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TABLEOFCONTENTSIntroduction...............................................................................................................................................................................................................3

EducationalGoalsforAstronomy2.................................................................................................................................................................4

MasterMaterialsListforAllLabs.....................................................................................................................................................................6

LabSafety...................................................................................................................................................................................................................7

Lesson#1:Stars,Planets,andBlackHoles...................................................................................................................................................8

Lesson#2:SolarSystemScaleModel...........................................................................................................................................................12

Lesson#3:Atmospheres....................................................................................................................................................................................15

Lesson#4:LunarPhases....................................................................................................................................................................................18

Lesson#5:EclipsesandTransits....................................................................................................................................................................21

Lesson#6:RustyBalloon...................................................................................................................................................................................24

Lesson#7:Meteorites.........................................................................................................................................................................................27

Lesson#8:Neptune’sFurnace.........................................................................................................................................................................30

Lesson#9:BinaryPlanetarySystems...........................................................................................................................................................33

Lesson#10:BuildYourOwnSolarSystem................................................................................................................................................36

Lesson#11:WatchYourWeight.....................................................................................................................................................................43

Lesson#12:Sundial.............................................................................................................................................................................................47

Lesson#13:Diffraction......................................................................................................................................................................................52

Lesson#14:InfraredVision..............................................................................................................................................................................55

Lesson#15:UVLight...........................................................................................................................................................................................58

Lesson#16:StarWobble...................................................................................................................................................................................62

Lesson#17:SpaceTelescopes.........................................................................................................................................................................64

Astronomy2Evaluation.....................................................................................................................................................................................67

Astronomy2Quiz..................................................................................................................................................................................................68

Astronomy2LabPractical................................................................................................................................................................................70

AnswerstoExercisesandActivities..............................................................................................................................................................71

VocabularyfortheUnit.......................................................................................................................................................................................76


Introduction

GreetingsandwelcometothestudyofAstronomy.Thisunitwascreatedbyamechanicalengineer,universityinstructor,airplanepilot,astronomer,robot‐builderandrealrocketscientist…me!IhavethehappyopportunitytoteachyoueverythingIknowaboutastronomyoverthenextsetoflessons.Ipromisetogiveyoumybeststuffsoyoucantakeitandrunwithit…orfly!

Astrophysicscombinestheknowledgeoflight(electromagneticradiation),chemicalreactions,atoms,energy,andphysicalmotionallintoone.Togetthemostoutoftheselabs,therearereallyonlyacoupleofthingstokeepinmind.Sinceweareallheretohavefunandlearnsomethingnew,thisshouldn’tbetoohard.

Oneofthebestthingsyoucandoasthestudentistocultivateyourcuriosityaboutthings.Whydidthatmove?Howdidthatspin?What’sreallygoingonhere?

ThisunitonAstronomyischock‐fullofdemonstrationsandexperimentsfortwobigreasons.First,they’refun.Butmoreimportantly,thereasonwedoexperimentsinscienceistohoneyourobservationalskills.ScienceexperimentsreallyspeakforthemselvesmuchbetterthanIcaneverputintowordsorshowyouonavideo.AndI’mgoingtohityouwithalotofthesesciencedemonstrationsandexperimentstohelpyoudevelopyourobservingtechniques.

Scientistsnotonlylearntoobservewhat’sgoingonintheexperiment,buttheyalsolearnhowtoobservewhattheirexperimentistellingthem,whichisfoundbylookingatyourdata.It’snotenoughtoinventsomenewkindofexperimentifyoudon’tknowhowitwillperformwhentheconditionschangeabit,likeonMars.We’regoingtolearnhowtopredictwhatwethinkwillhappen,designexperimentsthatwilltestthisidea,andlookovertheresultswegottofigureoutwheretogofromthere.Scienceisaprocess,it’sawayofthinking,andwe’regoingtogetplentyofpracticeatit.

Goodluckwiththisastronomyunit!


FortheParent/Teacher:EducationalGoalsforAstronomy2

Astrophysicscombinestheknowledgeoflight(electromagneticradiation),chemicalreactions,atoms,energy,andphysicalmotionallintoone.You’llsoonbediscoveringhowtomakearealscalemodelofthesolarsystem(andwheremostmodelsgowrong),you’lllearnaboutthedifferentatmospheresonplanets,howtocapturemeteorites,designasolarsystem,learnaboutdifferentspacemissionsandsomuchmore.

Herearethescientificconcepts:

Objectsintheskymoveinregularandpredictablepatterns.Thepatternsofstarsstaythesame,althoughtheyappeartomoveacrosstheskynightly,anddifferentstarscanbeseenindifferentseasons.

ThepositionoftheMoonchangesduringthecourseofthedayandfromseasontoseason. ThephasesoftheMoonandthelunarcycle. TheEarthisoneofseveralplanetsthatorbittheSun,andtheMoonorbitstheEarth. ThesolarsystemconsistsofplanetsandotherbodiesthatorbittheSuninpredictablepaths. Oursolarsystemincludesrockyterrestrialplanets(Mercury,Venus,Earth,andMars),gasgiants(Jupiter

andSaturn),icegiants(UranusandNeptune),andassortedchunksoficeanddustthatmakeupvariouscometsandasteroids.

Twoplanets(CeresandPluto)havebeenreclassifiedafterastronomersfoundoutmoreinformationabouttheirneighbors.

TheOortCloudholdsanestimated1trillioncomets.TheKuiperBeltholdschunksoficeanddust,likecometsandasteroidsaswellaslargerobjectslikedwarfplanetsErisandPluto.

Theappearance,generalcomposition,relativepositionandsize,andmotionofobjectsinthesolarsystem,includingplanets,planetarysatellites,comets,andasteroids.

HowtouseastronomicalunitsandlightyearsasmeasuresofdistancebetweentheSun,stars,andEarth. ThepathofaplanetaroundtheSunisduetothegravitationalattractionbetweentheSunandtheplanet. TheSun,anaveragestar,isthecentralandlargestbodyinthesolarsystemandiscomposedprimarilyof

hydrogenandhelium.TheSunusesnuclearreactionstogenerateitsenergy. ThepositionoftheSunintheskychangesduringthecourseofthedayandfromseasontoseason. Starsarethesourceoflightforallbrightobjectsinouterspace.TheMoonandplanetsshinebyreflected

sunlight,notbytheirownlight. Visiblelightisasmallbandwithinaverybroadelectromagneticspectrum. Whitelightisamixtureofmanywavelengths(colors),includinginfrared,ultra‐violet,visible,andmore.

Differentinstrumentsdetectandmeasuredifferentwavelengthsoflight. Galaxiesareclustersofbillionsofstars,andmayhavedifferentshapes.TheSunisoneofmanystarsinour

ownMilkyWaygalaxy.Starsmaydifferinsize,temperature,andcolor. Gravitationallensingoccurswhenblackholesandothermassiveobjectsbendlight.


Bytheendofthelabsinthisunit,studentswillbeableto:

DesignandbuildanexperimentthatshowshowtheshapeoftheMoonchangesovertime. Knowhowtodemonstratehowthepositionofobjectsintheskychangesovertime. Knowthecelestialobjectsinthesolarsystemandhowtheyrelateandinteractwitheachother. Measureandestimatethelengthandvolumeofobjects. Formulateandjustifypredictionsbasedoncause‐and‐effectrelationships. Conductmultipletrialstotestapredictionanddrawconclusionsabouttherelationshipsbetween

predictionsandresults. Constructandinterpretgraphsfrommeasurements. Followasetofwritteninstructionsforascientificinvestigation.


MasterMaterialsListforAllLabs

Thisisabrieflistofthematerialsthatyouwillneedtodoalloftheactivities,experimentsandprojectsinthisunit.Thesetofmaterialslistedbelowisjustforonelabgroup.Ifyouhaveaclassof10labgroups,you’llneedtoget10setsofthematerialslistedbelow.Mostmaterialsarereusable.

BakingsodaBallbearingormagneticmarbleBalloons(4)BlackpaperBouncyballCalciumchlorideCalculatorCamera(videoorstillcamera)CardboardorsmallpieceofclayCDorDVDChalkClockDiffractiongratingEmptyCDCaseFeatherFlashlightGallonmilkjugcontainerHandheldmagnifyingglass

Indexcards(3)Magnet(strong!)MarkersMeasuringtapePencilPhenolredorredfooddyePieceoffabricPlasticwrapPopsiclesticksProtractorRemotecontrolforTVorstereoRulerSaltSandScaletoweighyourselfScissorsSkewerSmallballs(5)

SoupcansorplasticcontainersSteelwoolStopwatchStringSunblockSunglassesTackorneedleTape(regularanddouble‐sided)TennisballThermometers(4)ThinplasticcuttingboardUVbeads(thesechangecolorswhenexposedtotheSun,5)VinegarWaterbottles(7)WaxpaperYardsticks/metersticks(2)


LabSafetyGoggles:Theseshouldbewornwhenworkingwithchemicals,heat,fire,orprojectiles.Theseprotectyoureyesfromchemicalsplatter,explosions,andtinyfast‐movingobjectsaimedattheeyes.Ifyouwearglasses,youcanfindgogglesthatfitoverthem.Don’tsubstituteeyeglassesforgoggles,becauseofthelackofsideprotection.Eyeglassesdon’tprovidethisimportantprotection.

CleanupMesses:Yourlabareashouldbeneat,organized,andspotlessbeforeyoustart,duringyourexperiment,andwhenyouleave.Scientistswastemoretimehuntingforlostpapers,piecesofanexperiment,andtryingtorepositionsensitiveequipment…allofwhichcouldhaveeasilybeenavoidedhadtheybeentaughtorganizationalskillsfromthestart.

DisposeofPoisons:Ifapoisonoussubstancewasused,created,orproducedduringyourexperiment,youmustfollowtheproperhandlingproceduresfordisposal.You’llfinddetailsforthisintheexperimentsasneeded.

SpecialNotesonBatteries:Donotusealkalinebatterieswithyourexperiments.Findthesuper‐cheapkindofbatteries(usuallylabeled“HeavyDuty”or“SuperHeavyDuty”)becausethesetypesofbatterieshaveacarbon‐zinccore,whichdoesnotcontaintheacidthatalkalinebatterieshave.Thismeanswhenyouwireupcircuitsincorrectly(whichyoushouldexpecttodobecauseyouarelearning),thecircuitswillnotoverheatorleak.Ifyouusealkalinebatteries(likeEnergizerandDuracell)andyourstudentsshortacircuit,theirwiresandcomponentswillgetsuper‐hotandleakacid,whichisverydangerous.

NoEatingorDrinkingintheLab:Allfoodsanddrinksarebannedfromyourclassroomduringscienceexperimentation.Whenyoueatordrink,youruntheveryrealriskofingestingpartofyourexperiment.Forelectricityandmagnetismlabs,alwayswashyourhandsafterthelabisovertorinseofftheleadfromtheelectricalcomponents.

NoHorsePlay:Whenyougoofaround,accidentshappen,whichmeanschemicalsspill,circuitsshort,andallkindsofhazardscanoccurthatyouweren’texpecting.Neverthrowanythingtoanotherpersonandbecarefulwhereyouputyourhands–itcouldbeinthemiddleofasensitiveexperiment,especiallywithmagnetismandelectricity.Youdon’twanttoruntheriskofgettingshockedorelectrifiedwhenit’snotpartofyourexperiment.

Fire:Ifyouthinkthere’safireintheroom(evenifyou’renotsure),letyourteacherknowrightaway.Iftheyarenotaround(theyalwaysshouldbe),smotherthefirewithafireblanketoruseafireextinguisherandsendsomeonetofindanadult.Stop,drop,androll!

Questions:Ifyou’renotsureaboutsomethingstopandask,nomatterwhatit’sabout.Ifyoudon’tknowhowtoproperlyhandleachemical,dopartofanexperiment,ask!Ifyou’renotcomfortabledoingpartoftheexperiment,thendon’tdoit.


Lesson#1:Stars,Planets,andBlackHolesOverviewGreetingsandwelcometothestudyofastronomy!Thisfirstlessonissimplytogetyouexcitedandinterestedinastronomysoyoucandecidewhatitisthatyouwanttolearnaboutastronomylateron.

WhattoLearnWe’regoingtocoveralotinthispresentation,includingstarslikeoursunaswellasdistantstars,iceandgasgiants,comets,asteroids,moons,ringedplanets,blackholesquasars,supernovaandmore.Thisisanoverviewofmanydifferentconceptswe’regoingtostudyinfurtherdepth,including:

TheSun,anaveragestar,isthecentralandlargestbodyinthesolarsystemandiscomposedprimarilyofhydrogenandhelium.

ThesolarsystemincludestheEarth,Moon,Sun,sevenotherplanetsandtheirsatellites,andsmallerobjectssuchasasteroidsandcomets.

Thestructureandcompositionoftheuniversecanbelearnedfromthestudyofstarsandgalaxies. Galaxiesareclustersofbillionsofstars,andmayhavedifferentshapes. TheSunisoneofmanystarsinourownMilkyWaygalaxy. Starsmaydifferinsize,temperature,andcolor.

Materials

Metalball(likeaballbearing)ORamagneticmarble Strongmagnet(thestrongestoneyouown).IhaveaneodymiummagnetthatIamusing. Thinplastic,cardboard,orwoodsheet(likeatableorcuttingboard).Makesurethemagnetcaninfluence

themetalballthroughit(don'tusemetal.) SmallbouncyballandtennisballORatennisballandabasketball(youneedtwoballsofdifferentsizes)

Experiment

Beforewatchingthevideo,printoutyourworksheetsoyoucanjotthingsdownasyoulisten.Thengrabyourpencil(andahandfulofpopcorn)andfillitinasyougoalong,orsimplyenjoytheshowandfillitoutattheend.


PlanetariumStarShowTable

Planet InterestingFactYouDidn’tKnow‘TilNow


Reading

Earlyastronomerstrackedthemovementofthestarssoaccuratelythatinmostcases,we’veonlymademinoradjustmentstotheirdata.AlthoughGalileowasn’tthefirstpersontolookthroughatelescope,hewasthefirsttopointitatthestars.Originally,astronomywasusedforcelestialnavigationandwasinvolvedwiththemakingofcalendars,butnowadaysit’smostlyclassifiedinthefieldcalledastrophysics.

Astronomersstudycelestialobjects(stars,planets,moons,asteroids,comets,galaxies,etc.)thatexistoutsideourplanet’satmosphere.It’stheonefieldthatcombinesthemostscience,engineeringandtechnologyareasinonefellswoop.Astronomyisalsooneoftheoldestsciencesontheplanet.

QuestionstoAnswer:

1. IsMercurythehottestplanet?Whyorwhynot?

2. Whatissolarwind?Whatprotectsplanetsfromit?

3. Canasteroidshavemoons?

4. WhyisIodifferentcolors?

5. Canmoonshaveatmospheres?Doallplanetshaveatmospheres?

6. HowmanyobjectsinthePlutosystem?

7. Nametwowaysyoucandetectblackholes.

8. Ifastarcollapseswhenitrunsoutoffuel,thenwhydosupernovasexplode?

9. Nametwoscientistswhocontributedtotheworkonblackholes.

10. Whatisagalaxy,andhowisitdifferentfromaquasar?


Lesson#2:SolarSystemScaleModelOverview:Todayyougettomakeascalemodelofthesolarsystem.Byscalemodel,Imeanboththesizesoftheplanetswillbetoscaleaswellasthedistancesbetweentheplanets.Yourjobistomakeitasaccurateasyoucan.

WhattoLearn:Youwilllearnhowoursolarsystemismostlymadeupofemptyspaceandthatthedistancesbetweentheobjectsarehuge.You’llalsofindoutwherethatpeskydwarfplanetCeres(whichwasdiscoveredin1801andthoughttobeaplanet,butquicklywasdemotedtoanasteroidandlateradwarfplanet)lives.

Materials

Measuringtape Ruler(metricorinches) Popsiclesticks Markers Indexcards Tape Tennisball Grassyfieldoroutdoorareatospreadout

Experiment

1. First,drawthesolarsystemonasheetofpaper.Onceyou’vecompletedthisstep,proceedtothenextstep.(Nopeeking!)

2. Moststudentswilltendtodrawtheplanetsevenlyspacedapart.You’lllearnhowtocorrectthismistakethenexttimeafteryou’veworkedthroughthisexperiment.

3. Whenbuildingthismodel,startbymarkingoffthelocationoftheSun(youcanusechalk,apapercirclecutto2.63”(66.8mm)orplaceatennisballasaplaceholderfortheSun).Therestisforthemtofigureout.

