terrestrial planets: earth
TRANSCRIPT
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Terrestrial Planets: Earth
Mercury Venus Earth Moon MarsDistance 1 AU
Orbital Period 1 year
Rotation Period 23.9 hours
Radius (km) 6378 km
Radius (R⊕) 1 R⊕Mass (kg) 6.0x1024 kg
Mass (M⊕) 1 M⊕
Avg. Surface T 59 ̊F
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Core: Iron & nickelliquid outer coresolid inner core
Mantle: Mostly Silicate RockSolid (upper mantle) Plastic (lower mantle)
Crust: Silicate Rock & MineralsSolid
Earth: Internal Structure
Trend?
Lithosphere: crust & uppermost mantle
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Differentiation•Denser materials in a liquid sink to the center
Gravity!why?
Implications?
• Planets were molten! (and hotter)
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Terrestrial Planets: Internal Structure
Core: Mantle: Crust:
Metallic, sometimes moltenSilicates & other rocksSilicates
highest densitymoderate densitylowest density
Back to beginning, Excerpt (15:40-18:30)
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Liquid Metal Core + Rotation = Magnetic Field
Planetary Magnetic Fields (B)
Warm planets act as electromagnets!
Current (moving charges) creates magnetic fields
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Liquid Metal Core + Rotation = Magnetic Field
Planetary Magnetic Fields (B)
Larger Liquid Metal Core ➝ Stronger Field
Faster Rotation ➝ Stronger Field
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Magnetic field protects us from the Solar Wind!!
Preserves our Atmosphere!
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Charged particles follow magnetic field lines.
Magnetic Fields on Earth - Create Aurorae!!
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Warm Planets...COOL OFF!Heat Escapes by
Convection in mantle
Conduction through lithosphere
Radiation from surface into space
Internal Heat Escaping Causes Geologic Activity!
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•Carries heat from interior of mantle (plastic) to base of lithosphere (solid)
Mantle Convection
•Solid Lithosphere Blocks Heat...
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...until the Lithosphere cracks!
Mantle Convection
Internal Heat Escaping Causes Geologic Activity: Plate Tectonics
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•Surface cracked into ~12 plates•Plates “float” on mantle •Motion causes geological features
Mantle Convection & Plate Tectonics
Tectonics (“building”): Creation of structures within lithosphere
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Plate Tectonics: Mountain Building
Ex: Himalayas (Indian➔Eurasian, 1cm/yr)
Convergent Plate Boundary - Plates Collide
Subduction:One plate pulled under another
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Ex: East African Rift Zone
Plate Tectonics: Rifts & ValleysDivergent Plate Boundary - Plates Move Apart
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Seafloor Spreading: Plates pull apart, lava seeps up and forms new crust
Plate Tectonics: Ocean Ridges/Seafloor Spreading
Ex: Mid Atlantic Ridge
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San Andreas Fault (Pacific & North American Plates)
Plates slip sideways few m/second!
Plate Tectonics: Earthquakes & Faults
2/27/10: Chilean Earthquake (Nazca/South American Subduction Zone)
1/12/10: Hatian Earthquake (Carribbean/North American Plates)
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Eruption of molten lava onto surface
Hotspot: Place where magma finds a path through the lithosphere
Volcanism (More Geologic Activity!)
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Plate motion over hotspots creates Island ChainsVolcanism on Earth
Kauai
Big Island
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Shaping Planetary Surfaces - 4 Main Processes
•(Plate) Tectonics•Volcanism
What else?
•Impact Cratering•Erosion
⧽Caused by HEAT!