table of contents - worldwide...

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TableofContentsIntroduction

ConstructionoftheDomeSupport

ToConstructaSmallerDomeSupport

TheDomeSpecificationUtility

ConstructionoftheDome

ToConstructaSmallerDome

AddingVentilationandPower

AddingSeatingandCarpeting

SettinguptheProjectorandMirrors

HighQualityMirrors

RunWorldWideTelescope

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WorldWideTelescopePlanetariumThisdocumentdescribeshowtobuildaplanetariumforusewithWorldWideTelescope.

TheplanetariumprovidesschoolsandothergroupswithagreatwaytovisualizethepanoramicviewoftheuniverseprovidedbyWorldWideTelescope.

Theplanetariumdescribedhereisjustunder12.5feetindiameter,andjustover9feettall.Sothefirststepisfindingasuitablelocationforit!Thematerialsusedarenotsuitableforanoutsidelocation,sothelocationshouldbeinside,levelanddry.Alternativemeasurementsaregivenforasmaller(9feetdiameter)planetarium,thoughalltheimagesinthisdocumentareforthe12.5feetmodel.Measurementsaregivenininchesasthisisthemostusedunitforpackingmaterialsandparticleboard,whicharethemainconstructionmaterialsused-48inchwidecorrugatedcardboard,and48inchwideparticleboardpanelingarebotheasytocomeby.TheDomeSpecificationUtilitycanbeusedifmetricmeasurementsarepreferred.

Oneofthemostinterestingfeaturesofthedomeisthatitistiltedatanangleof20degrees.Thismakesconstructionalittlemorecomplex,butthedesigngivesamuchbetterexperience.TheideaisthatstudentswillfeeltheyaretravelinginaspaceshiptowardsaplanetsuchasSaturn,whichwouldnotbethecaseiftheviewwasvertical.Thetiltalsogivesroomforareasonablepairofdoors,androomfortheprojectorandmirror,withoutexcessiveheight.Thecosttothisthoughisthatconstructingthedomesupportisasinvolvedasconstructingthedome(ageodesichalf-dometobeprecise)itself.

Costsformaterialsvary,howeverareasonablebudgetforthedomeandsupportcomponentsisUS$700.00at2009prices.Inadditiontothisasphericalmirrorisrequired,optionallyaflatsecondarymirror,andasuitableprojector.Toolsarenotincludedinourbudgeting,astheyarecommonhouseholdtoolsthatmanyteachersandparentswillownalready.AlaptoprunningWorldWideTelescopeisobviouslynotincludedinthebudgetingeither.

Notethatanumberofthetasksinvolvetheuseofcuttingtoolsandpowersaws,soresponsibleadultinvolvementintheprojectisessential.

Introduction

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ConstructionoftheDomeSupportConstructionofthedome,andthedomesupportcanlargelyproceedinparallel.Toconstructthedomesupport,gothroughthefollowingprocedure:

1. Purchasethenecessarymaterials:

5sheetsofparticleboard,orplywood,96inchesby48inches.17feetof2x3inchwood.20feetof2x2inchwood.120woodscrews(1or1.25inch).20heavydutyclipstoattachthedometothesupport.10lengthsof1x1.5inchwood,eachpieceexactly48incheslong.Twohingesandonehandleperdoor.Black2inchwidetape.

2. Assemblethenecessarytools:

Mitersaw,orcompoundmitersaw.Portablecircularsaw.Handsaw.Safetygogglesandmasks.Sandpaper.Drill.Mattblackpaint.Chalkline,orlongmeasuringrulers.Othertoolsmaybehelpful:files,screwdrivers,planes,clamps,sawhorses,andsoon.


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3. Understandtheshapesinvolved.Boththedomeanddomesupportarebasedonadecagon-10sidedfigure-showninthefollowingdiagram:

Thedomeisadecagon-eachsideis48inches.

Eachinsideangleis144degrees.

Thefronttobackdiameteris147.72inches.Thesidetosidediameteris155.32inches.


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Aftertilting20degreestheplanviewofthesupportbecomesanelliptical,ratherthanregular,decagon.Thetopedgeofeachpanelis48inches,butthewidthsoftheotherpanelsvary-48inchesfortherectangularpanels.but47.02inchesand45.4inchesfortheangledpanels.


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Thedomesupportprofile.

