modern theory called physical process reduced density early universe making universe cosmic microwave background radiation uniform years big bang travelled hot regions space cold ones temperatures regions effect responsible acoustic effect effects gravity electromagnetic radiation eventual formation galaxy clusters dominant large scale structures observed universe strength calculated mathematical expression factor figures equation equation describes strength chiefly governed distance travel scattered length affect length primarily properties question different sorts experience different sorts evolution affect process scale works called silk scale value corresponds size present day mass contained silk scale called silk mass corresponds mass introduction took place billion years ago stage early universe called matter radiation period occurred years big bang equivalent stage simple hydrogen began form cooling hot soup composed universe prior soup largely electromagnetic radiation meant permanently excited scattered travel far straight lines universe cooled rapidly free captured atomic formed constituent parts universe transparent scattering decreased dramatically scattering travel greater distances significant nearly far similar circumstances electron compared acoustic initial density fluctuations universe regions space differences temperature density called hot regions cold ones dragged pushed turn pulled force caused temperatures hot cold regions averaged universe uniform reduction temperature density early universe matter escaping dense areas temperature density remained constant process described joseph silk paper entitled cosmic black body radiation galaxy formation published journal called silk term apply possible scenario silk named magnitude magnitude calculated factor suppression factor represented symbol formula figures equation equation describes strength chiefly governed distance travel scattered length affect length primarily properties question different sorts experience different sorts evolution affect process formula formula time formula differential optical depth scattering scattering scattering electromagnetic radiation light charged particles formula wave number wave suppressed formula visibility function formula factor formula equation cosmic microwave background radiation reduces formula formula time formula distribution function formula potential gauge gauge quantity importance general theory formula effective temperature mathematical calculations factor depend formula effective scale turn depends crucial value length formula length relates far travel comprises finite number short steps random directions average steps mean free path denoted formula direction steps randomly taken formula approximately equal formula formula number steps takes time formula length increases mean free path scattering occurring increases mean free path increases electron fraction formula decreases hydrogen free charged occurs mean free path increases formula mean free path proportional electron fraction number density formula means shorter average travel encountering scattered small changes values augment effect considerably dependence density allows scientists use analysis investigate addition history effect greatly augmented finite width surface scattering finite width means emitted time fluctuations phase means length changed dramatically fraction shifted model dependence general produces effects independent model studied effects model dependent phenomena means accurate model scientists judge relative merits models theoretical predictions compared data data obscured effects example peaks power spectrum acoustic decreased power spectrum hides features curve features visible general damp dark matter simply term silk applies models matter coupled dark matter silk significant models development early fluctuations fluctuations require constant ratio case increases density require corresponding increases density lower density dependent causes initial fluctuations density universe effects speed occurs different scales process working quickly short ranges longer distances short length lower mean free path long distance greater mean free path length smaller scale larger scale decreased slowly significant degradation happening unit time silk scale silk mass decreases scale silk scale smaller degree smaller approximately angular scale corresponds moment formula mass contained silk scale silk mass numerical silk mass yield results order formula solar masses order mass present day galaxy galaxy cluster current era formula scientists affects small angles corresponding effects operate scale called intermediate formula large formula searches small scale difficult larger scales partly employ ground based results easily predicted current theoretical models galaxy formation scientists study general insight subject provides question universe come specifically temperature density universe supposed causes later large scale structure formation small pre universe grew galaxy clusters present era universe distances order silk scale scale corresponds size observed passage time taken account implies responsible limiting size theory matter early universe today size related temperature density significant effect evolution cosmic magnetic fields fields time magnetic fields cosmic magnetic fields acoustic waves waves travelling process began era ended time


