Locations on The Earth - The Coordinate System

Degrees, Latitude, & Longitude

You're probably aware that angles are generally measured in degrees (such as 90 degrees for a right angle). Did you know that circles and spheres are also measured in degrees? Circles and spheres can be divided into 360 degrees, as shown in this illustration. The earth, as represented on globes and maps, is divided into 360 degrees. This division makes it easier to locate places.
Look at the horizontal (latitude) and vertical (longitude) lines drawn across the map below. Lines of latitude run east-west, while lines of longitude run north-south. Latitude and longitude are expressed as coordinates, or numbers. Each number represents the number of degrees north or south of the equator (for latitude) or east or west of the prime meridian (for longitude). For example, Chicago, Illinois is located at approximately 42ºN 87º W, and Sydney, Australia is at approximately 34ºS, 151ºE.