NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea) Current Distance~100 AU Perihelion Distance~75 AU Mass~1/2 Pluto Eccentricity0.85 Semi Major Axis~500

NEW “PLANETOID” - SEDNA NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea)(Inuit Goddess of the Sea)

NEW “PLANETOID” - SEDNA NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea)(Inuit Goddess of the Sea)

Current Distance ~100 AU

Perihelion Distance ~75 AU

Mass ~1/2 Pluto

Eccentricity 0.85

Semi Major Axis ~500 AU

Period 11,000 years

Aphelion Distance ~925 AU

Inclination to Ecliptic 12 Degrees

EARTH AS A PLANETEARTH AS A PLANET

Chapter 7

SOME PROPERTIES of SOME PROPERTIES of EARTHEARTH

SOME PROPERTIES of SOME PROPERTIES of EARTHEARTH

Semi major Axis 1.00 AU

Period 1.00 year

Mass 5.98 x 1024 kg

Diameter 12,756 km

Escape Velocity 11.2 km/s

Rotation Period 23h 56m 4s

Surface Area 5.1 x 108 km2

Atmospheric Pressure 1.00 bar

EARTH as a PLANETEARTH as a PLANETEARTH as a PLANETEARTH as a PLANET

Only planet with water in liquid form.Only planet with water in liquid form. Composition: iron, silicates, oxygen.Composition: iron, silicates, oxygen. Density: highest in Solar System.Density: highest in Solar System. Interior: 4 major layers – inner core, outer Interior: 4 major layers – inner core, outer

core, mantle, crust.core, mantle, crust.

EARTH as a PLANETEARTH as a PLANETEARTH as a PLANETEARTH as a PLANET

Only planet with water in liquid form.Only planet with water in liquid form. Composition: iron, silicates, oxygen.Composition: iron, silicates, oxygen. Density: highest in Solar System.Density: highest in Solar System. Interior: 4 major layers – inner core, outer core, Interior: 4 major layers – inner core, outer core,

mantle, crust.mantle, crust. Magnetic Field and Magnetosphere: Earth Magnetic Field and Magnetosphere: Earth

behaves as if it had a bar magnet inside it. behaves as if it had a bar magnet inside it.

MAGNETOSPHERE and VAN MAGNETOSPHERE and VAN ALLEN BELTSALLEN BELTS

MAGNETOSPHERE and VAN MAGNETOSPHERE and VAN ALLEN BELTSALLEN BELTS

The MAGNETOSPHERE The MAGNETOSPHERE SHAPESHAPE

The MAGNETOSPHERE The MAGNETOSPHERE SHAPESHAPE

EARTH’S STRUCTURE – EARTH’S STRUCTURE – HOW DO WE KNOW IT? HOW DO WE KNOW IT? EARTH’S STRUCTURE – EARTH’S STRUCTURE – HOW DO WE KNOW IT? HOW DO WE KNOW IT?

SEISMIC WAVESSEISMIC WAVESSEISMIC WAVESSEISMIC WAVES

Earthquakes produce two kinds of waves that Earthquakes produce two kinds of waves that travel through our planet.travel through our planet.P (pressure) waves are P (pressure) waves are longitudinallongitudinal waves analogous waves analogous

to those produced by pushing a spring in and out.to those produced by pushing a spring in and out.S (shear) waves are S (shear) waves are transversetransverse waves analogous to waves analogous to

waves produced by shaking a rope up and down.waves produced by shaking a rope up and down.

SEISMIC WAVESSEISMIC WAVESSEISMIC WAVESSEISMIC WAVES

Earthquakes produce two kinds of waves that Earthquakes produce two kinds of waves that travel through our planet.travel through our planet.P (pressure) waves are P (pressure) waves are longitudinallongitudinal waves analogous waves analogous

to those produced by pushing a spring in and out.to those produced by pushing a spring in and out.S (shear) waves are S (shear) waves are transversetransverse waves analogous to waves analogous to

waves produced by shaking a rope up and down.waves produced by shaking a rope up and down. P waves travel through solids and liquids (5-6 P waves travel through solids and liquids (5-6

km/s).km/s). S waves cannot travel through liquids (3-4 km/s).S waves cannot travel through liquids (3-4 km/s). Velocity of waves depends on density of material Velocity of waves depends on density of material

in which they travel. Velocity is faster in higher in which they travel. Velocity is faster in higher density materials.density materials.

