Cartography: Flattening the Earth
Have you ever let a map spur your imagination, wondering how life was as a world explorer sailing the oceans in search of new land? Maybe you see yourself drawing a map of your new discoveries. Wait a minute – you just realize Earth is round, so how do you create an accurate flat map? Throughout history, cartographers all around the world have found different methods for creating flat maps of Earth. None can represent reality exactly, but each is useful for specific purposes. Do this activity and see how cartographers today could have helped explorers of the past.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Creating a map of a small area might be relatively easy; however, making a flat map of Earth is a completely different challenge. Cartographers (map makers) have found various ways to create flat maps of the world. These are called projections. How do they do it? There are several ways it can be done, but every type of projection distorts reality in some way. Scientists use a Tissot's indicatrix to quantify distortions that are introduced when creating a map. You will do something similar in this activity. You will draw identically sized circles all over your Earth, create a projection similar to a type of projection called a Mercator projection, and study how the circles are distorted in area, shape, and distance on the flat map. You will be surprised how your circles look on your flat map!
Safety Tip: You will pin the cut-open balloon onto a piece of cardboard in this activity. As further explained later, it is important that the push pins are placed slightly slanted outward (with the points aimed inward and the tips of the pins aimed outward, away from the balloon) so the tension in the stretched balloon does not propel the pins out.
Extra: Investigate if the relative direction of the circles, with respect to each other, is maintained in your projection. How would you describe the direction of a circle with respect to another in terms of north, northeast, etc. on your map? Is this identical to how you would have described the relative direction of that circle to the others on the globe? If so, the direction has been maintained in that area of your map.
Extra: The projection you created is similar to the Mercator projection frequently used to create world maps. Find a Mercator projection world map and compare the size of North America and Africa. Having done this activity and after looking at the Mercator world map, would you conclude that North America is bigger than Africa, smaller than Africa, about equal in size, or do you not have enough information to compare their sizes?
Observations and Results
Were the circles no longer identical in size on the map? Were they still circles?
As parts of the balloon get stretched more than others, the size of the circles is no longer identical on the map. This indicates that relative size and distance are distorted in this projection. Circles on the equator (or any other line of latitude) are still mostly equal in size, indicating that features located on the same line of latitude can be compared in size. Compared to the size at the equator, enlargement gets more prominent as you move away from the equator, and is most extreme at the poles. This explains why Mercator projections can provide misleading information when comparing size or distance. Note that you cannot extrapolate all of your findings to Mercator projection. The balloon map you just created shows distortions on the edges that would not appear in Mercator projections.
On your projection, most circles should still look like circles, indicating that shape is maintained in those areas of the map and directions of the features relative to each other are maintained. In a real Mercator projection, the lines of longitude are perfectly straight and direction is exactly maintained, making them particularly useful in navigation.
More to Explore
Sabine De Brabandere, PhD, Science Buddies
Science Buddies |
Earth Science, cartography, map projection, line of latitude, line of longitude, equator, distortion
Explore Our Science Videos
How to Make an Electromagnet
How to make an anemometer (wind speed meter)
10 Robotics Projects Kids Can Really Make!