## Thursday, August 13, 2009

### Longitude and Latitude

Started the Earth As A Sphere topic by explaining the concept of longitude and latitude.

Lines of latitude run East & West or horizontal but measure distance North & South of the Equator—vertically. The equator is labeled as zero degrees latitude. The greatest amount of latitude is 90 degrees at the North or South poles. We can then label our equator as 0 and our North and South poles as 90. These lines of latitude are parallel to the equator and are even referred to as “parallels” or “parallels of latitude.”

Moving to lines of longitude, they run perpendicular to lines of latitude. That is, longitude lines run North and South but measure East and West of zero degrees longitude which is a line called the Prime Meridian. This arbitrary north/south line was marked by the British in the 17th century and runs through a town just outside of London called Greenwich.

Starting at the Prime Meridian, we measure the earth east or west with these north/south-running lines called “meridians.” We can measure halfway around the world till these meridians meet at 180 degrees. This meridian line at 180 east or west is called the International Date Line. So unlike latitude, where the greatest or maximum latitude is 90 at either the north or south poles, the greatest amount of longitude is 180—halfway around the world from the prime meridian. One other important way these longitude lines differ from parallel latitude lines is that lines of longitude are not parallel, and in fact converge at both the North and South poles.

You can read more on longitude and latitude below :
What Is Longitude and Latitude?