S and P WAVE PATHSS and P WAVE PATHSS and P WAVE PATHSS and P WAVE PATHS

FLASHCARDFLASHCARDFLASHCARDFLASHCARD

P WAVES MOVE AT ABOUT 5 KM/S. HOW LONG P WAVES MOVE AT ABOUT 5 KM/S. HOW LONG WILL IT TAKE A P-WAVE TO REACH THE OPPOSITE WILL IT TAKE A P-WAVE TO REACH THE OPPOSITE SIDE OF EARTH AFTER AN EARTHQUAKE? (RADIUS SIDE OF EARTH AFTER AN EARTHQUAKE? (RADIUS OF EARTH IS 6500 KM)OF EARTH IS 6500 KM)

A)A) ABOUT 4 SECONDSABOUT 4 SECONDS

B)B) ABOUT 4 MINUTES ABOUT 4 MINUTES

C)C) ABOUT 40 MINUTES ABOUT 40 MINUTES

D)D) ABOUT 400 MINUTES ABOUT 400 MINUTES

EARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTURE Under Oceans CrustUnder Oceans Crust

6 km thick. Basalts 6 km thick. Basalts (volcanic rock, Si, O, (volcanic rock, Si, O, Fe, Al, Mg).Fe, Al, Mg).

Under Continents CrustUnder Continents Crust 20 to 70 km thick. 20 to 70 km thick.

Granite (volcanic Granite (volcanic silicates).silicates).

CrustCrust

MantleMantle

OuterOuterCoreCoreInnerInnerCoreCore

EARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTURE MantleMantle

Down to 2900 km. Down to 2900 km. Solid with some Solid with some melting.melting.

Ejected volcanoes Ejected volcanoes allows study.allows study.

CoreCore 3500 km radius.3500 km radius.Outer core is liquid. Outer core is liquid.

Inner core dense and Inner core dense and solid.solid.

Inner core rich in Inner core rich in heavy elements - Fe, heavy elements - Fe, Ni, S. Ni, S.

CrustCrust

MantleMantle

OuterOuterCoreCoreInnerInnerCoreCore

EARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTUREEARTH’S STRUCTURE

Structure Structure indicates that indicates that Earth is Earth is differentiateddifferentiated which suggests which suggests Earth was Earth was once molten so once molten so heavier heavier elements could elements could sink to core. sink to core.

PLATE TECTONICSPLATE TECTONICSPLATE TECTONICSPLATE TECTONICS

Earth’s crust consists of about 12 plates. Earth’s crust consists of about 12 plates.


Energy escaping from the interior drives the Energy escaping from the interior drives the plates (few cm/year).plates (few cm/year).

50 million years 50 million years from nowfrom now


Where plates interact, dramatic changes occur Where plates interact, dramatic changes occur in Earth’s crust.in Earth’s crust. Rift Zones: Plates pulling apart. Material Rift Zones: Plates pulling apart. Material

rises from mantle to fill spaces (volcanoes). rises from mantle to fill spaces (volcanoes). E.g. Mid Atlantic Ridge.E.g. Mid Atlantic Ridge.


Where plates interact, dramatic changes occur Where plates interact, dramatic changes occur in Earth’s crust.in Earth’s crust. Subduction Zone: Two plates come together, Subduction Zone: Two plates come together,

one forced down and melts. Earthquakes and one forced down and melts. Earthquakes and volcanoes common along subduction zones.volcanoes common along subduction zones.


Coastal BC is on the upper part of a Coastal BC is on the upper part of a subduction zone. subduction zone.