4. Cutout,orhavecutoutforyou,the10sidepanelsin0.5inchparticleboardorplywood.The10panelsare:

1at48inchby12inchrectangle.2at47inchbase,withonesideat12inchesandoneat215/8inches.2at453/8inchbase,withonesideat215/8inchesandoneat371/4inches.2at453/8inchbase,withonesideat371/4inchesandoneat527/8inches.2at47inchbase,withonesideat527/8andoneat621/2inches.1at48inchby621/2inchrectangle.

5. Lightlysandandsmooththeedgesofthewood.

6. Cutout20woodenconnectingblocksforthepanels,from2x3(orsimilar)wood.Becauseofthetilt,theblocksarenotallexactlythesamesize.Thethicknessofthewoodisnotthatimportant-itistheanglesthatarecritical.Themoreaccurateyoucancuttheanglesthelessadjustmentwillbenecessarywhenthedomesupportismatchedtothedome.Mostmitersawswillnotcutatsuchanacuteangleas17degrees,sofirstmakeatemplateblockwithacutat73degreesusingamitersaw,thentocutthe17degreeangleclampthetemplateblockinplace,carefullyplacetheactualblock,andthena90degreecutwillgivethedesiredresult.Notethatthetwocutsoneachblockneednotmeetatanexactpoint,thoughtheycan.Ashortflatsectionbetweenthetwoangledcutsisnotaproblem.Withasimple10inchmitersawblockwidthsshouldbechosenthatthesawcancutrightthrough-whichlimitsthethicknessto2.5inchesorso.Acompoundmitersawwillgivegreaterflexibility.Beforestartingontheangledcuts,cutthe2x3woodinto10inchlengths(20areneeded).


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BlockA.Eightoftheseareneeded.Aftercuttingthemoutmarkthemwithan"A",astheanglesofallblocksareverysimilar.

Theexactangleshereare72.85and17.15degrees.

Notethe73degreetemplateblockhasbeenmarkedandclampedtothemitersaw.

BlockB.Eightoftheseareneeded.Markthesewitha"B".


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Makea72degreetemplateblocktostartwith.ThencutouteightBblocks.

BlockC.Onlyfouroftheseareneeded.Markthemwitha"C".



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Makea71degreetemplateblocktostartwith.ThencutoutfourCblocks.

7. Takeoneofthepanelsmarked"Door"intheprecedingimages.Cutoutarectangulardoorshape,andfithingesandahandleontheoutside.Thedoorwillopentotheoutside,sothereisnoneedforahandleontheinside.


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Thedoorheightwillbemoresuitableforchildrenthanforadults.

Ifalargerdoorisrequiredconsideraddinganequalamounttotheheightsofallthesidepanels.

Inordertohaveafullsizedoorthewholestructurecanberaisedbymakingthelowersideofthedomesupporthigherthan12inches.However,tohavea6footdoorthelowersidewillneedtobearound36inches,addingafurther2feettotheheightoftheplanetarium.

Addaseconddoortotheothersideofthedomesupport-toprovidebothan"In"andan"Out",andafireescape.


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Notethe2x2inchwoodusedtostrengthenboththesideofthedoorframecontainingthehinges,andacrossthebottomofthedooropening.Usescrapsofwoodtostrengthenthehingesonthedooritself.

Forarectangulardoor,considerusingapoweredcircularsawtocutoutmostofthedoor,butuseahandsawtofinishoffthecuts.Fortheroundeddoorshowninthepicture,useahandheldjigsawtocutouttheshape,aftercarefullydrawingthearconthepanel.

Therectangulardoorshowninsomeoftheimagesisquiteshort-duetoheightrestrictionsintheassemblyareafortheprototype-whichisthereasonwhytheroundeddoorwasmadeasanimprovementtomakealittlemoreheadroom.

8. Usingshortscrews(1.5inchwoodscrews,orsimilar)assemblethedomesupportbyscrewingoneblocklowdownoneachpanel,andonenearbutnotatthetop(atleast1inchshortofthetopoftheshortestofthetwopanels).Pilotholesforthescrewsshould


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bedrilledfirst,andthescrewsdrilledintoplacebutnottightenedtothemaxuntilthewholesupportisinplace.

NotethepositionsoftheA,BandCblocks,andthattherearetwoofthemperjoint.

Aplanviewofthedomesupportshowsittobeanellipticaldecagon.

Thefirstblock.UseanAblocktoconnecttheshortestrectangularpanelwiththeshortestangledpanel.

