Solutions Manual
Earth: Portrait Of A Planet
By Stephen Marshak
7th Edition
, Solutions Manual For Earth Portrait Of A
Planet, 7e, By Stephen Marshak
CHAPTER 1
Cosmology And The Birth Of Earth
Learning Objectives
1. Students Should Be Aware Of The Big Bang Theory And The Major Evidence
Supporting It. Distant Galaxies Are Uniformly Red-Shifted Rather Than
Blue- Shifted; This Implies That They Are All Moving Away From Us. The
Farthest Galaxies Are Those That Are Most Strongly Red-Shifted, Meaning
That They Are Receding The Fastest. Extrapolation Of Velocities And
Trajectories Into The Past Suggests That All Matter In The Universe Was
Contained In A Single Point, Approximately 13.7 Billion Years Ago. At That
Time, The Universe Explosively Came Into Existence.
2. Stars, Including Our Sun, Are Nuclear Fusion Reactors. For Most Of Their Life
Histories (On The Order Of Billions Of Years), Hydrogen Atoms Are Fused
Together To Form Helium. Later Stages In Stellar Evolution Include Fusion Of
Helium Atoms And Other, Heavier Elements; Ultimately, Iron Is The Heaviest
Element That Can Be Produced Through Fusion Reactions Within Stars.
3. After Their Cycles Of Fusion Are Complete, Large Stars Violently Explode
(Forming Supernovae), Producing Elements Heavier Than Iron And Leaving
Behind A Residue Of Diffuse Nebulae, Which May Be Recycled To Form A New
Star At Some Point In The Future.
4. Our Solar System Is Approximately 4.57 Ga (Billion Years Old). All Eight
Planets Revolve Around The Sun In Coplanar, Elliptical Orbits. All Planets
Orbit In The
, Same Direction (Counterclockwise As Viewed From Above Earth’s North Pole).
These Facts Imply Simultaneous Planetary Formation From A Swirling Nebula
Surrounding The Sun (The Similarities In Orbits Would Then Be A Natural
Result Of Conservation Of Angular Momentum). The Planets Accreted From
This Nebula Through Gravitational Attraction And Haphazard Collisions. Pluto,
Long
Considered The “Ninth Planet,” Has Seen Its Status Demoted; Astronomers Now
Recognize Eight Major Planets.
5. The Terrestrial Planets (Mercury, Venus, Earth, And Mars) Are Relatively
Small, Dense, And Rocky Worlds. The Giant Planets Are Predominantly
Composed Of The Light Gases Hydrogen And Helium (Jupiter And Saturn) Or
Ices (Uranus And Neptune); They Are Much Larger And Much Less Dense Than
The Terrestrial Planets.
6. Our Moon Is Chemically Similar To The Earth’s Mantle. The Moon Is Thought
To Have Originated From Debris Accumulated When A Protoplanet Collided
With Earth Approximately 4.3 Ga.
Summary From The Text
The Geocentric Model Placed Earth At The Center Of The Universe, With The
Planets And Sun Orbiting Around The Earth Within A Celestial Sphere Speckled With
Stars. The Heliocentric Model, Which Gained Acceptance During The Renaissance,
Placed The Sun At The Center.
Eratosthenes Was Able To Measure The Size Of Earth In Ancient Times, But It
Was Not Until Fairly Recently That Astronomers Accurately Determined The
Distances To The Sun, Planets, And Stars. Distances In The Universe Are So Large
That They Must Be Measured In Light-Years.
The Earth Is One Of Eight Planets Orbiting The Sun, And This Solar System Lies
On The Outer Edge Of A Slowly Revolving Galaxy, The Milky Way, Which Is Composed
Of About 300 Billion Stars. The Universe Contains At Least Hundreds Of Billions Of
Galaxies.
The Red Shift Of Light From Distant Galaxies, A Manifestation Of The Doppler
Effect, Indicates That All Distant Galaxies Are Moving Away From Earth. This
Observation Leads
, To The Expanding Universe Theory. Most Astronomers Agree That This Expansion
Began After The Big Bang, A Cataclysmic Explosion About 13.7 Billion Years Ago.