april lunar eclipse total lunar eclipse took place april total lunar total lunar series subsequent october april september eclipse visible americas pacific_ocean region including australia new_zealand hour minute long eclipse moon passed south center earth shadow result northern moon noticeably darker southern lasted hour minutes eclipse occurred ascending phase moon orbit lunar mars near opposition 56th member lunar previous event april lunar eclipse event april lunar eclipse background lunar eclipse occurs moon passes earth shadow eclipse begins earth shadow moon slightly shadow begins cover moon turning dark red brown color typically color vary based atmospheric conditions moon appears reddish scattering effect causes appear reddish light earth atmosphere following simulation shows approximate appearance moon passing earth shadow moon exaggerated shadow northern portion moon closest center shadow making red appearance description april moon passed southern earth shadow visible western hemisphere including east australia new_zealand pacific_ocean americas western pacific half eclipse occurred europe africa eclipse began mars passed opposition appeared magnitude northwest moon west north saturn east southeast moon entered earth shadow utc shadow lasted hour minutes moment greatest eclipse occurred point moon approximately kilometres southwest islands moon left shadow shadow peak magnitude moment northern moon arc minutes south center earth shadow southern arc minutes center gamma eclipse eclipse member lunar 56th eclipse timing phase eclipse changes appearance moon slightly generally noticeable moon visible eclipse time zone timing total lunar determined contacts contact beginning eclipse earth touches moon outer limb second contact beginning partial eclipse earth touches moon outer limb contact beginning total eclipse moon surface entirely earth greatest eclipse peak stage total eclipse moon closest center earth fourth contact end total eclipse moon outer limb exits earth fifth contact end partial eclipse earth leaves moon surface sixth contact end eclipse earth longer makes contact moon viewing events museums planned special events eclipse united_states national_park_service sponsored events great basin national park sleeping bear dunes national university hawaii institute astronomy held events locations islands observatory los_angeles california streamed eclipse live internet nasa hosted live question answer sessions online happened roughly hours eclipse ask second web chat hosted nasa site eclipse began nasa streamed eclipse live website nasa provided hours live coverage beginning gallery relation prophecy starting christian john mark began teaching blood moon said second coming jesus occur end began april eclipse said sign significant idea gained popular media attention united_states prompted response scientific radio earth sky according christian today small group christians saw eclipse having religious significance despite attention related april eclipse eclipse consecutive total partial eclipse lunar cycles october april september lunar year series repeats cycles days causing date shift compared solar calendar shift means earth shadow degrees west subsequent eclipse started ascending moon orbit series started series starting april half cycle lunar eclipse preceded followed solar years days half lunar eclipse related hybrid total solar solar


type types categories stellar explosions caused core collapse massive stars stars shed stripped outer envelope hydrogen compared spectrum type lack absorption line compared type type lost initial envelope including types usually referred stripped core collapse observed categorized classification scheme based absorption lines appear spectrum categorized type type sub categorized based specific traits belonging general category type lack hydrogen lines contrast type display lines hydrogen type category sub divided type type type type distinguished type lack absorption line singly type age display lines elements oxygen calcium contrast type dominated lines iron type distinguished type lack lines formation prior evolved massive star organized manner layers different elements undergoing fusion layer consists hydrogen followed carbon oxygen forth outer envelope hydrogen shed layer consists primarily mixed elements occur hot massive star reaches point evolution significant mass loss occurring stellar wind highly massive stars times mass sun lose solar masses year equivalent years type produced core collapse massive stars lost outer layer hydrogen winds mass transfer companion types lost outer strong stellar winds interaction close companion rapid mass loss occur case wolf star massive objects spectrum lacking hydrogen type ejected hydrogen outer type lost hydrogen shells words type lost envelope layer type respects underlying mechanism type similar type placing type type type similarity type collectively called type evidence small percent type gamma ray bursts particular type broad lines corresponding high velocity thought strongly associated gamma ray bursts hydrogen stripped type dependent geometry explosion case believe type probably type result core collapse stripped massive stars runaway white formed rare massive stars rate type occurrence lower corresponding rate type normally occur regions new star formation observed elliptical galaxy share similar operating mechanism type type collectively called core collapse particular type referred stripped core collapse light curves light curves plot versus time type vary form cases nearly identical type type light curves peak lower infrared portion spectrum light curve type similar type light curve type usually slower decline rates curves type light curves useful measuring distances scale serve standard candles similarity type form source contamination surveys carefully removed observed samples making distance estimates


