GROUP 1- ___THE-TERRESTRIAL-PLANETS. PPT

It is all about the terrestrial planets

1. THE TERRESTRIAL
PLANETS
ASTRONOMY: Group 1 Topic 2
John David R. Artiza
Nathalie R. Rubion
Alijo Jasper Aragon
Sean Robea

2. WHAT ARE TERRESTRIAL PLANETS?
●They are rocky worlds composed of rock, silicate, water, and/or carbon.
●They have bulk composition and is dominated by rock or iron, and solid or
liquid surface.
●In our solar system, there are for terrestrial planets, which also happen to be
the four closest to the Sun: Mercury, Venus, Earth, and Mars. During the
formation of the solar system, there were likely more terrestrial planetoids,
but they either merged with each other or were destroyed.

3. VENUS EARTH MARSMERCURY
THE TERRESTRIAL
PLANETS

4. MERCURY
“SUNBURN!!”
“NIGHT TIME IS
JUST COLD…”

5. MERCURY
●ThesmallestplanetinoursolarsystemandnearesttotheSun,Mercuryis
onlyslightlylargerthanEarth'sMoon.FromthesurfaceofMercury,theSun
wouldappearmorethanthreetimesaslargeasitdoeswhenviewedfrom
Earth,andthesunlightwouldbeasmuchasseventimesbrighter.
●Mercury'ssurfacetemperaturesarebothextremelyhotandcold.Because
theplanetissoclosetotheSun,daytemperaturescanreachhighsof800°F
(430°C)(Cannotgosunbathingtwiceonlyonce.Gwenchana).Withoutan
atmospheretoretainthatheatatnight,temperaturescandipaslowas-
290°F(-180°C).

6. MERCURY NAME ORIGIN
TheRomansbelievedthatgodsandgoddesses
wereinchargeofeverythingonEarth.Mercury
isnamedafterthemessengerfortheirgods.
TheRomanMercuryhadwingsonhishelmet
andshoes.Hecouldtravelveryquicklyfrom
placetoplace.TheplanetMercurymoves
quicklyaroundthesun.Thatishowitgotits
name.

7. MERCURY’S ORBIT AND ROTATION
Mercuryspinsslowlyonitsaxisandcompletesone
rotationevery59Earthdays.ButwhenMercuryis
movingfastestinitsellipticalorbitaroundtheSun
(anditisclosesttotheSun),eachrotationisnot
accompaniedbysunriseandsunsetlikeitisonmost
otherplanets.ThemorningSunappearstorise
briefly,set,andriseagainfromsomepartsofthe
planet'ssurface.Thesamethinghappensinreverse
atsunsetforotherpartsofthesurface.OneMercury
solarday(onefullday-nightcycle)equals176Earth
days–justovertwoyearsonMercury.

8. MERCURY’S SURFACE
●Mercury'ssurfaceresemblesthatofEarth'sMoon,scarredbymanyimpact
cratersresultingfromcollisionswithmeteoroidsandcomets.Cratersand
featuresonMercuryarenamedafterfamousdeceasedartists,musicians,
orauthors,includingchildren'sauthorDr.SeussanddancepioneerAlvin
Ailey.
●TemperaturesonMercuryareextreme.Duringtheday,temperatureson
thesurfacecanreach800degreesFahrenheit(430degreesCelsius).
Becausetheplanethasnoatmospheretoretainthatheat,nighttime
temperaturesonthesurfacecandroptominus290degreesFahrenheit
(minus180degreesCelsius).

9. MERCURY’S SURFACE

10. MERCURY’S FORMATION
Mercuryformedabout4.5billion
yearsagowhengravitypulledswirling
gasanddusttogethertoformthis
smallplanetnearesttheSun.Likeits
fellowterrestrialplanets,Mercuryhas
acentralcore,arockymantle,anda
solidcrust.

11. MERCURY’S ATMOSPHERE
Insteadofanatmosphere,Mercury
possessesathinexospheremadeup
ofatomsblastedoffthesurfaceby
thesolarwindandstriking
meteoroids.Mercury'sexosphereis
composedmostlyofoxygen,
sodium,hydrogen,helium,and
potassium.

12. MERCURY’S STRUCTURE
Mercuryistheseconddensestplanet,afterEarth.Ithasalargemetalliccore
witharadiusofabout1,289miles(2,074kilometers),about85percentofthe
planet'sradius.Thereisevidencethatitispartlymoltenorliquid.Mercury's
outershell,comparabletoEarth'soutershell(calledthemantleandcrust),is
onlyabout400kilometers(250miles)thick.

