Where in the world?: Boston's swaps classroom maps

Boston schools are changing maps. The city's school district, with 57,000 students in 125 schools, is switching from the Mercator projection map to the Peters projection in classrooms.

The Mercator map is what many people in the US and elsewhere are familiar with. It was devised by Flemish cartographer Gerardus Mercator in 1569, primarily to help explorers and traders navigate the seas. For the last 500 years, it could be found in atlases and on many classroom walls - but it distorts the size of countries and whole continents. The Peters projection is truer to the actual size of continents and offers school children a more realistic picture of where countries are actually located.

Nothing is where you think it is

If you have internalized the Mercator map as your picture of the world, you will be as surprised as Boston school children were when teachers presented them with the Peters projection for the first time last week. Africa looks a lot bigger in the Peters projection and Europe is situated a lot further north than many are used to.

"It's a paradigm shift," Colin Rose, assistant superintendent of opportunity and achievement gaps for Boston public schools, told Britain's "Guardian" newspaper. Boston school officials say their district will be the first in the US to make the complete shift away from Mercator to "decolonize" their curriculum, as Rose put it.

The Mercator map is an "equal angle" projection. It preserves the angles between longitudes and latitudes and works well for nautical navigations - it has straight lines across the oceans that seafarers would use.

But Gerardus Mercator also focused much more on the Northern Hemisphere, and the simplifications in his map lead to grossly distorted size representations. Greenland looks like it is just about the same size as Africa, when in reality the continent is about 14 times larger. South America looks roughly the same size as Europe, even though it's almost twice as large.

The Peters projection was published by German historian Arno Peters in 1974. It is based on work by 19th century Scottish cartographer James Gall and also called the Gall-Peters projection. It is an "equal area" projection as opposed to "equal angle." Sizes are portrayed realistically. Africa looks larger than Greenland and Europe is smaller and a lot further north than on the Mercator projection.

Experts are careful to stress that the Peters projection isn't the be-all and end-all of maps. While the area of a continent is represented correctly, the shapes are distorted, which becomes perhaps most obvious when looking at elongated Africa.

According to German Cartographer Rolf Böhm, which projection is best depends on what purpose the map is used for.

"The Peters projection is a little better suited for use in schools [than the Mercator projection], but it's not great either," Böhm told DW. "At least the Mercator projection correctly represents shapes, with Scandinavia and Australia for example looking like they're supposed to."

Böhm says the ideal map for students learning geography is an almost "equal area" projection, since a 100 percent "equal area" one like Peters distorts the shapes so much. One of his favorites is the Wagner VIII projection.

The hundreds of different projections have been a topic of discussion among cartographers for decades, but it hardly ever reaches the public eye. One notable exception is an episode of the US television show "The West Wing" about a fictional US president and his staff. In a 2001 episode, press secretary C.J. Cregg, played by Allison Janney, learns about the difference between the Mercator and the Peters projection and can't believe what she's seeing.

The surprise about anything that looks a little different, like the Peters projection, shows why it's important to keep in mind that there isn't one right map. After all, perfectly transposing the spherical Earth onto a two-dimensional sheet of paper just isn't possible.

"There is only one perfect representation that's both 'equal angle' and 'equal area,'" cartographer Böhm says. "It's called a globe."