stellar rotation stellar rotation angular motion star axis rate rotation measured spectrum star timing movements active features surface rotation star produces force stars solid bodies undergo differential rotation equator star rotate different angular velocity higher latitudes differences rate rotation star significant role generation stellar magnetic field magnetic field star stellar wind wind moves away star rate angular velocity magnetic field star wind applies drag stellar rotation result angular momentum transferred star wind time gradually star rate rotation measurement star observed direction pole sections surface movement away observer component movement direction observer called radial velocity portion surface radial velocity component observer radiation shifted higher frequency shift likewise region component moving away observer shifted lower frequency absorption lines star observed shift end spectrum causes line carefully separated effects increase line width component radial velocity observed line depends star pole line sight derived value given formula velocity equator known result gives minimum value star velocity right angle actual velocity greater formula referred projected velocity giant stars atmospheric result line larger effects effectively drowning signal alternate approach employed makes use events occur massive object passes distant star functions like lens briefly image detailed information gathered means allows effects distinguished rotation star displays magnetic surface activity features tracked estimate rotation rate features form locations equator migrate latitudes course life span differential rotation star produce varying measurements stellar magnetic activity associated rapid rotation technique measurement stars observation shown features actually vary rotation rate star magnetic fields modify flow gases star physical effects gravity tends contract bodies perfect sphere shape mass close center gravity possible rotating star spherical shape rotating stellar disk contracts form star shape spherical doesn proceed way perfect sphere poles gravity acts increase equator effective gravity diminished force final shape star star formation shape sense effective gravity region diminished pull star spherical shape rotation gives rise gravity equator described von extreme example found star equator star measured velocity corresponds rotation period hours velocity star break apart radius star larger polar radius rapidly rotating stars include alpha break velocity star expression describe case force equator equal force star stable velocity value differential rotation surface differential rotation observed stars sun angular velocity varies latitude typically angular velocity decreases increasing latitude reverse observed star designated star sun differential rotation mapped detail underlying mechanism causes differential rotation turbulent convection inside star convective motion carries energy surface mass movement mass carries portion angular velocity star occurs shear rotation angular momentum different latitudes flow regions sharp differences rotation believed efficient sites processes generate stellar magnetic field complex interaction star rotation distribution magnetic field conversion magnetic energy energy modifying velocity distribution rotation braking formation stars believed form result collapse low temperature cloud gas dust cloud collapses conservation angular momentum causes small net rotation cloud increase forcing material rotating disk dense center disk forms gains heat energy collapse collapse continues rotation rate increase point break force equator rotation rate years avoid scenario possible explanation braking interaction magnetic field stellar wind magnetic braking expanding wind carries away angular momentum rotation rate collapsing main sequence stars class found rotate rapidly stars range measured rotation velocity increases mass increase rotation peaks young massive class stars expected life span star decreases increasing mass explained decline velocity age formation main sequence stars decline rotation mathematical relation formula formula angular velocity equator star age relation named law andrew discovered determination star age based rotation rate sun stars slowly lose mass stellar wind star magnetic field ejected matter resulting steady transfer angular momentum away star stars rate rotation greater exhibit rapid mass loss consequently faster rate rotation decay rotation star slowed braking decrease rate loss angular momentum conditions stars gradually approach reach condition zero rotation close systems close star system occurs stars orbit average separation order magnitude distances complex interactions occur tidal effects transfer mass collisions tidal interactions close system result modification parameters total angular momentum system angular momentum transferred periods rotation rates members close system raises tides interaction slightly respect direction attraction force gravity produces component resulting transfer angular momentum tidal acceleration causes system steadily evolve approach stable effect complex cases axis rotation perpendicular plane contact semi detached transfer mass star companion result significant transfer angular momentum companion spin point reaches critical rotation rate begins losing mass equator stars star finished generating energy fusion compact state process dimensions star significantly reduced result corresponding increase angular velocity white dwarf white dwarf star consists material product fusion earlier life lacks mass burn massive elements compact body supported quantum mechanical effect known electron pressure allow star collapse generally white low rate rotation likely result braking angular momentum star lost outer envelope slow rotating white dwarf star exceed limit solar masses collapsing form star exploding type white dwarf reaches mass collision force exceed pressure exerted white dwarf rotating rapidly effective gravity diminished region allowing white dwarf exceed limit rapid rotation occur example result mass