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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
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