What do the Co-ordinates Mean?

To find an exact position on Earth we must have two coordinates: Latitude and Longitude.

Latitude and longitude are the lines that are drawn on charts (and maps). It is standard practice (and easier) to decimalise the minutes in order to use formulas for navigation.


The equator: An imaginary line on a chart or map which perfectly bisects the Earth midway between the two poles. It is halfway between the North Pole and the South Pole.

The equator is the line of the 0° latitude and therefore the starting point for measuring latitude.

All lines on the Earth’s surface which run parallel to the equator are called Parallels of Latitude. Depending on which side of the equator they lie, they are named North or South.

The image shows the lines of latitude (they are parallel to the equator). Of course, the lines follow the curve of the Earth, even though they appear straight on this diagram.

Above the equator (0°) the latitudes are north, and below they are south.

The Tropic of Cancer and The Tropic of Capricorn are used in this image as the example, they are at 23.5° north and south respectively.

You can see that latitude is measured from 0° to 90° north or south.

TIP: If you read or write a latitude measurement that is more than 90°, you instantly know there is an error somewhere.

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