Projecting the World
||edHelper's suggested reading level:
||grades 6 to 8
||Flesch-Kincaid grade level:
||directions-north, distortion, Gerdhaus, pie-shaped, rhumb, west-with, mapmakers, cartographers, projector, relation, geographical, projection, relatively, grid, cylindrical, region
||Gerdhaus Mercator, On Conic, Winkel Tripel, National Geographic Society
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Projecting the World
By Trista L. Pollard
1 Years after agreeing that the Earth is a sphere, cartographers and scientists continue to map its surface. Early mapmakers relied on information from sailors and explorers. Today, they use computers, satellites, and cameras to get information about Earth. One tough task still remains. How do you make an accurate flat map out of a sphere? Gerdhaus Mercator had the right idea. He introduced one of the first map projections.
2 Map projections are pictures of the Earth that are drawn on flat maps. The Earth is a three-dimensional object. Cartographers use projections to draw this sphere on a two-dimensional surface, which is the paper. If you could place a projector light inside a globe, the image you would get would be a projection. This image would be projected onto a flat screen. Move the projector and the image changes. Mercator was the first geographer to use a projection. He designed his map in 1569. This is when the Mercator projection was made. Mercator designed the spaces between the meridians and parallels so that they could be drawn as straight lines. These lines were called rhumb lines. This was amazing since Earth was curved. Mercator also did not use a light projector! Sailors could use a compass that was set to a specific straight line. This straight line was connected to their home and to their destination. The sailors also had to adjust their compasses so that they could find the true magnetic north.
3 Just like Mercator's projection, map projections are based on our geographical grid. Geographers have to change this grid that is on a globe so that it can be accurate on a flat map. As they change this grid, they pay attention to four different concerns: area, direction, distance, and shape. When cartographers draw maps, they have to pay attention to the size of land features and water regions. Area focuses on the measurements of these features in relation to each other. Cartographers compare cardinal directionsónorth, south, east, and westówith their true locations on our geographic grid. Scale is another way to make sure that the distance between map locations is in relation to the true distances on Earth. Finally, they are also concerned about the shape of land and water. Cartographers want to make sure that the shapes of these features are close to their shapes on Earth.
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