Why Greenland looks as big as Africa on maps

HostI was looking at the world map hanging in my hallway this morning, and it hit me how huge Greenland is. It looks like this massive, icy giant that could almost swallow up Africa. But then I read that if you tried to flatten out a soccer ball, the whole thing just breaks and stays curved.

HostHow does a soccer ball explain why our maps look so wrong?

GuestWell, if you think about that soccer ball, or maybe an orange, the problem is that it's round. It sounds simple, but there's actually a law in math called the Theorema Egregium which says it's impossible to flatten the surface of a ball onto a flat page without stretching it or ripping it. Think about peeling an orange in one big piece. If you take that skin and try to press it flat onto a table, it's going to rip. It has to. The only way to stop those rips and make a nice, clean rectangle for a map is to stretch the skin until the gaps are filled in. So, every map you have ever seen is basically a set of choices about where to stretch the world and where to keep it looking real.

HostSo every map is kind of a lie? I mean, if it's that bad, why not just make a map that doesn't stretch things so much?

GuestYou have to stretch something. It's the only way to get a round thing onto a flat sheet. The map most of us see in schools was made by a man named Gerardus Mercator way back in the fifteen hundreds. But he didn't make it for kids in a classroom. He made it for sailors. Back then, the most important thing for a person on a ship was being able to draw a straight line between two spots and follow a single compass direction. To make that work on a flat map, he had to make sure the angles were kept the same. This is what people call a conformal map. It keeps the shapes of the land and the directions right, but the cost is that he had to give up on making the sizes true.

HostOkay, so it helps sailors find their way. But I still don't get why that makes Greenland look like a giant and Africa look like a tiny little thing by comparison.

GuestIt all comes down to where you're on the map. On a real globe, those lines that run from top to bottom, the ones we call longitude, all meet up at the North and South Poles. They get closer and closer as they go up. But on a flat, square map, those lines are forced to stay perfectly straight and side by side. To make that happen, you have to stretch the top and bottom of the map out wide.

HostSo it's like pulling a piece of gum sideways?

GuestYeah, but if you only pulled it sideways, everything would look short and fat. Greenland would look like a squashed pancake. So, to keep the shapes of the countries looking right for the sailors, Mercator had to stretch the map up and down by that same amount. It creates this zoom effect that gets stronger and stronger the further you get from the middle of the map. Africa sits right on the equator, in the middle, so it doesn't get stretched much at all. But Greenland is way up north. By the time you get that far up, the map is zooming in so much that everything looks way bigger than it really is.

HostBut is it really that much of a zoom? It feels like we're talking about a small mistake, not something that changes the whole world.

GuestNo, it's a huge difference. In the real world, Africa is about fourteen times larger than Greenland. Greenland isn't even the size of a whole continent. It's actually smaller than the country of Algeria. Africa is so huge that you could fit the entire United States, China, India, and most of Europe inside of its borders all at once, and you would still have some space left over. When you see them on a normal map, they look almost the same size, but that's just a trick of the geometry.

HostThat's wild. It feels like we're being taught a version of the world that's just totally out of whack. Is there any way to see it for how it actually is without carrying a globe in my pocket?

GuestThere are other ways to draw it. Some geographers prefer what they call equal-area maps. You might hear names like Gall-Peters or Mollweide. On those maps, a square inch in one spot shows the same amount of land as a square inch anywhere else. But because we're so used to the sailor map, these look really strange to us. The continents look like they have been stretched out or smeared down the page.

GuestThe continents look a bit melted on those maps, but equal-area views are the only honest way to show the real size of the land we live on.

HostMy hallway map has been playing a trick on me this whole time, making a small island look like a giant just because of an old rule about soccer balls and orange peels.