Our EarthOur Earth

Not What You ThinkNot What You Think Earth is not a Earth is not a

perfect sphereperfect sphere Oblate SpheroidOblate Spheroid

Slightly flattened Slightly flattened spheresphere

Spinning on the Spinning on the axis causes the axis causes the polar regions to polar regions to flatten and the flatten and the equatorial regions equatorial regions to bulgeto bulge

HydrosphereHydrosphere• Made up of all the Made up of all the

earth’s waterearth’s water• Earth is 71% Earth is 71%

covered by watercovered by water

– 97% saltwater97% saltwater– 3% fresh water3% fresh water

• Blanket of gasBlanket of gas• Provides air to Provides air to

breathebreathe• Shields from Shields from

radiationradiation– 78% nitrogen78% nitrogen– 21% oxygen21% oxygen– 1% other1% other

AtmospherAtmospheree

Zones of the Zones of the EarthEarth

Crust

Mantle Cor

e

The Geosphere isThe Geosphere is

The The CrustCrust Thin, solid, Thin, solid,

outmost zoneoutmost zone Only 1% of Only 1% of

earth’s massearth’s mass Two kindsTwo kinds

Oceanic crustOceanic crust Continental Continental

crustcrust

The MantleThe MantleMakes up 2/3 of the earth’s massMakes up 2/3 of the earth’s massDivided into 2 regionsDivided into 2 regions

Lithosphere

•Upper part of mantle

•Cool and brittle

Lithosphere

•Rigid

•15km- 300km

The MantleThe MantleAsthenosphere•Under enormous heat and pressure

•Solid rock has the ability to flow (plasticity)

•200 km thick

The The CoreCore

Outer CoreOuter CoreDense liquid Dense liquid layerlayer

2250 km thick2250 km thick

Inner CoreInner CoreDense, solid Dense, solid spheresphere

1228 km 1228 km thickthick

Made mostly of ironMade mostly of ironMakes up 1/3 of earth’s Makes up 1/3 of earth’s

massmass

The Layers were discovered by studying seismic waves: vibrations that travel through the earth.

Two Types of Seismic Two Types of Seismic WavesWaves

Primary Waves: P Primary Waves: P waveswaves

Travel through liquids, Travel through liquids, solids, and gasessolids, and gases

Travel faster than S Travel faster than S waveswaves Secondary Secondary

Waves: S wavesWaves: S wavesOnly travel through Only travel through

solidssolids

*boundary between the crust *boundary between the crust and and the mantlethe mantle*seismic waves speed up*seismic waves speed up

-indicates the mantle is -indicates the mantle is more more dense than the crust dense than the crust

The MohoThe Moho

*Locations on the surface where*Locations on the surface whereneither S waves or P waves neither S waves or P waves

are are detected OR only P waves detected OR only P waves are are detected.detected.*Occur because of differences in *Occur because of differences in

rigidityrigidity

Shadow Shadow ZonesZones

Magnetosphere

• Region of space affected by the earth’s magnetic field

The Source?Liquid iron in the outer core

May be another source

Force of attraction that Force of attraction that exists between all exists between all

matter in the universematter in the universe

Sir Isaac NewtonSir Isaac Newton Law of Gravitation: Law of Gravitation:

force of attraction force of attraction between any 2 between any 2 objects depends on objects depends on their masses and their masses and the distance the distance between them.between them.

Larger the mass Larger the mass and the closer and the closer together, the together, the greater the forcegreater the force

WeightMeasure of the strength of the pull of gravity on an object

Measured in newtons (N)

Depends on the object’s mass and its distance from the earth’s center

MassThe amount of matter in an object

Does not change with location

The Earth The Earth in Spacein Space

Rotating EarthRotating Earth►RotationRotation

Spinning on Spinning on the earth’s the earth’s axisaxis

1 rotation = 1 rotation = 24 hours24 hours

Rotates from Rotates from west to eastwest to east

Revolving Revolving EarthEarth

PerihelionPerihelion Closest point to Closest point to

the sunthe sun January 3January 3

AphelionAphelion Farthest point Farthest point

from the sunfrom the sun July 4July 4

Movement of the earth around the sun

1 revolution= 365.24 days

The SeasonsThe SeasonsCaused by changes Caused by changes in the angle at which in the angle at which the sun’s rays strike the sun’s rays strike the earth’s surfacethe earth’s surface

If the North Pole is If the North Pole is tilted away from the tilted away from the sun, the angle of the sun, the angle of the sun’s rays on the sun’s rays on the Northern Hemisphere Northern Hemisphere is lower = winteris lower = winter