Mercator Projection

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What is a Map Projection?

Before getting into the intricacies of Mercator projection, let us understand what is map projection. A map projection is one of the numerous methods to represent the 3-dimensional surface of the earth on a 2-dimensional plane in Cartography. It is a way to flatten a globe’s surface into a plane to make a map. This conversion requires a systematic transformation of the latitudes and longitudes from a particular location of the world on a plane. All projections of a sphere on a sheet distort the surface in some way or the other. Depending on the map's purpose, some of the distortions are acceptable, and others are not. The primary mercator meaning of map projections is to preserve some of the original sphere-like properties at the expense of others. The study of map projections is the examination of the distortions.


What is a Mercator Projection?

The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer - Gerardus Mercator - in 1569. Now, you may ask what a cylindrical map projection is. In Cartography, any map projection of the terrestrial sphere done on the surface of a cylinder unrolled as a plane is known as a cylindrical projection. Mercator projection became the standard projection for navigation due to its ability to conserve lines of constant course; that is, it represents the north as up and south as down everywhere while preserving local directions and shapes. The Mercator projection is derived mathematically. The meridians are equally spaced vertical lines, and the latitudes are parallel horizontal straight lines that are spaced farther apart as the distance from the Equator increases.


The prime detriment of the Mercator projection is that it inflates the size of objects away from the Equator. The inflation is minuscule near the Equator and increases latitude, and becomes infinite at the poles. The result of such distortion is that areas like Greenland and Antarctica appear much more extensive than they are. For example, on a Mercator projection, the landmass of Greenland appears greater than that of the continent of South America; although, Greenland is even smaller than the Arabian Peninsula.

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The Working of Mercator Projection

You can understand the construction of the Mercator projection by taking a cylinder with a globe inside. You should light up the globe from within so that you can project an image of the earth on the surrounding cylinder. As the cylinder only touches the globe at the Equator, the parallels along that specific region are entirely accurate. Furthermore, as the cylinder is perpendicular to the globe, the lines of longitudes and latitudes appear straight instead of curved lines when transferred to the cylinder. 


We can imagine the Mercator chart as a small section peeled from the cylinder and laid flat. The Mercator chart is mathematically constructed, which means that the distance representing the spacing between meridians and parallels is numerically derived.


The graticule transferred on to the cylinder has a consistent 90-degree angle between the parallels and meridians. Thus, the rhumb lines are also straight on the Mercator projection.


Uses of Mercator Projection

  1. The Mercator projection is significant for navigation, and almost every marine chart is based on it.

  2. Street mapping services such as Google Maps, Bing Maps, MapQuest, etc., use a Mercator called Web Mercator for their map images.

  3. Mercator projections were vital for the mathematical development of plate tectonics during the 1960s.


Critique of the Mercator Projection

Owing to its expansive land distortions, many consider Mercator projection unsuitable for use in world maps. However, on account of its common usage, the Mercator projection has influenced people’s view of the world. Since it shows countries near the Equator as too small compared to Europe and North America, it has compelled people to consider those small countries as less critical. As a result, modern atlases no longer use the Mercator projection for world maps or areas far away from the Equator. Mercator projections, currently, are found in maps of time zones.


Conclusion

The topic of Mercator projection may seem very tricky to grasp. However, the concept does get manageable with thorough understanding, regularly solving questions and numerical, practising papers and proper revision. Before understanding the whole idea, we must grasp the basics of map projections and then move to Mercator. Past years' question papers, along with Vedantu's concept pages, are the perfect companions to guide you through the journey of absorbing knowledge.


Facts About Mercator Projection

  • The parallels and meridians on the Mercator are straight and perpendicular to one another. This phenomenon is typical among all cylindrical projections.

  • The Mercator is a conformal map projection which means that the angles around all locations are preserved.

  • All latitudes beyond 70 degrees north or south of the Mercator projection are unusable as the linear scale becomes infinitely large at the poles.

  • A Mercator map can fully show the polar areas.

  • The two features of a Mercator map – conformality and straight rhumb lines – make the projection uniquely appropriate for navigation.

  • The Mercator projection was the most commonly used projection for world maps during the 19th and 20th centuries.

FAQs (Frequently Asked Questions)

Q1. What are the Common Distortions Caused by Mercator Projection?

Ans. The Mercator projection exaggerates that it is far away from the Equator. Some of the common distortions are -

  • The continent of Antarctica appears to be extremely large. In case the entire globe was represented using Mercator, Antarctica would inflate infinitely.

  • Ellesmere Island, located in the north of Canada’s Arctic Archipelago, appears the same size as Australia. The fact is that Australia is over 39 times larger than Ellesmere Island.

  • Greenland appears the same size as Africa when Africa is 14 times larger in actuality.

Q2. How is a Map Projection Created?

Ans. The creation of map projection involves three steps –

  1. Selecting the model for the earth’s shape or round body, that is, you have to choose between a sphere and an ellipsoid.

  1. The second step is to transform geographic coordinates to plane coordinates.

  1. The last step is to reduce the scale.

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