terrestrial planets: earth
TRANSCRIPT
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
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
Differentiation•Denser materials in a liquid sink to the center
Gravity!why?
Implications?
• Planets were molten! (and hotter)
Terrestrial Planets: Internal Structure
Core: Mantle: Crust:
Metallic, sometimes moltenSilicates & other rocksSilicates
highest densitymoderate densitylowest density
Back to beginning, Excerpt (15:40-18:30)
Liquid Metal Core + Rotation = Magnetic Field
Planetary Magnetic Fields (B)
Warm planets act as electromagnets!
Current (moving charges) creates magnetic fields
Liquid Metal Core + Rotation = Magnetic Field
Planetary Magnetic Fields (B)
Larger Liquid Metal Core ➝ Stronger Field
Faster Rotation ➝ Stronger Field
Magnetic field protects us from the Solar Wind!!
Preserves our Atmosphere!
Charged particles follow magnetic field lines.
Magnetic Fields on Earth - Create Aurorae!!
Warm Planets...COOL OFF!Heat Escapes by
Convection in mantle
Conduction through lithosphere
Radiation from surface into space
Internal Heat Escaping Causes Geologic Activity!
•Carries heat from interior of mantle (plastic) to base of lithosphere (solid)
Mantle Convection
•Solid Lithosphere Blocks Heat...
...until the Lithosphere cracks!
Mantle Convection
Internal Heat Escaping Causes Geologic Activity: Plate Tectonics
•Surface cracked into ~12 plates•Plates “float” on mantle •Motion causes geological features
Mantle Convection & Plate Tectonics
Tectonics (“building”): Creation of structures within lithosphere
Plate Tectonics: Mountain Building
Ex: Himalayas (Indian➔Eurasian, 1cm/yr)
Convergent Plate Boundary - Plates Collide
Subduction:One plate pulled under another
Ex: East African Rift Zone
Plate Tectonics: Rifts & ValleysDivergent Plate Boundary - Plates Move Apart
Seafloor Spreading: Plates pull apart, lava seeps up and forms new crust
Plate Tectonics: Ocean Ridges/Seafloor Spreading
Ex: Mid Atlantic Ridge
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)
Eruption of molten lava onto surface
Hotspot: Place where magma finds a path through the lithosphere
Volcanism (More Geologic Activity!)
Plate motion over hotspots creates Island ChainsVolcanism on Earth
Kauai
Big Island
Shaping Planetary Surfaces - 4 Main Processes
•(Plate) Tectonics•Volcanism
What else?
•Impact Cratering•Erosion
⧽Caused by HEAT!