Solutions Manual for Earth Portrait of a Planet, 5th edition, by Stephen Marshak All Chapters Covered

Solutions Manual
Earth Portrait of a Planet, 5th edition,
by Stephen Marshak All Chapters Covered

, CHAPTER 1 H




Cosmology and the Birth of Earth
H H H H H




LearningHObjectives


1. StudentsHshouldHbeHawareHofHtheHBigHBangHtheoryHandHtheHmajorHevidenceHsupp
ortingHit.HDistantHgalaxiesHareHuniformlyHred-shiftedHratherHthanHblue-
H shifted;HthisHimpliesHthatHtheyHareHallHmovingHawayHfromHus.HTheHfarthestHgalaxie
sHareHthoseHthatHareHmostHstronglyHred-
shifted,HmeaningHthatHtheyHareHrecedingHtheHfastest.HExtrapolationHofHvelocitiesHa
ndHtrajectoriesHintoHtheHpastHsuggestsHthatHallHmatterHinHtheHUniverseHwasHcontai
nedHinHaHsingleHpoint,HapproximatelyH13.7HbillionHyearsHago.HAtHthatHtime,HtheHUni
verseHexplosivelyHcameHintoHexistence.
2. Stars,HincludingHourHSun,HareHnuclearHfusionHreactors.HForHmostHofHtheirHlifeHhistorie
sH(onHtheHorderHofHbillionsHofHyears),HhydrogenHatomsHareHfusedHtogetherHtoHformHhe
lium.HLaterHstagesHinHstellarHevolutionHincludeHfusionHofHheliumHatomsHandHother,Hh
eavierHelements;Hultimately,HironHisHtheHheaviestHelementHthatHcanHbeHproducedHthr
oughHfusionHreactionsHwithinHstars.
3. AfterHtheirHcyclesHofHfusionHareHcomplete,HlargeHstarsHviolentlyHexplodeH(formingHsu
pernovae),HproducingHelementsHheavierHthanHironHandHleavingHbehindHaHresidueHofH
diffuseHnebulae,HwhichHmayHbeHrecycledHtoHformHaHnewHstarHatHsomeHpointHinHtheHf
uture.
4. OurHSolarHSystemHisHapproximatelyH4.57HGaH(billionHyearsHold).HAllHeightHplanetsHre
volveHaroundHtheHSunHinHcoplanar,HellipticalHorbits.HAllHplanetsHorbitHinHthe

, sameHdirectionH(counterclockwiseHasHviewedHfromHaboveHEarth’sHNorthHPole).HThes
eHfactsHimplyHsimultaneousHplanetaryHformationHfromHaHswirlingHnebulaHsurroundin
gHtheHSunH(theHsimilaritiesHinHorbitsHwouldHthenHbeHaHnaturalHresultHofHconservationH
ofHangularHmomentum).HTheHplanetsHaccretedHfromHthisHnebulaHthroughHgravitation
alHattractionHandHhaphazardHcollisions.HPluto,Hlong
consideredHtheH“ninthHplanet,”HhasHseenHitsHstatusHdemoted;HastronomersHnow
recognizeHeightHmajorHplanets.
5. TheHterrestrialHplanetsH(Mercury,HVenus,HEarth,HandHMars)HareHrelativelyHsmall,Hden
se,HandHrockyHworlds.HTheHgiantHplanetsHareHpredominantlyHcomposedHofHtheHlightHg
asesHhydrogenHandHheliumH(JupiterHandHSaturn)HorHicesH(UranusHandHNeptune);Hthe
yHareHmuchHlargerHandHmuchHlessHdenseHthanHtheHterrestrialHplanets.
6. OurHMoonHisHchemicallyHsimilarHtoHtheHEarth’sHmantle.HTheHMoonHisHthoughtHtoHh
aveHoriginatedHfromHdebrisHaccumulatedHwhenHaHprotoplanetHcollidedHwithHEarth
H approximatelyH4.3HGa.