The First Atoms (Hydrogen And Helium) Of The Universe Developed Within
Minutes Of The Big Bang. These Atoms Formed Vast Gas Clouds, Called Nebulae.
Gravity Caused Clumps Of Gas In The Nebulae To Coalesce Into Revolving Balls. As
These Balls Of Gas Collapsed Inward, They Evolved Into Flattened Disks With Bulbous
Centers. The Protostars At The Center Of These Disks Eventually Became Dense And
Sufficiently Hot That Fusion Reactions Began Within Them. When This Happened, They
Became True Stars, Emitting Heat And Light.
Heavier Elements Form During Fusion Reactions In Stars; The Heaviest Are
Mostly Made During Supernova Explosions. Earth And The Life Forms On It Contain
Elements That Could Have Only Been Produced During The Life Cycle Of Stars. Thus,
We Are All Made Of Stardust.
According To The Nebular Theory Of Planet Formation, Planets Developed From
The Rings Of Gas And Dust Surrounding Protostars. The Gas And Dust Condensed
Into Planetesimals, Which Then Clumped Together To Form Protoplanets And
Finally True Planets. Inner Rings Became The Terrestrial Planets; Outer Rings Grew
Into Giant Planets.
The Moon Formed From Debris Ejected When A Protoplanet Collided With Earth
In The Young Solar System.
A Planet Assumes A Near-Spherical Shape When It Becomes So Soft That Gravity
Can Smooth Out Irregularities.
Answers To Review Questions
1. Why Do The Planets Appear To Move With Respect To The Stars?
ANS: Stars Are So Relatively Distant That They Appear Fixed With Respect To
One Another As Viewed From Earth. As Earth And The Other Planets Traverse
Through Their Orbits Around The Sun, The Positions Of The Planets Vary With
Respect To The “Fixed” Celestial Sphere.
Earth: Portrait Of A Planet
By Stephen Marshak
7th Edition
, Solutions Manual For Earth Portrait Of A
Planet, 7e, By Stephen Marshak
CHAPTER 1
Cosmology And The Birth Of Earth
Learning Objectives
1. Students Should Be Aware Of The Big Bang Theory And The Major Evidence
Supporting It. Distant Galaxies Are Uniformly Red-Shifted Rather Than
Blue- Shifted; This Implies That They Are All Moving Away From Us. The
Farthest Galaxies Are Those That Are Most Strongly Red-Shifted, Meaning
That They Are Receding The Fastest. Extrapolation Of Velocities And
Trajectories Into The Past Suggests That All Matter In The Universe Was
Contained In A Single Point, Approximately 13.7 Billion Years Ago. At That
Time, The Universe Explosively Came Into Existence.
2. Stars, Including Our Sun, Are Nuclear Fusion Reactors. For Most Of Their Life
Histories (On The Order Of Billions Of Years), Hydrogen Atoms Are Fused
Together To Form Helium. Later Stages In Stellar Evolution Include Fusion Of
Helium Atoms And Other, Heavier Elements; Ultimately, Iron Is The Heaviest
Element That Can Be Produced Through Fusion Reactions Within Stars.
3. After Their Cycles Of Fusion Are Complete, Large Stars Violently Explode
(Forming Supernovae), Producing Elements Heavier Than Iron And Leaving
Behind A Residue Of Diffuse Nebulae, Which May Be Recycled To Form A New
Star At Some Point In The Future.
4. Our Solar System Is Approximately 4.57 Ga (Billion Years Old). All Eight
Planets Revolve Around The Sun In Coplanar, Elliptical Orbits. All Planets
Orbit In The
, Same Direction (Counterclockwise As Viewed From Above Earth’s North Pole).