4. Ononeendofeachstick,writethenameofeachplanet/objectfromthedatatable.1. Ontheotherend,drawthescalesizeoftheplanet.IftheplanetislargerthanthePopsiclestick,drawiton

anindexcardandtapeittothestick.Usethefraction‐to‐decimalconverterifneeded(dependingonyourruler).

2. Placeyourtennisballatoneendoftheareamarkedoffforyourexperiments.ThisistheSun.3. Usingthetableandthemeasuringtape,measurethedistancefromtheSuntoMercury.Havealabpartner

holdoneendofthemeasuringtapeatthecenterofthetennisball(oranXyou’vemarkedonthegroundthat’sunderthetennisball).At10.4inches,placeyourPopsiclestickintothegroundsoitstandsup.Ifyou’reonconcrete,layitdownwiththedotrepresentingMercury10.4inchesawayfromtheSun.

4. Continuewiththerestoftheplanets,asfarasyouhaveroomtogo.Whichplanetdidyouhavetostopatbecauseyourareawasn’tbigenough?Ordidn’tyou?


SolarSystemDataTable

AlldistancesaremeasuredfromthecenteroftheSun.TheSunis2.63”(66.8mm)indiameter.

Planet/Object ObjectDiameter DistancefromtheSun

Mercury 0.009inches 0.2mm 10.4inches 0.264m

Venus 0.023inches 0.5mm 1foot7.4inches 0.493m

Earth 0.024inches 0.6mm 2feet2.9inches 0.682m

Mars 0.013inches 0.3mm 3feet4.9inches 1.039m

Jupiter 0.27inches 6.8mm 11feet7.76inches 3.649m

Saturn 0.22inches 5.5mm 21feet4.3inches 6.51m

Uranus 0.089inches 2.2mm 42feet11.5inches 13.094m

Neptune 0.086inches 2.1mm 67feet4.2inches 20.529m

Pluto(dwarfplanet) 0.004inches 0.1mm 88feet6inches 36.975m

Reading

HowlargeofasheetofpaperdoyouneedtomakeascalemodelofthesolarsystemiftheSunwasasbigasabeachball?Youwouldneedasheetofpapernearlyamilelong!

Howwouldyoumeasurethedistanceofafootballfieldifyouonlyhadaruler?Howwouldtheymeasurehowhighatreeis(withoutclimbingit)usingthesameruler?HowwouldyoumeasurethedistancetotheMoon?

Oneofthefirstwayswefiguredoutthedistancestotheplanets.Sincetheplanetsmoveintheirorbits,scientistshadtotakethatintoaccountwhentheydidtheirmeasurementsandcalculations.Inordertogetthehangofhowbigandfarawaycelestialobjectsreallyare,we’regoingtomakeascalemodelofthesolarsystem.


AGreekmathematician,Eratosthenes,wasthefirstpersontomeasuretheEarth’scircumferenceaswellascalculatethetiltoftheEarth’saxis,bothwithremarkableaccuracy.ScientiststhinkhewasalsothefirsttocorrectlycalculatethedistancefromtheEarthtotheSun.Hissystemoflatitudeandlongitudeisstillusedtoday.

Thediameterofoursolarsystemisalittlehardertofigureout,sincetheexactboundarystillhasn’tbeenexploredthoroughlyyetinordertoprovideenoughinformationaboutwhatshouldbeincludedandwhatdoesn’tbelong.Formeasuringlargedistances,astronomersuse“AU”or“au”meaningastronomicalunit.OneAUisthedistancefromtheEarthtotheSun,or93millionmiles(150millionkm).

GianDomenicoCassinimadethefirstgoodplanetmeasurementsin1672byusingparallax.Here’showhedidit:Ifyouholdyourhandoutatarm’slengthandlookatitwithonlyoneeyeatatime,you’llseeyourhandshiftslightlybackandforth.Thisiscalledparallax.Thishappensbecauseyoureyesareseparatedbyacoupleinches.Ifweknowhowfarapartyoureyesare,andcarefullymeasurethehowfaryourhandappearstoshift,wecanfindouthowlongyourarmis.

Nowimaginedoingthisbutinsteadthedistancebetweenyoureyes,we’llusethedistancetheEarthmoveswhenit’sononesideoftheSunversustheother,likeinwinterandsummer.Thespacingbetweentheeyesnowisn’tacoupleinches;it’snearly2AU’sapart.Bycarefullymeasuringhowmuchanobjectappearstoshift,wecanfindouthowfarthatobjectisfromus.

TodayweusearadiosignalandtimehowlongittakesthesignaltotravelfromtheEarthtoaspacecraftparkedinorbitaroundanotherplanet.Sincethesignaltravelsatthespeedoflight(186,000milespersecond),it’seasytofindouthowfarawaytheobjectis.ScientistsalsobounceradarsignalsoffaplanetandtimehowlongittakestoechobacktoEarth,muchthesamewaythepolicecanfindoutyourspeedusingaradargun.

QuestionstoAnswer

1. Whatdoyounoticeaboutthepositionoftherockyterrestrialplanets?

2. Aretheicegiantsfurtherapartfromeachotherthanthegasgiantsare?

3. Mariner10took147daystoreachMercuryfromEarth.HowlongdoyouthinkitwouldtaketogettoNeptune?

4. IftheEarthis93millionmiles(150millionkm)fromtheSun,andCeresis413millionmiles(665millionkm)fromtheSun,wherewouldyouplaceitinyourscalemodel?


Lesson#3:AtmospheresOverview:ScientistsdoexperimentshereonEarthtobetterunderstandthephysicsofdistantworlds.We’regoingtosimulatethedifferentatmospheresandtakedatabasedonthemodelweuse.

WhattoLearn:Eachplanethasitsownuniqueatmosphericconditions.MarsandMercuryhaveverythinatmospheres,whileEarthhasadecentatmosphere(asleast,weliketothinkso).Venus’satmosphereissothickanddense(92timesthatoftheEarth’s)thatitheatsuptheplanetsoit’sthehottestrockaround.JupiterandSaturnaresogaseousthatit’shardtotellwheretheatmosphereendsandtheplanetstarts,soscientistsdefinethelayersbasedonthedensityandtemperaturechangesofthegases.UranusandNeptunearecalledicegiantsbecauseoftheamountsoficeintheiratmospheres.

Materials

4thermometers 3jarsorwaterbottles Plasticwraporclearplasticbaggie Waxpaper Stopwatch

Experiment

1. Placeonethermometerindirectsunlight.ThisisliketheatmosphereofMercuryandMars.2. Placeasecondthermometerinajarandcapit.Placethisinsunlight.ThisistheEarth’s,Jupiter’sand

Saturn’satmosphere.3. Linethesecondjarwithwaxortissuepaper.Placethethirdthermometerinthejarandcapit.Placeitnext

totheothertwoinsunlight.ThisistheatmosphereonVenus.4. Insertthefourththermometerintoaplasticbaggie,insertitintothebottleandcapit.Makesurethebaggie

isloose.ThisisNeptuneandUranus.5. Recordyourdataobservationsinthetable,takingdataeverycoupleofminutes.


AtmospheresDataTable

Don’tforgettolabelyourunits!

Time NakedThermometer

ClearJarThermometer

WaxJarThermometer

IceJarThermometer

Reading

Venusishotenoughtomeltcannonballsandcrushanyspaceshipthattriestolandonthesurface.Carbondioxideisa“greenhousegas,”meaningthatsomewavelengthsoflightcanpassthroughit,butspecificallynotinfraredlight,whichisalsoknownasheat.LightfromtheSuneitherbouncesofftheuppercloudlayersandbackintospace,orpenetratesthecloudsandstrikesthesurfaceofVenus,warminguptheland.Thegroundradiatestheheatbackout,butthecarbondioxideatmosphereissodenseandthickthatittrapsandkeepstheheatdownonthesurfaceoftheplanet.Thinkofrollingupyourwindowsinyourcaronahotday.

TheheatissointenseonVenusthatthecarbonnormallylockedintorockssublimated(turnedstraightfromsolidtogas)andaddedtothecarbonintheatmosphere,tomakeevenmorecarbondioxide.

Mercurydoesn’thavemuchofanatmosphere,whichisjustlikeabarethermometer.There’snothingtoholdontotheheatthatstrikesthesurface.Marsisinasimilarsituation.

Earth’satmosphereissimulatedbyplacingthethermometerinabottle.TheEarthhasacloudlayerthatkeepssomeoftheheatontheplanet,butmostofitdoesgetradiatedbackintospace.Whenthecloudsareinatnight,theplanetstayswarmerthanwhenit’sclear(andcold).

Venus’sheavy,densecarbondioxideatmosphereissimulatedbyusingthewaxedpaper.Venusisthehottestplanetinoursolarsystembecauseoftherunawaygreenhouseeffectthattrapsmostoftheheatthatmakesitthroughtheatmosphere,bouncingitbackdowntothesurface.TheaveragetemperatureofVenusisover900oF.


JupiterandSaturn’satmospheresarethinnerlayersofhydrogenandheliumthandeeperinthecore.

UranusandNeptunearecalledicegiantsbecauseoftheamountsoficeintheiratmospheres.Theiratmospheresarealsomadeofmostlyhydrogenandhelium.

QuestionstoAnswer

1. Whichatmospherereachedthehighesttemperature?

2. EachofthejarsreceivedthesameamountofenergyfromtheSun.Whyisthisnotquiteliketherealsolarsystem?


Lesson#4:LunarPhasesOverview:TheMoonappearstochangeinthesky.Onemomentit’sabigwhitecircle,andnextweekit’sshapedlikeasidewaysbikehelmet.There’sevenadaywhereitdisappearsaltogether.Sowhatgives?

WhattoLearnTheSunilluminateshalfoftheMoonallthetime.Imagineshiningaflashlightonabeachball.Thehalfthatfacesthelightislitup.There’snolightonthefarside,right?FortheMoon,whichhalfislitupdependsontherotationoftheMoon.AndwhichpartoftheilluminatedsidewecanseedependsonwherewearewhenlookingattheMoon.Soundcomplicated?Thislabwillstraighteneverythingoutsoitmakessense.

Materials

Ball Flashlight

Experiment

1. Thislabworksbestifyourroomisverydark.Buttondownthoseshadesandmakeitasdarkasyoucan.2. AssignonepersontobetheSunandhandthemtheflashlight.Staystandingupaboutfourfeetawayfrom

thegroup.TheSundoesn’tmoveatallforthisactivity.3. AssignonepersontobetheMoonandhandthemtheball.Staystandingup,asyou’llbecirclingtheEarth.4. TherestofthepeoplearetheEarth,andtheystandorsitrightthemiddle(sotheydon’tgetaflashlightin

theireyesastheMoonorbits).5. StartwithanewMoon.ShinetheflashlightabovetheheadsoftheEarth.MovetheMoon(ball)intoposition

sothattheballblocksallthelightfromtheflashlight.AsktheEarthkidshowmuchlighttheycanseeontheirsideoftheMoon(shouldbenone).WhichphaseoftheMoonisthis?

6. NowtheMoonmovesaroundtotheoppositesideoftheEarthsothattheEarthkidscanseetheentirehalfoftheballlitupbytheflashlight.AsktheEarthkidshowmuchlighttheycanseeontheirsideoftheMoon(shouldbehalftheball).WhichphaseoftheMoonisthis?

7. Nowfindthepositionsforfirstquarter.WheredoestheMoonneedtostandsothattheEarthkidscanseethefirstquarterMoon?

8. Continuearoundinacompletecircleandfilloutthediagram.ColorinthecirclestoindicatethedarkhalfoftheMoon.Forexample,thenewMoonshouldbecompletelydarkened.


LunarPhasesDataObservations

1. Nowit’stimetoinvestigatewhyVenusandMercuryhavephases.PuttheSuninthecenterandassignastudenttobeVenus.Venusgetstheball.

2. VenusshouldbewalkingslowlyaroundtheSun.TheSunisgoingtohavetorotatetoalwaysfaceVenus,sincetheSunnormallygivesofflightineverydirection.

3. TheEarthkidsneedtomovefurtheroutfromtheSunthanVenus,sotheywillbewatchingVenusorbittheSunfromadistanceofacoupleoffeet.

4. Earthkids:WhatdoyounoticeabouthowtheSunlightsupVenusfromyourpointofview?IsthereatimewhenyougettoseeVenuscompletelyilluminated,andothertimeswhenit’scompletelydark?


5. Drawadiagramofwhat’sgoingon,labelingVenus’sfullphase,newphase,halfphases,crescent,andgibbousphases.LabeltheSun,Earth,andalleightphasesofVenuslikewedidontheboardfortheEarthatthebeginningofthislesson:

Reading

TheSunilluminateshalfoftheMoonallthetime.Imagineshiningaflashlightonabeachball.Thehalfthatfacesthelightislitup.There’snolightonthefarside,right?SofortheMoon,whichhalfislitupdependsontherotationoftheMoon.AndwhichpartoftheilluminatedsidewecanseedependsonwherewearewhenlookingattheMoon.Soundcomplicated?Thislabwillstraighteneverythingoutsoitmakessense.

Onequestionyoumighthaveis:Whydon’twehaveeclipseseverymonthwhenthere’sanewMoon?Thenextlessonisallabouteclipses,butrememberthattheMoon’sorbitaroundtheEarthisnotinthesameplaneastheEarth’sorbitaroundtheSun(calledtheecliptic).It’sactuallyoffbyabout5o.Infact,onlytwicepermonthdoestheMoonpassthroughtheecliptic.

Thelunarcycleisapproximately28days.Tobeexact,ittakesonaverage29.53days(29days,12hours,44minutes)betweentwofullmoons.Theaveragecalendarmonthis1/12ofayear,whichis30.44days.SincetheMoon’sphasesrepeatevery29.53days,theydon’tquitematchup.That’swhyonMoonphasecalendars,you’llseeaskippeddaytoaccountforthemismatch.

AsecondfullMooninthesamemonthiscalledablueMoon.It’salsoablueMoonifit’sthethirdfullMoonoutoffourinathree‐monthseason,whichhappensonceeverytwoorthreeyears.

TheMoonisn’ttheonlyobjectthathasphases.MercuryandVenusundergophasesbecausetheyareclosertotheSunthantheEarth.IfwelivedonMars,thentheEarthwouldalsohavephases.

QuestionstoAnswer

1. DoestheSunalwayslightuphalftheMoon?

2. HowmanyphasesdoestheMoonhave?

3. WhatisitcalledwhentheMoonappearstogrow?

4. WhatisitcalledwhenyouseemorelightthandarkontheMoon?

5. Howlongdoesittakeforacompletelunarcycle?


Lesson#5:EclipsesandTransitsOverview:ItjustsohappensthattheSun’sdiameterisabout400timeslargerthantheMoon,buttheMoonis400timescloserthantheSun.ThismakestheSunandMoonappeartobeaboutthesamesizeintheskyasviewedfromEarth.Thisisalsowhytheeclipsethingissuchabigdealforourplanet.You’reabouttomakeyourowneclipsesasyoulearnaboutsyzygy.

WhattoLearn:AtotaleclipsehappensaboutonceeveryyearwhentheMoonblockstheSun’slight.LunareclipsesoccurwhentheSun,Moon,andEartharelinedupinastraightlinewiththeEarthinthemiddle.Lunareclipseslasthours,whereassolareclipseslastonlyminutes.

Materials

2indexcards Flashlightorsunlight Tackorneedle Blackpaper Scissors

Experiment

1. Tracethecircleofyourflashlightontheblackpaperandcutoutthecirclewithpaper.ThisisyourMoon.IfyouareusingtheSuninstead,cutoutacircleaboutthesizeofyourfist.

2. Makeatinyholeinoneoftheindexcardsbypushingatackthroughthemiddleofthecard.3. Holdthepunchedindexcardacoupleinchesabovetheplainoneandshineyourlightthroughtheholeso

thatasmalldiskappearsonthelowercard.Movethecardsclosertogetherorfurtherapartuntilitcomesintofocus.ThediskoflightistheSun.

4. AskyourlabpartnertoslowlymovetheblackpaperdiskinfrontofyourlightasyouwatchwhathappenstotheSunonthebottomindexcard.

5. ContinuemovingtheblackpaperuntilyoucanseetheSunagain.6. Wheredoesyourcircleneedtobeinordertocreateanannulareclipse?Apartialeclipse?7. HowwouldyousimulateMercurytransitingtheSun?Whatwouldyouuse?8. Filloutthetable.


EclipsesandTransitsDataTable

Forthesecondcolumn,describewhereyourobjectwascomparedtotheflashlight/Sun,andhowlargeitwas.Forthethirdcolumn,drawthechangeyousawintheSun.

TypeofEclipse WherewastheMoonlocated? Whatdiditlooklike?