SAN ANDREAS FAULTSAN ANDREAS FAULTSAN ANDREAS FAULTSAN ANDREAS FAULT

ACTIVE SITES on EARTH’S ACTIVE SITES on EARTH’S SURFACESURFACE




CONTINENTAL DRIFTCONTINENTAL DRIFTCONTINENTAL DRIFTCONTINENTAL DRIFT

FLASHCARDFLASHCARDFLASHCARDFLASHCARD

AT 2 CM/YEAR, HOW LONG WOULD IT TAKE A AT 2 CM/YEAR, HOW LONG WOULD IT TAKE A TYPICAL PLATE TO TRAVERSE THE PRESENT TYPICAL PLATE TO TRAVERSE THE PRESENT WIDTH OF THE ATLANTIC OCEAN, ABOUT 6000 WIDTH OF THE ATLANTIC OCEAN, ABOUT 6000 KM? KM?

A)A) 3 X 103 X 1066 YR YR

B)B) 1.2 X 10 1.2 X 1077 YR YR

C)C) 3 X 10 3 X 1088 YR YR

D)D) 1.2 X 10 1.2 X 1099 YR YR

< 10 km, most atmosphere here. (N2 78%, O2 21%, Ar 1%, traces H2O, CO2)

TroposphereTroposphere

10 - 80 km, cold (-50ºC), cloudless StratosphereStratosphere

50 - 80 km, O3, absorbs UV radiation

OzoneOzoneLayerLayer

Atmosphere very thin, constant leakage of H and He

> 100 km> 100 km

GREENHOUSE EFFECTGREENHOUSE EFFECTGREENHOUSE EFFECTGREENHOUSE EFFECT COCO22 content of atmosphere is critical for its content of atmosphere is critical for its

role in retaining heat from Sun. role in retaining heat from Sun. Greenhouse EffectGreenhouse Effect: : Earth absorbs sunlight Earth absorbs sunlight

and re-emits it as and re-emits it as infrared (IR) radiation infrared (IR) radiation (Earth acts like a (Earth acts like a

blackbody).blackbody). COCO22 transparent to transparent to

sunlight but absorbs IR sunlight but absorbs IR acting like a blanket. acting like a blanket.

The more COThe more CO22, the , the

hotter Earth is.hotter Earth is.

GREENHOUSE EFFECT and GREENHOUSE EFFECT and GLOBAL WARMINGGLOBAL WARMING


Greenhouse effect has raised Earth’s average Greenhouse effect has raised Earth’s average temperature by 23ºC. temperature by 23ºC.

Without the greenhouse effect, Earth’s Without the greenhouse effect, Earth’s average temperature would be below freezing average temperature would be below freezing and Earth would be in a constant global ice and Earth would be in a constant global ice age. age.



COCO22 levels are increasing. levels are increasing. Prediction: rising COPrediction: rising CO22 levels will lead to levels will lead to

global warming with uncertain consequences.global warming with uncertain consequences.

Vegetation mapVegetation mapVegetation mapVegetation map Rainforests extract CORainforests extract CO22

Destruction rainforestsDestruction rainforests

This plus increasing fossil This plus increasing fossil fuel burning causes fuel burning causes increasing COincreasing CO2 2 by 0.5%/yrby 0.5%/yr

Exacerbates Global Exacerbates Global WarmingWarming

Cf Venus – 700KCf Venus – 700K

LIFE on EARTHLIFE on EARTHLIFE on EARTHLIFE on EARTH Earth is the Earth is the onlyonly planet known to be planet known to be

harbouring life.harbouring life. Life arose early on. Fossils date back 3.5 Life arose early on. Fossils date back 3.5

billion years.billion years.Origin of life is unsure.Origin of life is unsure.Miller experimentMiller experiment: :

produced amino acids produced amino acids and other pre-biological and other pre-biological molecules from molecules from primitive Earth primitive Earth atmosphere - mainly atmosphere - mainly methane, water, methane, water, ammonia, COammonia, CO22, no O, no O22..

LIFE on EARTHLIFE on EARTHLIFE on EARTHLIFE on EARTH

Development of plants:Development of plants:

Formation of the ozone (OFormation of the ozone (O33) layer) layer

Use up COUse up CO22 and produce O and produce O2 2 - photosynthesis- photosynthesis..

