Terrestrials Chap 17 new-v12

Terrestrials Chap 17 new-v12 - Planet Formation ( upper...

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Unformatted text preview: Planet Formation ( upper half of diagram ) Planet Evolution for Terrestrials (lower half of diagram) Gas/Dust Cloud Planetesimals (1mm 100km Protoplanets ( > 100km) Terrestrial planets Jovian planets Crust Mantel Core Crust Craters Lava or Water Tectonic plates c o n d e n s a t i o n & a c c r e t i o n a c c r e t i o n ( h e t e r o . o r h o m o . ) a c c r e t i o n H & He grav. capture d i f f e r e n t i a t i o n ( h e a t f o r m . , r a d . d e c a y ) r a p i d c r a t e r i n g ( t i l l s o l a r n e b u l a g o n e ) f l o o d i n g b y l a v a , w a t e r s l o w s u r f . e v o l u t i o n ( p l a t e t e c t o n i c s , e r o s i o n ) Core, Mantle, Crust, Atmosphere All terrestrial planets have a similar structure . Inner solid metallic (usually Fe, Ni) core surrounded by a liquid metallic core A mantle of molten lava (a plastic solid like asphalt) A crust of solid, low- density rocks, e.g., SiO 2 An atmosphere (large range of compositions and pressures) FOUR STAGES OF TERRESTRIAL PLANET EVOLUTION differentiation cratering flooding surface evolution What are the 3 principal sections of a differentiated planet? Core, Mantle, Crust For Earth, what type of materials are in these 3 sections? Heavy metals, heavy metal oxides, silicates, respectively. Are these materials solid, liquid, plastic or gaseous? What is the difference between cratering and accretion? Head-on collisions vs sticking together. What event marks the end of the era of rapid cratering? Clearing of the solar nebula by light pressure & solar wind about 4 billion years ago. What types of flooding occurs on Earth? Both water and lava. How does flooding modify the effects of cratering? Fills in the craters and smooths the crust. What are the sources of slow surface evolution on Earth? Water and wind; water is most important. This may differ on other terrestrial planets. SEISMIC WAVE ANALYSIS OF THE EARTHS INTERNAL STRUCTURE An earthquake on one side of the Earth causes two types of seismic waves, which can travel through the Earth to other parts of the crust, and be detected by seismographs. The two wave types are pressure (P) waves, and shear (S) waves. Which waves pass through solid material? Both types . Which waves pass through liquid material? Only the P-waves, not the S-waves. Detecting where P or S waves are present or absent allows charting of liquid core. What other evidence do we have that part of the Earths core is liquid metallic? Presence of Earths magnetic field. What is the dynamo effect? Convection/rotation of liquid metallic core causes electrical currents that produce a planets magnetic field. Earths Atmosphere Secondary atmosphere Rich in O 2 (~19%), N 2 (~78%), CO 2 (~2%) 1) Removal of CO 2 : Earth cooled oceans dissolved CO 2 limestone (CO 2 removed faster than replenished by outgassing from volcanism.) 2) Addition of O 2 : oceans green algae photosynthesis free oxygen (This happened about 3.3 billion years ago.)(This happened about 3....
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This note was uploaded on 04/25/2008 for the course PHY 122 taught by Professor Bernstein during the Spring '08 term at SUNY Buffalo.

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Terrestrials Chap 17 new-v12 - Planet Formation ( upper...

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