Total

Partial

Annular

Transit

Reading

Aneclipseiswhenoneobjectcompletelyblocksanother.Ifyou’rebigonvocabularywords,thenletthestudentsknowthateclipsesareonetypeofsyzygy(astraightlineofthreeobjectsinagravitationalsystem,liketheEarth,Moon,andSun).

AlunareclipseiswhentheMoonmovesintotheEarth’sshadow,makingtheMoonappearcopper‐red.

AsolareclipseiswhentheMoon’sshadowcrawlsovertheEarth,blockingouttheSunpartiallyorcompletely.Therearethreekindsofsolareclipses.AtotaleclipseblockstheentireSun,whereasinapartialeclipsetheMoonappearstoblockpart,butnotalloftheSun’sdisk.AnannulareclipseiswhentheMoonistoofarfromEarthtocompletelycovertheSun,sothere’sabrightringaroundtheMoonwhenitmovesinfrontoftheSun.

ItjustsohappensthattheSun’sdiameterisabout400timeslargerthantheMoon,buttheMoonis400timescloserthantheSun.ThismakestheSunandMoonappeartobeaboutthesamesizeintheskyasviewedfromEarth.Thisisalsowhytheeclipsethingissuchabigdealforourplanet.


Transitsarewherethediskofaplanet(likeVenus)passeslikeasmallshadowacrosstheSun.IotransitsthesurfaceofJupiter.Inrarecases,oneplanetwilltransitanother.Thesearerarebecauseallthreeobjectsmustaligninastraightline.

Astronomersusethismethodtodetectlargeplanetsarounddistantbrightstars.Ifalargeplanetpassesinfrontofitsstar,thestarwillappeartodimslightly.

Note:Atransitisnotanoccultation,whichcompletelyhidesthesmallerobjectbehindalargerone.

QuestionstoAnswer

1. Whatotherplanetscanhaveeclipses?

2. WhichplanetstransittheSun?

3. Howisasolareclipsedifferentfromalunareclipse?

4. Whatphasecanalunareclipseoccur?

5. Canasolareclipseoccuratnight?


Lesson#6:RustyBalloonOverview:Marsiscoatedwithironoxide,whichnotonlycoversthesurfacebutisalsopresentintherocksmadebytheMartianvolcanoes.

WhattoLearn:Todayyougettoperformachemistryexperimentthatinvestigatesthedifferentkindsofrustandshowsthatgiventherightconditions,anythingcontainingironwilleventuallybreakdownandcorrode.When iron rusts, it’s actually going through a chemical reaction: Steel (iron) + Water (oxygen) + Air (oxygen) = Rust

Materials

Fouremptywaterbottles Fourballoons Water Steelwool Vinegar Water Salt

Experiment

1. Thislabisbestdoneovertwoconsecutivedays.Plantosetuptheexperimentonthefirstday,andfinishupwiththeobservationsonthenext.

2. Lineupfouremptybottlesonthetable.3. Labelyourbottlessoyouknowwhichiswhich:Water,Water+Salt,Vinegar,Vinegar+Salt4. Filltwobottleswithwater.5. Filltwowithvinegar.6. Addatablespoonofsalttooneofthewaterbottles.7. Addonetablespoonofsalttooneofthevinegarbottles.8. Stuffapieceofsteelwoolintoeachbottlesoitcomesincontactwiththeliquid.9. Stretchaballoonacrossthemouthofeachbottle.10. Letyourexperimentsit(overnightisbest,butyoucanshortenthisabitifyou’reinahurry).11. Thetricktogettingthisonetoworkisinwhatyouexpecttohappen.Theballoonshouldgetshovedinside

thebottle(notexpandandinflate!).Checkbackoverthecourseofafewhourstoafewdaystowatchyourprogress.

12. Fillinthedatatable.


RustyBalloonDataTable

What’sintheBottle? Whathappened?Describewhathappenedtothewool,bottle,andballoon.

Reading

Rustisacommonnameforironoxide.Whenmetalsrust,scientistssaythattheyoxidize,orcorrode.Ironreactswithoxygenwhenwaterispresent.Thewatercanbeliquidorthehumidityintheair.Othertypesofrusthappenwhenoxygenisnotaround,likethecombinationofironandchloride.Whenrebarisusedinunderwaterconcretepillars,thechloridefromthesaltintheoceancombineswiththeironintherebarandmakesagreenrust.

Marshasasolidcorethatismostlyironandsulfur,andasoftpastel‐likemantleofsilicates(therearenotectonicplates).Thecrusthasbasaltandironoxide.TheironisintherocksandvolcanoesofMars,andMarsappearstobecoveredinrust.

When iron rusts, it’s actually going through a chemical reaction: Steel (iron) + Water (oxygen) + Air (oxygen) = Rust

Therearemanydifferentkindsofrust.Stainlesssteelhasaprotectivecoatingcalledchromium(III)oxidesoitdoesn’trusteasily.

Aluminum,ontheotherhand,takesalongtimetocorrodebecauseit’salreadycorroded—thatis,assoonasaluminumisexposedtooxygen,itimmediatelyformsacoatingofaluminumoxide,whichprotectstheremainingaluminumfromfurthercorrosion.


Aneasywaytoremoverustfromsteelsurfacesistorubthesteelwithaluminumfoildippedinwater.Thealuminumtransfersoxygenatomsfromtheirontothealuminum,formingaluminumoxide,whichisametalpolishingcompound.Andsincethefoilissofterthansteel,itwon’tscratch.

QuestionstoAnswer

1. Whydidoneballoongetlargerthantherest?

2. Whichhadthehighestpressuredifference?Why?


Lesson#7:MeteoritesOverview:Ameteoroidisasmallrockthatzoomsaroundouterspace.WhenthemeteoroidzipsintotheEarth’satmosphere,it’snowcalledameteoror“shootingstar.”Iftherockdoesn’tvaporizeenroute,it’scalledameteoriteassoonasitwhacksintotheground.ThewordmeteorcomesfromtheGreekwordfor“highintheair.”

WhattoLearn:Meteoritesareblack,heavy(almosttwicethenormalrockdensity),andmagnetic.However,thereisanEarth‐maderockthatisalsoblack,heavy,andmagnetic(magnetite)thatisnotameteorite.Totellthedifference,scratchalinefrombothrocksontoanunglazedtile.Magnetitewillleaveamarkwhereastherealmeteoritewillnot.

Materials

Whitepaper Strongmagnet Unglazedporcelaintile Handheldmagnifyingglass(optional)

Experiment

1. Imagineyouaregoingonarockhunt.YouaretofindwhichrocksaremeteoritesandwhichareEarthrocks.Ifyoudon’thaveaccesstorocksamples,justwatchtheexperimentvideoofthedifferentrocksamples.Ifyou’dliketomakeyourownsamplecollection,herearesomeideas:

a. 8‐10differentrocks,includingpumice(fromavolcano),lodestone(anaturallymagnetizedpieceofmagnetite,andoftenmistakenformeteorites),afossil,tektite(dryfusedglass),pyrite(alsoknownasfool’sgold),marble(calciteordolomite),andacoupleofdifferentkindsofrealmeteorites(ironmeteorite,stonymeteorite,etc.)Alsoaddtoyourbaganunglazedtileandamagnet.

2. Asyouwatchtheexperimentvideo,recordyourobservationsonyourdatasheet.a. Sincenearlyallmeteoriteshavelotsofiron,theyareusuallyattractedtoamagnet.However,

lodestoneisanEarthrockthatalsohasalotofiron.Ironisheavy,andmeteoritescontainalotofiron.Whenlookingthroughthepossibilities,removeanylightweightrocks,astheyarenotusuallymeteorites.

b. Meteoritesaresmall.Mostnevergetbigenoughorhotenoughformetaltosinkintothecore,sothemajorityaremixedwithrockanddust(stonymeteorites).Thefewthatdogetbigandformmetalcoresarecalledironmeteorites.

c. MostmeteoritescomefromtheAsteroidBelt.Somemeteoritesgetadarkcrust.Whileotherslooklikesplashedmetal.Theyarealldark,atleastontheoutside.Removeanylight‐coloredrocks.

d. Rocksthathaveholesvaporizeorexplodewhentheygothroughtheatmosphere,theydon’tburnup.Onlystrongspacerockswithoutholesmakeittotheground.Removeanyporousrocks.

e. Theonesyouhaveleftareeithermeteoritesorlodestone.Totellthedifference,scratchalinefrombothrocksontoanunglazedtile.Magnetite(lodestone)willleaveamarkwhereastherealmeteoritewillnot.

FindingMeteorites

3. Placeasheetofwhitepaperoutsideontheground.Dothisinthemorningwhenyoufirststartupclass.4. Afterafewhours(likejustbeforelunchtime),yourpaperstartstoshowsignsof“dust.”


5. Carefullyplaceamagnetunderneaththepaper,andseeifanyoftheparticlesmoveasyouwigglethemagnet.Ifso,you’vegotyourselfafewbitsofspacedust.

6. Useamagnifyinglenstolookatyourspacemeteoritesupclose.

MeteoritesDataTable

RockSample#

Color? HeavyorLight?

LargeorSmall?

PorousorDense?

Magnetic? MarksonTile?

Reading

94%ofallmeteoritesthatfalltotheEartharestonymeteorites.Stonymeteoriteswillhavemetalgrainsmixedwiththestonethatareclearlyvisiblewhenyoulookataslice.

Ironmeteoritesmakeuponly5%ofthemeteoritesthathittheEarth.However,sincetheyarestronger,mostofthemsurvivethetripthroughtheatmosphereandareeasiertofindsincetheyaremoreresistanttoweathering.Morethanhalfthemeteoriteswefindareironmeteorites.TheyaretheoneofthedensestmaterialsonEarth.TheystickstronglytomagnetsandaretwiceasheavyasmostEarthrocks.TheHobameteoriteinNamibiaweighs50tons.

Sincenearlyallmeteoriteshavelotsofiron,theyareusuallyattractedtoamagnet.However,lodestoneisanEarthrockthatalsohasalotofiron.Ironisheavy,andmeteoritescontainalotofiron.Whenlookingthroughthepossibilities,removeanylightweightrocks,astheyarenotusuallymeteorites.


Meteoritesaresmall.Mostnevergetbigenoughorhotenoughformetaltosinkintothecore,sothemajorityaremixedwithrockanddust(stonymeteorites).Thefewthatdogetbigandformmetalcoresarecalledironmeteorites.

MostmeteoritescomefromtheAsteroidBelt.Somemeteoritesgetadarkcrust,whileotherslooklikesplashedmetal.Theyarealldark,atleastontheoutside.

Rocksthathaveholesvaporizeorexplodewhentheygothroughtheatmosphere,theydon’tburnup.Onlystrongspacerockswithoutholesmakeittotheground.

Everyyear,theEarthpassesthroughthedebrisleftbehindbycomets.CometsaredirtysnowballsthatleaveatrailofparticlesastheyorbittheSun.WhentheEarthpassesthroughoneofthesetrails,thetinyparticlesentertheEarth’satmosphereandburnup,leavingspectacularmeteorshowersforustowatchonaregularbasis.Thebestmeteorshowersoccurwhenthemoonisnewandtheskyisverydark.

Meteoritesareblack,heavy(almosttwicethenormalrockdensity),andmagnetic.However,thereisanEarth‐maderockthatisalsoblack,heavy,andmagnetic(magnetite)thatisnotameteorite.Totellthedifference,scratchalinefrombothrocksontoanunglazedtile(orthebottomofacoffeemugortheundersideofthetoilettank).Magnetitewillleaveamark,whereastherealmeteoritewillnot.

Ifyoufindameteorite,headtoyournearestgeologydepartmentatalocaluniversityorcollegeandletthemknowwhatyou’vefound.IntheUSA,ifyoufindameteorite,yougettokeepit…butyoumightwanttolettheexpertsinthegeologydepartmenthaveathinsliceofittoseewhattheycanfigureoutaboutyourparticularspecimen.

AnnualMeteorShowers

Jan3‐4 Quadrantids

Apr21‐22 AprilLyrids

May4‐5 EtaAquarids

Jul28‐29 DeltaAquarids

Aug12‐13 Perseids

Oct21‐22 Orionids

Nov3‐13 Taurids

Nov16‐17 Leonids

Dec13‐14 Geminids

Dec21‐22 Ursids

QuestionstoAnswer

1. Aremeteorsmembersofthesolarsystem?

2. Howbigaremeteors?

3. Whydowehavemeteorshowersatpredictabletimesoftheyear?


Lesson#8:Neptune’sFurnaceOverview:We’regoingtodoachemistryexperimenttosimulatetheheatgeneratedbytheinternalcoreofNeptunebyusingasubstanceusedformeltingsnowmixedwithbakingsoda.

WhattoLearn:Calciumchloridesplitsintocalciumionsandchlorideionswhenitismixedwithwater,andenergyisreleasedintheformofheat.Theenergyreleasedcomesfromthebondenergyofthecalciumchlorideatoms,andisactuallyelectromagneticenergy.Whenthecalciumionsandchlorideionsarefloatingaroundinthewarmsolution,theyarefreetointeractwiththerestoftheingredientsadded,likethesodiumbicarbonate,toformcarbondioxidegasandsodiumchloride(tablesalt).

Materials

Calciumchloride Sodiumbicarbonate(bakingsoda) Phenolredorredfooddye Resealableplasticbaggie Gallonmilkjugcontainer Straightpin Warmwater Coldwater

Experiment

1. Cutthetopoffthemilkjugjustabovethehandlesoyoucaneasilyputyourexperimentinthejug.2. Fillyourmilkjugwithcoldwatermostoftheway.Leaveenoughroomforyoutoaddthebagwithout

overflowingthewater,andmakesureyouputinverycoldwater.Setthisaside.3. Addaninchofwarmwatertotheplasticbag.4. Addacoupleofdropsofreddyetothebag.5. Ifyouareusingahotpack,openthehotpack(usescissors)carefully.Youdon’twanttopuncturethewater

pouchinside.Throwthewaterpouchawayandpourtherestofthecontentsintoacontainer(thisiscalciumchloride).Youwantacoupleoftablespoonsofcalciumchlorideintheplasticbaggie.

6. Sealthebagclosedandrollthepelletsbetweenyourfingers.7. Useastraightpinandmakesixholesnearthetopofthebag,awayfromthewater.8. Openthebagandaddacoupleoftablespoonsofsodiumbicarbonate(bakingsoda).Quicklyzipupyour

bag!9. Makesurethebagissealedbeforeinsertingitintoyourcoldwaterjug.Watchcarefullyforseveralminutes

andrecordyourobservationswiththenextstep.10. Drawyourexperimentduringstep9.Labelallpartsofwhat’sgoingonwithyourexperiment:


Reading

We’resimulatingtheheatgenerationonNeptuneusingachemistryexperimentwithahotpack.

Mostinstanthotpacksavailableindrugstoresworkonthissameprinciplewe’reabouttoinvestigate.Whenthehotpackisneeded,thebagissqueezedtocausethewaterandsalttomix.Dependingonthesaltusedinthepack,energyiseitherabsorbed(coldpack)orgivenoff(hotpack).Ammoniumnitrateisthemostcommonlyusedsaltincoldpacks.Andcalciumchlorideisthemostcommonlyusedsaltinhotpacks.

Calciumchloridesplitsintocalciumionsandchlorideionswhenitismixedwithwater,andenergyisreleasedintheformofheat.Thisisthesameheatenergyyouwillfeelwhenholdingthebaggieandrubbingthepellets.

Dissolvingcalciumchlorideishighlyexothermic,meaningthatitgivesoffalotofheatwhenmixedwithwater(thewatercanreachupto140oF,sowatchyourhands!).Theenergyreleasedcomesfromthebondenergyofthecalciumchlorideatoms,andisactuallyelectromagneticenergy.

Whenthecalciumionsandchlorideionsarefloatingaroundinthewarmsolution,theyarefreetointeractwiththerestoftheingredientsadded,likethesodiumbicarbonate,toformcarbondioxidegasandsodiumchloride(tablesalt).Youcantellthere’scarbondioxidegasinsidewhenthebagpuffsup.

Asthegasinthebagincreases,itpuffsoutandincreasesthepressure.Thisstretchesthebagandsomeofthegasisreleasedouttheholesinthetopofthebag,bubblinguptothesurfaceofthemilkjug.Afterawhile,thewarmwaterwillalsoriseoutoftheholesduetothetemperaturedifferencebetweenthebagandjugandyou’llseereddriftuptothetopsurfaceofthemilkjug.TheheatgeneratedbyNeptuneisdeepinthecore,anditbubblesupandradiatesouttospace,justlikethewarmbagbubblingitscontentstothecoldwaterjug.Theentireplanetisawhirling,swirling,fast‐movingballofgasandicethatmovebecauseoftemperatureandpressuredifferences.