Nextaddthesecondblocktothisjoint.

Thenaddthematchingshortestangledpaneltotheotherside.

Theprogression.Movingleftandrightassemblethedomesupportpanelsfromtheshortesttowardsthetallestpanel.


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Unevennessinthefloormightcausesomeminoralignmentissues.Ifthisisthefinallocationofthedome,thenensurethatitisasstableasitcanbe.Minormismatchesintheheightsofthepanelsisdealtwithwhenscrewingintheledges.

Notethepositionsofthetopjointblocksafewinchesbelowtherim.

1. Ontheoutsideofthetopedgeofeachpanelscrewinalengthof1x1.5inchwood(orsimilar)thatisexactly48incheslong.Thisshouldcreatealedgeallthewayroundtheoutsideofthedomesupport.Accuratelyaligntheledgewiththetopofthepanels,butmoreimportantlywiththeprecedingledges,sothatthesupportingsurfaceforthedomedoesnotchangeheightfromtheendofonesidepaneltothestartofthenext.Startatthetallrectangularpanel,andusing3screwsperledge,carefullyworkyourwayaroundthedomesupport.

2. Usinga2inchdiameterholedrillingbit(orsimilar)-drilloutagridof3x4or4x4holestobeusedtoventtheplanetarium.

Asmallextractorfanwillbeaddedtothedomesupportatalaterstage,toprovidesomeairflow.

3. Cleanthedomesupportareaofallsawdust,screws,andanyleftoverpiecesofwood.

4. Painttheinsideofthedomesupportaflatmattblack.

Makesuretopaintaroundalltheblocks,thedoorsupports,andthetopoftheledges.Alsopainttheinsidesoftheventholes,andtheedgesofthedoors.Trytopainttothebottomofeachpanelwithoutpaintingtoomuchofthefloor!Useplastictarps,orsimilar,toprotecttheflooringifnecessary.

5. Painttheoutsideofthedomeanycoloryoulike.

6. Sealallthegapsontheoutside.Nolightshouldgetinthroughthejointsbetweenthepanels,noraroundthesidesofthedoor.Useathicktapetosealthejoints.Thedoorismorecomplicated,considerattachingablackfeltcurtainontheinsidetoblockoutanylight.

ToConstructaSmallerDomeSupport

Toconstructadomesupportusing36inch,ratherthan48inch,sides,usethefollowingtableofmeasurementsforthepanelsizes.Thiswillcreateadomesupportforadomethatisjustover9feetindiameter.Thedomesupportwillhaveasidetosidediameterof116.5inches(about9.5feet)andafronttobackdiameterof104.1inches.Obviouslyuse36inch


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longledgesections,buttheblocksthatfitthedomesupporttogetherhaveexactlythesameanglesasforthe48inchsideddomesupport.Notethatthedoorforentrywillnowbequiteshort,soconsideradding12inchestotheheightofallthepanels,ifyourlocationhastheheadroom!

Number Sizes

1 36inchx12inchrectangle.

2 351/4inchbase,oneside12inches,othersideis191/4inches.

2 34inchbase,onesideis191/4inches,othersideis3015/16inches.

2 34inchbase,onesideis3015/16inches,othersideis4211/16inches.

2 35.26inchbase,onesideis4211/16inches,othersideis497/8inches.

1 36inchx497/8inchrectangle.

TheDomeSpecificationUtility

Clickonthelinkbelowtorunautilityprogramthatwillcalculatethetriangleandpanelsizesrequired,giventhreeinputs:

1. Thelengthofthesidesoftheequilateraltriangles(triangleA).2. Theheightoftheshortestpanelinthedomesupport.3. Thetiltangleindegrees.Though20degreesisrecommended,otheranglescanbe

used,andthesoftwarecanbeconfiguredtomatch.

Notethattheutilityrequiresscriptstoberun,soifyougetasecuritywarning,besuretoAllowBlockedContent.Notealsothatanglesdonotchangewiththesizeofthedome.

DomeSpecificationutility


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ConstructionoftheDomeToconstructthedome,gothroughthefollowingprocedure:

1. Purchasethenecessarymaterials:

40sheetsofcorrugatedcardboard,ideallywithonesidealreadywhite,48x48inches.Purchaseanextraoneortwoifmistakesmightbemade.Alternativelyslightlyfewersheetsareneededwith48x96inchcardboardsheets(asthreeofthesmallertrianglescanbecutpersheet)butthereisatransportissuewithsheetsofthissize!Soeitherbuy4048x48inchsheets,or1548x96inchsheets,plusafewextraasspares.165large(2ormoreinchwide)paperbinderclips.Thisprovidesthreeclipsperjoint.Blackpapersheetstotaling48incheslongby110incheswide.Mattflatgrey(notwhite)paint.

