# Why Maps Can you use a square globe?

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Why Maps Can you use a square globe?
Could you fold up a globe and put it in your pocket? Why do we need maps? What types are there?

Map Makers Cartography: map making
Develop a way to put a curved surface onto a flat surface (Map Projection) Mercator Gnomonic Conic Are the most common projections

Map Projections

Mercator Projection

Mercator Projection Wrap a cylinder around a globe.
Meridians appear straight. This creates distortion near the poles where the meridians normally come together.

Mercator Projection Compass directions appear as straight lines
Latitude & Longitude are shown clearly and easily measured with a ruler. Shapes are shown correctly.

Gnomonic Projection

Gnomonic Projection Imagine a sheet of paper touching a globe at one point (tangent) Little distortion occurs at the point of contact. It is usually the poles.

Gnomonic Projection There is a great distortion in both directions from the point of contact. Used in navigation of great circle routes Great circle appears as a straight line on these maps.

Conic Projections

Conic Projection Cone placed over a globe so that the axis of the cone is aligned with the axis of the globe. Cone touches the globe along one parallel.

Conic Projection The area near the contacted latitude has the least distortion. Good for studying a specific area.

Polyconic Projection Placing many conic map projections together can give you a continuous map. The relative shape and size of small areas are the same as the globe.

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