Geographic coordinates have latitude and longitude. Latitude represents north-south location, and longitude represents the east-west location. By combining them, you can pinpoint any spot on the surface of the earth. These coordinates aren’t expressed in units of distance but degrees. That is because the earth is a sphere.
The Air Force created the first generation of the Global Positioning System in 1973 for finding lost soldiers. GPS isn’t only for positioning anymore, but also for timekeeping situations where everything needs to be synchronized perfectly.
How do GPS coordinates work?
The earth is divided up into horizontal lines of latitude and vertical lines of longitude. Latitude is read first, longitude second. Latitude lines are known as parallels that are read in terms of north and south of the equator. The starting point is the equator that is zero degrees latitude.
Latitudes and longitudes are invisible lines that help us identify a place using geometrical coordinates. An easy way to remember the orientation is that latitudes are lateral and longitudes are long.
Latitudes: Latitude lines circled the globe in the east-west direction. It measures how far north or south a specific point lies from the equator. They’re also known as parallels. The distance between each degree of latitude is approximately 69 miles.
Longitudes: Longitudinal lines run from the North Pole to the South Pole. It measures how far east or west a point lies from the prime meridian. These are also known as prime meridians. Longitudes can value from 0 degrees to 180 degrees east. The distance between longitudes at the equator is the same as latitude, roughly 69 miles. At 45 degrees south or north, the distance between is about 49 miles.
- 90 degrees south of the Equator is the South Pole or southern hemisphere.
- 90 degrees latitude north of the Equator is the North Pole or northern hemisphere.
- West of the Prime Meridian is the Western Hemisphere.
- East of the prime meridian is Eastern Hemisphere.
- South of the Equator is the Tropic Capricorn ( 23°26′11.9″ S).
- North of the Equator (23°26′11.9″ N) is the Tropic of Cancer.
- At 66 degrees 33 minutes 44 seconds north and south of the Equator are have the Arctic and Antarctic circles.
- The starting point for reading longitude is the Prime Meridian. It is a line passing near the Royal Observatory in Greenwich near London in the United Kingdom.
To locate a precise point on the Earth’s surface, degrees of latitude and longitude have been divided into minutes and seconds. There are 60 minutes in each degree, and each minute is divided into 60 seconds.
For example, the Great Pyramid of Giza coordinates is 29 degrees 58 minutes 45.03 seconds north, 31 degrees 08 minutes, and 03.69 seconds east.
Imagine a line running from the equator to the center of the earth. And then another line running from the center of the earth to the north or south pole. These two lines make a 90-degree angle. All latitudes in each hemisphere can be represented by drawing the third line somewhere between them. So the equator would have 0 degrees latitude, and the north pole would have 90 degrees north latitude. And a location halfway between the north pole and the equator would lie at 45 degrees north.
The same thing for the southern hemisphere, except you call it degrees south. For more precision, each degree of the earth’s surface is divided evenly into 60 “minutes,” and each minute is divided into 60 “seconds.”
- For more specific, add decimals to seconds. Alternately, write the whole coordinate in decimal notation.
Learn about GPS coordinates
To do this, you have to convert minutes and seconds, which are base-60, into our regular base-10 counting system by dividing each unit by sixty and then summing them up. The results sometimes look counterintuitive.
Lines of longitude also called meridians, run north-south and measure position along the east-west axis. While the lines of latitude run parallel to each other, meridians converge at the poles and spread farthest apart at the equator, like the segments of an orange.
Longitude is also measured in degrees, but its zero-degree line is known as the Prime Meridian, and it runs from the North Pole to the South Pole through Greenwich, England.
- If the Prime Meridian is zero degrees, the opposite side of the earth is 180 degrees, and lines in between are expressed as degrees east or degrees west, between 0 and 180.
Since the lines of latitude are parallel, each degree covers about the same distance the world over roughly 111 kilometers. As meridians converge at the poles, the distance covered in each degree of longitude varies hugely depending on latitude.
- At 20 degrees North, which is about the latitude of Cuba and Hawaii, one degree of longitude is approximately 104 kilometers.
- At 80 degrees North, the latitude of Svalbard and northern Greenland, it’s only about 19 kilometers.
Even without looking at a map, we can start to make a guess where this would be. Since it’s 43 degrees north, it’s almost halfway between the equator and the north pole again, halfway being 45 degrees. Since it’s 89 degrees west, it’s almost halfway west between the prime meridian and the opposite side of the globe, halfway being half of 180 degrees or 90 degrees. On Google Earth, these coordinates point to the U.S. National Mustard Museum in Middleton, Wisconsin.
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