2. Acquirethenecessarytools:

Sharpknife.Longmetaledgedscale.Sharppoint,string,andpencil.Paintbrushes,cleaningmaterials,newspaper.

3. Verycarefullydrawoutandthencutoutthetemplatetriangles.Twosizesoftrianglearenecessary,labeledasAandBinthefollowingdiagrams:


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Usethefullwidthofthe48inchsheets.

Todrawthetriangleyoucanuseasharppointwithastring48incheslong,anddrawtwoarcs.Wherethearcsintersectisthetipofthetriangle.Alternativelycalculatetheheightofthetriangle(41.57inches)-measurethisalongbothedgesofthecardboard,thendrawalinefromonesidetotheother,andmarkthecenter-24inchesalongtheline.

Aftercuttingoutthetemplate,10trianglesoftypeAareneeded.

Notethatthetriangleis48inchesonallsides,andthattheflapsareinadditiontothis.Thisispossibleonasheetofcardboardonly48incheswidebyhavingthetaperedflapsshownatthecorners.


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Aftercuttingoutthetemplate,30trianglesoftypeBareneeded.Thiswillrequire3048x48inchsheets,or1048x96inchsheets,asthreetrianglescanbecutfromthelargersheet.

13/16thsisagoodapproximationfor.82inch.Theheightofthetriangleis34.25inches.

Notethatthetriangleis48inchesononeside,and41.82ontheothertwosides,andthattheflapsareinadditiontothis.

4. Wheneachtriangleiscutoutlabeltheoutside(notthewhitesideifwhite-sidedcardboardisused),withthelettersAorB.

5. Markthelineswheretheflapsneedtobefoldedwithapencil,thenuseadullpointlikeaball-pointpentoscorethecardboardwithoutcuttingittomuch.Practiceonsomescrapstogainsomeexpertisefirst.Scorethecardboardtrianglesaccuratelyandfoldtheflapsout.

6. Doublecheckyouhavethecorrectquantities:10oftriangleA,30oftriangleB,notincludingthetwotemplatetriangles(whichshouldbestoredseparatelyandnotpainted-incaseyouneedtoredooneormoretriangles).

7. Atthisstagetheinsideofthetrianglesshouldbepaintedaflatmattlatexgrey.Ifwhitecardboardisusedthisshouldnottakemorethanonecoatofpaint.Makesurethatthepaintingisdoneinaventilatedarea,andappropriatebreathingmasksareused.Brown


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cardboardmaytakeasecondcoatofpaint.Althoughthetemptationistouseapurewhitepaint,thiswillreflecttoomuchoftheprojection.Aflat,lightgreyshouldgivethebestresults.Itisnotnecessarytopainttheflapscompletely,butpaintovertheedgesofthetrianglesandintotheflapareatoensuregoodcoverage.

Paintingisfun-thoughisusuallydoneonaflatlevelsurface!

8. Afterthecardboardispainteditmaybowtovaryingdegrees.Whenthepaintisdryconsiderstackingthetriangles,perhapswithhalffacingtheoppositedirection,withaweightcarefullyplacedontoptohelpcounteractthebowingeffectofthepaint.Inanycasewhentheflapsareturnedoutthiswilltendtoflattenoutthetrianglesagainconsiderably,sothebowingisnottheseriousissuethatitmightfirstlook.

9. Optionalstep.Makeblackshadestoblockoutlightalongtheedgesofthepentagon.Thereare55sidesinternaltothedome,and10sidesaroundthebase.The55internaledgesareamixof48and41.8inches.Cutoutstripsofblackpaperlongenoughthattwooverlappingpieceswillcoverthewholeedge.Obviouslyshorterpiecescanbeusedforthe41.8inchsides.Theinternalstripsshouldbe2.25incheswide(assumingcardboardthatisoneeighthofaninchwide),withafoldat1and1.25inchesalongtheirfulllength.Ifthecardboardyouhaveusedisnotoneeighthofaninchwide,thenthethicknessofthesquarefoldsshouldsimplybetwicethethicknessofthecardboard.Thefoldsneedtobeverystraightfortheshadestofitneatlyontotheedges.Ifasinglefoldisusedtheshadeswilltendtokeepthebinderclipsoutfromthejoin,whichweakensthestructureandispronetoerror.Thereasonwhythisstepisoptionalisthattogetstraightfoldededgescanrequirepaperfoldingequipmentthatmightnotbereadilyavailable.Theimagesshowafoldingmachineandthecompletedshades.Fortheexternal10sidesaroundthebase,thepaperstripsshouldbe3incheswide,foldedat1and2inchesalongtheentirelengthofthestrip.