Neptuneisoneoftheicegiantsofoursolarsystem,andthefurthestplanetfromthesun.Becauseit’sagasgiant,youcouldn’tlandyourspaceshiponthesurfacebecauseitdoesn’thaveone.You’dcontinuouslyfalluntilthepressurecrushedyourship.Andthenwhenyougotdownfarenough,you’dberoasted,becauseNeptuneradiates2.6timesmoreenergythanitgetsfromtheSun.That’simpressive,especiallysinceit’ssofarfromtheSun(30.1AU,ormorethan30timestheEarth‐Sundistance).TheaveragedailywindspeedonNeptuneis1,200mph.That’sfourtimesfasterthanthebiggesthurricanesonEarth!

NeptunehasmoremassthanUranuseventhoughit’ssmallerthanUranus.Theringsaroundtheplanetweren’tconfirmeduntilaspaceprobepasseditandsentusbackpicturesoftheblueplanet.It’shardforbackyardastronomerstofindthisplanet,sinceit’snotanaked‐eyeobject.Youneedacomplicated‐lookingsetofstarchartsoraGPStrackingsystemcoupledwithastronomicaldatatopointyourscopeintherightdirection.Eventhen,allyouseeisawhite‐bluelookingstar.

Althoughit’sagasgiant,it’sclassifiedasanicegiant,sincetherearelargeamountsofmethaneandammoniaicesintheupperatmosphere,givingtheplanetitsbluecolor.Thelargestof13moonsisTriton(nottobeconfusedwithSaturn’smassivemoon,Titan),whichorbitsNeptuneintheoppositedirectionfromtheplanet’srotationandalsoupataninclinefromtheplanet’sequator.


QuestionstoAnswer

1. Whathappenswhenthechemicalscomeincontactwitheachother?

2. Whatdidyounoticewhenyousealedthebagclosedandrolledthepelletsbetweenyourfingers?

3. Whathappenedwhenthesolutionwasplacedinthecoldwaterjug?

4. WhatdoesthisexperimenthavetodowithNeptune?Whydidweusethebakingsodaatall?


Lesson#9:BinaryPlanetarySystemsOverview:Abinarysystemexistswhenobjectsapproacheachotherinsize(andgravitationalfields),thecommonpointtheyrotatearound(calledthecenterofmass)liesoutsidebothobjectsandtheyorbitaroundeachother.Astronomershavefoundbinaryplanets,binarystars,andevenbinaryblackholes.Studentswillknowthatthepathofaplanetaroundanobjectisduetothegravitationalattractionbetweentheobjectandtheplanet.

WhattoLearn:ThepathofaplanetaroundtheSunisduetothegravitationalattractionbetweentheSunandtheplanet.ThisistrueforthepathoftheMoonaroundtheEarth,andTitanaroundSaturn,andtherestoftheplanetsthathaveanorbitingmoon.

Materials

Soupcansorplasticcontainerswithholespunched(likeplasticyogurtcontainers,buttertubs,etc.) String Water Sand Rocks Pebbles Bakingsoda Vinegar

Experiment

1. Threadoneendofthestringthroughoneoftheholesandtieastrongknot.Reallystrong.2. Tietheotherendthroughtheotherholeandtieoff.3. Gooutside.4. Fillyourcanpartwaywithwater.5. Moveawayfromeveryonebeforeyoustarttoswingyourcontainerinagentlecircle.Asyouspinfasterand

faster,noticewherethewaterisinsidethecontainer.6. Nowemptyoutthewaterandreplaceitwithrocks.Spinagainandfilloutthedatatable.7. Tomakecarbondioxidegas,you’llneedtoworkwithanotherlabteam.Coverthebottomofyourcontainer

withbakingsoda.Addenoughvinegarsothatthebubblesreachthetopwithoutoverflowing.Waitpatientlyforthebubblestosubside.Younowhaveacontainerfilledwithcarbondioxidegas(andalittlesodiumacetate,theleftoversfromthereaction).Carefullypourthecarbondioxideintotheemptycontainerfromtheotherlabteam.Theycanspinagainandrecordtheirresults.Whentheyaredone,borrowtheircontainerandgivethemyourssotheycanfillitforyou.


BinaryPlanetarySystemsDataTable

Whenfillingoutthethirdcolumn,noticehowhardoreasyitwastospinthecontainer,whatitfeltlike,whichwayitfaced,etc.Recordeverythingyoucanabouteachone.

ItemintheCan StateofMatter(solid,liquid,orgas?)

Whatdidyounotice?

Water

Rocks

Sand

Air

Pebbles

CarbonDioxideGas

Reading

ThepathofaplanetaroundtheSunisduetothegravitationalattractionbetweentheSunandtheplanet.ThisistrueforthepathoftheMoonaroundtheEarth,andTitanaroundSaturn,andtherestoftheplanetsthathaveanorbitingmoon.

CharonandPlutoorbitaroundeachotherduetotheirgravitationalattractiontoeachother.However,CharonisnotthemoonofPluto,asoriginallythought.PlutoandCharonactuallyorbitaroundeachother.PlutoandCharonalsoaretidallylocked,justliketheEarth‐Moonsystem,meaningthatonesideofPlutoisalwaysfacesthesamesideofCharon.

Imagineyouhaveabuckethalffullofwater.Canyoutiltabucketcompletelysidewayswithoutspillingadrop?Surething!Youcanswingitbythehandle,andeventhoughit’supsidedownatonepoint,thewaterstaysput.What’skeepingthewaterinsidethebucket?


Beforeweanswerthis,imagineyouareapassengerinacar,andthedriverislateforanappointment.Theytakeaturnalittletoofast,andyouforgottofastenyourseatbelt.Thecarmakesasharpleftturn.Whichwaywouldyoumoveinthecariftheytookthisturntoofast?Exactly–you’dgoslidingtotheright.So,whopushedyou?

Noone!Yourbodywantedtocontinueinastraightline,butthecaristurning,sotherightsidecardoorkeepspushingyoutoturnyouinacurve–intotheleftturn.Thecardoorkeepsmovinginyourway,turningyouintoacircle.Thecardoorpushingonyouiscalledcentripetalforce.Centripetalmeans“center‐seeking.”It’stheforcethatpointstowardthecenterofthecircleyou’removingon.Whenyouswingthebucketaroundyourhead,thebottomofthebucketismakingthewaterturninacircleandnotflyaway.Yourarmispullingonthehandleofthebucket,keepingitturninginacircleandnotlettingitflyaway.That’scentripetalforce.

Thinkofitthisway:IfIthrowaballinouterspace,doesitgoinastraightlineordoesitwiggleallovertheplace?Straightline,right?Centripetalforceistheforceneededtokeepanobjectfollowingacurvedpath.

Rememberhowobjectswilltravelinastraightlineunlesstheybumpintosomethingorhaveanotherforceactingonthem,suchasgravity,dragforce,andsoforth?Well,tokeepthebucketofwaterswinginginacurvedarc,thecentripetalforcecanbefeltinthetensionexperiencedbythehandle(oryourarm,inourcase).Swinginganobjectaroundonastringwillcausetheropetoundergotension(centripetalforce),andifyourropeisn’tstrongenough,itwillsnapandbreak,sendingthemassflyingoffinatangent(straight)lineuntilgravityanddragforcepulltheobjecttoastop.Thisforceisproportionaltothesquareofthespeed‐thefasteryouswingtheobject,thehighertheforce.

QuestionstoAnswer

1. HowisspinningthecontainerlikePlutoandCharon?

2. Whatwouldhappenifwecutthestringwhileyouarespinning?Whichwaywouldthecontainergo?

3. Whathappensifwetriplethesizeofyourcontainerandwhat’sinsideofit?


Lesson#10:BuildYourOwnSolarSystemOverview:Whatwouldhappenifoursolarsystemhadthreesuns?OrtheEarthhadtwomoons?Youcanfindoutalltheseandmorewiththislessononorbitalmechanics.Insteadofwaitinguntilyouhitcollege,wethoughtwe’dthrowsomeuniversity‐levelphysicsatyou…withoutthehardmath.

WhattoLearnKeyconceptsaboutgravity:

a. Gravityisaforcethatattractsthingstooneanother.b. Allbodies(objects)haveagravitationalfield.c. Thelargerabodyis,thegreaterthestrengthofthegravitationalfield.d. Bodiesmustbevery,verylargebeforetheyexertanynoticeablegravitationalfield.e. Gravityacceleratesallthingsequally.Whichmeansallthingsspeedupthesameamountastheyfall.f. Gravitydoesnotcarewhatsizethingsareorwhetherthingsaremoving.Allthingsareaccelerated

towardtheEarthatthesamerateofspeed.g. Gravitydoespullonthingsdifferently.Gravityispullinggreateronobjectsthatweighmore.h. Weightisameasureofhowmuchgravityispullingonanobject.i. Massisameasureofhowmuchmatter(howmanyatoms)makeupanobject.

Materials

AccesstoacomputerwithInternet Ruler

Experiment

AbouttheConceptofGravity

1. Eventhoughwedealwithgravityonaconstantbasis,thereareseveralmisconceptionsaboutit.Let’sgettoanexperimentrightawayandI’llshowyouwhatImean.

2. Whenyoudropagolfballandapingpongballfromthesameheight,whathappens?3. Whatyoushouldseeisthatbothobjectshitthegroundatthesametime!Gravityacceleratesbothitems

equallyandtheyhitthegroundatthesametime.Anytwoobjectswilldothis,abrickandaBuick,aflowerandafish,akumquatandacow!

4. Butwhatifyoudropafeatherandaballatthesametime?Thereisonethingthatwillchangetheresultsandthatisairresistance.Thebigger,lighterandfluffiersomethingis,themoreairresistancecanaffectitandsoitwillfallmoreslowly.Airresistanceisatypeoffrictionwhichwewillbetalkingaboutlater.Infact,ifyouremovedairresistance,afeatherandaflounderwouldhitthegroundatthesametime!!!

5. Wherecanyouremoveairresistance?TheMoon!!!OneoftheApollomissionsactuallydidthis(well,theydidn’tuseaflounder,theyusedahammer).Anastronautdroppedafeatherandahammeratthesametimeandindeed,bothfellatthesamerateofspeedandhitthesurfaceofthemoonatthesametime.

6. Whichwillhitthegroundfirst,ifdroppedfromthesameheight,abowlingballoratennisball?Mostpeoplewillsaythebowlingball.Infact,ifyouaskedyourselfthatquestion5minutesago,wouldyouhavegottenitright?It’sconventionalwisdomtothinkthattheheavierobjectfallsfaster.

7. Unfortunately,conventionalwisdomisn’talwaysright.Gravityacceleratesallthingsequally.Inotherwords,gravitymakesallthingsspeeduporslowdownatthesamerate.


8. Thisisagreatexampleofwhythescientificmethod(moreonthislater)issuchacoolthing.Many,manyyearsago,therewasamanofgreatknowledgeandwisdomnamedAristotle.Whateverhesaid,mostpeoplebelievedtobetrue.Thetroublewas,hedidn’ttesteverythingthathesaid.Oneofhisstatementswasthatobjectswithgreaterweightfallfasterthanobjectswithlessweight.Everyonebelievedthatthiswastrue.Hundredsofyearslater,Galileocamealongandsaid“Yaknow...thatdoesn’tseemtoworkthatway.I’mgoingtotestit”ThestorygoesthatGalileograbbedamelonandanorangeandwenttothetopoftheLeaningTowerofPisa.Hesaid,“Lookoutbelow!”anddroppedthem!Bydoingthat,heshowedthatobjectsfallatthesamerateofspeednomatterwhattheirsize.ItistruethatitwasGalileowho“proved”thatgravityacceleratesallthingsequallynomatterwhattheirweight,butthereisnorealevidencethatheactuallyusedtheLeaningTowerofPisatodoit.

9. KeyconceptsaboutGravity:a. Gravityisaforcethatattractsthingstooneanother.b. Allbodies(objects)haveagravitationalfield.c. Thelargerabodyis,thegreaterthestrengthofthegravitationalfield.d. Bodiesmustbevery,verylargebeforetheyexertanynoticeablegravitationalfield.e. Gravityacceleratesallthingsequally.Whichmeansallthingsspeedupthesameamountastheyfall.f. Gravitydoesnotcarewhatsizethingsareorwhetherthingsaremoving.Allthingsareaccelerated

towardtheEarthatthesamerateofspeed.g. Gravitydoespullonthingsdifferently.Gravityispullinggreateronobjectsthatweighmore.h. Weightisameasureofhowmuchgravityispullingonanobject.i. Massisameasureofhowmuchmatter(howmanyatoms)makeupanobject.

AbouttheComputerSimulation

1. Togetyouexperiencedwiththeforceofgravitywithoutgettinglostinthemath,there’sanexcellentcomputerprogramthatallowsyoutoseehowmulti‐objectsystemsinteract.Mosttextbooksarelimitedtotheinteractionbetweenaverylargeobject,liketheEarth,andmuchsmallerobjectsthatareveryclosetoit,liketheMoon.Thisseriouslycutsoutmostoftheinterestingsolarsystemsthatareoutthereintherealuniverse.

2. TheUniversityofColoradoatBoulderdesignedagreatsystemtodothehardmathforyou.Don’tbefooledbythesimplisticappearance–thephysicsbehindthesimulationarerock‐solid…meaningthattheresultsyougetareexactlywhatscientistswouldpredicttohappen.

3. GototheMySolarSystemsimulationonthePhETwebsiteandcarefullyfollowtheinstructionsforeachactivity.Answerthequestionsandrecordyourresultsbeforegoingontothenextactivity.Visit:http://phet.colorado.edu/sims/my‐solar‐system/my‐solar‐system.swf

4. Oncetheprogramopens,hitstart.You’llseethepurpleEarthorbitaroundtheyellowSun.DoyounoticehowtheEarthalsocausestheSuntofollowatinyorbit?That’sbecausetheEarthpullsontheSunjustastheSunpullsontheEarth.

5. Pressstop.Noticethe“V?”Thatstandsfordirectionandspeed,asin55mphnorth.Itgiveshowfastyouaregoingaswellasthedirectionyou’regoing.Orinthiscase,theplanet.Noticenearthebottomthatyoucanchangethemassoftheobject.Increasethemasssothatit’slargerthantheSun.Pressstart.

6. Reset,andchangethepurpleobject(Earth)tobethesizeoftheMoon(makeit1).Didyounoticeachangeintheorbitpath?

7. Changethepurplemassbackto10,andincreasethespeedtoalargernumber.Whathappened?8. TheEarthisataveryspecialmassandspeed,isn’tit?9. Resetandmakeyourspeed200.Diditstayinorbit?


10. Addathirdandfourthobjectbypullingdownthemenuontheupperright.Select“Sun,planet,andmoon”andhit“Start.”

11. Whathappensifyouuncheck“showtrace?”(You’llonlyseetheobjectsthemselvesorbiting,notthepaththeytake.)

12. Whathappensifyouuncheck“systemcentered?”(Thesystemwilleventuallywanderoffthescreenastheentiresystemhasacceleration.)

13. Playwiththeprogramforabit,changingthelocationdistancetheobjectsareapart,thespeedanddirectiontheyinitiallystartoutat,andtheirmasses.

b. Whatdoestheyellowobjectrepresent?________________________________________

c. Whatisthemassoftheyellowobject?________________________________________

(Note:Nounitsaregiven,sonounitsarenecessary.)

d. Whatdoesthepurpleobjectrepresent?________________________________________

e. Whatisthemassofthepurpleobject?________________________________________

f. Whatdoestheredarrowrepresent?________________________________________

14. Completethedatatable.Noticeattheendthatyouwillpredictthenecessarymass,velocity,anddistancefromthesunofaplanetinorderforthisplanettomakeacircularorbitaroundasun.

Reading

In1666,IsaacNewtondidhisearlyworkonhisThreeLawsofMotion.Tothisday,thoselawsstillholdtrue.Therehasbeensomeallowancesforreallybigthings(likethecosmos)andforreallysmallthings(liketheatom).Otherthanthat,Newton’sLawsareprettymuchdeadon.

Newton’sLawsareallscientistsandengineersusedtogetthefirstmantothemoon.Theyareanamazinglypowerfulandwonderfulareaofphysics.Ilikethembecauseevidenceofthemiseverywhere.Ifsomethingmovesorcanbemoved,itfollowsNewton’sLaws.Youcan’tsitinacar,walkdowntheroad,drinkaglassofmilk,orkickaballwithoutusingNewton’sLaws.Ialsolikethembecausetheyarerelativelyeasytounderstandandyetopenupworldsofanswersandquestions.Theyaretrulyafoundationforunderstandingtheworldaroundyou.

