Using Maps to Understand Our Planet

What Shape is Earth? The true shape of the Earth called an Oblate Spheroid. "Oblate" refers to it's slightly oblong appearance. Slightly wider at the middle and slightly flat at the poles. "Spheroid" means that it is almost a sphere, but not quite. It is only very slightly oblate. The diameter from the North Pole to the South Pole (the shortest diameter) is approximately 12,714 km. The equatorial diameter (the longest diameter) is approximately 12,756 km.

The earth is a 3- dimensional, round shape A map is a flat piece of 2-dimensional, rectangular paper So how do you create a 2D map of a 3D surface??

Map Projection : the method of representing information from the curved (3- dimensional) surface of the earth on a flat (2-dimensional) piece of paper

Map Breaks Because the earth is round, it’s not possible to transfer surface information onto paper without “breaking” the map

Map Distortion If we force our map to have no breaks, then certain parts must stretch for the map to lay flat Stretching our map causes distortion Distortion means that something about the map is not accurate: direction, shape, area, or distance. EVERY MAP HAS DISTORTION

Mercator Projection Direction and shapes are accurate, but the area is significantly distorted near the poles Look how gigantic Antarctica and Greenland appear!

Unreliable Mercator Maps On Mercator projection maps, Africa and Greenland look the same size. In real life, Africa is almost 14 times larger than Greenland!

Which is best? South America in selected projections at identical scale. Which projection is best? Which is right? The short answer is none are right, at least not all the time.

Making Map Projections

Robinson Projection It makes the world “look right” There is minimal distortion, but it is fairly accurate

Gall-Peters Projection Area is accurate but shape is not

Goode Homolosine Projection True size and shape of continents Splits up the ocean and the Polar regions, distance is wrong Called the “orange peel map”, popular in the 1960s

Mollweide Projection Areas of landmasses are accurate

Sinusoidal Projection Equal Area Representation

Polar Projections Distance from North Pole is accurate

Albers Projection

Van der Grinten Projection

Werner Projection Distance from the North Pole is accurate

New Kind of Accurate Map a new map called AuthaGraph, created by a Tokyo artist and architect, won an award for accurately representing the relative sizes of landmasses and bodies of water on Earth. The map is so proportionally accurate that you can fold it up into a three-dimensional globe.

Maps and Flight Paths Say you want to fly from Vancouver to Paris. Your flight path would probably look something like this, right? A straight line should be the quickest route!

Quickest Route The shortest distance between two points is a straight line, but when a line on a 3D globe is shown on a 2D map, it looks like an arc. So your flight path would actually look more like this:

See? This is why when you fly to Europe you’re probably going to fly over Greenland!

Great Circles Flights like this one follow what are know as Great Circle routes. Great Circle: a circle on the surface of a sphere that lies in a plane passing through the sphere's center. As it represents the shortest distance between any two points on a sphere, a great circle of the earth is the preferred route taken by a ship or aircraft.