00:04 If I want to turn this globe into a flat map, I’m going to have to cut it open.
00:17 In order to get this to look anything like a rectangle.
00:21 I’ve had to cut it in places. I’ve had to stretch it so that the countries look all wonky.
00:27 And even still, it’s almost impossible to get it to lie flat.
00:34 And that right there is the eternal dilemma of map makers: The surface of a sphere cannot be represented as a plane without some form of distortion.
00:43 This guy proved that with math a long time ago.
00:46 Since around 1500s, mathematicians have set about creating algorithms that would translate the globe into something flat.
00:52 To do this, they use a process called projection.
00:56 Popular rectangular maps use a cylindrical projections.
00:59 Imagine putting a theoretical cylinder over the globe and projecting each point of the sphere onto the cylinder’s surface.
01:07 Unroll the cylinder, and you have a flat, rectangular map.
01:10 But you could also project the globe onto other objects, and how exactly a map maker projects the globe will affect what the map looks like once it’s all flattened out.
01:20 And here’s the big problem: Every one of these projections comes with trade offs in shape, distance, direction and land area.
01:28 Certain map projections can be either misleading or very helpful depending on what you are using them for.
01:34 Here’s an example.
01:35 This map is called the Mercator projection.
01:38 If you’re American, you probably studied it in school.
01:41 It’s the projection Google Maps uses.
01:43 Mercator projection is popular for a couple of reasons.
01:46 First, it generally preserves the shape of the countries.
01:49 Brazil on the globe has the same shape as Brazil on the Mercator projection.
01:53 But the real purpose of the Mercator projection was navigation — it preserves direction, which is a big deal if you are trying to navigate the ocean with only a compass.
02:03 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 points.
02:12 If we go back into a globe, you can see that this line is not shortest route.
02:15 But it provides a simple, reliable way to navigate across oceans.
02:20 Gerardus Mercator, who created the projection in the 16th century, was able to preserve direction by varying the distance between latitude lines while also making them straight, creating a grid of right angles..
02:32 But that created other problems.
02:34 Where mercator fails is its representation of size.
02:37 Look at the size of Africa as compared to Greenland.
02:39 On the mercator map they look about the same size.
02:42 But look at a globe for Greenland’s true size, and you’ll see it’s way smaller than Africa.
02:48 By a factor of 14 in fact.
02:51 If we put some dot that are all the same size on a globe, then we projected as a mercator map, we would end up with this.
02:59 The circles retain their shape but are enlarged the closer you get the poles.
03:04 One modern critique is that this distortion perpetuates imperialist attitudes of European domination over the southern hemisphere “The Mercator projection has fostered imperialist attitudes for centuries and created a ethnic bias against the third world.”
03:19 If you want to see a map that more accurately displays size, you can use the Gall-Peters projection, which is called an equal-area map.
03:27 Look at Greenland and Africa.
03:29 The size comparison is now accurate.
03:31 Much better than the mercator.
03:32 but it’s obvious that the country shapes are now stretched.
03:36 Here are the dots again so you can see how the projection preserves area while totally distorting shape.
03:45 Something happened in the late 60s that would change the whole purpose of mapping and the way we think about projections.
03:51 Satellites orbiting our planet started sending location and navigation data to little receiver units all over the world.
04:12 This global positioning system wiped out the need for paper maps as a means of navigating both the seas and the sky.
04:19 Map projection choices became less about navigational imperatives and more about aesthetics, design, and presentation.
04:26 The mercator map, that vital tool of pre-GPS navigation, was shunned by cartographers who now saw it as misleading.
04:34 But most web mapping tools like Google maps still use the mercator.
04:38 According to Google 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 90degree left turn on the street you’re driving down.
04:50 But when trying to display something on a world map, cartographers rarely use the mercator.
04:57 Most modern cartographers have settled on a variety of non-rectangular projections that split the difference between totally distorting either size or shape.
05:05 In 1998 The National Geographic Society adopted The Winkel tripel projection because of it’s a pleasant balance between size and shape accuracy.
05:12 But the fact remains, that there is no one right projection.
05:16 cartographers and mathematicians have created a huge library of available projections, each a new perspective on the planet.
05:23 The best way to see what the earth really looks like is to look at a globe.
05:27 But as long we use flat maps, we will deal with the tradeoffs of projections, Just remember: there’s no right answer.