Mapping Our World

What you need to learn:

n How latitude and longitude are used to locate places on Earth

n How maps are made, and what types of maps are best suited to particular purposes

n What technology is used to map Earth from space

Why do you care?

n Maps help us locate exact places on Earth

n All forms of transportation rely on them

n Maps make our traveling easier

Latitude and Longitude

n Latitude: run parallel to the equator

• Degrees north or south of equator

0° = equator

90° = poles

• 1 degree = 111km

(40000km / 360°)

• 1 minute = 1.85km

(111km / 60΄)

Locating Places

n You need both latitude and longitude

n Latitude comes first when writing coordinates

Time Zones

n The Earth is divided into 24 time zones; each representing a different hour of the day

n Each zone is 15° wide, but divided by local areas

n There are 6 zones in the U.S.

n The International Date Line (180° meridian) is the transition line for the calendar day

• Example: if you travel west across it you advance a day, if you travel east across it you move back a day

n Mercator projection: parallel lines of latitude and longitude

• Shapes of land masses are accurate, but their areas are distorted

Maps Continued

n Gnomonic projections: projecting points and lines from a globe onto paper that touches the globe at a single point

• Distorts distance and direction

• Good for plots long distance

• Based on the principal of great-circles, such as the equator

Maps cont.

n Topographic maps: show changes in elevation

• Show mountains, rivers, forests, bridges, etc.

• Use a variety of symbols to represent objects and features

• Provide contour lines to show elevation

Remote Sensing

n Process of collecting data about Earth from far above the Earth’s surface

n Data in the form of electromagnetic radiation is interpreted to use in map making

A look at Maps

Mt. Saint Helens

Washington

Satellites

n Receive data from Earth

n Landsat satellites: receives different types of reflected wave energy from Earth and produces images of different color

n Topex/Poseidon satellite: sends and receives high frequency waves though the oceans to map ocean floors

n Sea Beam: located on a ship; uses sonar to map ocean floors

Satellites cont.

n Global Positioning System (GPS)

• Uses a radio-navigation system from at least 24 satellites to determine exact positions on earth

• Helpful for determining elevation, direction of travel, speed, earthquake detection, map creation, tracking wildlife