results transfer angular momentum star star highly dense remnant star primarily composed particle found atomic net electrical charge mass star range times mass sun result collapse newly formed star rapid rate rotation order second rotating stars magnetic field narrow beam electromagnetic radiation emitted poles rotating beam sweeps past direction solar system produce periodic pulse detected earth energy magnetic field gradually rotation rate older require long seconds pulse black hole black hole object field sufficiently powerful prevent light escaping formed collapse rotating mass retain angular momentum shed form ejected gas rotation causes space shaped volume called dragged black hole mass falling volume gains energy process portion mass ejected falling black hole mass ejected black hole loses angular momentum process rotation rate black hole measured high speed light


black hole black hole region exhibiting strong effects including particles electromagnetic radiation light escape inside theory general sufficiently compact mass form black hole boundary region escape possible called event horizon crossing event horizon enormous effect fate object crossing appears locally features ways black hole acts like ideal black body reflects light quantum field theory curved event radiation spectrum black body temperature proportional mass temperature order black holes stellar mass making essentially impossible observe objects fields strong light escape considered 18th century john simon modern solution general characterize black hole found interpretation region space escape published david black holes long considered mathematical curiosity 1960s theoretical work showed generic prediction general discovery stars sparked interest collapsed compact objects possible reality black holes stellar mass expected form massive stars collapse end life cycle black hole formed continue grow absorbing mass surroundings absorbing stars merging black holes black holes millions solar masses form general consensus black holes exist centers despite invisible interior presence black hole interaction matter electromagnetic radiation visible light matter falls black hole form external disk heated friction forming objects universe stars black hole determine black hole mass location observations exclude possible alternatives stars way identified numerous stellar black hole candidates systems established radio source known core way galaxy contains black hole million solar masses february collaboration announced observation waves waves generated black hole merger direct detection black hole merger june second detection wave event black holes announced history idea body massive light escape forward john letter written henry royal society semi diameter sphere density sun exceed sun proportion body falling infinite height acquired surface greater velocity light consequently light attracted force proportion bodies light emitted body return proper gravity mathematician simon promoted idea second editions book exposition removed later editions justified argument dark stars largely ignored nineteenth century understood wave light influenced gravity general albert developed theory general having earlier shown gravity influence light motion months later found solution field describes field point mass spherical mass months student independently gave solution point mass wrote extensively properties solution peculiar behaviour called radius singular meaning terms infinite nature surface understood time arthur showed disappeared change coordinates coordinates took realize meant radius coordinate arthur comment possibility star mass compressed radius book noting theory allows rule overly large visible stars like star million radius possibly high density sun firstly force great light unable escape rays falling star like stone earth secondly red shift lines great spectrum shifted existence mass produce space time metric space close star leaving outside calculated special non rotating body electron matter certain limiting mass called limit stable solutions arguments opposed contemporaries like argued unknown mechanism stop collapse partly correct white dwarf slightly massive limit collapse star stable exclusion principle robert predicted stars approximately limit collapse black holes reasons presented concluded law physics likely intervene stop stars collapsing black holes authors interpreted boundary radius indicating boundary bubble time stopped valid point view external observers observers property collapsed stars called frozen stars outside observer surface star frozen time instant collapse takes inside radius golden age david identified surface event horizon perfect membrane influences cross direction strictly results extended include point view observers solution extended solution future observers falling black hole complete extension found martin urged publish results came beginning golden age general marked general black holes mainstream subjects research process helped discovery shown rapidly rotating stars time stars like black holes regarded theoretical discovery showed physical relevance spurred interest types compact objects formed collapse period general black hole solutions found roy found exact solution rotating black hole years later newman found solution black hole rotating electrically charged work israel carter david robinson hair emerged stating stationary black hole solution completely described parameters newman metric mass angular momentum electric charge suspected strange features black hole solutions artifacts symmetry conditions imposed appear generic situations view held particular tried prove appear generic solutions late 1960s roger stephen global techniques prove appear work james jacob carter early 1970s led black hole laws describe behaviour