Alright, here we go. If I want to turn this globe into a flat map, I'm going to have to cut it open. In order to get this globe to look anything close to a rectangle lying flat, I've had to cut it in several places, I've had to stretch it so that the countries are starting to look all wonky, and even still, it's almost impossible to get it to lay flat. And that right there is the eternal dilemma of mapmakers.
The surface of a sphere cannot be represented as a plane without some form of distortion. That was mathematically proved by this guy a long time ago. Since around the 1500s, mathematicians have set about creating algorithms that would translate the globe into something flat.
And to do this, they use a process called projection. Popular rectangular maps use a cylindrical projection. Imagine putting a theoretical cylinder over the globe and projecting each of the points of the sphere onto the cylinder's surface.
Unroll the cylinder and you have a flat rectangular map. But you could also project the globe onto other objects. And the math used by map makers to project the globe will affect the way the map looks once it's all flattened out.
And here's the big problem. Every one of these projections comes with trade-offs in shape, distance, direction, and land area. Certain map projections can either be misleading or very helpful depending on what you're using them for.
Here's an example. This map is called the Mercator projection. If you're American, you probably studied this map in school. It's also the projection that Google Maps uses.
The Mercator projection is popular for a couple of reasons. First, it generally preserves the shape of countries. Brazil on the globe has the same shape as Brazil on the Mercator projection.
But the original purpose of the Mercator projection was navigation. It preserves direction, which is a big deal if you're trying to navigate the ocean with only a compass. It was designed so that a line drawn between two points on the map would provide the exact angle to follow on a compass to travel between those two points.
If we go back to the globe, you can see that this line is not the shortest route, but at least it provides a simple, reliable way to navigate across the ocean. Gerardus Mercator, who created the projection in the 16th century, was able to preserve direction by varying the distance between the latitude lines, and also making them straight, creating a grid of right angles. But that created some other problems.
Where the Mercator fails is its representation of size. Look at the size of Africa as compared to Greenland. On the Mercator map, they look about the same size. But if you look at a globe for Greenland's true size, you'll see that it's way smaller than Africa.
By a factor of 14, in fact. If we put a bunch of dots onto the globe that are all the same size, and then project that onto the Mercator map, we will end up with this. The circles retain their round shape, but are enlarged as they get closer to the poles. One modern critique of this is that the distortion perpetuates imperialist attitude of European domination over the southern hemisphere. The Mercator projection has fostered European imperialist attitudes for centuries and created an ethnic bias against the third world.
Really? So if you want to see a map that more accurately displays land area, you can use the Gall-Peters projection. This is called an equal area map. Look at Greenland and Africa now.
The size comparison is accurate, much better than the Mercator. But it's obvious now that the country shapes are totally distorted. Here are those dots again so that we can see how the projection preserves area while totally distorting shape.
Something happened in the late 60s that would change the whole purpose of mapping in the way that we think about projections. Satellites orbiting our planet started sending location and navigation data to little receiver units all around the world. Today, orbiting satellites of the Navy Navigation Satellite System provide round-the-clock, ultra-precise position fixes from space to units everywhere in any kind of weather.
This global positioning system wiped out the need for paper maps as a means of navigating both the sea and the sky. Map projection choices became less about navigational imperatives and more about aesthetic, design, and presentation. The Mercator projection that once vital tool of pre-GPS navigation, was shunned by cartographers who now saw it as misleading. But even still, most web mapping tools, like Google Maps, use the Mercator. This is because the Mercator's ability to preserve shape and angles makes close-up views of cities more accurate.
A 90-degree left turn on the map is a 90-degree left turn on the street that you're driving down. The distortion is minimal when you're close up. But on a world map scale, cartographers rarely use the Mercator. Most modern cartographers have settled on a variety of non-rectangular projections that split the difference between distorting either size or shape. In 1998, the National Geographic Society adopted the Winkle Triple Projection because of its pleasant balance between size and shape accuracy.
But the fact remains that there's no right projection. Cartographers and mathematicians have created a huge library of available projections. each with a new perspective on the planet, and each useful for a different task. The best way to see the Earth is to look at a globe, but as long as we use flat maps, we'll have to deal with the trade-offs of projections.
And just remember, there's no right answer. If you yourself want to poke fun at the Mercator Projection, you can do so by going to thetruesizeof.com Which is a fun tool that allows you to drag around whatever country you want Around the map and see how it is distorted depending on where it is I also want to say a big thanks to Mike Bostock whose open source project on map projections was a huge help in this video I'll put a link for both of those things down in the description