Locating Places on EarthUnit 9, Lesson 9.1
By Margielene D. Judan
Lesson Outline• Locating Places By Latitudes and Longitudes• Latitude and Longitude Distance Measurements• Layers of the Earth
Celestial Navigation• Relied on celestial objects
(rising and setting of the sun, location of the stars, etc.)• Established first by the Greeks• Polaris – a star followed by
travelers heading north• Rising sun – east • Constellations – easily
recognizable patterns that help people orient themselves using the night sky
Modern Navigation• Uses two imaginary lines
that run from pole to pole and from west to east.• Latitude – run from west to
east• Longitude run from pole
to pole
Modern Navigation• Two starting points, known
as the great circles, are used (marked 0 degrees):• Equator – passes
horizontally through the center of the earth• Prime Meridian – the
vertical line that passes through Greenwich, England, dividing the earth into western and eastern hemispheres
Latitudes• Indicates north or south location• Imaginary lines are called parallels of latitude. • Equator – starting point • Parallels of latitude bet. the
equator and north pole is written with N, while those between the equator and south pole is written with S.• Measurements ranges from - N
or S.
- N
- S
Longitudes• Indicates west or east
location• Imaginary lines are called meridians of longitude• Prime meridian – starting
point passing through Greenwich and England (by international agreement)• Measurements ranges from
- E and WGreenwich Prime Meridian
Longitudes• Unlike latitudes, lines of longitude
converge in the poles.• Thus, the more we get near the
poles, the distance between two meridians decreases.
Point of convergence
Recitation (1-5)• Locate the following using latitudes and longitudes.
(next slide) Western Hemisphere
NorthernHemisphere
1. Texas
1. Texas - 30N, 100W
2. South Dakota
2. South Dakota - 45N, 100W
3. Himalayas
3. Himalayas- 30N, 90E
4. South Africa
4. South Africa- 30S, 30E
5.Australia
5.Australia- 30S, 150E
Distance Measurements• Distance are expressed in
angular measurements called degree.• Furthermore, a degree is even
divided into 60’ (minutes) • The minutes is further divided
into 60’’ (seconds)• Below is an example showing
the degree, minute, and second:• 3050’12’’ N, 15045’25’’ E
Distance Measurements• 1 degree (1) = 70 mi (112 km)• 1 minute (1’) = 1.667 miles• 1 second (1’’) = 100 ft
Ex. 1. What is the latitude of 840 miles north of the equator?Solution: Answer: 12N840 mi 1 70 mi
x = 12_____
Distance MeasurementsEx. 2. South Korea is at 35N. How far is South Korea from the Tropic of Cancer?Solution: Answer: 805 milesTropic of Cancer is located at 23.5N. 35N – 23.5N= 11.5 11.5 70 mi 1x = 805 mi_____
Important Latitude Lines• North Pole 90N• Tropic of Cancer
23.5N • Equator 0• Tropic of Capricorn 23.5S• South Pole
90S
The Philippines• Location - 1300’00’’ N,
12200’00’’ E• 2nd largest archipelago
in the world (1st – Indonesia)• 7,107 islands• Land area = 300,000
km2
Layers of the Earth
Layers of the Earth (Basic)Based on their properties, the earth is divided into:• Crust • Mantle• Core
Layers of the Earth• Continental Crust• Oceanic Crust• Mohorovicic
discontinuity• Upper Mantle• Lower Mantle• Gutenberg Discontinuity• Outer Core• Inner Core
Crust• Thinnest and outermost
layer• Shows greatest
variations in thickness• Divided into:1. Continental crust2. Oceanic crust
Continental Crust• Thickness : 30-50 km• Mineral composition:
Silicon Aluminum (SIAL) rocks• Basic type of rock:
Granite• Thicker than oceanic
crust
Oceanic Crust• Thickness : 7.5 km• Mineral composition:
rocks rich with silicon, iron, and magnesium (SIMA)• Basic type of rock:
Basalt• Thinner than continental
crust• Denser than continental
crust (due to basalt)
Mohorovicic discontinuity (Moho)• Discovered by Andrija
Mohorovicic by studying seismic waves• Rigid zone• Separates crust from upper
mantle
Mantle• Characteristic: plastic
solid (it flows, but it is solid; ex. lava)• Thickest layer of the
earth• The convection currents in it are responsible for movements in the earth’s tectonic plates.
Upper Mantle• Thickness: 965 km• Composition: silicates of
metallic compounds• Characteristic: elastic,
denser than crust• Lithosphere = crust +
upper mantle• Asthenosphere = upper
mantle (flowing, plastic)
Lower Mantle• Thickness : 1,930 km• Composition: Iron and
magnesium• Characteristic: elastic,
denser than crust
Gutenberg discontinuity• Discovered by
Beno Gutenberg by studying seismic waves• Separates lower
mantle from outer core
Outer core• Thickness : 2,880-
5,035 km• Composition: Iron-rich
metal alloy• Characteristic: liquid
Inner core• Composition: heavy
iron and nickel• Characteristic: solid,
very dense, highly elastic• Responsible for the
earth’s magnetic field • Hotter than the sun’s
surface