Download Notes_ stars and sun

TheSunandStars
Thesunisthecenterofoursolarsystem.
Forthousandsofyears,thesunhasbeenrevered,honored,andmisunderstood.
Oursunisamid-rangesizestarthathasbeeninexistenceforbillionsofyears.
Itisthecloseststartoearth.
Thesunis93millionmilesawayandtakes8minutesforsunlighttoreachus.
Let’stalkaboutthebirthanddeathofstarsbeforediscussingourmostimportantstar-thesun.
Birthofastar
• Starsbeginlifeinswirlingcloudsofgasanddustcallednebulae.
• Thiscloudofdustismadeupofhydrogenandheliumthatcanbetrillionsofmilesacross.
• Astronomersstudyingtheskysometimesseethesecloudsandmistakethemforgalaxies.
• Nebulaecomeinavarietyofshapesandsizes.Somearenamedbecauseoftheshapethattheyform.
• Thesecloudsgraduallyshrinkasgravitypullsthedustandgastogether.
• Atthecenter,thegasgetshotterandhotteruntilanewstarisborn.
• Starsbegintheirliveswhentheystartmakingenergy.Whenthedustandgasgetspulledtogethertightlyitgets
veryhot.
• Theenergymakesthestarshine,givingoutheatandlightliketheSun.
• Eachnebulaecantake10millionyearstoformastar.
• Sometimes,theextramaterialfromthestarformationbecomesasteroidsorcomets.Sometimesnewplanets
areformedaroundthestar.
• Imaginetheexcitementofastronomerswhentheyareactuallyabletowitnessthebirthofastar.
• Whatisalightyear?
• Alightyearisaunitofdistancethatmeasureshowfaralightcantravelinoneyear.
• Itisusedinastronomytomeasurehowfarthingsarefromearth….inotherwords,howlongdoesittakefora
planetorstarslighttoreachearth.
• Sinceitonlytakessunlight8minutestoreachearth,itcanbesaidthatthesunis8lightminutesaway.
• ThecloseststartothesuniscalledProximaCentauri.Thisstaris4.24lightyearsawayfromearth.Thismeans
thatwhenweseethelightfromProximaCentauri,itwasactuallygeneratedalittlemorethan4yearsago.
• Thereare32starsthatliewithin12.5lightyearsfromthesun.Theremainingbillionsofstarsthatyoucansee
onaclearnightaremuchfurtheraway.
TypesofStars
• Inthenightsky,allstarslookliketinypinpricksoflight.
• Inreality,starsvaryinsize,color,brightness,andlifespan.
• Dwarfstars-Thesemakeupthemajorityofthestarsintheskyandarethesmalleststarsinhesky.
• Mostdwarfstarsarereddwarfs.
• Eventhoughtherearemorereddwarfstarsintheskythananyotherstar,theyaredifficulttoseebecauseof
theirsizeandtheymakeverylittlelight.
• Dwarfstarsaretheoldeststarsintheuniverse?Whyisthis?
• Dwarfstarsarelesshotsoburnlessfuel.Thinkofaforestfire,whichisthehottestpart?Whichisthecoolest
part?
• Starsworkthesameway.Thecoolestpartisatthetopwhereitglowsred,thenexthottestpartisthemiddle
whereitglowsorange/yellow.Thehottestpartisatthebase….wherethefuelis,whichglowsblue.
• Wecandeterminehowhotastarisbasedonit’scolor.
• Thehotterthetemperature,thequickerthestarwilldieorburnout.
• Yellowstar-Thesearemediumsizedstarsthataresimilartothesun.
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Theyhaveamediumtemperature,causingthemtonotliveaslong.
Don’tworry…thesestarscanliveupto10billionyears.Itisestimatedthatthesunis4.6billionyearsold.Itstill
has5billionyearsoflifeleft.
• Whenyellowstars(mediumsized)die,theyswellupbecomingverylarge.Wethencallthesestarsgiantstars.
• Giantstar-Whensunsizedstarsbegintodie,theyexpand.Asthecenterofthestarburnsout,thehydrogen
moleculesgetveryclosetogether.Thisignitesanewfuelwhichishelium.
• Heliumburnshotterthanhydrogenandbeginstopushthestaroutmakingitlarger.Thinkofahotairballoon.
Astheairinsidegetshotter,itstretchestheballoonoutfurther.
• Manyofthestarsyouseeatnightaregiantstars.
• In5billionyears,whenthesuntransformsintoagiantstar,itwillengulfMercury,Venus,Mars,andEarth.
• BlueGiants-Thesearethehottestofthegiantstars.Becausetheyburnfuelsofast,theyburnoutinbetween
10,000-100,000years.
• Thesestarsareincrediblybright.Whentheydie,theyexplodeinwhatiscalledasupernova.