Apaperfoldingmachineisthebestapproachtogettingverystraightfolds.

Ifsuchafoldingmachineisnotavailable,tryotherlongstraightedgessuchasametalruler.

Firstmarkasheetofblackpaperwhereitneedstobecutandfolded.Thenfoldthesheettwicetocreatethequarterinchsquareend.Thencutoutthestrip.Repeatuntileveryedgehastwoshades.

Theimageshowsaquarterinchfoldforthetriangles,andaoneinchfoldforthebase.

Apentagonwithshadesattached.


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10. Timetogetoutthosepaperclips.StartwithallthetriangleBs.Theseareusedtomakethepentagons.VerycarefullyaligntheshorteredgesoftheBtriangles,placeoneormoreoftheblackshadesalongeachjoint,andcliptogetherapentagon.Notethatjoiningthelastsidewillliftthecenterofthepentagonabout9inches.Ensurethereisenoughspacearoundsothatthesepentagonsarenotsteppedon.

Theoutsideedgesofthepentagonshouldallbethelonger48inchsides.

The30triangleBsshouldbeassembledintosixpentagons.

11. Withalotoflaborassistance(aminimumoffivepeopleworkswell),assemblethedomeintheordershowninthefollowingdiagram:


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Notethatthecentralpolygonistheverylastpiecetobeassembled.Thedomewillbequitefloppyuntilthisisdone,andalotofhandsarehelpfulatthisstage.

Whenbuildingthedometrytoalignthepointsandedgesasaccuratelyaspossiblebeforeproceedingtothenext.

Thecriticalstageinassemblyishavingenoughhandsinsidethedometocompleteallbutthetoppentagon.

Becauseofthedifficultyinclippinginthetoppentagon,considerhavingsomeonestandonasteppingstoolandheldinplacebyasecondperson,whilstthefirstleansoverthedomeandclipsinthefivelastsides.Thepeopleontheinsideneedtosupportboththelasttoppentagon,andallthesides-atthesametime.

Onlywhenthelasttoppentagonisclippedintoplacedoesthedomebecomeself-supporting.

12. Admireyourwork!Thedomeshouldnowbereasonablyrigid.


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13. Ensurealltheflapsoftheloweredgearebentout,andcarefullyliftthedomeontothesupport-witheachofthe10cornerssupportedbyanassistant(hencetheneedforaminimumoffivepeople).Donotliftthedomeatanytimeotherthatatitscorners.Obviouslythecornersand48inchedgesofthedomeshouldmatchtheledgesofthedomesupportexactly.

14. Usethe20heavydutyclipstoattachthedometothesupport,twoclipsperside.

Theheightofthedomewhenitisonthefloorandbeforeitistiltedisjustunder6.5feet.Afterthe20degreetilttheheightisabout6feet.Addtothistheheightofthecenterofthedomesupport(justover3feet),andtheheightoftheplanetariumisafewinchesover9feet.

15. Openupadoorandgoinside!

ToConstructaSmallerDome

Toconstructadometofitthe36inchsidedomesupport,triangleAshouldbeanequilateraltrianglewith36inchsides.TriangleBshouldbeanisoscelestrianglewitha36inchbaseandtwosidesof313/8inches.

Theheightofaplanetariumofthissizeisaround7feet.Thefollowingimagesshowstherelativesizesofthedomes.

</th>|48inchtriangleplanetarium|36inchtriangleplanetarium||:--|:--|

AddingVentilationandPowerAddingventilationtotheplanetariumwillmaketheexperiencemorepleasantformostpeople.Electricpowerwillbeneededtopowertheexternalfan,andalsoobviouslytopowertheinternalprojector.

