What different world maps get right, and what they get wrong

The Mercator map was designed to help sailors navigate, not to show the world’s countries at their true relative sizes. Created in 1569 by Flemish cartographer Gerardus Mercator, it lets a straight line on the map represent a straight course when a sailor follows a compass bearing.

“That was what it was intended to do, and that's what it does brilliantly well,” James Cheshire, a cartography professor at University College London, told the BBC. To preserve those angles on a flat surface, Mercator widened the grid as it moved from the equator toward the poles.

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He wanted a straight line to be drawn on a map to look like a straight line in reality if you followed a compass bearing

The result stretches countries near the poles and makes countries near the equator look smaller than they are. The distortion reflects a basic limitation of cartography: the curved surface of a globe cannot be represented perfectly on a two-dimensional chart.

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That was what it was intended to do, and that's what it does brilliantly well

More than 450 years after its creation, the projection still underpins many maps used in classrooms, on television and online, including Google Maps. Critics say its visual imbalance can also influence how people assign importance, because larger-looking places may seem more significant.

For Kenyan geographer Kioko Muendo, the effect has implicitly diminished perceptions of Africa’s resources, population and investment opportunities. “Maps are more than just guides for travellers, they shape how regions are perceived politically and economically,” he told the BBC.

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Maps are more than just guides for travellers, they shape how regions are perceived politically and economically