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Longitude and Latitude

The ancient Babylonians originally divided any circle or sphere into 360 degrees. Ptolemy was a Greek thinker who borrowed their ideas as he wrote his book on geography. The furthest point at the right or left side of a circle is 90 degrees from the top of the circle. There are 180 degrees between any two sides of a circle or sphere. The north and south poles are 180 degrees apart from one another, and both are 90 degrees from the equator. The equator is the imaginary line that is as far from the North Pole as it is from the South Pole.

The horizontal lines that circle the globe are called Lines of Latitude. Lines of Latitude are also known as parallels because they parallel, or run in the same direction as the Equator. The lines that run between the North and the South Poles are called Lines of Longitude, or meridians. The line at zero degrees longitude is called the prime meridian. The prime meridian runs through the Royal Observatory in Greenwich, England. Meridians are counted east and west from the prime meridian, which is numbered zero degrees longitude. The International Date Line is located 180 degrees, or as far away as possible, from the prime meridian. When it is noon along the prime meridian, it is midnight along the International Date Line.

Geographers also divide the earth into hemispheres. Hemi- is a prefix that means half. Everything north of the equator is in the Northern Hemisphere, while everything south of the equator is in the Southern Hemisphere. The Western Hemisphere is west of the prime meridian, while the Eastern Hemisphere is east of the prime meridian. The hemispheres both end at the International Date Line. The United States is in the Northern and Western Hemispheres. West Palm Beach, Florida is 80 degrees west of the prime meridian and 27 degrees north of the equator. This is commonly expressed as 27^oN, 80^oW.

To cite this page:
Dowling, Mike, "Mr. Dowling's Longitude and Latitude Page," available from http://www.mrdowling.com/601-grid.html; Internet; updated Saturday, June 17, 2006 . ©2008, Mike Dowling. All rights reserved.