Exploring Our Fluid Earth
Teaching Science as Inquiry
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Compare-Contrast-Connect: Map Orientation and Shape
NGSS Science and Engineering Practices:
NGSS Crosscutting Concepts:
The presentation of information in a table, diagram, or map can be as important, or even more important, than the words that accompany it. For instance, people often remember an image from a science textbook long after they have forgotten the words written near the image explaining it. While the orientation or shape of a map might seem harmless, it can have a significant effect on the perception of the relative importance of different places.
Map Orientation—Up is the New Down
Most maps of earth have north at the top (so north is up). However, this map orientation is arbitrary. Putting north at the top of maps became standard when European exploration was at its height in the 16th century. This might have been because Europeans navigated using the North Star and magnetic compasses, or it might just have been because they liked to keep themselves at the top of the world. Regardless, map orientation with north at the top has led people to refer to places as being “above” or “below” others. People also say that they travel “up” or “down” to visit these locations. Because people often assume height correlates with importance, the north-up convention reinforces the idea that countries or people in the north are more important than those in the south. When the South Pole is rotated so that it is “up” on a map, the unfamiliar orientation forces people to view the world from a fresh perspective (SF Fig. 1.6).
Map Shape—Mercator Maps
Mercator-projection maps are a type of cylindrical-projection map commonly used in classrooms. Whereas all maps distort the earth’s surface in some way, the Mercator projection displays a grossly distorted image of the area and boundaries of landmasses. This is because a Mercator map displays the spherical earth as a rectangle with perpendicular lines of longitude and latitude, when in reality these lines are circular. Mercator maps are useful for nautical navigation, but they are a poor choice for learning about the earth. The Mercator map has generated a lot of confusion about geography (SF Fig. 1.7 A) as compared to other types of map projections (for example, pseudocylindrical maps, SF Fig. 1.7 B). For example, on a Mercator map, Europe looks larger than South America, and Africa looks the same size as Greenland. In reality, South America is more than 50% larger than Europe, and Greenland it is one-fourteenth the size of Africa.
Maps convey data, but they also convey ideas and opinions. When viewing a map, remember that each type provides a unique perspective, and it is important to understand that perspective in order to correctly use and interpret the map.
Question Set:
- The “upside-down” Mercator projection map clearly shows how the continents are bunched in the northern hemisphere, and makes South America particularly prominent. What other observations can you make about the earth from this vantage point that you may have overlooked on a conventional map?
- When comparing a Mercator projection to a pseudocylindrical map or to a globe, what areas become the most distorted? What areas are the least distorted? Do the locations of the most and least distorted areas have anything in common?
- Mercator maps can be centered on any region of the world, from the Pacific ocean basin to the Middle East. Why do you think cartographers choose to center maps in different regions? Research whether different countries predominately use maps centered on different areas and, if so, why.
Different map projections affect our perception of the world. This is apparent in the star and heart-like map projections in SF Fig. 1.8. These map projections were developed to highlight specific features of planet Earth. Use SF Fig. 1.8 to answer questions 4 through 7.
- The star-like map projection (SF Fig. 1.8 A) was designed so that the North Pole, an area often distorted on other map projections, is at the center of the map, making it the least distorted area. The southern hemisphere has been cut into lobes (the points of the star) and splayed out around the intact northern hemisphere to make both hemispheres visible. How does the star map projection affect your perception of the world?
- The heart-shaped pseudoconic map projection (SF Fig. 1.8 B) was developed in the 1500s and was commonly used for world maps and some continental maps into the 17th century. The benefit of the heart-shaped map is that there is little distortion to the center of the map and, even though distortion increases towards the poles, all of the northern hemisphere continents are visible, and the map retains the cylindrical shape of earth. How does the heart-shaped map projection affect your perception of the world?
- Research the history of other map projections and how they affect the viewer’s perception of the world.
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