14. VENUS
“UHHHH…”
“YES…”

15. VENUS
●It'sacloud-swaddledplanetnamedforalovegoddess,oftencalledEarth’s
twin.Butpullupabitcloser,andVenusturnshellish.Ournearestplanetary
neighbor,thesecondplanetfromtheSun,hasasurfacehotenoughtomelt
lead.Theatmosphereissothickthat,fromthesurface,theSunisjusta
smearoflight.
●InsomewaysitismoreanoppositeofEarththanatwin:Venusspins
backward,hasadaylongerthanitsyear,andlacksanysemblanceof
seasons.Itmightoncehavebeenahabitableoceanworld,likeEarth,but
thatwasatleastabillionyearsago.Arunawaygreenhouseeffectturnedall
surfacewaterintovapor,whichthenleakedslowlyintospace.Thepresent-
daysurfaceofvolcanicrockisblastedbyhightemperaturesandpressures.

16. VENUS NAME ORIGIN
TheancientRomanscouldeasilyseeseven
brightobjectsinthesky:theSun,theMoon,and
thefivebrightestplanets(Mercury,Venus,Mars,
Jupiter,andSaturn).Theynamedtheobjects
aftertheirmostimportantgods.Venus,thethird
brightestobjectaftertheSunandMoon,was
namedaftertheRomangoddessofloveand
beauty.It’stheonlyplanetnamedafterafemale
god.

17. VENUS’S ORBIT AND ROTATION
SpendingadayonVenuswouldbequiteadisorientingexperience–thatis,if
yourshiporsuitcouldprotectyoufromtemperaturesintherangeof900
degreesFahrenheit(475Celsius).Foronething,your“day”wouldbe243
Earthdayslong–longereventhanaVenusyear(onetriparoundtheSun),
whichtakesonly225Earthdays.Foranother,becauseoftheplanet's
extremelyslowrotation,sunrisetosunsetwouldtake117Earthdays.Andby
theway,theSunwouldriseinthewestandsetintheeast,becauseVenus
spinsbackwardcomparedtoEarth.

18. WHY VENUS SPINS CLOCKWISE AND NOT ANTI -
CLOCKWISE?
●OnetheoryofthisunusualrotationisthatVenuswasknockedoffits
uprightpositionearlierinitshistory.
●Thisrotationisalsocalledasretrograderotation(backwardscomparedto
earth).
●AnothertheorybyateamofscientistsoftheFrenchResearchInstitute
AstronomieetSystemesDynamiqueshaveproposedthatVenusoriginally
spinslikemostotherplanets:itsimplyflippeditsaxis180degreesat
somepoint.

19. WHY VENUS SPINS CLOCKWISE AND NOT ANTI -
CLOCKWISE?
●Scientistshavearguedthatthesun’sgravitationalpullontheplanet’s
verydenseatmospherecouldhavecausedstrongatmospherictides.
ThesetidescombinedwithfrictionbetweenVenus’smantleandcore,
couldhavecausedthefliponthefirstplace.
●AnothertheorybyAlexandreCorreiraandJacquesLaskarsuggestthat
Venusmayhavenotflippedatallbutratherreversedspin.
Inconclusion,scientistsarestillinconclusiveaboutwhatreallycausedthis
unusualspinofVenus.(Gwenchanatengnengnengneng)

21. VENUS’S STRUCTURE
IfwecouldsliceVenusandEarthinhalf,
poletopole,andplacethemsideby
side,theywouldlookremarkably
similar.Eachplanethasanironcore
envelopedbyahot-rockmantle;the
thinnestofskinsformsarocky,exterior
crust.Onbothplanets,thisthinskin
changesformandsometimeserupts
intovolcanoesinresponsetotheebb
andflowofheatandpressuredeep
beneath.

22. VENUS’S STRUCTURE
Venusisalandscapeofvalleysandhighmountainsdottedwiththousandsof
volcanoes.Itssurfacefeatures–mostnamedforbothrealandmythical
women–includeIshtarTerra,arocky,highlandareaaroundthesizeof
Australianearthenorthpole,andanevenlarger,South-America-sizedregion
calledAphroditeTerrathatstretchesacrosstheequator.Onemountain
reaches36,000feet(11kilometers),higherthanMt.Everest.Notably,except
forEarth,Venushasbyfarthefewestimpactcratersofanyrockyplanet,
revealingayoungsurface.

