Mapping the Earth

Before looking at the world, the chapter asks a question about looking itself: can the round Earth be drawn accurately on a flat page?

The Earth is an oblate spheroid: nearly a sphere, but bulging at the equator and slightly flattened at the poles, because it spins. (Picture a volleyball squashed a little at the top and bottom.)

Try the chapter's experiment. Take an orange, peel it, and try to lay the peel flat without tearing it. You cannot.

That is why all maps have some distortion (some things drawn out of true). Showing the Earth on a flat surface is called a map projection, and map-makers (cartographers) have tried many ways.

Each way gives up one kind of accuracy for another. Some maps show the right shapes of countries but the wrong sizes; others show the right sizes but distorted shapes.

The Mercator Projection keeps shape and direction correct, which makes it excellent for navigation. But it greatly stretches sizes near the poles: on it, Greenland looks as big as Africa, and bigger than India, when in fact Greenland is smaller than India.

The Robinson Projection is a deliberate compromise, balancing size and shape errors to give a more realistic-looking world map.

So the chapter's conclusion is a rule for reading maps, not just drawing them: "Every map is a compromise. To understand the world fairly, we must look at multiple projections, not just one." Physical maps also have their own colour code:

• blue: water;
• green: plains;
• yellow-brown: plateaus;
• dark brown: high mountains;
• light yellow: deserts;
• white: ice.