Locating Positions on the Earth’s Surface

Coordinate System

• Surface grid used to locate any position on the Earth

• Latitude and Longitude

System uses two reference points:

1. Equator – (00 latitude)• Imaginary line that circles the earth• The angular distance north or south of the

equator is called latitude• Lines of latitude are parallel to each other2. Prime Meridian (00 longitude)• Runs from the north pole to the south pole

through Greenwich, England• The angular distance east or west of the Prime

Meridian is called longitude. • Longitude lines meet at the poles and run

north to south

Lines of latitude and longitude on the Globe

Equator--

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Globe

Globe to Mercator

Notice the distortion in the polar regions.

South America is actually 9 times the size of Greenland

An area of the world will always be distorted with these projections.

Projections

Projections

Map Projections.asf

Distance using Latitude

• One degree of latitude = 111km• Each degree is divided into 60 minutes

(60’) Each minute = 1.85km• Each minute is divided into 60 seconds

(60”)– 420 30’ 15” N is read as 42 degrees, 30

minutes and 15 seconds north– This means the location is 4718km north of

the equator

Distance using Longitude

• At the equator, one degree of longitude = 111km

• As you go towards the poles, this distance decreases