23. VENUS’S ATMOSPHERE
Venus’atmosphereisoneofextremes.Withthehottestsurfaceinthesolar
system,apartfromtheSunitself,Venusishottereventhantheinnermost
planet,charbroiledMercury.Tooutlivetheshort-livedVeneraprobes,your
ramblingsojournonVenuswouldpresumablyincludeunimaginablystrong
insulationastemperaturespushtoward900degreesFahrenheit(482Celsius).
Youwouldneedanextremelythick,pressurizedoutershelltoavoidbeing
crushedbytheweightoftheatmosphere–whichwouldpressdownonyouas
ifyouwere0.6miles(1kilometer)deepintheocean.

24. VENUS’S ATMOSPHERE
Theatmosphereismostlycarbondioxide–thesamegasdrivingthe
greenhouseeffectonVenusandEarth–withcloudscomposedofsulfuric
acid.Andatthesurface,thehot,high-pressurecarbondioxidebehavesina
corrosivefashion.Butastrangertransformationbeginsasyourisehigher.
Temperatureandpressurebegintoease.

25. ASTRONAUTS ON
VENUS:
You good Mark?
This is nothing
like the name
origin.
The last thing
I’d expect is to
see the Lor-.

26. EARTH

27. EARTH
●OurhomeplanetisthethirdplanetfromtheSun,andtheonlyplacewe
knowofsofarthat’sinhabitedbylivingthings.WhileEarthisonlythefifth
largestplanetinthesolarsystem,itistheonlyworldinoursolarsystem
withliquidwateronthesurface.JustslightlylargerthannearbyVenus,
EarthisthebiggestofthefourplanetsclosesttotheSun,allofwhichare
madeofrockandmetal.
●With a radius of 3,959 miles (6,371 kilometers), Earth is the biggest of the
terrestrial planets and the fifth largest planet overall.

28. EARTH
Fromanaveragedistanceof93millionmiles(150millionkilometers),
EarthisexactlyoneastronomicalunitawayfromtheSunbecauseone
astronomicalunit(abbreviatedasAU),isthedistancefromtheSunto
Earth.Thisunitprovidesaneasywaytoquicklycompareplanets'
distancesfromtheSun.

29. EARTH’S NAME ORIGIN
ThenameEarthisatleast1,000yearsold.
Alloftheplanets,exceptforEarth,were
namedafterGreekandRomangodsand
goddesses.However,thenameEarthisa
Germanicword,whichsimplymeans“the
ground.

30. EARTH’S POTENTIAL FOR LIFE
Earthhasaveryhospitabletemperature
andmixofchemicalsthathavemadelife
abundanthere.Mostnotably,Earthis
uniqueinthatmostofourplanetis
coveredinliquidwater,sincethe
temperatureallowsliquidwatertoexist
forextendedperiodsoftime.Earth'svast
oceansprovidedaconvenientplacefor
lifetobeginabout3.8billionyearsago.

31. EARTH’S ORBIT AND ROTATION
AsEarthorbitstheSun,itcompletesonerotationevery23.9hours.Ittakes
365.25daystocompleteonetriparoundtheSun.Thatextraquarterofaday
presentsachallengetoourcalendarsystem,whichcountsoneyearas365
days.TokeepouryearlycalendarsconsistentwithourorbitaroundtheSun,
everyfouryearsweaddoneday.Thatdayiscalledaleapday,andtheyear
it'saddedtoiscalledaleapyear.

32. EARTH’S ORBIT AND ROTATION
Earth'saxisofrotationistilted23.4degreeswithrespecttotheplaneofEarth's
orbitaroundtheSun.Thistiltcausesouryearlycycleofseasons.Duringpartof
theyear,thenorthernhemisphereistiltedtowardtheSun,andthesouthern
hemisphereistiltedaway.WiththeSunhigherinthesky,solarheatingis
greaterinthenorthproducingsummerthere.Lessdirectsolarheating
produceswinterinthesouth.Sixmonthslater,thesituationisreversed.When
springandfallbegin,bothhemispheresreceiveroughlyequalamountsofheat
fromtheSun.

34. EARTH’S ATMOSPHERE
Ourhomeplanetisthethirdplanetfrom
theSun,andtheonlyplaceweknowofso
farthat’sinhabitedbylivingthings.While
Earthisonlythefifthlargestplanetinthe
solarsystem,itistheonlyworldinour
solarsystemwithliquidwateronthe
surface.Justslightlylargerthannearby
Venus,Earthisthebiggestofthefour
planetsclosesttotheSun,allofwhichare
madeofrockandmetal.

35. EARTH’S ATMOSPHERE
Nearthesurface,Earthhasanatmospherethatconsistsof78%nitrogen,21%
oxygen,and1%othergasessuchasargon,carbondioxide,andneon.The
atmosphereaffectsEarth'slong-termclimateandshort-termlocalweatherand
shieldsusfrommuchoftheharmfulradiationcomingfromtheSun.Italso
protectsusfrommeteoroids,mostofwhichburnupintheatmosphere,seen
asmeteorsinthenightsky,beforetheycanstrikethesurfaceasmeteorites.