Free OFree O22 in atmosphere 2 billion years ago. in atmosphere 2 billion years ago.

Protects Earth from UV.Protects Earth from UV.This allowed life to leave protective oceans This allowed life to leave protective oceans

and colonize the land. Not possible earlier.and colonize the land. Not possible earlier.

COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION


Moon is heavily cratered - caused by impacts.Moon is heavily cratered - caused by impacts.Where are Earth’s Where are Earth’s

craters?craters?Most lost by erosion Most lost by erosion

and geological and geological activity.activity.



More than 150 impact craters are still More than 150 impact craters are still recognized on Earth’s surface. recognized on Earth’s surface.

METEOR CRATERMETEOR CRATER0.1 km meteor0.1 km meteor

Crater size = 10 x Crater size = 10 x size of impacting objectsize of impacting object

1.2 km1.2 km






Concern is that a large object, ≥10 km, will Concern is that a large object, ≥10 km, will collide with Earth releasing a few billion times collide with Earth releasing a few billion times as much energy as Hiroshima bomb. as much energy as Hiroshima bomb.



Concern is that a large object, 10 km, will Concern is that a large object, 10 km, will collide with Earth releasing a few billion times collide with Earth releasing a few billion times as much energy as Hiroshima bomb. as much energy as Hiroshima bomb.

One such object crosses Earth’s orbit every One such object crosses Earth’s orbit every 100 million years.100 million years.

ORBITS of the 100 LARGEST ORBITS of the 100 LARGEST KNOWN NEAR-EARTH KNOWN NEAR-EARTH

ASTEROIDSASTEROIDS

ORBITS of the 100 LARGEST ORBITS of the 100 LARGEST KNOWN NEAR-EARTH KNOWN NEAR-EARTH

ASTEROIDSASTEROIDS

IMPACT FREQUENCYIMPACT FREQUENCYIMPACT FREQUENCYIMPACT FREQUENCY

1.00E-12

1.00E-09

1.00E-06

1.00E-03

1.00E+00

1.00E+03

1.00E+06

1.00E+091.00E-08 1.00E-04 1.00E+00 1.00E+04 1.00E+08

Diameter (Metres)

Mea

n T

ime

to Im

pac

t E

arth

(Y

ears

) Impactors on the surface of the space shuttleImpactors on the surface of the space shuttle11m, 30m, 30secsec

Shooting starsShooting stars1 mm, 30 sec1 mm, 30 sec

MeteoritesMeteorites1m, 1yr1m, 1yr

Arizona CraterArizona Crater100 m, 10100 m, 104 4 yryr

Sudbury, OntarioSudbury, Ontario10 km, 1010 km, 1088 yr yr




METEOR CRATERMETEOR CRATER0.1 km meteor0.1 km meteor

Crater size = 10 x Crater size = 10 x size of impacting objectsize of impacting object

1.2 km1.2 km

TUNGUSKA EVENTTUNGUSKA EVENTTUNGUSKA EVENTTUNGUSKA EVENT

SiberiaSiberiaJune 30, 1908June 30, 1908

Projectile Projectile exploded before exploded before impacting Earthimpacting Earth

Projectile’s mass Projectile’s mass estimated to be estimated to be

100,000 tons100,000 tons

Caused Caused widespread widespread

damage.damage.

TUNGUSKA EVENTTUNGUSKA EVENTTUNGUSKA EVENTTUNGUSKA EVENT

THE SOLAR SYSTEMTHE SOLAR SYSTEMTHE SOLAR SYSTEMTHE SOLAR SYSTEM Comets can be captured by Jupiter.Comets can be captured by Jupiter. Actually orbit Jupiter – orbits unstable.Actually orbit Jupiter – orbits unstable. Comet Shoemaker-Levy9 discovered 1992Comet Shoemaker-Levy9 discovered 1992 Broke into fragments near “Peri-Jupiter”Broke into fragments near “Peri-Jupiter” Fragments predicted to crash into Jupiter 1994Fragments predicted to crash into Jupiter 1994

