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Gerhard Kremer, who’s much better known by his adopted Latin name, Gerardus Mercator, developed the Mercator projection in 1569. This cylindrical projection (see Figure 4-5) is easily the most famous world map of all time. Mercator crafted his projection to aid navigation, and in that regard, the map is a gem. Straight lines on this map correspond to true compass bearings so a navigator could use it to plot an accurate course. This achievement was a very big deal in the late 16th century, and by the middle of the 17th century, a majority of Western European navigators swore by this map.

(© John Wiley & Sons Inc.)

FIGURE 4-5: The Mercator projection.

Because of its seafaring fame, the Mercator Projection later came into widespread use as a general-purpose map. That is, it found its way into classrooms as wall maps and into books and atlases. It became more or less the official world map, which is unfortunate because, although the shapes of landmasses are fairly accurate, the projection is extremely distorted with respect to size.

Notice that the lines of longitude on the Mercator projection don’t meet at the Poles, as is the case in reality. Instead, the map shows the lines of longitude as parallel lines. This means that the North and South Polar regions have been stretched and become lines (the top and bottom borders of the map) that are as long as the Equator — 25,000 miles. One result is that land areas become disproportionately enlarged the closer they are to the areas of maximum distortion — the Poles. Alaska and Greenland are good examples. Alaska appears much larger than Mexico, while Greenland appears much larger than the Arabian Peninsula. In reality, Mexico is larger than Alaska, and the Arabian Peninsula is bigger than Greenland, but you’d never know by looking at the Mercator projection.

Keep in mind that there is nothing wrong with this projection. It is a representation of Earth, nothing more. Are there better representations for showing the size of Earth features? Sure. But this projection shows shapes quite well. Just as a hammer is great for striking a nail, but poor for drilling a hole, the same idea is true for projections. Some tools are better used for some purposes than others. It’s up to the user to be wise about that choice.

Quite famously about two decades ago, a very reputable news magazine was not so wise. Hoping to portray how far North Korean missiles could travel, they drew a set of concentric circles atop a Mercator projection. This of course ignored the distortion toward the poles and made the missiles appear to have a much shorter range than reality. The implication? Hand a wrongly made map to a policy maker and you could have decision making that does amount to a whole world of trouble.