1
, Solutions Manual for Earth Portrait of a Planet, 5th edition
by Stephen Marshak (All Chapters) A+
CHAPTER k1
Cosmology kand kthe kBirth kof kEarth
Learning kObjectives
1. Students kshould kbe kaware kof kthe kBig kBang ktheory kand kthe kmajor kevidence
ksupporting kit.
Distant kgalaxies kare kuniformly kred-shifted krather kthan kblue- kshifted; kthis kimplies kthat kthey
kare kall kmoving kaway kfrom kus. kThe kfarthest kgalaxies kare kthose kthat kare kmost kstrongly
kred-shifted, kmeaningkthat kthey kare kreceding kthe kfastest. kExtrapolation kof kvelocities kand
ktrajectories kinto kthe kpast ksuggests kthat kall kmatter kin kthe kUniverse kwas kcontained kin ka
ksingle kpoint, kapproximately k13.7 kbillion kyears kago. kAt kthat ktime, kthe kUniverse
kexplosively kcame kinto kexistence.
2. Stars, kincluding kour kSun, kare knuclear kfusion kreactors. kFor kmost kof ktheir klife
khistories k(on kthe korder kof kbillions kof k years), khydrogen katoms kare kfused ktogether kto kform
khelium. kLater kstages kinkstellar kevolution kinclude kfusion kof khelium katoms kand kother,
kheavier kelements; kultimately, kiron kis kthe kheaviest kelement kthat kcan kbe kproduced kthrough
kfusion kreactions kwithin kstars.
3. After ktheir kcycles kof kfusion kare kcomplete, klarge kstars kviolently kexplode
k(forming ksupernovae), kproducing kelements kheavier kthan kiron kand kleaving kbehind ka
kresidue kof kdiffuseknebulae, kwhich kmay kbe krecycled kto kform ka knew kstar kat ksome
kpoint kin kthe kfuture.
2
,4. Our kSolar kSystem kis kapproximately k4.57 kGa k(billion kyears kold). kAll keight kplanets
krevolvekaround kthe kSun kin kcoplanar, kelliptical korbits. kAll kplanets korbit kin kthe
3
, same kdirection k(counterclockwise kas kviewed kfrom kabove kEarth’s kNorth kPole). kThese kfacts
kimply ksimultaneous kplanetary kformation kfrom ka kswirling knebula ksurrounding kthe kSun k(the
ksimilarities kinkorbits kwould kthen kbe ka knatural kresult kof kconservation kof kangular
kmomentum). kThe kplanets kaccreted kfrom kthis knebula kthrough kgravitational kattraction kand
khaphazard kcollisions. kPluto, klong kconsidered kthe k“ninth kplanet,” khas kseen kits kstatus
kdemoted; kastronomers know
recognize keight kmajor kplanets.
5. The kterrestrial kplanets k(Mercury, kVenus, kEarth, kand kMars) kare krelatively ksmall,
kdense, kandkrocky kworlds. kThe kgiant kplanets kare kpredominantly kcomposed kof kthe klight
kgases khydrogen kand khelium k(Jupiter kand kSaturn) kor kices k(Uranus kand kNeptune); kthey kare
kmuch klarger kand kmuch kless kdense kthan kthe kterrestrial kplanets.
6. Our kMoon kis kchemically ksimilar kto kthe kEarth’s kmantle. kThe kMoon kis kthought kto
khave koriginated kfrom kdebris kaccumulated kwhen ka kprotoplanet kcollided kwith kEarth
kapproximately k4.3kGa.
Summary kfrom kthe kText
The kgeocentric kmodel kplaced kEarth kat kthe kcenter kof kthe kUniverse, kwith kthe kplanets kand
kSun korbiting karound kthe kEarth kwithin ka kcelestial ksphere kspeckled kwith kstars. kThe
kheliocentric kmodel,kwhich kgained kacceptance kduring kthe kRenaissance, kplaced kthe kSun kat
kthe kcenter.