These Facts Imply Simultaneous Planetary Formation From A Swirling Nebula
Surrounding The Sun (The Similarities In Orbits Would Then Be A Natural
Result Of Conservation Of Angular Momentum). The Planets Accreted From
This Nebula Through Gravitational Attraction And Haphazard Collisions. Pluto,
Long
Considered The “Ninth Planet,” Has Seen Its Status Demoted; Astronomers Now
Recognize Eight Major Planets.
5. The Terrestrial Planets (Mercury, Venus, Earth, And Mars) Are Relatively
Small, Dense, And Rocky Worlds. The Giant Planets Are Predominantly
Composed Of The Light Gases Hydrogen And Helium (Jupiter And Saturn) Or
Ices (Uranus And Neptune); They Are Much Larger And Much Less Dense Than
The Terrestrial Planets.
6. Our Moon Is Chemically Similar To The Earth’s Mantle. The Moon Is Thought
To Have Originated From Debris Accumulated When A Protoplanet Collided
With Earth Approximately 4.3 Ga.
Summary From The Text
The Geocentric Model Placed Earth At The Center Of The Universe, With The
Planets And Sun Orbiting Around The Earth Within A Celestial Sphere Speckled With
Stars. The Heliocentric Model, Which Gained Acceptance During The Renaissance,
Placed The Sun At The Center.
Eratosthenes Was Able To Measure The Size Of Earth In Ancient Times, But It
Was Not Until Fairly Recently That Astronomers Accurately Determined The
Distances To The Sun, Planets, And Stars. Distances In The Universe Are So Large
That They Must Be Measured In Light-Years.
The Earth Is One Of Eight Planets Orbiting The Sun, And This Solar System Lies
On The Outer Edge Of A Slowly Revolving Galaxy, The Milky Way, Which Is Composed
Of About 300 Billion Stars. The Universe Contains At Least Hundreds Of Billions Of
Galaxies.
The Red Shift Of Light From Distant Galaxies, A Manifestation Of The Doppler
Effect, Indicates That All Distant Galaxies Are Moving Away From Earth. This
Observation Leads
, To The Expanding Universe Theory. Most Astronomers Agree That This Expansion
Began After The Big Bang, A Cataclysmic Explosion About 13.7 Billion Years Ago.
The First Atoms (Hydrogen And Helium) Of The Universe Developed Within
Minutes Of The Big Bang. These Atoms Formed Vast Gas Clouds, Called Nebulae.
Gravity Caused Clumps Of Gas In The Nebulae To Coalesce Into Revolving Balls. As
These Balls Of Gas Collapsed Inward, They Evolved Into Flattened Disks With Bulbous
Centers. The Protostars At The Center Of These Disks Eventually Became Dense And
Sufficiently Hot That Fusion Reactions Began Within Them. When This Happened, They
Became True Stars, Emitting Heat And Light.
Heavier Elements Form During Fusion Reactions In Stars; The Heaviest Are
Mostly Made During Supernova Explosions. Earth And The Life Forms On It Contain
Elements That Could Have Only Been Produced During The Life Cycle Of Stars. Thus,
We Are All Made Of Stardust.
According To The Nebular Theory Of Planet Formation, Planets Developed From
The Rings Of Gas And Dust Surrounding Protostars. The Gas And Dust Condensed
Into Planetesimals, Which Then Clumped Together To Form Protoplanets And
Finally True Planets. Inner Rings Became The Terrestrial Planets; Outer Rings Grew
Into Giant Planets.
The Moon Formed From Debris Ejected When A Protoplanet Collided With Earth
In The Young Solar System.
A Planet Assumes A Near-Spherical Shape When It Becomes So Soft That Gravity
Can Smooth Out Irregularities.
Answers To Review Questions
1. Why Do The Planets Appear To Move With Respect To The Stars?
ANS: Stars Are So Relatively Distant That They Appear Fixed With Respect To
One Another As Viewed From Earth. As Earth And The Other Planets Traverse
Through Their Orbits Around The Sun, The Positions Of The Planets Vary With
Respect To The “Fixed” Celestial Sphere.