SummaryHfromHtheHText


TheHgeocentricHmodelHplacedHEarthHatHtheHcenterHofHtheHUniverse,HwithHtheHplanetsHa
ndHSunHorbitingHaroundHtheHEarthHwithinHaHcelestialHsphereHspeckledHwithHstars.HTheHhelio
centricHmodel,HwhichHgainedHacceptanceHduringHtheHRenaissance,HplacedHtheHSunHatHtheHc
enter.
EratosthenesHwasHableHtoHmeasureHtheHsizeHofHEarthHinHancientHtimes,HbutHitHwasHnotH
untilHfairlyHrecentlyHthatHastronomersHaccuratelyHdeterminedHtheHdistancesHtoHtheHSun,Hpla
nets,HandHstars.HDistancesHinHtheHUniverseHareHsoHlargeHthatHtheyHmustHbeHmeasuredHinHlig
ht-years.
TheHEarthHisHoneHofHeightHplanetsHorbitingHtheHSun,HandHthisHSolarHSystemHliesHonHtheH
outerHedgeHofHaHslowlyHrevolvingHgalaxy,HtheHMilkyHWay,HwhichHisHcomposedHofHaboutH300H
billionHstars.HTheHUniverseHcontainsHatHleastHhundredsHofHbillionsHofHgalaxies.
TheHredHshiftHofHlightHfromHdistantHgalaxies,HaHmanifestationHofHtheHDopplerHeffect,Hindi
catesHthatHallHdistantHgalaxiesHareHmovingHawayHfromHEarth.HThisHobservationHleads

, toHtheHexpandingHUniverseHtheory.HMostHastronomersHagreeHthatHthisHexpansionHbeganHafterHt
heHBigHBang,HaHcataclysmicHexplosionHaboutH13.7HbillionHyearsHago.
TheHfirstHatomsH(hydrogenHandHhelium)HofHtheHUniverseHdevelopedHwithinHminutesHofHt
heHBigHBang.HTheseHatomsHformedHvastHgasHclouds,HcalledHnebulae.
GravityHcausedHclumpsHofHgasHinHtheHnebulaeHtoHcoalesceHintoHrevolvingHballs.HAsHtheseH
ballsHofHgasHcollapsedHinward,HtheyHevolvedHintoHflattenedHdisksHwithHbulbousHcenters.HTheH
protostarsHatHtheHcenterHofHtheseHdisksHeventuallyHbecameHdenseHandHsufficientlyHhotHthatHf
usionHreactionsHbeganHwithinHthem.HWhenHthisHhappened,HtheyHbecameHtrueHstars,HemittingH
heatHandHlight.
HeavierHelementsHformHduringHfusionHreactionsHinHstars;HtheHheaviestHareHmostlyHmad
eHduringHsupernovaHexplosions.HEarthHandHtheHlifeHformsHonHitHcontainHelementsHthatHcould
H haveHonlyHbeenHproducedHduringHtheHlifeHcycleHofHstars.HThus,HweHareHallHmadeHofHstardus
t.
AccordingHtoHtheHnebularHtheoryHofHplanetHformation,HplanetsHdevelopedHfromHtheHrin
gsHofHgasHandHdustHsurroundingHprotostars.HTheHgasHandHdustHcondensedHintoHplanetesim
als,HwhichHthenHclumpedHtogetherHtoHformHprotoplanetsHandHfinallyHtrueHplanets.HInnerHrin
gsHbecameHtheHterrestrialHplanets;HouterHringsHgrewHintoHgiantHplanets.
TheHMoonHformedHfromHdebrisHejectedHwhenHaHprotoplanetHcollidedHwithHEarthHinHtheH
youngHSolarHSystem.
AHplanetHassumesHaHnear-
sphericalHshapeHwhenHitHbecomesHsoHsoftHthatHgravityHcanHsmoothHoutHirregularities.



AnswersHtoHReviewHQuestions


1. WhyHdoHtheHplanetsHappearHtoHmoveHwithHrespectHtoHtheHstars?
ANS:HStarsHareHsoHrelativelyHdistantHthatHtheyHappearHfixedHwithHrespectHtoHoneHanoth
erHasHviewedHfromHEarth.HAsHEarthHandHtheHotherHplanetsHtraverseHthroughHtheirHorbitsHarou
ndHtheHSun,HtheHpositionsHofHtheHplanetsHvaryHwithHrespectHtoHtheH“fixed”HcelestialHsphere.