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Exploring the Solar System: Planetary Interiors & Surfaces (Astro 120, Fall 2003), Assignments of Astronomy

An overview of the solar system, focusing on planetary interiors and surfaces. Topics include the inner and outer planets, asteroids, comets, probes, density, rotation, magnetic fields, seismic activity, accretion heating, differentiation, impact cratering, and volcanism. Students are encouraged to review chapter 9 and 10, complete homework 2, and prepare for exam 1.

Typology: Assignments

Pre 2010

Uploaded on 09/02/2009

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Astro 120 Fall 2003: Lecture 12 page 1

Overview of our Solar System• •

Inner (Terrestrial) planets: M V E M Asteroids• Outer (Jovian) planets: J S U N• Outer bodies (Pluto/Charon, comets)•

•^

Probes of planetary interiorsDensity: mass via Kepler (with moons)•^ rotation: shapes of bodies, plasticity•^ Magnetic fields: metallic cores (iron, hydrogen)•^ Seismic probes (Earth/Moon quakes)•^

Brief review of last time:

Solar System Probes

Reading: Chapter 9, Section 9.

Chapter 10, Section 10.1, 10.3, 10.4, 10. Homework 2: Posted soon, due 10/17 and 10/20Exam 1: Grades posted on WebCT

Astro 120 Fall 2003: Lecture 12 page 2

•^

Dense molten iron

core

(density, magnetic field)

•^

Rocky but elastic

mantle

(oblateness)

•^

thin, light surface

crust

(density)

The Earth’s Interior

With some simple physics,

compute what the inside of theEarth might be like

Astro 120 Fall 2003: Lecture 12 page 3

•^

earthquakes send vibrations through the Earth

•^

speed of various kinds of waves depends ondensity•^ temperature•^ phase (liquid or solid)•^ can map out structure of Earth (or planet) interior

Testing the Model Directly: Seismology

Astro 120 Fall 2003: Lecture 12 page 4

•^

Why are planetary interiors so hot? accretion heating – •^

residual heat from formation

radioactive decay of elements in rocks• tidal heating (moons, Mercury)• Why are planetary interiors stratified? • •

initially fully mixed (at formation)

•^

accretional heating

•^

differentiation: heavy stuff sinks, light stuff floatscrustal material is less dense (in terrestrials)•^ iron is densest (in terrestrials)•^

Planetary Interiors

Astro 120 Fall 2003: Lecture 12 page 5

Astro 120 Fall 2003: Lecture 12 page 6

•^

Impact Cratering

•^

Volcanism and melting

•^

Weathering and chemical change

•^

Planetary Surfaces Plate tectonics

M,V,E,M, Moon(s), asteroids

Processes that Alter Planetary Surfaces

Astro 120 Fall 2003: Lecture 12 page 7

Solar system has always contained “small” bodies• these impact larger (planetary) bodies• produces crater 5 – 10 times larger than impactor• impact sprays ejecta over a much larger area • accumulated ejecta = regolith•

dust to pebble sized rubble over entire surface

Impact Cratering

(Mercury,Venus, Moons, Mars,

Asteroids)

rubble

ejecta

ejecta

rim

Astro 120 Fall 2003: Lecture 12 page 8

Mercury

Text

Moon

Moon

Earth

Mars

Eros

Ganymede(Ice geology)