SHOEMAKER-LEVY9 COMETSHOEMAKER-LEVY9 COMETSHOEMAKER-LEVY9 COMETSHOEMAKER-LEVY9 COMET

IMPACTIMPACTIMPACTIMPACT

Earth’s Earth’s ViewView

Voyager’sVoyager’sViewView

SHOEMAKER-LEVY IMPACTSHOEMAKER-LEVY IMPACTSHOEMAKER-LEVY IMPACTSHOEMAKER-LEVY IMPACT

DEVELOPMENT of DUST CLOUDDEVELOPMENT of DUST CLOUDDEVELOPMENT of DUST CLOUDDEVELOPMENT of DUST CLOUD

ImpactImpact

IMPACT DUST CLOUDSIMPACT DUST CLOUDSIMPACT DUST CLOUDSIMPACT DUST CLOUDS

IR IMAGE of IMPACTSIR IMAGE of IMPACTSIR IMAGE of IMPACTSIR IMAGE of IMPACTS

IoIo

COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTION con’tEARTH’S EVOLUTION con’tCOSMIC INFLUENCES on COSMIC INFLUENCES on

EARTH’S EVOLUTION con’tEARTH’S EVOLUTION con’t

EFFECTS of a MASSIVE EFFECTS of a MASSIVE IMPACTIMPACT




Huge tidal waves.Huge tidal waves. Dust high up in the atmosphere.Dust high up in the atmosphere. Block out Sun for about one year, kills Block out Sun for about one year, kills

photosynthesis.photosynthesis. World-wide fires, forests and grasslands World-wide fires, forests and grasslands

destroyed.destroyed. Highly acidic rains.Highly acidic rains. Animals depending on plants die Animals depending on plants die

(dinosaurs?), rise of mammals. (dinosaurs?), rise of mammals.

Global earthquakes.Global earthquakes.

EXTINCTIONS, the SOLAR EXTINCTIONS, the SOLAR SYSTEM and our GALAXYSYSTEM and our GALAXYEXTINCTIONS, the SOLAR EXTINCTIONS, the SOLAR SYSTEM and our GALAXYSYSTEM and our GALAXY

Past 100 million years many large scale extinctions (~ Past 100 million years many large scale extinctions (~ 10) identified on Earth.10) identified on Earth.In these, a significant fraction of existing

species were extinguished.

Best known is extinction Best known is extinction of the dinosaurs 65 of the dinosaurs 65 million years ago after million years ago after flourishing for 100 flourishing for 100 million years.million years.


Impact of ~ 20 km asteroid.

Evidence: crater in Gulf of Mexico and Iridium layer.

What caused the extinctions?What caused the extinctions?


What caused the extinctions?What caused the extinctions?Impact of ~ 20 km asteroid.

Evidence: crater in Gulf of Mexico and Iridium layer.

Nearby supernova (depletes O3, forming NO2).

Crab NebulaCrab Nebula

EXTINCTION of the EXTINCTION of the DINOSAURSDINOSAURS

EXTINCTION of the EXTINCTION of the DINOSAURSDINOSAURS

ALTERNATE DINOSAUR ALTERNATE DINOSAUR EXTINCTION THEORYEXTINCTION THEORY

ALTERNATE DINOSAUR ALTERNATE DINOSAUR EXTINCTION THEORYEXTINCTION THEORY

SPIRAL GALAXYSPIRAL GALAXYSPIRAL GALAXYSPIRAL GALAXY


Supernovae and impacts more likely when Sun passes Supernovae and impacts more likely when Sun passes through spiral arm in our Galaxythrough spiral arm in our GalaxyOort cloud comets get perturbed.

OORT CLOUD GETS OORT CLOUD GETS PERTURBEDPERTURBED

OORT CLOUD GETS OORT CLOUD GETS PERTURBEDPERTURBED

Documents

NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea) Current Distance~100 AU Perihelion Distance~75 AU Mass~1/2 Pluto Eccentricity0.85 Semi Major Axis~500