Download Planetary Surfaces: Processes That Shape Them - Astro 120 Fall 2005 Lecture 12 and more Study notes Astronomy in PDF only on Docsity!
Astro 120 Fall 2005: Lecture 12 page 1
Reading:
Chapter 10; Chapter 9, Section 9.
Recitations: Quiz #2 next timeA Brief Review of Last Time^ • Overview of our
planetary system
•Planetary Interiors
- bulk density• shape• magnetic field
Astro 120 Fall 2005: Lecture 12 page 2
Today
Planetary Surfaces – Physical Processes
What processes act to form and shape
the surfaces of these planets? •Looking at the rocky terrestrial worlds
- Mercury, Venus, Earth, Mars, Moon
Reading:
Chapter 10; Chapter 9, Section 9.
Recitations: Quiz #2 next time
Astro 120 Fall 2005: Lecture 12 page 3
Impact Cratering
Tectonics
Volcanism
Erosion
Processes That Alter Planetary Surfaces
Astro 120 Fall 2005: Lecture 12 page 4
Process 1 - Impact Cratering
- Solar system hasalways containedsmaller bits of rock &ice • These impact largerobjects (planets)• More frequent inthe past – smallermaterial gets sweptup by larger objects
Earth having a rough day ~ 65 Myr ago
Astro 120 Fall 2005: Lecture 12 page 5
Planet Surface(say part of thefuture SW USA)
10-70 km/s
Impactor
(say a largechunk of Iron)
Astro 120 Fall 2005: Lecture 12 page 6
Daniel Barringer – purchased
land around 1903 to look for Fe ore
Age: 49,000 yrsDiameter: 1.2 km(0.7 mi)Depth: 174 m(570 ft)
Barringer Meteor Crater, Arizona
Astro 120 Fall 2005: Lecture 12 page 7
Crater visited by Apollo 14 astronauts – November 1970
1280 ft
320 ft
Astro 120 Fall 2005: Lecture 12 page 8
Astro 120 Fall 2005: Lecture 12 page 13
Heat ~ V ~ R
3
Heat LossRate ~ A ~ R
2
Time to cool ~ Heat/Heat Loss ~ R
Loss of internal heat
Astro 120 Fall 2005: Lecture 12 page 14
Very low viscosity
Low viscosity
High viscosity
Chemical Composition (Si compounds)Viscosity of Magma/LavaDetermines type of structure
Astro 120 Fall 2005: Lecture 12 page 15
Volcanism & the Atmosphere
Both a source& and an ongoinginfluence.
Astro 120 Fall 2005: Lecture 12 page 16 Sapas Mons^ 400 km diameter
Olympus Mons
Loki Patera 250 km
Astro 120 Fall 2005: Lecture 12 page 17
Process 3 - Tectonics
- Large scale changesas a planet’s crustresponds to stress.• Earthquakes –sliding and crackingof crust• Mountain building –buckling and foldingof crust
Himalayas from the ISS
Astro 120 Fall 2005: Lecture 12 page 18
Stresses on Crust
Structure
Astro 120 Fall 2005: Lecture 12 page 19
The Earth’s Fractured Crust
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- partially molten asthenosphere (upper
mantle)
- crustal plates “float” atop asthenosphere• subduction zones: where plates overlap• faults: where plates slide past
Plate Tectonics
Astro 120 Fall 2005: Lecture 12 page 25
Old Volcanic Landform + Glacier =
Astro 120 Fall 2005: Lecture 12 page 26
Erosion – Forming landforms
- water and wind cantransport materialand form newlandforms• e.g. sand dunes,river deltas
Astro 120 Fall 2005: Lecture 12 page 27
Ancient
More Recent(?)
Erosion on Mars
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Size
Heat
Drives Volcanism & Tectonics
Size
Gravity
Retain Atmosphere
Erosion
Astro 120 Fall 2005: Lecture 12 page 29
Distance
Surface T
Water Phase
Erosion
Distance
Atmospheric T
Atmosphere Loss
Astro 120 Fall 2005: Lecture 12 page 30
Rotation
Wind/Weather
Erosion
