Every map ever printed is wrong, by definition. The job of a map is to provide a simpler representation of the world. A completely accurate map would need to be life-size. Worse, the Earth is round and paper is flat.
Over small areas, the curvature isn’t noticeable, but to unwrap the entire globe, you either have to stretch it or cut it to make it fit on a flat sheet. There are lots of different ways of doing this, but the Mercator projection, invented by Gerardus Mercator in 1569, is still the most widely used.
Imagine a glass globe with the continents painted on it. If you wrapped a sheet of paper into a cylinder around the equator and shone a light from within, the landmasses would appear on the paper as shadows. This is the Mercator projection.
On this map, north points to the top, and the coastline is the right shape, which makes it useful for navigation. But because the cylinder is open at the top and bottom, the poles can’t be shown and north-south distances get increasingly stretched the further you get from the equator. Alaska looks as big as Brazil on a Mercator map, but isreally a fifth the size, and Greenland appears 14 times too large.
In the map shown above, the outline is the Mercator projection. In green, you can see the Gall-Peters projection, which was designed so that all the countries have the correct area.
Although digital maps could now display the Earth as a globe (Google Earth does this), most still use a version of the Mercator projection.
Read more:
- Has all of the Earth been mapped?
- Where does our sense of direction come from within the brain?
- How do we know the geology of the British isles?
- Why do some people have such a poor sense of direction?
Asked by: Emma Smith,Holyhead
To submit your questions email us at questions@sciencefocus.com (don't forget to include your name and location)
