Everything Everywhere Daily: History, Science, Geography & More - The Mercator Projection (Encore)

Episode Date: May 23, 2021

Have you ever looked at a map and said to yourself “Wow, Greenland is really big!”, only to then look at a globe and realize, that Greeland wasn’t actually that big? If so, then you have discovered the Mercator Projection. A map that was originally created in 1569 and is still with us today. Learn more about the Mercator Projection, its problems, and its benefits, on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

The following is an encore presentation of Everything Everywhere Daily. I'll be back again tomorrow with a brand new show. Have you ever looked at a map of the world and said to yourself, Wow, Greenland is really big? Only to then look at a globe and realize that Greenland actually wasn't that big? If so, you've probably discovered the Mercator Projection, a map that was originally created in 1569 and is still with us today. Learn more about the Mercator projection, its problems, and its benefits,

on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. This episode is sponsored by audible.com. Today's audiobook recommendation is Maphead.

Charting the wide, weird world of geography wonks by Ken Jennings. It comes as no surprise that, as a kid, Jeopardy legend Ken Jennings slept with a bulky Hammond World Atlas by his pillow every night. Maphead recounts his lifelong love affair with geography and explores why maps have always been so fascinating to him and to fellow enthusiasts everywhere. Jennings takes listeners on a tour of Geogeeks from the London Map Fair to the bowels of the Library of Congress, from the prepubescent geniuses at the National Geographic Spelling Bee, to the computer programmers at Google Earth.

You can get a free one-month trial to Audible and two free audiobooks by going to audibletrial.com slash everything everywhere, or by clicking on the link in the show notes. Before we get into the Mercator projection, we first need to establish what a projection is. As you might have noticed, the Earth is a sphere, and a map is not. Putting a sphere onto a map is called a cylindrical projection. The problem with the projection is that there's no way

to properly put a sphere onto a flat surface because a sphere isn't a flat surface. Let's conduct the following thought experiment. Imagine you have a large flat sheet of paper and you wrap it around a globe which is made of glass, except that you can't see through the parts of the globe that represent land. The paper you wrap around the sphere will become a cylinder and only touch the globe at the equator. Now imagine that there's a light in the middle of the globe that cast shadows onto the paper. The shadows which are cast onto the paper would be a projection of the globe. At the equator, the shadow would be just like the globe.

However, as you went up the paper and the shadows from higher latitudes are cast, they would get bigger and bigger compared to the size on the globe. The polar regions wouldn't even appear on the map because the light would go straight up. There are many ways that you can project a sphere onto a cylinder. However, all of them are going to fail in some respect. you will either distort size, shape, or angles. And this brings us to Gerardis Mercator. He was a Flemish mapmaker who in 1569 set to create a map that would be useful for navigation.

Cartography back then wasn't very good. People didn't know what land existed or its general shape. Moreover, they had no idea how to determine longitude. So it wasn't as if any map from 1569 was going to be very good. What Mercator did, really for the first. time was attempt to systematize what was on a globe with what was on a map. He tried to make a mathematical projection. He wanted a map that would preserve angles. That way, if a navigator on a ship were to draw a line that went southwest on a map, that is where they would actually wind

up. A 90-degree angle on the map would correspond to a 90-degree angle in the real world. Mathematically, the Mercator projection is the only cylindrical projection, which allows for conformity with angles and constant rum lines, also known as bearing lines, across all the meridians. And that is why it's so good at navigation. It really was a remarkable innovation. As maps and knowledge of land masses improved, the maps got better, but the projection technique remained because it worked so well for navigation, which was the primary purpose of having maps. And just as an aside, Mercator was also the person who coined the term Atlas, as a book with a collection of maps. The Mercator projection is still used heavily today.

Every major online map basically uses the Mercator projection. Google, Apple, Yahoo, MapQuest, and pretty much anything else, uses what's called the Web Mercator projection, which for all practical purposes is pretty much the same as the old Mercator projection. The reason for this is that when you use a map on your smartphone, you want it as much as possible to resemble what an aerial photo might look like. For example, if a city block is square, then you want it to be a square on your map. And the Mercator projection does this splendidly.

