Unit 1: What is Geography? Part 2: Mapping the Earth’s Surface

The Earth is called an oblate spheroid. T he most accurate way to depict the earth is as a globe, a round scale model of the earth. A globe gives a true picture of the continents’ relative sizes and the shapes of landmasses and bodies of water. Globes accurately represent distance and direction.  Lines of latitude are called parallels. The equator is defined a zero degrees latitude. Latitude is the angular distance measured in degrees north and south parallel to the equator.

The Earth as an Oblate Spheroid

Lines of longitude are called meridians. The prime meridian is defined as zero degrees longitude. Longitude is the angular distance measured in degrees east or west of the prime meridian. The Earth is divided into 4 major hemispheres (you will learn about spheres as layers of the Earth later). They are the Northern Hemisphere, the Southern Hemisphere, the Eastern Hemisphere, and the Western Hemisphere.

The Major Hemispheres of the Earth

Lines of Latitude

Lines of Longitude

A map is a drawing or other representation, usually on a flat surface, of all or part of the earth's surface, ordinarily showing countries, bodies of water, cities, mountains, etc. Cartography is the science, or technology, of mapmaking. In order to create accurate maps, one must understand the spherical aspect of the Earth. The Earth’s circumference is approximately 25,000 miles! The diameter around the equator is 7, miles. The diameter from the North Pole to the South Pole is 7, miles.

There are many different types of maps and map projections. The reason for this is rather simple…the Earth is round not flat! To fill in the gaps, mapmakers stretch parts of the earth. They choose to show either the correct shapes of places or their correct sizes. Most cartographers use software programs called Geographic Information Systems (GIS). A Global Positioning System (GPS) helps mapmakers and consumers locate places based on coordinates broadcast by satellites.

Common Map Projections

The Mercator projection shows true direction and land shapes fairly accurately, but not size or distance. Areas that are located far from the Equator are quite distorted on this projection.

Map Interpretation In order for you to fully read and interpret a map, the map must contain key elements before you can successfully understand what the map is trying to communicate to you. Maps have legends. Here, cartographers create the map key where symbols and colors are used to represent various geographic data including elevation, population, precipitation totals, infant mortality rates, etc. The possibilities are endless!

Map Legend (Key) Examples

Cartographers are now using computers and computer programs called Geographic information systems (GIS). Remote sensing is the small- or large-scale acquisition of information of an object or phenomenon, by the use of either recording or real- time sensing device(s) that are wireless, or not in physical or intimate contact with the object (such as by way of aircraft, spacecraft, satellite, buoy, or ship).

Remote Sensing Examples