1. Purchaseoracquireasmallextractorfan(thefanmustbecapableofgoingintoreverse-toextracttheair-ratherthanjustblowwarmair).

2. Usingblackfoam-board,orasimilarmaterial,constructaboxasshownintheimagebelow.

Picsoffanandbox

1. Powerupthefanandcheckthattheventilationsystemworks.2. Runablackpowercable(25,30oreven50feet)throughoneoftheventilationgrill

holesandupandoveroneofthedoorssothatthepoweroutletsareavailabletotheprojectorthatwillbesittingonashelfbetweenthetwodoors.Considerusingsafety


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hooks(cuphooksthatclosewithaspring),orsimilarsmallhooks,toguidethepowercable.Ensurethatitdoesnotcrosstheflooratanystageinsidethedomesupport,whereitcouldbetrippedon.,andfollowsasafepathtothepoweroutletoutsideoftheplanetarium.Ifthepowercableorhooksarenotblack,thenconsiderpaintingthehooksandcoveringthecableinsidetheplanetariumwithblacktape.

Thecableinthisimagehasbeenleftredtoshowitscourse.Coveringthecablewithblacktapefortheinsidesectionensuresminimalreflectivity.

AddingSeatingandCarpetingIdeallytheviewersinsidetheplanetariumwillbeseatedentirelybelowthebaselineofthedome-thisistoensurethatnopartofthemblocksthereflectionfromthemirrorontothedomesurface.Inpracticethismaybedifficulttoachieve,especiallyifheightwasanissueduringconstruction.Thesuggestedlayoutistolayblackcarpettilesacrossmostoftheflooroftheplanetarium,withperhapsafewseatssetatthebackneartheprojector.Shorterviewerssitatthefrontandmiddleoftheplanetarium,onthecarpet,tallerviewerscanusetheseatsattheback.Theexactlayoutdependsonthenumberofviewersyouplantoaccommodateatanyonetime-allcarpetingandnoseats,orallseatsandnocarpeting,areobviouslyoptionstoo.

Theseats,similartoallitemsunderthedome,shouldbeasmattblackaspossible.

SettinguptheProjectorandMirrors1. Themirrorneedstobeahalf-domesphericalmirrorasshownintheimagebelow.High

QualityMirrors

Experimentingwithdifferentsizesofsphericalmirror.Thesmaller,approximately9inchradius,workedwellinourtests.

1. Theprojectorshouldprovideashighadefinitionaspossible.IdeallytheprojectorshouldbecapableoffullHD,1920x1080pHDforexample(whichgivesa16x9aspectratio).SuchaprojectorwillrequireaDVIorHDMIcable

ADVIcable.

2. Themirrorshouldbeplacedinthedirectcenteronthehighestsideofthedomesupport,angleddownwardsatanangleof20degrees,anditsbaseshouldbeatthesameheightatthebaseofthedome.Thesupportforthemirrorcanbemadeoutofwood,cuttogivea20degreeangle,orotheroptionscanbeusedtoprovidesomefine


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adjustmentshoulditbenecessaryorhelpful.Intheimagebelowasecondtierkeyboardsupport(foramusickeyboard)hasbeencutanddrilledtoprovideamirrorsupportthatcanbothtakeavariablesizeofmirror,andhavetheangleofthemirrorfinelyadjusted.

3. Theprojectorneedstobeplacedpointingupatthemirrorsothattheimageisreflectedoffthemirrortofillthedome,butnotthedomesupport.Forthisasolidsupportsystemisneededthatwillsafelyholdtheprojectoratanangleofabout20degrees,andprovidefineturningadjustment.Onegoodsolutiontothisistouseasolidmusicorconductorsstand(asshownintheimagebelow).Thesecanbefoundreasonablycheaply(around$50)andaresurprisinglysturdy.Findonethatenablesadjustmentinbothsidetoside,andupanddowndirections,andisvariableinheightfromaround24to40inches.

Primaryprojection.

Eventhoughamusicstandisdesignedtoholdjustpaper,asturdyonecaneasilysupportandholdaprojectoratanangle.

4. Analternativetotheprimaryprojectiondescribedinstep4,istouseasecondarymirror.Useofasecondarymirrorhastheadvantagethattheprojectorandsupportarenolongernearthecenterofthedomeusingupvaluablespectatorspace.Howeverthedownsidetousingasecondarymirroristhatitinvolvesadditionalcost(ofthesecondarymirroritself,andsomeshelving),andcomplicatesthealignment-theprojector,secondarymirror,andsphericalmirrornowallhavetobealignedsimultaneouslyandcorrectly.

