NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea) Current Distance~100 AU Perihelion...
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Transcript of NEW “PLANETOID” - SEDNA (Inuit Goddess of the Sea) Current Distance~100 AU Perihelion...
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.
PLATE TECTONICSPLATE TECTONICSPLATE TECTONICSPLATE TECTONICS
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
PLATE TECTONICSPLATE TECTONICSPLATE TECTONICSPLATE TECTONICS
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.
PLATE TECTONICSPLATE TECTONICSPLATE TECTONICSPLATE TECTONICS
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.
PLATE TECTONICSPLATE TECTONICSPLATE TECTONICSPLATE TECTONICS
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
ACTIVE SITES on EARTH’S ACTIVE SITES on EARTH’S SURFACESURFACE
ACTIVE SITES on EARTH’S ACTIVE SITES on EARTH’S SURFACESURFACE
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 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.
GREENHOUSE EFFECT and GREENHOUSE EFFECT and GLOBAL WARMINGGLOBAL WARMING
GREENHOUSE EFFECT and GREENHOUSE EFFECT and GLOBAL WARMINGGLOBAL WARMING
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
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.
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
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
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
More than 150 impact craters are still More than 150 impact craters are still recognized on Earth’s surface. recognized on Earth’s surface.
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
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.
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
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
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
COSMIC INFLUENCES on COSMIC INFLUENCES on EARTH’S EVOLUTIONEARTH’S EVOLUTION
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
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
EFFECTS of a MASSIVE EFFECTS of a MASSIVE IMPACTIMPACT
EFFECTS of a MASSIVE EFFECTS of a MASSIVE IMPACTIMPACT
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.
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
Impact of ~ 20 km asteroid.
Evidence: crater in Gulf of Mexico and Iridium layer.
What caused the extinctions?What caused the extinctions?
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
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
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
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