1. Latitude and Longitude
Measuring the Earth
Latitude and Longitude

2. Mapping Earth’s Surface
1.  A map is a model of earth’s surface.
2. Coordinate systems – a method of locating objects on a map by labeling them with coordinates.
3. Latitude – Longitude Coordinate System

3. Latitude/Parallels
Parallels are imaginary east-west lines on earth’s surface
Parallels never cross
Parallels tell you how far North or South of the Equator you are

4. What is the approximate
Show what you know
33° North
33° North
What is the approximate
latitude of
Point A?
Point B?
They’re the same
because they are on
the same line of Latitude!

5. Important Latitudes Equator = 0º Latitude North Pole = 90º N Latitude
South Pole = 90º S Latitude

6. Longitude/Meridians
Meridians are imaginary north-south lines on earth’s surface
All meridians cross over the poles and converge there
Meridians tell you how far east or west of the Prime Meridian you are

7. Important Longitudes Prime Meridian = 0° Longitude
International Date Line = 180° Longitude

8. Show what you know What is the approximate longitude of Point A?
75° West
What is the approximate longitude of Point A?
What is the approximate longitude of Point B?

9. Using Latitude and Longitude
Combine your latitude and longitude measurement to get a coordinate
Make sure you include direction with both latitude and longitude
20°30’N, 75°30’E

10. What is the Latitude and Longitude of Jamestown? 79° W

11. What is the Latitude and
Longitude of Ithaca?

12. Determining Latitude and Longitude
Latitude – The angle of Polaris above the horizon is equal to your latitude in the Northern Hemisphere

13. Longitude – You can find longitude by knowing the local time and the time at Greenwich, England. If it is one hour earlier than Greenwich, you are 15 degrees West of Greenwich.

15. Royal Observatory, Greenwich England

16. Mrs. Ellis on the Prime Meridian
Wow! I must really be a geek if I’m posing on the Prime Meridian!

17. Royal Observatory
Why might the roof be retractable?

18. The Greenwich Meridian was chosen to be the Prime Meridian of the World in Forty-one delegates from 25 nations met in Washington DC for the International Meridian Conference. By the end of the conference, Greenwich had won the prize of Longitude 0º by a vote of 22 in favor to 1 against (San Domingo), with two abstentions (France and Brazil). There were two main reasons for the victory:
the USA had already chosen Greenwich as the basis for its own national time-zone system.
at the time, 72% of the world's commerce depended on sea-charts which used Greenwich as the Prime Meridian.