36. EARTH’S FORMATION
Whenthesolarsystemsettledintoits
currentlayoutabout4.5billionyears
ago,Earthformedwhengravitypulled
swirlinggasanddustintobecomethe
thirdplanetfromtheSun.Likeits
fellowterrestrialplanets,Earthhasa
centralcore,arockymantle,anda
solidcrust.

37. EARTH’S STRUCTURE
●Earthiscomposedoffourmainlayers,startingwithaninnercoreatthe
planet'scenter,envelopedbytheoutercore,mantle,andcrust.
●Theinnercoreisasolidspheremadeofironandnickelmetalsabout759
miles(1,221kilometers)inradius.Therethetemperatureisashighas9,800
degreesFahrenheit(5,400degreesCelsius).
●Surroundingtheinnercoreistheoutercore.Thislayerisabout1,400miles
(2,300kilometers)thick,madeofironandnickelfluids.

38. EARTH’S STRUCTURE
●Inbetweentheoutercoreandcrustisthemantle,thethickestlayer.This
hot,viscousmixtureofmoltenrockisabout1,800miles(2,900kilometers)
thickandhastheconsistencyofcaramel.
●Theoutermostlayer,Earth'scrust,goesabout19miles(30kilometers)
deeponaverageonland.Atthebottomoftheocean,thecrustisthinner
andextendsabout3miles(5kilometers)fromtheseafloortothetopofthe
mantle.

41. THE MOON
Earthistheonlyplanetthathasasinglemoon.OurMoonis
thebrightestandmostfamiliarobjectinthenightsky.In
manyways,theMoonisresponsibleformakingEarthsuch
agreathome.Itstabilizesourplanet'swobble,whichhas
madetheclimatelessvariableoverthousandsofyears.

42. HOW DID THE MOON FORMED?
Somemoonsarebitsofrockthatwerecapturedbyaplanet'sgravity,
butourMoonislikelytheresultofacollisionbillionsofyearsago.
WhenEarthwasayoungplanet,alargechunkofrocksmashedintoit,
displacingaportionofEarth'sinterior.Theresultingchunksclumped
togetherandformedourMoon.Witharadiusof1,080miles(1,738
kilometers),theMoonisthefifthlargestmooninoursolarsystem
(afterGanymede,Titan,Callisto,andIo).

44. MARS

45. MARS
●Marsisnoplaceforthefaint-hearted.It’sdry,rocky,andbittercold.Thefourth
planetfromtheSun,MarsisoneofEarth'stwoclosestplanetaryneighbors
(Venusistheother).Marsisoneoftheeasiestplanetstospotinthenightsky–
itlookslikeabrightredpointoflight.
●Witharadiusof2,106miles(3,390kilometers),Marsisabouthalfthesizeof
Earth.IfEarthwerethesizeofanickel,Marswouldbeaboutasbigasa
raspberry.
●Fromanaveragedistanceof142millionmiles(228millionkilometers),Marsis
1.5astronomicalunitsawayfromtheSun.Oneastronomicalunit(abbreviated
asAU),isthedistancefromtheSuntoEarth.Fromthisdistance,ittakes
sunlight13minutestotravelfromtheSuntoMars.
1au
●149,597,871km
●149,597,870,700meter
●92,955,807.3miles

46. MARS NAME ORIGIN
MarswasnamedbytheancientRomansfor
theirgodofwarbecauseitsreddishcolor
wasreminiscentofblood.Othercivilizations
alsonamedtheplanetforthisattribute–for
example,theEgyptianscalledit"Her
Desher,"meaning"theredone."Eventoday,
itisfrequentlycalledthe"RedPlanet"
becauseironmineralsintheMartiandirt
oxidize,orrust,causingthesurfacetolook
red.

47. MARS’S POTENTIAL FOR LIFE
Scientistsdon'texpecttofindliving
thingscurrentlythrivingonMars.
Instead,they'relookingforsignsof
lifethatexistedlongago,whenMars
waswarmerandcoveredwithwater.

48. MARS’S ORBIT AND ROTATION
Mars'axisofrotationistilted25degreeswithrespecttotheplaneofitsorbit
aroundtheSun.ThisisanothersimilaritywithEarth,whichhasanaxialtiltof
23.4degrees.LikeEarth,Marshasdistinctseasons,buttheylastlongerthan
seasonshereonEarthsinceMarstakeslongertoorbittheSun(becauseit's
fartheraway).AndwhilehereonEarththeseasonsareevenlyspreadoverthe
year,lasting3months(oronequarterofayear),onMarstheseasonsvaryin
lengthbecauseofMars'elliptical,egg-shapedorbitaroundtheSun.

