1. Finding Locations on Earth
Earth and Space Science
Ms. Pollock

2. Finding Locations on Earth
Earth nearly a perfect sphere
Axis of rotation used for reference points
Reference points geographic North and South Poles and the equator
Hemispheres created

3. Latitude Positions north and south of equator
Parallels – circles running east and west parallel to the equator
Latitude – angular distance north or south of the equator
Measured in degrees
Equator 0 latitude
Poles 90 latitude

4. Latitude 1 latitude = 111 km
Parallels north of equator labeled N, parallels south of equator labeled S
Each degree divided into 60 minutes (1.85 km)
Each minute divided into 60 seconds

5. Longitude How far east or west along a parallel
Meridian – a semicircle that runs from pole to pole
Prime meridian selected by international agreement to pass through Greenwich, England
Longitude – angular distance east or west of the prime meridian

6. Longitude All locations east of prime meridian 0 to 180 E
All locations west of prime meridian 0 to 180 W
Distance between meridians varies because meridians end at poles

7. Great Circles Any circle that divides the globe into halves
Meridians directly across globe from each other
Equator only line of latitude that is a great circle
Shortest distance between two points on the globe

8. Finding Direction Magnetic compass Uses Earth’s magnetic properties
Compass needle points toward geomagnetic north pole
Geomagnetic poles different from geographic poles

9. Magnetic Declination
Angle between geomagnetic north pole and geographic north pole
Measured east and west of poles

10. The Global Positioning System
Global network of 24 satellites that transmit radio waves to Earth
First NAVSTAR, 1978
GPS receiver signaled by three satellites calculating latitude, longitude, and altitude
Personal receivers accurate to within m of location
Commercial receivers accurate to within cm