WheneverIteachaclassaboutgravity,I’lldropsomething(usuallysomethinglarge).Aftertheheadswhiparound,Iaskthehardquestion:“Whydiditfall?”Youalreadyknowtheanswer–gravity.

Butwhy?Whydoesgravitypullthingsdown,notup?Andwhendidpeoplefirststartnoticingthatwesticktothesurfaceoftheplanetandnotfloatupintothesky?

Noonecantellyouwhygravityis…that’sjustthewaytheuniverseiswired.Gravitationisanaturalthingthathappenswhenyouhavemass.Galileowasactuallyoneofthefirstpeopletodoscienceexperimentsongravity.


BuildYourOwnSolarSystemDataTable1

Usetheoriginalpresetforallvaluesforasunandplanet,exceptchangethemassofbody2(purpleobject)asshownbelow:

MassofBody2 DiameterofOrbit(measurewithruler)

1000

100

10

1

0.1

0.01

0.001

0.0001

QuestionstoAnswer:(Notethattheexercisequestionsarebeloweachdatatable)

1. Whateffectdoeschangingthemassoforbitingplanethaveonthediameteroftheorbit?



Usetheoriginalpresetforallvaluesforasunandplanet,exceptchangethemassofbody2(purpleobject)andvelocityasshownbelow:

MassofBody2 VelocityofBody2 Describewhathappened…?

0.1 yvelocity=130

0.1 yvelocity=140

0.1 yvelocity=150

0.1 yvelocity=600

0.1 yvelocity=80

0.1 yvelocity=40

0.1 yvelocity=20

0.1 yvelocity=0

2. Whateffectdoeschangingthespeedhaveonaplanet’sorbit?



Usetheoriginalpresetforallvaluesforasunandplanet,exceptchangethemassofbody2to50andthex‐distanceofbody2asshownbelow:

xdistanceforBody2 DiameterofOrbit(measurewithruler)

30

60

90

120

150

180

210

240

3. Whathappenstotheplanet'sorbitwhenyouincreasetheinitialdistancebetweentheplanetandthesun?



Usetheoriginalpresetforabinarystarandplanet.Changeonlythemassesandrecordyourobservationsbelow.

MassofBody1

MassofBody2

MassofBody3

Istheorbitstable?

4. Findthemassvaluesneededforastableorbit.Circlethevaluesonthetablethatmakeastableorbit.


Usetheoriginalpresetforellipses.Changeonlythemassesandrecordyourobservationsbelow.

MassofBody1

MassofBody2

MassofBody3

MassofBody4

Whathappened?

250 10 1 0.1

5. Whydon’tafeatherandabrickhitthegroundatthesametime?


Lesson#11:WatchYourWeightOverview:IfyoucouldstandontheSunwithoutbeingroasted,howmuchwouldyouweigh?Thegravitationalpullisdifferentfordifferentobjects.Let’sfindoutwhichcelestialobjectyou’dcrackthepavementon,andwhichyourlightweighttoeswouldhavetobecarefulaboutjumpingonincaseyouleaptofftheplanet.

WhattoLearn:Weightisnothingmorethanameasureofhowmuchgravityispullingonyou.Massisameasureofhowmuchstuffyou’remadeoutof.Weightcanchangedependingonthegravitationalfieldyouarestandingin.Masscanonlychangeifyouloseanarm.

Materials

Scaletoweighyourself Calculator Pencil

Experiment

1. Weneedtotalkaboutthedifferencebetweenweightandmass.Ineverydaylanguage,weightandmassareusedinterchangeably,butscientistsknowbetter.

2. Massishowmuchstuffsomethingismadeoutof.Ifyou’reholdingabowlingball,you’llnoticethatit’shardtogetstarted,andonceitgetsmoving,itneedsanotherpushtogetittostop.Ifyouleavethebowlingballonthefloor,itstaysput.Onceyoupushit,itwantstostaymoving.This“sluggishness”iscalledinertia.Massishowmuchinertiaanobjecthas.

3. Everyobjectwithmassalsohasagravitationalfield,andisattractedtoeverythingelsethathasmass.Theamountofgravitysomethinghasdependsonhowfaraparttheobjectsare.Whenyousteponabathroomscale,youarereadingyourweight,orhowmuchattractionisbetweenyouandtheEarth.

4. Ifyousteppedonascaleinaspaceshipthatisparkedfromanyplanets,moons,blackholes,orotherobjects,itwouldreadzero.Butisyourmasszero?Noway.You’restillmadeofthesamestuffyouwereonEarth,soyourmassisthesame.Butyou’dhavenoweight.

5. WhatisyourweightonEarth?Let’sfindoutnow.6. Steponthescaleandreadthenumber.Writeitdown.7. Now,whatisyourweightontheMoon?Thecorrectionfactoris0.17.Somultiplyyourweightby0.17to

findwhatthescalewouldreadontheMoon.8. Forexample,ifIweigh100poundsonEarth,thenI’dweightonly17poundsontheMoon.Ifthescalereads

10kgonEarth,thenitwouldread1.7kgontheMoon.Completethedatatable..


WatchYourWeightDataTable

WeightonPlanet/Object=WeightonEarthxGravityCorrection

Planet/Object WeightonEarth GravityCorrectionWeighton

Planet/Object

TheSun 28

Mercury 0.38

Venus 0.91

Earth 1

Moon 0.17

Mars 0.38

Jupiter 2.14

Saturn 0.91

Uranus 0.86

Neptune 1.1

Pluto 0.08

OuterSpace 0

Betelgeuse 14,000

WhiteDwarf 1,300,000

NeutronStar(Pulsar) 140,000,000,000

BlackHole ∞


Reading

Weightisnothingmorethanameasureofhowmuchgravityispullingonyou.Thisiswhyyoucanbe“weightless”inspace.Youarestillmadeofstuff,butthere’snogravitytopullonyousoyouhavenoweight.Thelargerabodyis,themoregravitationalpull(orinotherwordsthelargeragravitationalfield)itwillhave.

TheMoonhasafairlysmallgravitationalfield(ifyouweighed100poundsonEarth,you’donlybe17poundsontheMoon).TheEarth’sfieldisfairlylargeandtheSunhasaHUGEgravitationalfield(ifyouweighed100poundsonEarth,you’dweigh2,500poundsontheSun!).

Asamatteroffact,thedogandIbothhavegravitationalfields!Sincewearebothbodiesofmass,wehaveagravitationalfieldwhichwillpullthingstowardus.Allbodieshaveagravitationalfield.However,mymassissosmallthatthegravitationalfieldIhaveisminiscule.Somethinghastobeverymassivebeforeithasagravitationalfieldthatnoticeablyattractsanotherbody.

Sowhat’sthemeasurementforhowmuchstuffyou’remadeof?Mass.Massisbasicallyaweightlessmeasureofhowmuchmattermakesyouyou.Ahamsterismadeofafairlysmallamountofstuff,soshehasasmallmass.Iammadeofmorestuff,somymassisgreaterthanthehamster’s.Yourhouseismadeofevenmorestuff,soitsmassisgreaterstill.So,here’saquestion.Ifyouare“weightless”inspace,doyoustillhavemass?Yes,theamountofstuffyou’remadeofisthesameonEarthasitisinyourspaceship.Massdoesnotchange,butsinceweightisameasureforhowmuchgravityispullingonyou,weightwillchange.

DidyounoticethatIputweightlessinquotationmarks?Wonderwhy?

Weightlessnessisamyth!Believeitornot,oneisneverweightless.Apersoncanbeprettyclosetoweightlessinverydeepspace,buttheastronautsinaspaceshipactuallydohaveabitofweight.

Thinkaboutitforasecond.IfaspaceshipisorbitingtheEarth,whatisitdoing?It’sconstantlyfalling!Ifitwasn’tmovingforwardattensofthousandsofmilesanhouritwouldhittheEarth.It’smovingfastenoughtofallaroundthecurvatureoftheEarthasitfallsbut,indeed,it’sfallingastheEarth’sgravityispullingittous.

Otherwisetheshipwouldfloatouttospace.Sowhatistheastronautdoing?She’sfalling,too!TheastronautandthespaceshiparebothfallingtotheEarthatthesamerateofspeedandsotheastronautfeelsweightlessinspace.Ifyouwereinanelevatorandthecablesnapped,youandtheelevatorwouldfalltotheEarthatthesamerateofspeed.You’dfeelweightless!(Don’ttrythisathome!)

Eithernow,oratsomepointinthefutureyoumayaskyourselfthisquestion,“Howcangravitypullharder(putmoreforceonsomethings,likebowlingballs)andyetaccelerateallthingsequally?”WhenwegetintoNewton’slawsinafewlessons,you’llrealizethatdoesn’tmakeanysenseatall.MoreforceequalsmoreaccelerationisbasicallyNewton’sSecondLaw.

Well,Idon’twanttotaketoomuchtimeheresincethisisalittledeeperthenweneedtogobutIdofeelsomeexplanationisinordertoavoidfutureconfusion.Theexplanationforthisisinertia.WhenwegettoNewton’sFirstLawwewilldiscussinertia.Inertiaisbasicallyhowmuchforceisneededtogetsomethingtomoveorstopmoving.

Now,let’sgetbacktogravityandacceleration.Let’stakealookatabowlingballandagolfball.Gravityputsmoreforceonthebowlingballthanonthegolfball.Sothebowlingballshouldacceleratefastersincethere’smoreforceonit.However,thebowlingballisheaviersoitishardertogetitmoving.Conversely,thegolfballhaslessforce


pullingonitbutit’seasiertogetmoving.Doyouseeit?Theforceandinertiathingequaloutsothatallthingsaccelerateduetogravityatthesamerateofspeed!

Gravityhadtobeoneofthefirstscientificdiscoveries.Whoeverthefirstguywastodroparockonhisfoot,probablyrealizedthatthingsfalldown!However,eventhoughwehaveknownaboutgravityformanyyears,itstillremainsoneofthemostelusivemysteriesofscience.Atthispoint,nobodyknowswhatmakesthingsmovetowardabodyofmass.

WhydidtherockdroptowardtheEarthandonthatguy’sfoot?Westilldon’tknow.Weknowthatitdoes,butwedon’tknowwhatcausesagravitationalattractionbetweenobjects.Gravityisalsoaveryweakforce.Comparedtomagneticforcesandelectrostaticforces,thegravitationalforceisextremelyweak.Howcome?Nooneknows.Alargeamountofamazingbrainpowerisbeingusedtodiscoverthesemysteriesofgravity.Maybeitwillbeyouwhofiguresthisout!

QuestionstoAnswer

1. Ofthefollowingobjects,whichonesareattractedtooneanotherbygravity?a)AppleandBananab)BeagleandChihuahuac)EarthandYoud)Alloftheabove

2. TrueorFalse:Gravityacceleratesallthingsdifferently

3. TrueorFalse:Gravitypullsonallthingsdifferently

4. IfIdropagolfballandagolfcartatthesametimefromthesameheight,whichhitsthegroundfirst?

5. Thereisamonkeyhangingonthebranchofatree.Awildlifebiologistwantstoshootatranquilizerdartatthemonkeytomarkandstudyhim.Thebiologistverycarefullyaimsdirectlyattheshoulderofthemonkeyandfires.However,thegunmakesaloudenoughnoisethatthemonkeygetsscared,letsgoofthebranchandfallsdirectlydownward.Doesthedarthitwherethebiologistwasaiming,ordoesitgohigherorlowerthanheaimed?(This,bytheway,isanoldthoughtproblem.)


Lesson#12:SundialOverview:UsingthepositionoftheSun,youcantellwhattimeitusbymakingoneofthesesundials.TheSunwillcastashadowontoasurfacemarkedwiththehours,andthetime‐tellinggnomonedgewillalignwiththepropertime.

WhattoLearn:Ingeneral,sundialsaresusceptibletodifferentkindsoferrors.Ifthesundialisn’tpointednorth,it’snotgoingtowork.Ifthesundial’sgnomonisn’tperpendicular,it’sgoingtogiveerrorswhenyoureadthetime.Latitudeandlongitudecorrectionsmayalsoneedtobemade.Somedesignsneedtobealignedwiththelatitudeatwhichtheyreside(ineffect,theyneedtobetippedtowardtheSunatanangle).Tocorrectforlongitude,simplyshiftthesundialtoreadexactlynoonwhenindicatedonyourclock.Thisisespeciallyimportantforsundialsthatliebetweenlongitudinalstandardizedtimezones.Ifdaylightsavingstimeisineffect,thenthesundialtimelinemustbeshiftedtoaccommodateforthis.Mostshiftsareonehour.

Materials

SimpleSundial Indexcard Scissors TapeIntermediateSundial 2yardsticksormetersticks Protractor Chalk ClockAdvancedSundial OldCD(thiscanalsobethetransparentCDatthetopofDVD/CDspindles) EmptyCDcase Skewer Stickytape Cardboardorsmallpieceofclay Protractor Scissors Tape Hotglue


SimpleSundial

1. Thissundialtakesonlyacoupleofminutestomake,andreadseasilyforbeginnerstudents.2. Cutoutthetemplatebelow.3. Cutyourindexcardintotwotrianglesbycuttingfromonecornertotheoppositediagonalcorner.Stackthe

twotrianglesandtapetogether.Thisiscalledyourgnomon.4. Tapethetriangletoyour12‐hourline,puttingtapeonbothsidesofthegnomonasyoustickittothepaper.5. Putthesundialinasunnyplacewhereitwon’tbedisturbed(likeinsideofasunnywindoworonatable

outdoors).6. Pointthesundialsothatthegnomonispointingnorth.Thisismosteasilydoneifyouorientyoursundialat

exactlynooninyourlocation.LineupthesundialwiththeSunsothattheshadowthegnomonmakeslinesupexactlywiththe12.

7. Tapethesundialdownsoitwon’tmoveorgetblownaway.8. Thegnomonmustbeexactlyperpendiculartothehourmarkers.Usearulerorabookedgetohelpyouline

thisup.

SimpleSundialTemplate

QuestionstoAnswer

1. Whatkindsofcorrectionsneedtobemadeforyoursundial?2. Whenwouldn’tyoursundialwork?3. Howcanyouimproveyoursundialtobemoreaccurate?

IntermediateSundial


1. Findasunnyspotthathasconcreteandgrassyarearightnexttoeachother.You’regoingtopoketheyardstickintothegrassanddrawontheconcretewithchalk,sobesurethattheconcretegoesinanapproximatelyeast‐westdirection.

2. Firstthinginthemorning,stickoneoftheyardsticksintothedirt,rightattheedgeoftheconcrete.3. Atthetopofthehour(likeat8a.m.or9a.m.),goouttoyouryardsticktomarkaposition.4. Laythesecondyardstickdownalongtheshadowthattheuprightyardstickmakesontheground.Usechalk

todrawtheshadow,andusetheyardsticktomakeyourlinestraight.5. Labelthislinewiththehour.6. Setyourtimerandrunbackoutatthetopofthenexthour.7. Repeatsteps3‐6untilyoufinishmarkingyoursundial.8. Whenyou’vecompletedyoursundial,filloutthetable.

IntermediateDataTable

Don’tforgettolabelyourunitsforcolumns2and3!

ExactTimeofDay ShadowLength

AnglethattheSunMovedfromLastHour

QuestionstoAnswer


AdvancedSundial


Thissundialwillworkforalllongitudes,buthasalimitedrangeoflatitudes.Ifyouliveinthefarnorthorfarsouth,you’llneedtogetcreativeabouthowtomounttheCDsothatthegnomonispointedatthecorrectangle.Forexample,attheequator,theCDwilllieflat(whichiseasy!),butnearthenorthandsouthpoles,theCDwillbeupsidedown.

1. Cutoutthetimeline.2. Putalineofdouble‐sidedstickytapealongthebackofthetimeline.Extendthetapeabout¼”(onthe

bottomedge)soit’shangingoffthepaperalittle.3. FlipthetimelineoverandrolltheCDalongthisbottomedge,stickingthetimelinetotheedgeoftheCD.

ThetimelineshouldbefacinginwardtowardthecenteroftheCD,perpendiculartotheCDsurface.4. Nowit’stimetoplugupthecenterhole.YoucancutoutcirclesfromaCDandattachwithtape,orusea

smallpieceofclay.5. PushtheskewerthroughtheexactmiddleoftheCD.6. OpenuptheCDcase.7. Positionthenoonmarkeratthebottomandstickitusingapieceofdouble‐sidedstickytapeorhotglue.8. TheothersideoftheCDisgluedtotheCDcaseatthesameangleasyourlatitude.Forexample,ifIliveat

43onorth,IwouldusemyprotractoronthegroundalongthebaseoftheCDcaseandlifttheCDuntilthegnomonreadsat43o.PutadabofhotgluetoattachtheCDtothelidofthecase.

