Chapter 2 - Mapping our world


science of map making


divides the Earth into the north and south pole (imaginary line)


Distance north or south of the equator


Distance east or west of the prime meridian, measured in degrees

Prime Meridian

The meridian, designated at 0° longitude, which passes through the Royal Observatory at Greenwich, England.

international date line

An arc that for the most part follows 180° longitude, although it deviates in several places to avoid dividing land areas. When you cross the International Date Line heading east (toward America), the clock moves back 24 hours, or one entire day. When you go west (toward Asia), the calendar moves ahead one day.

Mercator Projection

a projection of a map of the world onto a cylinder in such a way that all the parallels of latitude have the same length as the equator, used especially for marine charts and certain climatological maps.

conic projection

a map created by projecting an image of Earth onto a cone placed over part of an Earth model

gnomic projection

made by projecting points and lines from a globe onto a piece of paper that touches the globe at a single point

topographic map

A map that shows the surface features of an area.

contour line

A line on a topographic map that connects points of equal elevation

contour line

A line on a topographic map that connects points of equal elevation

contour interval

the difference in elevation from one contour line to the next

geologic map

A map showing the distribution of rock units and structures across a region.

map legend

Explains the meaning of symbols used on a map.

map scale

The relationship between the size of an object on a map and the size of the actual feature on Earth's surface.

remote sensing

The acquisition of data about Earth's surface from a satellite orbiting the planet or other long-distance methods.

landsat satellite

Information-gathering satellite that uses visible light and infrared radiation to map Earth's surface.

TOPEX/Poseidon satellite

Data-gathering satellite that uses radar to map features on the ocean floor.


use of sound waves to detect and measure objects underwater

Global Positioning System (GPS)

A system that determines the precise position of something on Earth through a series of satellites, tracking stations, and receivers.

Geographic Information System (GIS)

A computer system that stores, organizes, analyzes, and displays geographic data.