the exact place on Earth where a city or other geographic feature can be found. Remember that location is one of the themes geographers use to describe Earth.Absolute location is expressed using the coordinates, or set of numbers, of the latitude and longitude lines. These coordinates are measured in degrees. Every place on Earth has only one absolute location.
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