9. Gooutsideandpointthegnomonnorth(youmaywanttouseacompassforthisifit’snotnoon.)10. Thedialwillhaveashadowthatfallsonthetimeline.Youcanreadthetimerightoffthetimeline.11. Foradvancedstudents:Timelinecorrection:DoyourememberhowtheSunwasfastorslowinthe

Stargazer’sWallChartfromthelessonentitled:What’sintheSky?ThatwavylineiscalledtheEquationofTime,andyou’llneedittocorrectyoursundialifyouwanttobecompletelyaccurate.ThisisagreatdemonstrationforaScienceFairproject,especiallywhenyouaddamodeloftheSunandEarthtohelpyouexplainwhat’sgoingon.

QuestionstoAnswer


Reading

SundialshavebeenusedforcenturiestokeeptrackoftheSun.Therearedifferenttypesofsundials.Someusealineoflighttoindicatewhattimeitis,whileothersuseashadow.

Hereareafewdifferentmodelsthat,althoughtheylookalotdifferentfromeachother,actuallyallworktogivethesameresults!YoursundialwillworkalldaysoftheyearwhentheSunisout.


You’llnoticethatnorthisthedirectionthatyourshadow’slengthistheshortest.However,ifyoudon’tknowwhereeastandwestare,allyoucandoisknowwherenorthis.TheequinoxisaspecialtimeofyearbecausetheSunrisesintheexacteastandsetsintheexactwest,makingthesetwopointsexactlyperpendicularwiththenorthforyourlocation(whichtheyusuallyaren’t).Atsunset,youcanviewyourshadow(quicklybeforeitdisappears)anddrawitwithchalkontheground,makingalinethatrunseast‐west.90ocounterclockwisefromthelineisnorth.

Ingeneral,sundialsaresusceptibletodifferentkindsoferrors.Ifthesundialisn’tpointednorth,it’snotgoingtowork.Ifthesundial’sgnomonisn’tperpendicular,it’sgoingtogiveerrorswhenyoureadthetime.Latitudeandlongitudecorrectionsmayalsoneedtobemade.Somedesignsneedtobealignedwiththelatitudetheyresideat(ineffect,theyneedtobetippedtowardtheSunatanangle).Tocorrectforlongitude,simplyshiftthesundialtoreadexactlynoonwhenindicatedonyourclock.Thisisespeciallyimportantforsundialsthatliebetweenlongitudinalstandardizedtimezones.TheEquationofTimefromtheadvancedlessonentitled:What’sintheSky?canbeusedtocorrectfortheSunrunningsloworfast.Remember,thiseffectisduetoboththeEarth’sorbitnotbeingaperfectcircleandthefactthatthetiltaxisisnotperpendiculartotheorbitpath.Ifdaylightsavingstimeisineffect,thenthesundialtimelinemustbeshiftedtoaccommodateforthis.Mostshiftsareonehour.


Lesson#13:DiffractionOverview:Whenlightpassesthroughdiffractiongratings,itsplits(diffracts)thelightintoseveralbeamstravelingindifferentdirections.Ifyou'veeverseenthe“iridescence”ofasoapbubble,aninsectshell,oronapearl,you'veseennature'sdiffractiongratings.

WhattoLearn:Everplaywithaprism?Whensunlightstrikestheprism,itgetssplitintoarainbowofcolors.Prismsun‐mixthelightintoitsdifferentwavelengths(whichyouseeasdifferentcolors).Diffractiongratingsaretinyprismsstackedtogether.Thedirectioninwhichthebeamgetssplitanddiffracteddependsonthespacingofthediffractiongratingandalsothewavelengthoftheincominglight.

Materials

Feather CDorDVD Diffractiongrating

Experiment

1. Takeafeatherandputitoveraneye.2. Stareatalightsourcethroughthefeather,likeanincandescentlight.3. YoushouldseetwoorthreelightsandarainbowX.4. AimtheCDsothelighthitstheCDandmakesrainbows.5. Lookatthelightsourcethroughthediffractiongrating.6. Drawwhatyouseeforallthree.Weretheythesame?7. Findanotherlightsourceandrepeattheexperiment,recordingyourobservationsasyougo.8. Completethetableasyouviewthedifferentlightsourcesthroughyourdiffractiongratings.


DiffractionDataTable

LightSource DiffractiveObject(Feather,CD,orGrating?)

DrawWhatYouSee:


Reading

Everplaywithaprism?Whensunlightstrikestheprism,itgetssplitintoarainbowofcolors.Prismsun‐mixthelightintoitsdifferentwavelengths(whichyouseeasdifferentcolors).Diffractiongratingsaretinyprismsstackedtogether.Thedirectioninwhichthebeamgetssplitanddiffracteddependsonthespacingofthediffractiongratingandalsothewavelengthoftheincominglight.Thefeatherworksbecausetherearetiny“hairs”onthefeatherthatareactingliketinyprisms.

DiffractiongratingswerefirstdiscoveredbyJamesGregory,rightaroundthetimeNewtonperformedhisfamousprismexperimentswithbirdfeathers.Thefirstdiffractiongratingstookalongtimetoconstruct,astheywereindividualhairsstrungbetweenscrews.

QuestionstoAnswer

1. Whichlightsourcegavethemostinterestingresults?

2. Whathappenswhenyouaimalaserbeamthroughthediffractiongrating?

3. HowisaCDdifferentandthesameasadiffractiongrating?

4. Whydoesthefeatherwork?


Lesson#14:InfraredVisionOverview:Infraredlightisinthepartoftheelectromagneticspectrumthatisn’tusuallyvisibletohumaneyes,butusingthisniftytrick,youwilleasilybeabletoseetheIRsignalfromyourTVremote,remote‐controllerforanRCcar,andmore!

WhattoLearn:WhenyoupressthebuttononyourremotecontroltoyourTV,you’reusinginfraredlight(IR)tocontrolyourTV.Infraredlightisinvisibletooureyes.However,snakescandetectIRandseetheredderhuesthatwecan’t.EverywarmbodygivesofflightintheIR,sosnakesusethistofindmiceinthecoolnight.

Materials:

Youwillneedtheseitems:

Remote control for TV or stereo

Camera (video or still camera) Thisisjustasuggestedlistofobjects.Feelfreetofindyourown! Metalfryingpanorcookiesheet Plasticsheet Plasticbaggie Trashbag(whiteorblack,orboth) Woodencuttingboard

Experiment

1. Grabaremotecontrolandverifythatitisindeedworking.Turnthedeviceonandoffusingtheremote.2. Grabasheetofplastic,likeacuttingboard,andplaceitbetweenyourremoteandthedevice.Doesitturn

onwhenyouaimthebeamatit?Doestheplasticblockthebeam?3. Openupatrashbagandplaceonesideofthebagbetweenyourremoteandthedevice.Didthatblockthe

beam,ordidtheremoteturnonthedevice?4. Whatelsecanyoutry?Howaboutaclearbag?5. Aclearbagfilledwithwater?6. Asheetofpaper?7. Whataboutametalpan?Findsomethingthat’snotcoatedwithTeflon.Doesinfraredgothroughmetal?8. Whatifyoupointitatawhitewallbehindyou,pretendingthewhitewallisamirrorandaimingitsoitwill

reflectitbacktothedevice?9. Completethedatatable.10. Nowlet’smaketheinvisibleinfraredlightvisible.Takeyourcamera(eitherstillorvideocamerawillwork)

andturniton.Putitonamodewhereyoucanseethroughtheviewscreen.Aimthecamerarightattheemitterfortheremote(usuallynearthetop)andpressabutton.Pointtheremoterightatthecameraandwatchthroughthecamera.Oureyesnormallycan’tseetheinfraredlight,butthecameracan!

11. Thecameracanalsoseetheotherwisedarkendoftheremote!Doesyourcamerahaveaspecialnightvisionmode,whereit’sespeciallysensitivetoinfraredlight?Ifso,tryit!


InfraredDataTable

Item/ObjectTested GuessFIRST!WilltheInfraredLight

PassThrough?

WhatHappened?(Diditpassthroughornot?)

Reading

Differentdetectorsaresensitivetodifferentcolors.Youreyeballsaresensitivetospecificcolorsinthe400‐700nm(nanometer)range,whichishowlongonewavelengthis.Ananometerisextremelytiny!

Thefrequencyofredlightisaround430trillionHz(Hertz,whichisonewavecyclepersecond).Ifyouweretocountthenumberofwavespassingacertainpointinonesecond,you’dcount430trillionwaves.Ifyoucounted750trillionwaves,thelightwouldbeviolet.Differentcolorshavedifferentfrequencies.

Lightenergy(alsocalledelectromagneticradiation)withthelowestamountsofenergyandlongestwavelengths(1mmto1km)areradiowaves.Theseareemittedbyradiogalaxieslikequasars,supernovaleftovers,andtheradiotoweratthetopofthehill.Radiowavesfromspacewithawavelengthgreaterthan100metersarereflectedbackintospacebyouratmosphere.RadiowavesaredetectedinspacebytheCOBEsatellite,theVLAinNewMexico,andtheAreciboObservatoryinSouthAmerica.

Thenextstepdowninwavesizeismicrowaves,whichhavemoreenergythanradiowavesbutareashorterwavelength.Thesearetheonesinsideyourmicrowavethatexcitethewatermoleculesinsideyourfoodsothatyourfoodheatsup.

Infrared(IR)hasslightlymoreenergyandanevensmallerwavelength(700nanometers,ornmto1mm),andyoucanfeelthislightaswarmthonyourskinwhenyoustepintotheSun.There’salotofinfraredradiationinspacearoundthestar‐formingcloudsandobjectswithatemperatureabove1000oC.SOFIAandtheInfraredObservatorybothdetectinfraredfromvariousstarsinspace.


Visiblelightoropticallightwavesarethevisiblerainbowyoucanseewithyoureyesafterarainyday.Thesewavelengthshavemoreenergyandshorterwavelengths(300to700nm)thaninfrared.TheHubbleSpaceTelescopeandEarth‐boundopticaltelescopeslookatstars,galaxies,andplanets.

Ultraviolet(UV)lighthasmoreenergyandshorterwavelengths(10nmto390nm)thanvisiblelight,andyou’llfindhotstarsemitlargelyinthisregionofthespectrum.TheozonelayerprotectsusfrommostoftheUV,butnotall.That’swhyyougetasunburnifyoudon’twearsunblock,andwhycolorsfadeinsunlight.SkyLab,AstrotelescopeandSOHOallsearchforUV.SOHOlooksdirectlyattheSun’scoronatogetamazingimagesinUV.

X‐rayshaveevenmoreenergyandshortwavelengths(0.01nmto10nm)thanUVlight,andyou’llfindtheseareemittedbyactiveblackholes,supernovaremnants,andveryhotstars(we’retalking1millionto100millionoC).Fortunatelyforus,thesearequicklyabsorbedintheupperatmosphereandmostnevermakeittothesurfaceofEarth.X‐raysgeneratedonearthareemittedbyelectronsoutsidethenucleusofanatom.ROSATlookedatclustergalaxiestodetectX‐raysources.

Deadlygammarayshavethemostamountofenergyandtheshortestfrequency(lessthan0.01nm),andyou’llfindtheseinareasofsuperflaresfrompulsars,supernovas,andradioactiveatoms.GammaraysarelikeX‐rays,inthattheybothcangothroughthickmaterials,andwouldrathergothroughyourdetectorthanintoittobedetected.GammaraysonEartharegeneratedinsidethenucleusofanatom.TheComptonObservatorylookedatquasarstodetectgammarays.

QuestionstoAnswer

1. Lookoveryourdatatable.Whatkindsofobjects(plastic,metal,natural,etc.)allowinfraredlighttopassthroughthem?

2. Whydoesthecameraworkinmakingtheinfraredlightvisible?


Lesson#15:UVLightOverview:Stars,includingourSun,produceallkindsofwavelengthsoflight,includingUV(ultra‐violet).That’sthewavelengththatgivesyousunburns.We’regoingtofindoutthebestwaytoprotectyoufromtheharmfulrays.

WhattoLearn:TheUVbeadswe’regoingtouseinourexperimentaremadefromachemicalthatreactswithlight.IttakestheUVlightfromtheSunandthenre‐emitsitinadifferentwavelengththat’svisibletous.

Materials

5UVbeads(thesechangecolorswhenexposedtotheSun) Tape(double‐sidediseasier) Sunblock Sunglasses Sunnyday Water Pieceoffabric Clearplasticbag

Experiment

1. Placeapieceoftapeonthedatatable,andstickyourbeadstothetape,oneineachbox.2. Walkoutsidewithyourdatatableandrecordyourobservations.

UVLightDataTable1

Bead ColorInside ColorWheninSunlight HowLongDidItTaketoReturntoIndoorColor?

(measureinseconds)

1

2

3

4

5

3. Walkbackindoorsandcoverthebeads,blockingoutalllight.Peekatthemeveryminuteortwotofindoutwhenthey’vereturnedtotheirunexposedcolor.


4. NowprepareyoursecondroundoftestingbydoingthefollowingbeforeexposingthebeadstotheSun:a. Placeabeadinsideabaggie.b. Placeasecondbeadinsideabaggiefilledwithwater.c. Smearacleanbaggiewithsunblockandplaceathirdbeadinside.d. Placeapairofsunglassesoverafourthbead.e. Placeafifthbeadunderapieceoffabric.

5. Walkyour5beadsoutsideandrecordyourobservationsinthedatatable.

UVLightDataTable2

Bead ColorInside ColorWheninSunlight

1:Baggie

2:Baggie+Water

3:Sunblock

4:Sunglasses

5:Fabric

6. Bringyourbeadsbackinsideandreturnthemtotheirunexposedcolor.7. Prepareyourthirdroundoftestingbyexposingyourbeadstosomeofthefollowing:

f. Afluorescentlampg. Anincandescentlamph. Flashlighti. Glowstickj. Computerscreenk. Reflectedsunlightusingamirrorl. Candleflame(pleasebecarefulwiththis!)m. Anyotherlightsourceyouhaveaccessto

8. Recordyourobservationsinthedatatable.


UVLightDataTable3

LightSource

ColorInside ColorWhenExposed HowLongDidItTaketoChangeColorwhenExposed?

Reading

UV‐sensitivematerialshaveapigmentinsidethatchangescolorwhenexposedtoUVlightfromeithertheSunorlightsthatemitinthe350nm–300nmwavelength.(UVAishigh‐energy:400‐320nm,andUVBislowenergy:320‐280nm).Ifyouhavefluorescentblacklights,usethem.(Doregularincandescentbulbswork?Ifnot,youknowtheyemitlightoutsidetherangeofthebeads!)

Stars,includingourSun,produceallkindsofwavelengthsoflight,evenUV.TheUVbeadswe’regoingtouseinourexperimentaremadefromachemicalthatreactswithlight.IttakestheUVlightfromtheSunandthenre‐emitsitinadifferentwavelengththat’svisibletous.WhenaparticleofUVlightsmacksintoanatom,itcollideswithanelectronandmakestheelectronjumptoahigher,moreenergeticstatethatisabitfurtherfromthecenteroftheatomthanit’scomfortablebeing.That’showenergygetsabsorbedbyanatom.Theamountofenergyanelectronhasdetermineshowfarfromtheatomithastobe.Theelectronprefersbeinginitslowerstate,soitrelaxesandjumpsbackdown,transferringablipofenergyawayasitdoes.ThisblipofenergyisthelightweseeemittedfromtheUVbeads.ThisprocesscontinuesaslongasweseeacolorcomingfromtheUVbeads.

Whenlighthitsthepigmentmolecule,itabsorbstheenergyandactuallyexpandsasymmetrically(oneendofthemoleculeexpandsmorethantheother).Differentexpansionamountswillgiveyouadifferentcolor.Althoughit’sabitmorecomplicatedthanthat,younowhavethebasicidea.Yourbeadswillchangecolorsthousandsoftimesbeforetheywearout,soenjoythesesuper‐inexpensiveUVdetectors.

Anoteaboutsunblock:YoucantestdifferentSPFlevelsofsunblock,buthere’sthemainideabehindtheratings:thenumberforSPFisthenumberofminutesittakestogetthesameSunexposurethanifyouweren’twearinganyforoneminute.Forexample,SPF30willgiveyouthesameSunexposureafter30minutesthatyouwouldnormallygetifyouweren’twearinganyafterjustoneminute.


