Wednesday, February 13, 2008

Latitude/longitude

Latitude and longitude is the oldest map-coordinate system for plotting locations on the earth. The Roman scholar Ptolemy devised it almost 2,000 years ago. Ptolemy wrote about the difficulties of accurately representing the earth on a flat piece of paper and created latitude and longitude as a way of solving the problem. That’s pretty impressive for a time way before computers and satellites.

Latitude and longitude are based on a little math, but they’re not really complicated. Angles are measured in degrees, and they’re used for measuring circles and spheres. Spheres can be divided into 360 degrees; because the earth is basically a sphere, it can also be measured in degrees. This is the basis of latitude and longitude, which use imaginary degree lines to divide the surface of the earth.

The equator is an imaginary circle around the earth; the circles are an equal distance from the north and south poles and perpendicular to the earth’s axis of rotation. The equator divides the earth into the Northern Hemisphere (everything north of the equator) and the Southern Hemisphere (everything south of the equator).

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