• SuperGiantStars-arethelargestofthegiantstars.IfthesunwereaSuperGiant,itwouldstretchallthewayto
Uranus….about1.8billionmiles.
• Whenagiantstarorsupergiantstardies,itbecomesablackhole.Wewilltalkmoreaboutsupernovasand
blackholesinafewweeks.
DeathofaStar
• Starsbegintodiewhentheyrunoutofgastomakeenergy.
• Themiddleofthestarshrinksbuttheouterpartsexpandmakingthestarmuchlarger.
• Mostofthetime,starsdieapeacefuldeath.Theyswellup,shedtheirouterlayersanddisintegrateforminga
planetarynebula.
• Aplanetarynebulalookslikeabeautifulcolorfulcloud.
• Planetarynebulaareusuallyvisiblefor50,000yearsbeforeitisabsorbedbytheatmosphere.
• Whenagiantstardies,itcausesahugeexplosionknownasasupernova.
• AccordingtoNASA,supernova’sarethelargestexplosionthatoccurinspace.
• Asupernova,ordeathofagiantstaroccursaboutevery50yearsintheMilkyWaygalaxy.Supernova’smay
occurabouteverysecondsomewhereintheuniverse.(Justanotherexampleofhowhugeouruniverseis).
• Wewilltalkmoreaboutsupernova’sinafewweeks.
• Ifthestarhasenoughweight,itwillbecomeablackhole.Ablackholeisoneofthemostmysteriousand
powerfulforcesintheuniverse.
• Ablackholeissomethingthatnothingcanescape…notevenlight.
• Whenastarexplodesintoasupernova,thepowerandenergythatisleftoversinksinonitselfcausingablack
hole….somethinglikeavacuum….butbillionstimesmorepowerful.
• Wewilltalkmoreaboutblackholesinafewweeks.
TheSun
• Oursunisastar,butisclosertousthananyotherstar.
• Likeallstars,thesunisahugeballofburninggas(hydrogen).
• Withoutthesun,ourplanetwouldbelifeless.
• Oursunstartedasababystarinanebula.
• Overaperiodofmillionsofyears,gasanddustbegantoforminward(gravity)causingatremendousamountof
heatandpressure.
• Oncethis“babysun/star”becameatemperatureofaboutonemilliondegrees,itcausesnuclearfusion….which
iswhenthiscelestialbodybeginstoburnit’sownfuel(hydrogen).
• Thesunisfartoohotforastronautstovisit.Itisalsofartoobrighttoseewithatelescope.
• Astronomersusespecialtelescopes/filterstoobservethesun.
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Theseobservationshavediscoveredanumberofthings.
Thesunhasslightlycoolerareasthatwecallsunspots.Sunspotsappearslightlydarkerincolor.
Ahighernumberofsunspotsgenerallyoccurevery11years.ThisisknownastheSaroscycle.
Whiteareasonthesunareareaswherethetemperaturesarehotterthannormal.
Therearetimeswhenthesunisveryactiveandreleasesmassiveamountsofgasintotheatmosphere.Theseare
calledsolarflares.
• Wecansometimesseethesesolarflaresinthenightsky.
• Haveyoueverdrunkarootbeerquickly?Whatdoesitdotoyourbody?
• Solarflaresarelikeagiantburp.
• AuroraBorealisisthelightdisplaythatoccursfromthesun.
• Whenthesesolarflareshitouratmosphere….whichismadeofmostlyoxygenandnitrogen…itcausesabeautiful
lightshow.
• Thereareveryfewplacesin2017thattheAuroraBorealis(Northernlights)canbeseen.
• TheNorthernLightsorAuroraBorealiscanbeseeninFairbanks,Alaskafor250nightsduringtheyear.
• ItcanalsobeseeninIceland,Norway,andSweden.
• Thesouthernlights,orAuroraAustraliscanbeseeninAntarctica.
Constellations
• Aconstellationisagroupofvisiblestarsthatformapattern.
• Theyhavebeenusedformanydifferentthings.
• Thefirstuseforconstellationswasprobablyreligious.Manycivilizationsbelievedthatthestarswerehowthe
godstoldstories.
• Amorepracticaluseforconstellationswasinfarmingcultures.
• PeoplebegantolearnthatwhenOrionwasfullyvisible,thatwinterwascomingsoon.
• Thestarpatternsmadeiteasierforearlyfarmingculturestoknowwhentoplant.
• ConstellationswerenamedfromtheGreeks.
• Theyarenamesfrommythologicallegendsandheroes.Theyallhaveastorythatgoesalongwiththeirname.
• Constellationswereusedduringourrecenthistorytoassistslaveswithescaping.
• Therewasaslavesongcalled“FollowtheDrinkingGourd”thatgaveinstructionsforslavestoescape.Whatdo
youthinkthedrinkinggourdreferredto?
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