QuestionstoAnswer

1. Whatkindsoflightsourcesdidn’tworkwiththeUVbeads?

2. DidyoursunblockreallyblockouttheUVrays?

3. WhichwasthebestprotectionagainstUVrays?


Lesson#16:StarWobbleOverview:Howdoastronomersfindplanetsarounddistantstars?Ifyoulookatastarthroughbinocularsoratelescope,you’llquicklynoticehowbrightthestaris,andhowdifficultitistoseeanythingotherthanthestar,especiallyasmallplanetthatdoesn’tgenerateanylightofitsown!Astronomerslookforashift,orwobble,ofthestarasitgetsgravitationally“yanked”aroundbytheorbitingplanets.Bymeasuringthiswobble,astronomerscanestimatethesizeanddistanceoflargerorbitingobjects.

WhattoLearn:Dopplerspectroscopyisonewayastronomersfindplanetsarounddistantstars.Ifyourecallthelessonwherewecreatedourownsolarsysteminacomputersimulation,yourememberhowthestarcouldbeinfluencedbyasmallerplanetenoughtohaveatinyorbitofitsown.Thistinyorbitiswhatastronomersaretryingtodetectwiththismethod.

Materials

Severalbouncyballsofdifferentsizesandweights,softenoughtostabwithatoothpick Toothpicks

Experiment

1. Doesyourballhaveanumberwrittenonit?Ifso,that’stheweight,andyoucanskipmeasuringtheweightwithascale.

2. Ifnot,weigheachoneandmakeanoteinthedatatable.3. Taketheheaviestballandspinitonthetable.Canyougetittospininplace?That’slikeaSunwithoutany

planetsaroundit.4. Insertatoothpickintotheball.Nowinserttheendofthetoothpickintothesmallestweightball.Nowspin

theoriginalball.Whathappened?5. Completethedatatable.


StarWobbleDataTable

WeightofBall#1 WeightofBall#2 HowMuchDiditWobble?(Useascaleof1to5,

with5beingthemostwobble)

Reading

Nearlyhalfoftheextrasolar(outsideoursolarsystem)planetsdiscoveredwerefoundbyusingthismethodofdetection.It’sveryhardtodetectplanetsfromEarthbecauseplanetsaresodim,andthelighttheydoemittendstobeinfraredradiation.OurSunoutshinesalltheplanetsinoursolarsystembyonebilliontimes.

ThismethodusestheideathatanorbitingplanetexertsagravitationalforceontheSunthatyankstheSunaroundinatinyorbit.Whenthisisviewedfromadistance,thestarappearstowobble.Notonlythat,thissmallorbitalsoaffectsthecolorofthelightwereceivefromthestar.Thismethodrequiresthatscientistsmakeveryprecisemeasurementsofitspositioninthesky.

QuestionstoAnswer

1. Forhomeworktonight,findouthowmanyextrasolarplanetsscientistshavedetectedsofar.

2. Alsoforhomework,findoutthenames(theywillprobablybeastringofnumbersandletterstogether)ofthe3mostrecentextrasolarplanetdiscoveries.


Lesson#17:SpaceTelescopesOverview:NASA’sGreatObservatoriesconsistoffourspacetelescopes,eachdesignedtolookattheuniverseinonesmallpartoftheelectromagneticspectrum:infrared,visible,X‐ray,andgammarays.EachtelescopeisasatellitethatorbitstheEarthinaveryspecificway.

WhattoLearn:There’sacommonmisconceptionaboutgravityandspace,inthatmostfolksbelievesatellitesdon’tmoveinorbit.Thetruthis,satellitesmustmaintainaveryspecificvelocityinordertomaintaintheirstableorbits.

Materials

Fivedifferentsizesofsmallballs:marbles,ping‐pong,rubberbouncy,etc. Tape Sheetofpaper

Experiment

1. Curlyourpaperintoaconeshapesooneendiswiderthantheother.Itshouldlooklikeanicecreamcone.2. Tapetheconeintoplaceusingyourtape.Youmightneedacoupleofpieces.3. Holdtheconewiththesmallenddown.4. Yourjobistoplaceyourmarbleontheinsideedgeoftheconenearthetopandrotatetheconesothatthe

marblestaysnearthetopedgewithoutfallingdowninsideorflyingoutofthetop.5. Placeyoursmallsatellitesinorderfromlightesttoheaviest.Entertheminthisorderinthedatatable.

Recordhowfastyouhadtocircletheconetokeepthesatelliteinorbitintheobservationscolumn.Didyouhavetomovethesatelliteslower,faster,orsomethinginbetween?

SpaceTelescopesDataTable

Item/Object Observations


Reading

Manypeoplethinkthatsatellitesdon’tmoveinorbit.Nothingcouldbefurtherfromthetruth!IfyoudropaballonEarth,itfalls16feetthefirstsecondyoureleaseit.Ifyouthrowtheballhorizontally,itwillalsofall16feetinthefirstsecond,eventhoughitismovinghorizontally…itmovesbothawayfromyouanddowntotheground.

Nowconsideranotherobject,likeabulletshothorizontally.Ittravelsalotfasterthanyoucanthrow–about2,000feeteachsecond.Butitwillstillfall16feetduringthatfirstsecond.Gravitypullsonallobjects(liketheballandthebullet)thesameway,nomatterhowfasttheygo.

Whatifyoushootthebulletfasterandfaster?Gravitywillstillpullitdown16feetduringthefirstsecond.RememberthatthesurfaceoftheEarthisround.Canyouimaginehowfastwe’dneedtoshootthebulletsothatwhenthebulletfalls16feetinonesecond,theEarthcurvesawayfromthebulletatthesamerateof16feeteachsecond?

Answer–thatbulletneedstotravelnearly5milespersecond.Thisishowsatellitesstayinorbit–goingjustfastenoughtokeepfromfallinginwardandnottoofastthattheyflyoutoforbit.Satellitesneedtoconstantlycourse‐correcttokeepontrack.

IfwelauncharocketstraightintotheskytobeinorbitaroundtheEarth,unlesswegivethatrocketahorizontalvelocityaswell,it’sgoingtocrashrightbacktoEarth.EverythingthatorbitstheEarthhasaspecificspeedatwhichittravelsinordertomaintainitsstableorbit.

TheHubbleSpaceTelescopewaslaunchedbythespaceshuttlein1990,andisthebest‐knownobservatory.Hubbleorbits380milesabovethesurfaceoftheEarthandhassentthousandsofphotostoscientistsonEarthtostudy.Hubbleoperatesinthevisiblepartofthespectrum.

TheComptonObservatorywasthesecondtobelaunchedin1991,andholdstherecordforheaviestastrophysicalpayloadever(17tons).Comptoncollectedinformationinthegammaraypartofthespectrum,whichmeantitlookedatsomeofthemostviolentpartsoftheuniversetorecorditsdata.Itwassafelyde‐orbitedin2000.

TheChandraObservatorywaslaunchedin1999,andcurrentlystudiesX‐raysfromblackholes,quasars,darkmatter,supernovas,andhigh‐temperaturegases.Chandraholdstherecordforthebestmirrors:Theyarethemostaccuratelyshaped,preciselyaligned,smoothestmirrorsevercreated.Chandra’salignmentissoprecisethatyoucanuseittoreadanewspaperfromahalfmileaway.

TheSpitzerSpaceTelescopewasthefourthtobelaunchedintotheprogramin2003.Spitzerspecializesinthermalinfraredlight,mostofwhichisblockedbytheEarth’satmosphereandnevermakesittothesurfaceoftheEarth.Sothisscopeisseeingthingswe’veneverbeenabletobefore.Sinceviewingintheinfraredmeansthatyoucanseethroughdustandgasparticles,Spitzerisabletoshowusthingsthatwouldnormallybehiddentousifweweretoviewthemoptically.Spitzerlooksforcoolerspaceobjects(thermallyspeaking)suchassmallstars,extrasolarplanets,andgiantmolecularclouds.


QuestionstoAnswer

1. Whathappenswhenyourmarblesatellitemovestooslowly?

2. Whathappenswhenthemarblesatelliteorbitstoofast?

3. Whateffectdoeschangingthemarblemasshaveonyoursatellitespeed?

4. Howisthismodelliketherealthing?


Astronomy2Evaluation

StudentWorksheet

Overview:Today,you’regoingtotaketwodifferenttests:thequizandthelabpractical.You’regoingtotakethewrittenquizfirst,andthelabpracticalattheendofthislab.Thelabpracticalisn’tapapertest–it’swhereyougettoshowyourteacherthatyouknowhowtodosomething.

LabTest&Homework

1. Yourteacherwillaskyoutosharehowmuchyouunderstandaboutastronomy.Sincescienceissomuchmorethanjustreadingabookorcirclingtherightanswer,thisisanimportantpartofthetesttofindoutwhatyoureallyunderstand.

2. Whileyouarewaitingforyourturntoshowyourteacherhowmuchofthisstuffyoualreadyknow,yougettochoosewhichhomeworkassignmentyouwanttocomplete.Theassignmentisduetomorrow,andhalfthecreditisforcreativityandtheotherhalfisforcontent,soreallyletyourimaginationflyasyouworkthroughit.Chooseone:a. WriteashortstoryorskitaboutastronomyfromtheperspectiveoftheSunoralightparticleitself.

You’llreadthisaloudtoyourclass.b. MakeaposterthatteachesamainconceptofeithertheSun,amoon,aplanet,oraparticular

spacecraft.Whenyou’refinished,you’lluseittoteachtoaclassoyoungerstudentsanddemonstratetheprinciplesthatyou’velearned.

c. WriteandperformapoemorsongabouttheSun,amoon,aplanet,oraparticularspacecraft.Thiswillbeperformedtoyourclass.


Astronomy2QuizStudentQuizSheet

Name__________________________________________________________

1. Nametwowaysyoucanfindablackhole.

2. Whatisagalaxy?

3. HowmanyphasesdoestheMoonhaveandwhatarethey?

4. Whichplanetsdonothaveamagneticfield?

5. CanyouseetheMoonduringthedaytime?

6. HowmanyAUsistheEarthfromtheSun?

7. WhatistheSunmadeoutof,andhowmuchofeach?

8. Canweseealllight?Ifnot,whichkindcanweseewithoureyes?

9. HowhotistheSun?

10. HowdoestheSunmakeenergy?


11. Whicharelightsources(LS)andwhichareseenbyreflectedlight(RL)?

a. Stars__________________________________

b. TheMoon__________________________________

c. Venus__________________________________

d. Pluto__________________________________

e. Comets__________________________________

f. Asteroids__________________________________

g. TheSun__________________________________


Astronomy2LabPracticalTeacher’sAnswerKey

Thisisyourchancetoshowhowmuchyouhavepickeduponimportantkeyconcepts,andifthereareanyholes.Youalsowillbeworkingonahomeworkassignmentasyoudothistestindividuallywithateacher.

Materials

Lamp Twoballsofdifferentsizes(likeatennisballandapingpongball) Sheetsofpaper Pencil

LabPractical:

ShowhowtheMoon'sappearancechangesduringthefour‐weeklunarcycle.

Onasheetofpaper,drawthesolarsystem.IncludetheSun,eightplanets,andtheAsteroidBelt.Approximatethescaleoftheplanetsanddistancesbetweenthem.


AnswerstoExercisesandActivitiesLesson#1:Stars,Planets,andBlackHoles

1. IsMercurythehottestplanet?Whyorwhynot?(No,Venusisbecauseit’sgotathickatmospherethatkeepstheheattrappedinside.)

2. Whatissolarwind?Whatprotectsplanetsfromit?(Mars,EarthandVenusarebathedinaflowofplasmathatcomesfromthesun,calledsolarwind.TheEarthhasamagneticfieldwhichactslikeaninvisiblecoattoprotecttheearthbecauseitdeflectsthesolarwindawayfromus,butVenusandMarsdon’thavethisprotectionsotheygetblastedwiththissolarwind.Solarwindisn’treallywind(there’snoairinspace,soitcan’tbelikethenormalkindofwind),butit’sasteamofhighlychargedparticlescomingfromtheSun.)

3. Canasteroidshavemoons?(Yes!Idaisanasteroiddetectedin1884,andin1993theGalileospacecraftdiscovereditsmoonDactyl.)

4. WhyisIodifferentcolors?(Fromvolcanicactivity.)5. Canmoonshaveatmospheres?Doallplanetshaveatmospheres?(MoonslikeTitanhaveatmospheres.Notall

planetshaveatmospheres,becauseofaplanet’slowgravity;theatmospherecangetblownawaybystrongsolarwinds.MercuryandMarshaveverythinatmospheres.)

6. HowmanyobjectsinthePlutosystem?(Four:Pluto,Charon,Hydra,andNix.)7. Nametwowaysyoucandetectblackholes.(LookforX‐rayemissions,lookforlightbendingaroundtheblack

hole,orlookforastarwobblingororbitingsomethingthatisn’tthere.)8. Ifastarcollapseswhenitrunsoutoffuel,thenwhydosupernovasexplode?(Whenthecoreofastarcollapses,

itsmackstogethersoHARDthatitrebounds–itbouncesback.Whenitreboundsandbouncesbackout,itcollideswiththerestofthegasthatisstillfallinginward(rememberthefoilintheballoonexperiment?)Whenthereboundingcorehitsthein‐fallinggas,thecoreblastseverythingoutintospace…andthismakesagiantexplosion.)

9. Nametwoscientistswhocontributedtotheworkonblackholes.(StephenHawking,KarlSchwarzschild,RobertOppenheimer,RogerPenrose,AlbertEinstein,JohnMitchell…)

10. Whatisagalaxy,andhowisitdifferentfromaquasar?(Agalaxyisasystem,ofmillionsorbillionsofstars,togetherwithgasanddustthatisheldtogetherbygravity.Wethinkquasarsarethebrilliantcoresofagalaxy,whichispoweredbyablackhole.)

Lesson#2:SolarSystemScaleModel

1.Whatdoyounoticeaboutthepositionoftherockyterrestrialplanets?(TheyareallbuncheduptogetherclosetotheSun.)

2.Aretheicegiantsfurtherapartfromeachotherthanthegasgiantsare?(Neptune‐Uranusis9.8AUandSaturn‐Jupiteris5AUwhentheyareonthesamesideoftheSun.)

3.Mariner10took147daystoreachMercuryfromEarth.HowlongdoyouthinkitwouldtaketogettoNeptune?(Approximately12‐22years,dependingontheflightpathandthespeedchosen.)

4.IftheEarthis93millionmiles(150millionkm)fromtheSun,andCeresis413millionmiles(665millionkm)fromtheSun,wherewouldyouplaceitinyourscalemodel?(Ceresis4.4AUor3metersor9.91feetaway.Ifyour


studentshaven’tcoveredthisyet,it’sokaytoeyeballthedistanceandapproximateCerestobeaboutfourtimesthedistancefromtheSunthattheEarthis.)

Lesson#3:Atmospheres

1.Whichatmospherereachedthehighesttemperature?(Refertodatatable,butyoushouldfindthewaxedpaperheatedupthemost.Ifthebaggiejardid,thenyoupackedittootightlyinthejar.)

2.EachofthejarsreceivedthesameamountofenergyfromtheSun.Whyisthisnotquiteliketherealsolarsystem?(EachplanetisadifferentdistancefromtheSun,andreceiveslessenergythefurtheroutit’slocated.Thisexperimentworksbecauseit’soverashortperiodoftime,andwe’refiguringoutwhichconditionstrapheatthebest.)

Lesson#4:LunarPhases

1.DoestheSunalwayslightuphalftheMoon?(Yes.Wedon’talwaysgettoseeit,whichisbecausetheMoonhasphases.)

2.HowmanyphasesdoestheMoonhave?(Eight)

3.WhatisitcalledwhentheMoonappearstogrow?(Waxing)

4.WhatisitcalledwhenyouseemorelightthandarkontheMoon?(Gibbous)

5.Howlongdoesittakeforacompletelunarcycle?(About29½days)

Lesson#5:EclipsesandTransits

1.Whatotherplanetscanhaveeclipses?(MercuryandVenusdon’thavemoons,andthemoonsofMarsaretoosmall.Jupiter,Saturn,UranusandNeptunecanhaveeclipsesastheirmoonsarelargeenoughandtheSunappearssmaller.PlutoandCharonareinaweirdorbitsothatonlyonesideofeitheronewilleverexperienceeclipses,andevenwhentheydo,it’severy120yearsorso.)

2.WhichplanetstransittheSun?(VenusandMercury)

3.Howisasolareclipsedifferentfromalunareclipse?(AlunareclipseiswhentheEarthcomesbetweentheSunandMoon.AsolareclipseiswhentheMooncomesbetweentheEarthandSun.)

4.Whatphasecanalunareclipseoccur?(Onlyonanightofafullmoon.)

5.Canasolareclipseoccuratnight?(No,becausetheSunisn’tvisibleatnight.)

