Global projections: can you draw a flat map of the earth?* OBJECTIVES Students should understand * cartographers Cartography is the study of map making and cartographers are map makers. Before 1400
* all maps distort the shape, area, and distance of Earth's surface Noun 1. Earth's surface - the outermost level of the land or sea; "earthquakes originate far below the surface"; "three quarters of the Earth's surface is covered by water" surface . * TEACHING STRATEGY Ask students: "What is a map? What do different kinds of maps show?" * BACKGROUND The Greek philosopher Anaximander was the first person credited with creating a world map. Although the ancient Babylonians, Egyptians, and Chinese practiced cartography cartography: see map. cartography or mapmaking Art and science of representing a geographic area graphically, usually by means of a map or chart. Political, cultural, or other nongeographic features may be superimposed. long before he did, the names of those mapmakers remain unknown. Anaximander, who lived in the 6th century B.C., was also the first person said to have constructed a globe and written a book on geography. * CRITICAL THINKING COMPREHENSION: Which map projection is most commonly used in U.S. textbooks? (The Robinson projection The Robinson projection is a map projection used for geographic maps. Overview Presented by Dr. Arthur H. Robinson in 1963, it is classified as a pseudo-cylindrical projection by reason of its straight parallels, along each of which the meridians are spaced evenly. is used most frequently in textbooks. This projection is a compromise that shows landmasses fairly accurately, without too much distortion.) NOTING DETAILS: What do all map projections have in common? (They all distort the size and shape of land areas. This happens because it is impossible to accurately depict Earth or any other spherical spher·i·cal adj. Having the shape of or approximating a sphere; globular. object on a flat surface.) * ACTIVITY MAP IT OUT: Tell students to imagine that they are about to embark on a drive across the country. Which U.S. states A U.S. state is any one of the fifty subnational entities of the United States, although four states use the official title "commonwealth". The separate state governments and the federal government share sovereignty, in that an American is a citizen both of the federal entity and or regions would they visit? Which highways would they travel? Direct students to create a U.S. map detailing their planned route. They should also write a brief explanation of why they chose their particular course. STANDARDS SOCIAL STUDIES, GRADES 5-8 * Science, technology, and society: How Earth's curved surface is represented differently in various map projections, which distort the shape and size of land areas. RESOURCES * Young, Karen, Small Worlds: Maps and Map Making (Scholastic, 2002). Grades 5-8. * Monmonier, Mark, How to Lie With Maps (Univ. of Chicago, 1996). Grades 7-8. GROLIER WEB SITE KEY TERM * Maps WEB SITES * The Secret Life of Maps www.bl.uk/whatson/exhibitions/ lieland/overview.html * The Mathematics of Cartography http:/ /math.rice.edu/-lanius/ pres/map ********** Suppose someone asked you to change a globe of the Earth into a map. Could you do it? For centuries, cartographers (mapmakers) have been devising different map projections--ways of showing the curved surface of the Earth in a flat drawing. But every map distorts shape, area (size), or distance. This happens because you cannot make a completely accurate flat map from a spherical Earth The concept of a spherical Earth was espoused by Pythagoras apparently on aesthetic grounds, as he also held all other celestial bodies to be spherical. It replaced earlier beliefs in a flat Earth: In early Mesopotamian thought, the world was portrayed as a flat disk floating in . (Just as you can't peel an orange and press the peel flat without causing breaks and tears.) Three different map projections are shown on these pages: * Mercator: Gerardus Mercator created this projection in 1569. It is ideal for navigation because all lines of latitude and longitude latitude and longitude Coordinate system by which the position or location of any place on the Earth's surface can be determined and described. Latitude is a measurement of location north or south of the Equator. cross each other at right angles so as to form a right angle or right angles, as when one line crosses another perpendicularly. See also: Right . Mercator maps show landmasses in their correct shape, but greatly distort their size. The farther a landmass land·mass n. A large unbroken area of land. landmass Noun a large continuous area of land landmass is from the Equator equator, imaginary great circle around the earth, everywhere equidistant from the two geographical poles and forming the base line from which latitude is reckoned. The equator, which measures c.24,902 mi (40,076 km), is designated as lat. 0°. , the more distorted its size. Asia, Europe, and North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. appear larger than they actually are. Africa, Australia, and South America South America, fourth largest continent (1991 est. pop. 299,150,000), c.6,880,000 sq mi (17,819,000 sq km), the southern of the two continents of the Western Hemisphere. appear smaller than they are. * Peters: Like Mercator, the Peters projection has straight lines of latitude and longitude--also good for sailors. Peters has a big advantage over Mercator: It shows landmasses at nearly their correct size. The Northern Hemisphere does not appear larger than it actually is. But Peters has a drawback: Continents and land areas are misshapen mis·shape tr.v. mis·shaped, mis·shaped or mis·shap·en , mis·shap·ing, mis·shapes To shape badly; deform. mis·shap . One critic joked that the continents look as though they were hung up on a line to dry. * Robinson: This projection is commonly used in textbooks, and in Junior Scholastic. It shows the size of landmasses fairly accurately, without too much shape distortion. One drawback is that lines of latitude and longitude do not meet at right angles. Some Area Comparisons * (in square miles) Africa 11,657,000 Alaska 587,878 Antarctica 5,400,000 Asia 17,028,000 Australia 2,988,888 Europe 4,015,000 Greenland 836,330 Mexico 756,002 North America 9,343,000 South America 8,898,000 QUESTIONS 1. Latitude and longitude appear as straight lines on which of the three map projections?-- 2. Which projection shows land areas in nearly the correct size?-- 3. Greenland looks the largest on which projection?-- 4. Which is larger: Australia, Greenland, or Mexico?-- 5. Which projection most distorts the shape of the continents?-- 6. Which map makes Antarctica look the largest?-- 7. Antarctica is larger than which continent(s) listed in the table?-- 8. Is Alaska larger, smaller, or the same size as Mexico?-- 9. Which projection is the best compromise for correctly showing both shape and size?-- 10. Why would sailors not use a Robinson projection for navigation?-- ANSWERS 1. Mercator and Peters 2. Peters 3. Mercator 4. Australia 5. Peters 6. Mercator 7. Europe and Australia 8. smaller 9. Robinson 10. Latitude and longitude lines are curved. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion