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TheStudyofOuterSpace Astronomy HistoryofAstronomy • Astronomyisthebranchofsciencethatdealswithcelestialobjects(objectlocatedoutsideof theearth’satmosphere),space,andthephysicaluniverse. • Astronomyisconsideredtheoldestofthenaturalsciences. • Manycivilizationslookedtotheskytounderstandtheirworld. • WhenStoneagepeopleturnedtoamoreagricultural(farmer)wayoflife,theirinterestlikely turnedtotheheavens. • Theseasonsbecameimportant.Peoplenoticedthatdifferentstarpatternsappearedat differenttimesoftheyear. • Howcouldthisbehelpfultothem? • WehavelearnedaboutsomesocietiesthatbelievedthattheSunGodwouldneedtobe honoredinorderforthesuntoriseeveryday. • Imaginethefearthatwouldexistduringasolarorlunareclipse. • Predictingeclipseswaspossiblytheearliestastronomicalactivity. • Stonehengeisaparticularlyinterestingastronomicalsite.Itisestimatedthatitwasconstructed between3100BCE-2000BCEinSalisburyPlain,England. • ManystoriesexistaboutthisstructureincludingthepossibilitythataliensbuiltStonehenge. • Amorerealisticviewofthisstructureisthatitwasbuilttokeeptrackofthemovementofthe sunandmoonaswellasmarkthechangingoftheseasons. • Astronomershavenotedthatthe“heelstone”isindirectalignmentwiththerisingsunonJuly 21(thesummersolstice). • Stonehengeistiedtothewintersolsticealso. • AroundDecember20,thesunsetsinthemiddleof3stonesknownastheTrilithon. • ThereislittleagreementonthesignificanceofStonehenge.Inrecentyears,scientistshave suggestedthatitisanancientburialground.Perhapsitisacombinationofboth. EarlyAstronomers • AncientChinesecivilizationskeptcarefultrackofeventsintheskies….particularlywhatthey called“gueststars.” • Agueststarwouldbeaneworunusuallightinthesky. • Asearlyas1059BCE,theChinesekepttrackofagueststarthatwenowcantracetobeHaley’s comet. • Pythagoras(580-500BCE)-wasaGreekmathematicianwellknownforhistheoremregarding triangles.a2+b2=c2 • Healsoiscreditedwithrecognizingthatthe“morningstar”and“eveningstar”areboththe planetVenus. • Aristotle(384–322BCE)cameupwithatheorythatearthwasthecenterofthesolarsystem. Hebelievedthattheearthdidnotmoveandtheuniversemovedaroundplanetearth. • HisfindingswerepresentinthewritingsofSt.ThomasAquinasandbecamethefoundationof Churchbeliefsformorethan14centuries. NikolasKopernig(Copernicus1473-1543AD)developedanideathatputthesunatthecenter oftheuniverse.Healsoestablishedtheproperorderoftheplanetsoutwardfromthesun. • GalileoGalilei(1564-1642)designedhisowntelescopesandmademanydiscoveriesin astronomy…. • Sunspotsonthesunandcraters/mountainsonthemoon. • MoonsofJupiter • RingsofSaturn • GalileoalsoconfirmedthatCopernicus’ideathatthesunisthecenterofthesolarsystem. • ThiswentagainstwhattheCatholicChurchtaughtandhewasputontrialin1633. • Hewasforcedto“disavow”hisworkandwassentencedtohousearrestfortheremainderofhis life…8moreyears. • IsaacNewton(1642–1727)isprobably2ndinimportanceofearlyastronomerstoGalileo. • NewtondevelopedtheLawsofMotionandusedittounderstandgravity. • TheLawsofMotionareasfollows: • Anobjectatresttendstostayatrest,andanobjectinmotiontendstoremaininthat stateofmotion,unlessanexternalforceisappliedtoit. • Aforcecausesaccelerationofanobject. • Foreveryactionthereisanequalandoppositereaction. • HowdotheLawsofMotionrelatetotheSolarSystem? • Newtonconcludedthatwithouta“force”(gravity)pullingonplanets,theywouldshootoffinto outerspace. • Thisideahelpedastronomersunderstandhowandwhyplanetsorbit. ToolsofSpaceExploration • Telescopesarethefirstinstruments,otherthanthenakedeye,tostudythesolarsystem. • ProbablythefirsttelescopewasinventedbyaDutcheyeglassmakernamedHansLippershey. Heappliedforapatentin1608. • WehavelearnedthatGalileoimprovedonthisideaandusedhisimprovementstofurtherthe developmentofspaceexploration. • Telescopeshaveadvancedsomuchthattherearenowhugebuildingsthathouse observatories….whicharegianttelescopesthatcanlookatthesolarsystem. • Mostofthesetelescopesusemirrorstoenlargeobjects. • ThelargestradiotelescopewasjustfinishedinJuly2016inChina.Thistypeoftelescope measuresradiowaves. • Thedishofthistelescopemeasures1,650feetthatisbeingusedtosearchforsignsoflifeand otherdiscoveries.Thisisalittlemorethan5footballfields. • Radiotelescopesmeasureradioormagneticwaves. • Planstobuildtheworld’slargestvisualtelescopetodatewasintendedforHawaii.This telescopewillhaveamirrorthatmeasures127feet. • Controversyaroundthistelescopehasoccurredsothemostrecentplansaretomovethe buildingofthistelescopetoChile. • OneofthemostimportanttelescopesinourhistoryisthelaunchoftheHubbletelescopein 1990.ItisconsideredthemostimportantadvanceinastronomysinceGalileo’stelescope. • • • • • • • • • • • • • • • • • • TheHubbletelescopeisnamedforEdwinHubblewhohelpedtoprovethatothergalaxies existedoutsideoftheMilkyWay. HeisconsideredtobeoneofthefoundersoftheAndromedagalaxy. Byshowingthatothergalaxiesexisted,EdwinHubblehelpedastronomersbegintograspthe sheersizeoftheuniverse. TheHubbletelescopefloatsinthethermospherelayeroftheatmosphere.Ittakesdigital picturesasitorbitstheearth. TheHubbletelescopetravelsataspeedof17,000mph. Itispoweredbysolarrays. TheHubbletelescopeisaboutthelengthofaschoolbus. TheHubbletelescopeisanexampleofaspacesatellite. Satellitesaremachinesthatarelaunchedintospaceandorbittheearth,moon,orotherplanet. Therearemorethan4500satellitesinouterspace.Someofthemaretakingpicturesbutsome ofthemareprovidingcellphonesignalsandtelevisionsignalsthatweuseeveryday. ThefirstsatellitelaunchedintospacewastheRussianSputnikIin1957.Thiswasthefirsthuman madeobjectlaunchedintospace.Wewilltalkmoreaboutthiswhenwediscussspace exporation.Itwasthestartofthe“racetospace”betweentheU.S.andRussia. Robotsareanothertoolthatastronomersusetogatherinformationaboutouterspaceand otherplanets. Wewilltalkmoreaboutthiswhenwegetintospaceexploration. 1976iswhenthefirstspacerobot,VikingIlandedonMarsandcollectedsoilsamples.Since then,manyotherrobotshaveexploredourplanets. Robotshavebeenthepreferredtypeofspaceexplorationbecauseitisextremelydangerousfor humanstotravelthatfarintoouterspaceandreturntoearth.Manytimes,scientistsexpect thattheirrobotsorsatelliteswilldisintegrateonthereturntriptoearth. Roboticarmshavebeenusedformanyyearstolaunchsatellitesandassistastronautswiththeir missions. OthermorerecentspacerobotshavebeenusedtoexplorethesurfaceofMars.