Lesson#6:RustyBalloon

1.Whydidoneballoongetlargerthantherest?(Theballoonwillshowyouhowmuchgasisgenerated–thelargertheballoon,themoregaswasproduced.Therust(ironoxide)isthenameofthereactiontakingplacebetweenthesteelwoolandtheliquids.)


2.Whichhadthehighestpressuredifference?Why?(Checkresultsfromdatatable.Inthevideo,thebottlewithjustwaternotonlysuckedintheballoon,italsosuckedinthesidesofthewaterbottleitself,showingyouthatitusedtheoxygenintheairtogeneratetherust.You’llseethismoredramaticallywhenyouaddsalttothewaterbeforeaddingthesteelwool.)

Lesson#7:Meteorites

1.Aremeteorsmembersofthesolarsystem?(Yes–theyarethesmallestmembers.)

2.Howbigaremeteors?(Theyrangefrompebblesizetosmallerthanagrainofsand,usuallyweighinglessthan2grams.)

3.Whydowehavemeteorshowersatpredictabletimesoftheyear?(Everyyear,theEarthpassesthroughthedebrisleftbehindbycomets.Theparticlesenterouratmosphereandburnup.Theonesthatmakeittothegroundaremeteorites.)

Lesson#8:Neptune’sFurnace

1.Whathappenswhenthechemicalscomeincontactwitheachother?(Whenthecalciumionsandchlorideionsinteractwiththesodiumbicarbonate,theyformcarbondioxidegasandsodiumchloride(tablesalt).)

2.Whatdidyounoticewhenyousealedthebagclosedandrolledthepelletsbetweenyourfingers?(Dissolvingcalciumchlorideishighlyexothermic,meaningthatitgivesoffalotofheatwhenmixedwithwater.)

3.Whathappenedwhenthesolutionwasplacedinthecoldwaterjug?(Thisremovesenergyfromthereactionsandcausesthetablesalttoprecipitateoutmorequickly.)

4.WhatdoesthisexperimenthavetodowithNeptune?Whydidweusethebakingsodaatall?(Asthegasinthebagincreases,itpuffsoutandincreasesthepressure.Thisstretchesthebagandsomeofthegasisreleasedouttheholesinthetopofthebag,bubblinguptothesurfaceofthemilkjug.Afterawhile,thewarmwaterwillalsoriseoutoftheholesduetothetemperaturedifferencebetweenthebagandjugand,you’llseereddriftuptothetopsurfaceofthemilkjug.TheheatgeneratedbyNeptuneisdeepinthecore,anditbubblesupandradiatesouttospace,justlikethewarmbagbubblingitscontentstothecoldwaterjug.Theentireplanetisawhirling,swirling,fast‐movingballofgasandicethatmovebecauseoftemperatureandpressuredifferences.)

Lesson#9:BinaryPlanetarySystems

1.HowisspinningthecontainerlikePlutoandCharon?(Youarealwaysfacingthesamesideofthecontainer,justlikePlutoandCharonarealwaysfacingthesamesidesofeachother.)

2.Whatwouldhappenifwecutthestringwhileyouarespinning?Whichwaywouldthecontainergo?(Inastraightlinetangenttothecurveatthemomentwecutthestring.)

3.Whathappensifwetriplethesizeofyourcontainerandwhat’sinsideofit?(Ittakesmoreenergytoswingalargerloadaround.Foroneobjecttoorbitanother,theymusthavestronggravitationalattractiontomovethatmuchmassaround.)


Lesson#10:BuildYourOwnSolarSystem

1.Whateffectdoeschangingthemassofanorbitingplanethaveonthediameteroftheorbit?

2.Whateffectdoeschangingthespeedhaveonaplanet’sorbit?

3.Whathappenstotheplanet'sorbitwhenyouincreasetheinitialdistancebetweentheplanetandtheSun?

4.Findthemassvaluesneededforastableorbit.Circlethevaluesonthetablethatmakeastableorbit.

5.Whydon’tafeatherandabrickhitthegroundatthesametime?(Theydo…ifyou’reonthemoon!OnEarth,thefrictionbetweentheairandthefeathercausesthefeathertoslowdownandthebricktowintherace.)

Lesson#11:WatchYourWeight

1.Ofthefollowingobjects,whichonesareattractedtooneanotherbygravity?

a)AppleandBananab)BeagleandChihuahuac)EarthandYoud)Alloftheabove

2.TrueorFalse:Gravityacceleratesallthingsdifferently

3.TrueorFalse:Gravitypullsonallthingsdifferently

4.IfIdropagolfballandagolfcartatthesametimefromthesameheight,whichhitsthegroundfirst?(Theybothhitthegroundatthesametime.)

5.Thereisamonkeyhangingonthebranchofatree.Awildlifebiologistwantstoshootatranquilizerdartatthemonkeytomarkandstudyhim.Thebiologistverycarefullyaimsdirectlyattheshoulderofthemonkeyandfires.However,thegunmakesaloudenoughnoisethatthemonkeygetsscared,letsgoofthebranchandfallsdirectlydownward.Doesthedarthitwherethebiologistwasaimingordoesitgohigherorlowerthanheaimed?(Themonkeyandthedartfalldownwardatthesamerateofspeed.Sothedartwouldhitexactlywherethebiologistaimed!Infact,ifthemonkeydidn’tletgo,thedartwouldhavehitlowerthanthebiologistaimed.)

Lesson#13:Diffraction

1. Whichlightsourcegavethemostinterestingresults?(Thisvarieswithdata.)

2. Whathappenswhenyouaimalaserbeamthroughthediffractiongrating?(Itsplitsintothreebeamsoflight,asshowninthesecondvideo.)

3. HowisaCDdifferentandthesameasadiffractiongrating?(ACDhasaspiraloffinely‐spaceddatatrackswhilethediffractiongratinghasaseriesofparallellines.TheCDsplitsthelightthesamewayasthediffractiongrating.TheCDsplitsthebeamintomorethanthreebeams.)

4. Whydoesthefeatherwork?(Therearetiny“hairs”onthefeatherthatareactingliketinyprisms.)


Lesson#14:InfraredVision

1.Whatkindsofobjectsallowinfraredlighttopassthroughthem?(Checkdata.)

2.Whydoesthecameraworkinmakingtheinfraredlightvisible?(Thecameraisaviewerthatletsusseethisspecialfrequencyoflight.Lightistechnicallywhatwecallelectromagneticradiation.Radiowaves,infrared,microwaves,X‐rays,andgammaraysareallelectromagneticradiation.Ifyoucouldseetheradiowaves,thenyoucouldseeradiotowersastheytransmit.Theywouldappeartolightup.Ifyoucouldseeallformsoflight,thennotonlycouldyouseetheradiotowers,butalsoyourcellphone,thedoctor’sX‐raycameras,andyourcarradiowouldallbelitupastheyoperated.It’sallmadeoutofthesamestuff,justnotallofitisvisibletooureyes.)

Lesson#15:UVLight

1.Whatkindsoflightsourcesdidn’tworkwiththeUVbeads?(Checkdata.)

2.DidyourSunblockreallyblockouttheUVrays?(Checkdata.)

3.WhichwasthebestprotectionagainstUVrays?(Checkdata.)

Lesson#16:StarWobble

1.Forhomeworktonight,findouthowmanyextrasolarplanetsscientistshavedetectedsofar.

2.Alsoforhomework,findoutthenames(theywillprobablybeastringofnumbersandletterstogether)ofthe3mostrecentextrasolarplanetdiscoveries.

Lesson#17:SpaceTelescopes

1.Whathappenswhenyourmarblesatellitemovestooslowly?(ItcrashesbacktoEarth.)

2.Whathappenswhenthemarblesatelliteorbitstoofast?(Thesatelliteleavesorbit.)

3.Whateffectdoeschangingthemarblemasshaveonyoursatellitespeed?(Theheavierthemarble,thefasteryouhavetomakeitmoveinordertokeepitsorbitstable.)

4.Howisthismodelliketherealthing?(YourmarbleisyoursatelliteandthetopoftheconeistheorbititmakesaroundtheEarth.)


VocabularyfortheUnitAsteroid.ObjectinorbitaroundtheSun,intermediateinsizebetweenmeteoroidsandplanets.

Asteroidbelt.Theregionofthesolarsysteminwhichmostasteroidshavetheirorbits,betweenMarsandJupiter.

BlackholesaretheleftoversofaBIGsupernova.Whenastarexplodes,itcollapsesdownintoawhitedwarforaneutronstar.However,ifthestarislargeenough,thereisnothingtokeepitfromcollapsing,soitcontinuestocollapseforever.Itbecomessosmallanddensethatthegravitationalpullissogreatthatlightitselfcan’tescape.

Centerofmass.Meanpositionofthemassesthatcompriseasystemorlargerbody:fortwobodies,thecenterofmassisapointonthelinejoiningthem.Forabinarystarsystem,themotionofeachstarcanbecomputedaboutthecenterofmass.

Comet.Smallbodyinthesolarsystem,inorbitaroundtheSun.SomeofitsfrozenmaterialvaporizesduringthecloserpartsofitsapproachtotheSuntoproducethecharacteristictail,rightbehindthehead.

Conjunction.Closestapparentapproachoftwocelestialobjects.PlanetaryconjunctionswereonceconsideredimportantomensforeventsonEarth.

Constellation.Agroupofstarsthatseemedtosuggesttheshapeofsomegod,person,animalorobject.Nowatermusedtodesignatearegionofthesky.Thereare88constellations.

Darkmatter:Matterinthecosmosthatisundetectablebecauseitdoesn’tglow.Darkmatter,someofitintheformofas‐yet‐undiscoveredexoticparticles,isthoughttocomprisemostoftheuniverse.

Eclipse.Blockingoflightfromonebodybyanotherthatpassesinfrontofit.Eclipsescanbetotalorpartial.

Eclipsepath.NarrowpathontheEarth’ssurfacetracedbytheMoon’sshadowduringaneclipse.

Eclipsingbinarystar.Binarystarwhosemutualorbitisviewedalmostedge‐onsothatlightobservedisregularlydecreasedeachtimeonestareclipsestheother.

Ecliptic.PaththattheSunappearstofollow,againstthestarsonthecelestialsphere,duringthecourseofayear.

Eclipticplane.PlanedefinedbytheEarth’sorbitaroundtheSun.

Electromagneticwave:Astructureconsistingofelectricandmagneticfieldsinwhicheachkindoffieldgeneratestheothertokeepthestructurepropagatingthroughemptyspaceatthespeedoflight,c.ElectromagneticwavesincluderadioandTVsignals,infraredradiation,visiblelight,ultravioletlight,xrays,andgammarays.

Ellipse.Typeofclosedcurvewhoseshapeisspecifiedintermsofitsdistancefromoneortwopoints.Acircleisaspecialformofellipse.Inappearance,anellipseisoval‐shaped.

Escapespeed:Thespeedneededtoescapetoinfinitelygreatdistancefromagravitatingobject.ForEarth,escapespeedfromthesurfaceisabout7milespersecond;forablackhole,escapespeedexceedsthespeedoflight.

Equinox.TwodayseachyearwhentheSunisaboveandbelowthehorizonforequallengthsoftime.


Eventhorizon:Asphericalsurfacesurroundingablackholeandmarkingthe“pointofnoreturn”fromwhichnothingcanescape.

Field:Awayofdescribinginteractingobjectsthatavoidsactionatadistance.Inthefieldview,oneobjectcreatesafieldthatpervadesspace;asecondobjectrespondstothefieldinitsimmediatevicinity.Examplesincludetheelectricfield,themagneticfield,andthegravitationalfield.

Galaxiesarestarsthatarepulledandheldtogetherbygravity.

Globularclustersaremassivegroupsofstarsheldtogetherbygravity,usuallyhousingbetweentensofthousandstomillionsofstars(thinkNewYorkCity).

Gravitationallensingisonewaywecan“see”ablackhole.Whenlightleavesastar,itcontinuesinastraightlineuntilyankedonbythegravityofablackhole,whichbendsthelightandchangesitscourseandshowsupasstreaksormultiple,distortedimagesonyourphotograph.

Gravitationaltimedilation:Theslowingoftimeinregionsofintensegravity(largespacetimecurvature).

Gravitationalwaves:Literally,“ripples”inthefabricofspacetime.Theypropagateatthespeedoflightandresultintransientdistortionsinspaceandtime.

Gravity:AccordingtoNewton,anattractiveforcethatactsbetweenallmatterintheuniverse.AccordingtoEinstein,ageometricalpropertyofspacetime(spacetimecurvature)thatresultsinthestraightestpathsnotbeingEuclideanstraightlines.

Latitude.Coordinateusedtomeasure(indegrees)theangulardistanceofapointorcelestialobjectsaboveorbelowanequator.

Lightyear.Distancethatlighttravelsin1year.

Longitude.Coordinateusedtospecifythepositionofapointordirectionaround(orparallelto)anequator.

TheKuiperBeltisanicyregionthatextendsfromjustbeyondNeptune(from3.7billionmilesto7.4billionmilesfromthesun).Thisiswheremostcometsandasteroidsfromoursolarsystemhangout.

NeutronstarswithHUGEmagneticfieldsareknownasmagnetars.

Magneticfield.Regionsurroundingamagnetorelectriccurrent,inwhichmagneticforcecanbedetectedinsucharegion,high‐speedelectricallychargedparticleswillgenerallymovealongcurvedpathsandradiateenergy.

Magneticpole.OneofthetworegionsonEarthtowhichacompassneedlewillpoint.Polesalsoexistonmagnets,andthemagneticfieldsofsomeelectriccurrentscanhaveanequivalentbehavior.

Magnetoshpere.Regionsurroundingstarorplanet(includingEarth)inwhichamagneticfieldexists.

Meridian.Greatcircle,onthecelestialsphereortheEarth,thatpassesthroughbothnorthandsouthpolesandanobserver’szenithorlocation.

Meteor.Glowingtrailintheupperatmosphere,producedbymeteoroidburningupasitmovesathighspeed.


Meteorshower.NumerousmeteorsseeninashorttimespanastheEarthmovesthroughacloudofmeteoroids,probablyremnantsofacometandstillfollowingthecomet’sorbit.

Meteorite.RemnantofameteoroidthathasbeenpartiallyerodedinpassagethroughtheEarth’satmospherebeforehittingthesurface.Termnowalsoappliedtosimilarbodiesthatcollidewiththesurfacesoftheotherplanetsandtheirsatellites,producingcraters.

Meteoroid.Largerock(butmuchsmallerthanminorplanets)movinginanorbitinthesolarsystem.MeteoroidsthatenterintheEarth’satmospherearetermedmeteorsormeteorites,dependingontheirbehavior.

Neutronstarsareformedfromstarsthatgosupernova,butaren’tbigandfatenoughtoturnintoablackhole.

TheOortCloudliesjustbeyondtheKuiperbelt,housinganestimated1trillioncomets.

Orbit.Pathtracedoutbyoneobjectaroundanother.

Thevisiblesurfaceofthesuniscalledthephotosphere,andismademostlyofplasma(remembertheplasmagrapeexperiment?)thatbubblesuphotandcoldregionsofgas.

Dyingstarsblowoffshellsofheatedgasthatglowinbeautifulpatternscalledplanetarynebula.

Pulsarsareatypeofneutronstarthatspinsveryfast,spewsjetsofhigh‐energyx‐rayparticlesoutthepoles,andhaslargemagneticfields.

Oursolarsystemincludesrockyterrestrialplanets(Mercury,Venus,Earth,andMars),gasgiants(JupiterandSaturn),icegiants(UranusandNeptune),andassortedchunksoficeanddustthatmakeupvariouscomets(dustysnowballs)andasteroids(chunksofrock).

Spacetime:Thefour‐dimensionalcontinuuminwhichtheeventsoftheuniversetakeplace.Accordingtorelativity,spacetimebreaksdownintospaceandtimeindifferentwaysfordifferentobservers.

Spacetimecurvature:ThegeometricalpropertyofspacetimethatcausesitsgeometrytodifferfromordinaryEuclideangeometry.Thecurvatureiscausedbythepresenceofmassiveobjects,andotherobjectsnaturallyfollowthestraightestpossiblepathsincurvedspacetime.Thisistheessenceofgeneralrelativity’sdescriptionofgravity.

Spacetimeinterval:Afour‐dimensional“distance”inspacetime.Unlikeintervalsoftimeordistance,whicharedifferentforobserversinrelativemotion,thespacetimeintervalbetweentwoeventshasthesamevalueforallobservers.

Specialtheoryofrelativity:Einstein’sstatementthatthelawsofphysicsarethesameforallobserversinuniformmotion.

www erchargedsciencecomets and asteroids. two planets (ceres and pluto) have been reclassified after...

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