You have probably noticed, however, as I mentioned in my introduction, that there is a small problem with the Mercator projection. While the Mercator projection is great for navigation, it fails at, well, just being a wall map. While it does a great job of preserving angles, it doesn't preserve size. That is why Greenland looks as big as Africa on a Mercator. projection map, even though in reality, Africa is 14 and a half times larger. Elzimir Island in Canada looks to be as large as Australia, but in reality, Australia is 39 times larger. Likewise, the island of Svalzbard in Norway looks larger than Borneo, but Borneo is actually

12 times larger. Most wall maps that were created for classrooms or libraries use the Mercator projection because that was the map that was used for commerce and military, for navigation. Most Mercator wall maps, if you look closely, do not have the equator in the middle of the map. That's because the one thing which is even larger than Greenland is Antarctica, and no one lives in Antarctica. Technically, Antarctica is actually infinitely large on a Mercator projection, so most maps will cut off all but the coastline and shift the equator further down south. There have been projections created which preserve size. The best known one is the Gaul Peters projection. This was originally created in 1855 by James Gull, and then recreated in 1970 by Arno Peters.

Unlike the Mercator projection, the Gaule Peters projection is an equal area projection. On this map, Africa is much larger than Greenland, which reflects reality. However, as I noted above, whenever you do a projection from a sphere onto a surface, something has to give. In the case of the Gaule Peters projection, what sacrificed is shape. In a Gull-Peters projection map, everything is the right. right size, but things at the equator are elongated and things closer to the poles are smushed. Advocates of the Gaul-Peter's map claim that it's fairer than the Mercator projection because every country is the appropriate size, and that is true. But to almost everyone that looks at it,

it looks odd. Is there a way that we could satisfy both area and shape? If we do a projection onto a cylinder, the answer is no. But who says we have to project it onto a cylinder? There are many flat maps that get around this problem by avoiding making the map a rectangle. In fact, once you stop projecting onto a cylinder, there are all sorts of things you can do. You can do a polar projection, with the North Pole at the center of the map. This is what is used on the United Nations logo. Buckminster Fuller created a map called the Dimaxian map, which treats the world as an isosahedron, and then unfolds it into a collection of triangles. It preserves area and shape, but has huge gaps between the continents. Probably the best world wall maps are called pseudo-sylindrical. They project

the earth onto an oval with the top and bottom parts flattened. They do a good job of preserving both size and shape. They're a compromise map. National Geographic has taken this approach with its world maps over the last several decades. In 1922, they began using the Vandergrinton projection, which projects the globe onto a circle. This was replaced in 1988 with the Robinson projection, which is more of an oval, and then in 1998 with the Winkle-Triple projection, which is what they use today. The Winkle-Triple projection is a compromise projection that does a good job, but not a perfect job at preserving size, and a good, but not perfect job at preserving area. On my personal travel website, I use dozens of maps. For the World Map, I use a projection

called the Kavriski-7 projection, which is similar to the Winkle-Triple projection. However, for individual countries or states, I use the Mercator projection, so they don't look distorted. So the Mercator projection is a very useful map. It's pretty much the basis of all the navigational mapping, which is what you use when you get directions on your smartphone or your computer. It works great for getting directions across town. However, it's not perfect. When you zoom out to see the entire earth, its flaws become evident. If you want something to display the whole world, your first choice should always be to get a globe. And if you want something to hang your wall, then go get a non-sylindrical projection like the Winkle Triple or the Robinson.

It's a good compromise. Executive producer of Everything Everywhere Daily is James McAlla. The associate producer is Thor Thompson. Today's five-star review comes from Apple Podcasts. Listener Z-Pick writes, love little bursts of historical information, easy to remember as they're told in a great storyline and not drawn out. I listen to many historical podcasts on many subjects, and this is one of my new favorites. Thank you, Zipic, and thanks to all of you who've left reviews. Remember, if you leave a five-star review, you too can have your review read on the show.