50. MARS’S MOONS
●Marshastwosmallmoons,PhobosandDeimos,thatmaybecaptured
asteroids.They'repotato-shapedbecausetheyhavetoolittlemassfor
gravitytomakethemspherical.
●Themoonsgettheirnamesfromthehorsesthatpulledthechariotofthe
Greekgodofwar,Ares.

52. MARS’S MOONS
●Phobos,theinnermostandlargermoon,isheavilycratered,withdeep
groovesonitssurface.ItisslowlymovingtowardsMarsandwillcrashinto
theplanetorbreakapartinabout50millionyears.
●DeimosisabouthalfasbigasPhobosandorbitstwoandahalftimes
fartherawayfromMars.Oddly-shapedDeimosiscoveredinloosedirtthat
oftenfillsthecratersonitssurface,makingitappearsmootherthan
pockmarkedPhobos.

53. STRUCTURE
Marshasadensecoreatitscenter
between930and1,300miles(1,500to
2,100kilometers)inradius.It'smadeof
iron,nickel,andsulfur.Surroundingthe
coreisarockymantlebetween770and
1,170miles(1,240to1,880kilometers)
thick,andabovethat,acrustmadeof
iron,magnesium,aluminum,calcium,and
potassium.Thiscrustisbetween6and30
miles(10to50kilometers)deep.

54. MARS’S SURFACE
Marshasadensecoreatitscenterbetween
930and1,300miles(1,500to2,100
kilometers)inradius.It'smadeofiron,
nickel,andsulfur.Surroundingthecoreisa
rockymantlebetween770and1,170miles
(1,240to1,880kilometers)thick,andabove
that,acrustmadeofiron,magnesium,
aluminum,calcium,andpotassium.This
crustisbetween6and30miles(10to50
kilometers)deep.

55. MARS’S SURFACE
●AlargecanyonsystemcalledVallesMarinerisislongenoughtostretchfrom
CaliforniatoNewYork–morethan3,000miles(4,800kilometers).This
Martiancanyonis200miles(320kilometers)atitswidestand4.3miles(7
kilometers)atitsdeepest.That'sabout10timesthesizeofEarth'sGrand
Canyon.
●Marsishometothelargestvolcanointhesolarsystem,OlympusMons.It's
threetimestallerthanEarth'sMt.Everestwithabasethesizeofthestateof
NewMexico.

56. MARS’S ATMOSPHERE
Marshasathinatmospheremadeup
mostlyofcarbondioxide,nitrogen,and
argongases.Tooureyes,theskywould
behazyandredbecauseofsuspended
dustinsteadofthefamiliarbluetintwe
seeonEarth.Mars'sparseatmosphere
doesn'toffermuchprotectionfrom
impactsbysuchobjectsasmeteorites,
asteroids,andcomets.

57. MARS’S ATMOSPHERE
ThetemperatureonMarscanbeashighas70degreesFahrenheit(20degrees
Celsius)oraslowasabout-225degreesFahrenheit(-153degreesCelsius).And
becausetheatmosphereissothin,heatfromtheSuneasilyescapesthisplanet.
IfyouweretostandonthesurfaceofMarsontheequatoratnoon,itwouldfeel
likespringatyourfeet(75degreesFahrenheitor24degreesCelsius)andwinter
atyourhead(32degreesFahrenheitor0degreesCelsius).

58. WHY MARS APPEAR TO GO BACKWARDS?
●TheEarthrevolvesaroundthesun
muchfasterthanMars.
●AsEarthpassesMars,ourviewofthe
RedPlanetchangesrelativetomore
distantconstellationsandittherefore
appearstomovebackwards.Itisan
illusioncausedbymarsbeingslower.
●Thisillusioniscalledtheretrograde
motion.Itistheorbitalmotionofa
spatialbodyinadirectionoppositeof
whatisnormalinagivensystem.

59. WHAT ARE TERRESTRIAL PLANETS?
●They are rocky worlds composed of rock, silicate, water, and/or carbon.
●They have bulk composition and is dominated by rock or iron, and solid or
liquid surface.
●They are the closest to the Sun.
●There are Four Terrestrial or Inner Planets: Mercury, Venus, Earth, and Mars

60. COMING UP NEXT :
THE OUTER PLANETS
“What really are they? How did they came to be? What’s in these Gas and Ice
Giants? We’ll all find out so tune in for the next episode of Astronomy.”