Secondaryprojection.


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Tousethesecondarymirrormethodofprojection,firstinstallashelvingsystemthatenablesavariationintheheightoftheprojector.Theshelfitselfshouldbeabout24incheswideand13inchesdeep-thoughthisdoesobviouslydependonthesizeoftheprojectoryouintendtouse.

Placetheprojectorontheshelfsothatthelensiscentered-whichiswhytheshelfshouldbe24incheswide,andnotsimplythewidthofaprojector.


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Thesecondarymirrorshouldbealignedatthetopofthemusicstand.HeavydutyVelcro(orsimilar)canbeusedtoattachthemirror.

Thefinealignmentofthethreemainelements(projector,secondarymirror,sphericalmirror)willinvolvesomeminoradjustmentstotheanglesofeachtogetacompleteimageprojectedontothedome.

Notehowclosethesecondarymirroristotheprojector.Justenoughroomisneededsothatthereflectedimageclearstheprojectoritselfandfindsthesphericalmirror.

Thissystemfreesupthecenterofthedomequitewell.

HighQualityMirrors

Mostmirrorsreflectlightfromtwosurfaces,theinsideandoutsidefacesoftheglassorplastic.Unfortunatelythismeansthattherewillbetwoimagesinviewonthedomeforeachsingleobjectinthesimulatedsky-theintendedimageandasecondfainterimageslightlyoffsetfromthefirst.Thisproblemisdoubledifasecondarymirroralsowithtworeflectivesurfacesisused-inthiscasetherewillnowbefourimagesonthedome,theintendedoneandthreefainterghostimages.Thisproblemcanbeeliminatedwiththeuseofhighqualityfirstsurfacemirrors.Thesemirrors,bothflatandspherical,haveonlyonereflectivesurface,soevenwhenasecondarymirrorisusednounwantedghostimagesappearonthedome.Ofcoursetheissuehereiscost,firstsurfacemirrorsareafewtimesmoreexpensivethannormalmirrors.

Theuseoffirstsurfacemirrorsisrecommendedifyourbudgetallows!


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RunWorldWideTelescope1. Connectalaptopcomputertotheprojector,andifpossibletotheinternet.Withoutan

internetconnectionyouwillberestrictedtoshowingthetoursandcollectionsfilesthatarestoredlocallyonthelaptop,sointhiscaserunallthetoursyoumightneedonce(whichstoresthemlocally)whilstconnectedtotheinternet,beforeremovingtheconnectionandmovingtothedome.

2. RuntheWorldWideTelescopeWindowsClientonthelaptop.TheWebClient(basedonSilverlight)doesnotcurrentlysupportthedomewarpingsoftware,somakesureyouareusingthedownloadedWindowsClientversion,andthattheversionnumber(whichcanbeverifiedintheAboutWorldWideTelescopedialog)is2.6.2.1orlater.ItisrecommendedthatyouuseaWindowsbasedlaptop(WindowsXP/Vista/7)forsimplicity,butyoucanuseaMaclaptopwithaWindowspartition.

3. SelectFullDomefromtheViewmenu,thenselectDomeSetuptobringupthefollowingdialog:

Formostmodernprojectorstheaspectratiois16:9,sosettheDomeTypetoMirrordome16:9.IfyouareusinganolderVGAprojector,thentheaspectratiomaywellbe4:3,sosetthisvaluetoMirrordome4:3.RefertotheConfigurationsectionoftheWorldWideTelescopeUserGuidefordetailsifyourprojectorisneitherofthese.

SetDomeTiltto70percent.Thisvaluecontainsthecenterofinterestinverticaldegrees.

Forhighresolutionprojectors(1920x1080orsimilar)selectLargeTextures,otherwiseleavethisunselected.

ClickOK.

4. IntheFullDomemenuensureFullDomehasatickbesideit.

5. Ifyouwishtocontrolthepresentationbylookingatthelaptop,thenyouaregoodtogo-themousemovementsandclicksonthelaptopscreencontroltheview.Ifyouwishtocontrolthepresentationbylookingatthedomeprojection,thenselectDetachMainViewtoSecondMonitor.ConsiderusinganXBoxcontrollerinthislattercase,asinputcontrolhasnowbepassedtothedomeviewandcontrollingthepresentationwithamousecanbeawkward.

6. Inviteyourstudentsandpeers!


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