Longitude and Latitude

The ancient Babylonians divided any circle or sphere into 360 degrees. Ptolemy was a Greek thinker who borrowed the Babylonians' ideas as he wrote one of the first books book on geography. Ptolemy wrote that the furthest point at the right or left side of a circle or a sphere is 90 degrees from the top. There are 180 degrees between any two sides of a circle or sphere. This means that 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 away 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 26 degrees north of the equator. This is commonly expressed as 26°N,80°W.

Find your longitude and latutude

Find the longitude and latitude of your home or school at World Atlas.

Absolute and Relative Locations

If someone were to ask where Roosevelt Middle School is, you might answer that the school is at 1901 North Australian Avenue in West Palm Beach, Florida.  It probably wouldn’t be very helpful, but you could also truthfully answer that our school is precisely at 26°43'46.24"N, 26°43'46.24"W—at least if you are in Portable 15.  These are examples of absolute locations.

It is often more helpful to describe your relative location.    For example, Roosevelt Middle School is a bit more than a block north of the intersection of Australian Avenue and Palm Beach Lakes Boulevard.  We could also say that our school is across the street from Lake Mangonia.  Both absolute and relative location are useful tools for geographers, and we will use both throughout our study.

Resources:

Download this lesson as Microsoft Word file or as an Adobe Acrobat file.

Download a lesson plan that includes the Florida Next Generation Sunshine State Standards (2011) as a Microsoft Word file or as an Adobe Acrobat file.

Listen to Mr. Dowling read this lesson. (mp3)