Aim: Latitude and Longitude:

The Earth’s Coordinate System

Earth Science: Measuring Earth

Learning Objective

By the end of today’s

class students should be able to determine and measure latitude and longitude.

Latitude

Distance in degrees north or south of the equator (0°)

If you Draw a line from any point on the Earth’s surface to the center of the Earth, the angle that line makes with the equator will be that location’s latitude.

Parallels of Latitude

30°N

30°S

Parallels of

latitude

90°S

90°N

45°S

60°S

15°S

15°N

Quick Review of Latitude and

Longitude

lATITUDE

Measured in degrees North and South of the Equator.

Lines drawn parallel to each other running west to east.

Longitude

Distance in degrees, measured east or west, of the Prime Meridian (0°).

Meridians are imaginary semicircles that converge at the poles.

The maximum longitude is 180°

Meridians of Longitude

°E °W

Quick Review of Latitude and

Longitude

Measured in degrees East or West of the Prime meridian. Lines drawn running North and South.

LONGITUDE

Writing latitude and longitude

From USGS Maps :

The latitude of White Plains, New York is about 41.06°N or Just… 41.1° N

The longitude of White Plains, New York is about 73.76°W or Just 73.8°W

The coordinates of WPNY are written

41.1°N Lat, 73.8°W Long

Latitude is always (usually) written first

Longitude is always written(usually) second

EX. 30.5° S 78.9° W

Latitude is always (usually) written first

Longitude is always written(usually) second

Writing latitude and longitude

Complete the following in your notebook:

Latitude = 5°N, Longitude = 176°W

Latitude = 81°S, Longitude = 2°E

5°N Lat, 176°W Long

81°S lat, 2°E Long

Where in the World

5°N, 176°W 81°S, 2°E 41°N, 73°W

Latitude above Equator using

Polaris The altitude of Polaris (height above your feet in the sky) equals the Latitude of where

you are at (only in the Northern hemisphere),

North Star is Polaris.

The position of Polaris (angle of elevation) is fixed throughout the night

The altitude of Polaris is equal to the

observers latitude. OR you can say…… Angle of Elevation = Latitude on Map

Polaris/North Star

Polaris is overhead at 90°N (The North Pole)

Polaris is at the horizon at The Equator

Measuring Latitude

What is the astronomers latitude??

= 41º

41ºN

Zenith: Point in the sky directly above the observer

Measuring Longitude Have to know:

The solar (clock) time at the Prime Meridian (Greenwich, UK)

• Called Greenwich Mean Time (GMT)

Local Solar Time (clock) is the time at your location. Such time, called mean solar time

• Look at your watch or a clock

Celestial HEMISPHERE

Altitude of Polaris is ?

50º

Movie about Northern Sky

http://player.discoveryeducation.com/index.cfm?guidAssetId=E4323B12-6BF2-42E0-9196-BD97E1F29643&blnFromSearch=1&productcode=US

Also, http://www.onr.navy.mil/focus/spacesciences/skyobserve/constellations4.htm

Measuring Longitude Step 1: Calculate the time difference, in hours, between local clock time and the Greenwich time

Step 2: Multiply this time difference by 15°

Step 3: Determining Longitude: EL WE

EL – East Later

WE – West Earlier

Why Multiply by 15°?? The Sun moves across the sky (It’s really the earth turning)at a rate of 15° per hour.

15° = 1 hour

Measuring Longitude example

Greenwich Time = 5:00 PM

Local Time = 12:00 PM

** Is local time earlier or later than Greenwich Time, are you east or west of the Prime Meridian?? EL WE

Multiply 5 * 15° =

5 hours

Time Difference =

75°W

Movie bout Longitude

http://www-c.pbs.org/wgbh/nova/longitude/find/

(www-c.pbs.org/wgbh/nova/longitude/find/)

Summary: Latitude

Latitude is measured in degrees north or south of the equator.

To find the latitude of a location you have to determine whether that location is north or south of the Equator!

Longitude is measured in degrees east or west of the Prime Meridian.

Summary: Longitude

To find the longitude of a location you have to determine whether that location is east or west of the Prime Meridian!

Measuring Latitude Using Polaris

Latitude = Altitude of Polaris

Polaris (The North Star) is only visible in the?

Northern Hemisphere

Ex. The altitude of Polaris is 78°. What is your latitude?

78°N