Geography For Dummies. Jerry T. Mitchell
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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.
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.
WHY IS AN ATLAS CALLED AN ATLAS?
An atlas is a book of maps. For the longest time, maps were published singly and tended to be stored as rolled-up scrolls standing in a corner. Gerardus Mercator was apparently the first person to compile a book of maps. His publisher decided to decorate the cover with a likeness of Atlas, the legendary Greek giant who supported Earth and the heavens on his shoulders. Other books of maps copied Mercator’s idea and the image of Atlas on the cover or title page became standard — which is why such volumes are called atlases.
The Goode’s Interrupted Homolosine projection
Noted American cartographer Dr. J. Paul Goode (1862–1932) developed this cylindrical projection (see Figure 4-6). It’s an equal area projection, which means that the land areas are shown in their true sizes relative to each other. In that respect, Goode’s projection is far superior to Mercator’s. Interrupted refers to the map’s outline. Earth is cut into once above the Equator and three times below it. Therefore, the Northern Hemisphere appears as two lobes and the Southern Hemisphere as four lobes.
(© John Wiley & Sons Inc.)
FIGURE 4-6: Goode’s Interrupted Homolosine projection.
As a result, the map’s outline is not a rectangle or some other compact form, but instead is interrupted. The word homolosine reflects the fact that Goode’s map is a combination of two other projections: the Mollweide homolographic and the Sinusoidal. (Whether or not you ever learn what that means, I will be happy to give you extra-credit for correct spellings.) Although Goode’s projection appears in various atlases and despite its desirable equal-area attribute, many people are visually uncomfortable with its interrupted format.
The Robinson projection
Dr. Arthur H. Robinson, a noted American cartographer, introduced this cylindrical projection in 1963 (see Figure 4-2). If you lie really well, people may not notice. In fact, they may love you because of it. With all due respect and admiration to the good doctor, his map lies really well!
Although the projection contains distortion with respect to size and shape of land areas as well as to distance and direction, it has good overall balance with respect to these elements. In particular, the high latitude land areas are much less distorted than in the Mercator projection. Furthermore, Robinson’s format does not have the interruptions of Goode’s map. As a result of these pluses, the Robinson projection has become one of the popular choices among publishers of atlases and classroom wall maps.
The Lambert Conformal Conic projection
Johann Heinrich Lambert (1728–1777), a noted German physicist and mathematician, developed the Lambert Conformal Conic projection in 1772 (see Figure 4-7). Projections cannot correctly show the shapes of large areas, but they can be drafted such that the shapes of small areas closely conform to reality. That is what the Lambert Conformal Conic Projection achieves.
(© John Wiley & Sons Inc.)
FIGURE 4-7: Lambert Conformal Conic projection.
Accuracy of shape (conformality) is most closely achieved where the cone, which is intrinsic to a conic projection, touches the globe. If you refer back to Figure 4-4, you can see that the conic projection makes contact in the latitudinal vicinity of the United States. For Americans, therefore, this projection is noteworthy because it is commonly used to make maps of their country.
The Lambert Azimuthal Equal Area projection
The same Herr Lambert who developed the conformal conic projection (see the preceding section) presented the Lambert Azimuthal Equal Area projection in 1772 (see Figure 4-3). Because it’s an azimuthal projection, as shown in Figure 4-4, it portrays only a hemisphere, as opposed to the entire world. On the other hand, it has two positive aspects: Areas are shown in true proportion to the same areas on Earth and, as revealed in my New York-to-Singapore exercise (see “Singapore, please. And step on it!” earlier in this chapter), long-range directions are depicted with a fair amount of accuracy.
Mapping a Cartographic Controversy!
If you’re under the impression that the world of map-making is rather staid and geeky, you’re right. In recent decades, however, a map known as the Peters projection has come along and stirred things up. An episode of the television series The West Wing showed just how geeky, wonky, and controversial map projections like Peters can be. Although this projection is controversial to some, it serves as an excellent example of why average citizens and novice geographers ought to know the facts about flat maps.
The Peters projection was introduced and subsequently promoted in 1972 by Arno Peters, a German historian (see Figure 4-8). It’s also the subject of his book The New Cartography (Die Neue Kartographie). As far as accurately showing the world is concerned, this map lies just like any other. The appearance of the continents has been likened to wet laundry hanging out to dry. The shape of land and water bodies is badly distorted, but size is maintained.