Eratosthenes kwas kable kto kmeasure kthe ksize kof kEarth kin kancient ktimes, kbut kit kwas knot
kuntil kfairlykrecently kthat kastronomers kaccurately kdetermined kthe kdistances kto kthe kSun,
4
, Solutions Manual for Earth Portrait of a Planet, 5th edition
by Stephen Marshak (All Chapters) A+
CHAPTER k1
Cosmology kand kthe kBirth kof kEarth
Learning kObjectives
1. Students kshould kbe kaware kof kthe kBig kBang ktheory kand kthe kmajor kevidence
ksupporting kit.
Distant kgalaxies kare kuniformly kred-shifted krather kthan kblue- kshifted; kthis kimplies kthat kthey
kare kall kmoving kaway kfrom kus. kThe kfarthest kgalaxies kare kthose kthat kare kmost kstrongly
kred-shifted, kmeaningkthat kthey kare kreceding kthe kfastest. kExtrapolation kof kvelocities kand
ktrajectories kinto kthe kpast ksuggests kthat kall kmatter kin kthe kUniverse kwas kcontained kin ka
ksingle kpoint, kapproximately k13.7 kbillion kyears kago. kAt kthat ktime, kthe kUniverse
kexplosively kcame kinto kexistence.
2. Stars, kincluding kour kSun, kare knuclear kfusion kreactors. kFor kmost kof ktheir klife
khistories k(on kthe korder kof kbillions kof k years), khydrogen katoms kare kfused ktogether kto kform
khelium. kLater kstages kinkstellar kevolution kinclude kfusion kof khelium katoms kand kother,
kheavier kelements; kultimately, kiron kis kthe kheaviest kelement kthat kcan kbe kproduced kthrough
kfusion kreactions kwithin kstars.
3. After ktheir kcycles kof kfusion kare kcomplete, klarge kstars kviolently kexplode
k(forming ksupernovae), kproducing kelements kheavier kthan kiron kand kleaving kbehind ka
kresidue kof kdiffuseknebulae, kwhich kmay kbe krecycled kto kform ka knew kstar kat ksome
kpoint kin kthe kfuture.
2
,4. Our kSolar kSystem kis kapproximately k4.57 kGa k(billion kyears kold). kAll keight kplanets
krevolvekaround kthe kSun kin kcoplanar, kelliptical korbits. kAll kplanets korbit kin kthe
3
, same kdirection k(counterclockwise kas kviewed kfrom kabove kEarth’s kNorth kPole). kThese kfacts
kimply ksimultaneous kplanetary kformation kfrom ka kswirling knebula ksurrounding kthe kSun k(the
ksimilarities kinkorbits kwould kthen kbe ka knatural kresult kof kconservation kof kangular
kmomentum). kThe kplanets kaccreted kfrom kthis knebula kthrough kgravitational kattraction kand
khaphazard kcollisions. kPluto, klong kconsidered kthe k“ninth kplanet,” khas kseen kits kstatus
kdemoted; kastronomers know
recognize keight kmajor kplanets.
5. The kterrestrial kplanets k(Mercury, kVenus, kEarth, kand kMars) kare krelatively ksmall,
kdense, kandkrocky kworlds. kThe kgiant kplanets kare kpredominantly kcomposed kof kthe klight
kgases khydrogen kand khelium k(Jupiter kand kSaturn) kor kices k(Uranus kand kNeptune); kthey kare
kmuch klarger kand kmuch kless kdense kthan kthe kterrestrial kplanets.
6. Our kMoon kis kchemically ksimilar kto kthe kEarth’s kmantle. kThe kMoon kis kthought kto
khave koriginated kfrom kdebris kaccumulated kwhen ka kprotoplanet kcollided kwith kEarth
kapproximately k4.3kGa.
Summary kfrom kthe kText
The kgeocentric kmodel kplaced kEarth kat kthe kcenter kof kthe kUniverse, kwith kthe kplanets kand
kSun korbiting karound kthe kEarth kwithin ka kcelestial ksphere kspeckled kwith kstars. kThe
kheliocentric kmodel,kwhich kgained kacceptance kduring kthe kRenaissance, kplaced kthe kSun kat
kthe kcenter.
Eratosthenes kwas kable kto kmeasure kthe ksize kof kEarth kin kancient ktimes, kbut kit kwas knot
kuntil kfairlykrecently kthat kastronomers kaccurately kdetermined kthe kdistances kto kthe kSun,
4
