Geography: Longitude Placard

Longitude is defined as measurement of distance in degrees east or west of the prime meridian. The word is derived from the Latin, “longus”, meaning “length”.

The prime meridian divides the earth in half too. The prime meridian as do all other lines of longitude, pass through the north and south poles. This is shown in the diagram to the right. These lines are not parallel. They make the earth look like a peeled orange. Because the earth is round like a ball, not all longitude lines are visible. There are 180 other lines of longitude on the other side of the globe. But on the opposite side, the prime meridian is 180 degrees and is called the International Date Line.

Longitude lines to the left of the prime meridian give locations west, in the western hemisphere. Longitude lines to the right of the prime meridian give locations east, in the eastern hemisphere.