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