November 23, 2020

#08-013: The Mercator Projection Map

Mercator projection map of the world

Note: They say, "The map is not the territory." Even more so, the map is not the globe!

Get Ready: Do you ever use maps (on paper)? Do you think they're accurate? How about digital maps, like Google Maps? Have you ever found a mistake on one?

The earth is approximately sphere, a three-dimensional figure. A map is two-dimensional--flat. How do we accurately portray the comparative sizes of the sphere's landmasses in two dimensions?

Most world maps, no matter how good they are, distort the sizes of landmasses the closer we get to the north and south pole. On most standard world maps, Greenland appears to be roughly the same size as Africa; in fact, Africa is 14 times larger!

All of this is thanks to a "Renaissance man" from Flanders (today part of Belgium) with the Latin name Gerardus Mercator, but born Geert (or Gerhard) Kremer; Kremer means "merchant" in Flemish, and Mercator means the same in Latin. He was a geographer, a cosmographer, and--most importantly for us--a cartographer.

The modern mapping of the globe was in its infancy. The first circumnavigation of the world, by the crew of the Portuguese navigator Ferdinand Magellan (Magellan himself was killed in the Philippines) was completed in 1521.

Prior to Mercator, the best maps had been produced by another Portuguese, a mathematician and cosmographer named Pedro Nunes. Nunes felt that the parallels (horizontal lines) and meridians (vertical lines) on a map should be shown as straight lines, but couldn't solve the math to make this possible.

Adapted from an illustration on Wikipedia

Mercator's solution, presented in 1569, was simplicity itself. Imagine a globe which is clear--made of glass, say--except where the land masses are. Now wrap a piece of paper into a cylinder, touching only the equator (the line of 0 degrees latitude). Put a light inside the globe so that it projects the shadows of the landmasses onto the paper, and trace them.

Voila! The Mercator Projection, which allows for straight-line navigation anywhere in the world. This procedure also explains why the areas closest to the equator are the most accurate, and the areas closer to the poles--being farther away from the paper--are enlarged out of proportion.

Nevertheless, the Mercator system, now over three and a half centuries old, remains the most commonly-used style of world map today.


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Practice: Match the term to its definition below:

  1. cartographer
  2. comparative
  3. distort
  4. enlarged
  5. merchant
  6. more so
  7. navigation
  8. prior to
  9. Renaissance
  10. sphere

  1. in relation to one another
  2. made bigger
  3. the 14th through 17th centuries in Europe
  4. the art of directing a ship or airplane
  5. before
  6. solid shaped like a ball
  7. one who buys and sells things
  8. to a greater degree
  9. person who makes maps
  10. misrepresent a shape

Answers are in the first comment below.

Submitted to the Shenzhen Daily for November 23, 2020

1 comment:

  1. Answers to the Practice: 1. i; 2. a; 3. j; 4. b; 5. g; 6. h; 7. d; 8. e; 9. c; 10. f