black hole close analogy laws relating mass energy area surface gravity temperature analogy completed showed quantum field theory black holes like black body temperature proportional surface gravity black hole use term black hole print journalist ann article black holes space dated january report meeting american association advancement science john term black hole lecture leading credit phrase use term quickly adopted general use properties structure hair states stable condition formation black hole independent physical properties mass charge angular momentum black holes share values properties parameters indistinguishable according classical non quantum mechanics properties special visible outside black hole example charged black hole like charges like charged object similarly total mass inside sphere containing black hole found analog law mass far away black hole likewise angular momentum measured far away frame dragging field object falls black hole information shape object distribution charge evenly distributed horizon black hole lost outside observers behavior horizon situation system closely analogous membrane friction electrical resistance membrane different field theories friction microscopic level time black hole eventually stable state parameters way avoid losing information initial conditions electric fields black hole little information went information lost includes quantity measured far away black hole horizon including approximately quantum numbers total number number behavior called black hole information loss physical properties simplest static black holes mass electric charge angular momentum black holes referred black holes discovered solution according vacuum solution means difference field black hole spherical object mass popular notion black hole surroundings correct near black hole horizon far away external field identical body mass solutions describing general black holes exist non rotating charged black holes described metric metric describes non charged rotating black hole general stationary black hole solution known newman metric describes black hole charge angular momentum mass black hole positive value charge angular momentum constrained mass units total electric charge total angular momentum expected satisfy formula black hole mass black holes satisfying inequality called solutions violate inequality exist possess event horizon solutions called naked observed outside deemed cosmic censorship hypothesis rules formation created collapse realistic matter supported numerical relatively large strength electromagnetic force black holes forming collapse stars expected retain nearly neutral charge star rotation expected common feature compact objects black hole candidate ray source appears angular momentum near maximum allowed value black holes commonly classified according mass independent angular momentum electric charge size black hole determined radius event horizon radius roughly proportional mass formula radius mass sun relation exact black holes zero charge angular momentum general black holes differ factor event horizon defining feature black hole appearance event horizon boundary matter light pass inward mass black hole light escape inside event horizon event horizon referred event occurs boundary information event reach outside observer making impossible determine event occurred predicted general presence mass way paths taken particles bend mass event horizon black hole strong paths lead away black hole distant observer near black hole appear slowly away black hole effect known time object falling black hole appears slow approaches event horizon taking infinite time reach time processes object slow view point fixed outside observer causing light emitted object appear effect known eventually falling object dim longer seen hand observers falling black hole notice effects cross event horizon according appear normally cross event horizon finite time noting singular behaviour impossible determine location event horizon local observations shape event horizon black hole approximately spherical non rotating static black holes geometry event horizon precisely spherical rotating black holes sphere center black hole described general lies region infinite non rotating black hole region takes shape single point rotating black hole form ring lies plane rotation cases singular region zero volume shown singular region contains mass black hole solution singular region thought having infinite density observers falling black hole non rotating charged avoid carried cross event horizon experience accelerating away slow descent limit attaining certain ideal velocity best free fall rest way reach crushed infinite density mass added total black hole happens torn apart growing tidal forces process referred effect case charged rotating black hole possible avoid extending solutions far possible reveals hypothetical possibility exiting black hole different black hole acting possibility traveling universe theoretical destroy possibility appears possible follow closed curves returning past lead problems like grandfather expected peculiar effects survive proper quantum treatment rotating charged black holes appearance general commonly perceived signaling breakdown theory breakdown expected occurs situation quantum effects describe actions extremely high density particle interactions date possible combine quantum effects single theory exist attempts theory quantum gravity generally expected theory feature sphere sphere spherical boundary zero thickness sphere trapped circular orbit black hole non rotating black holes sphere radius times radius unstable small particle matter cause instability grow time setting outward trajectory causing escape black hole inward spiral eventually cross event horizon light escape sphere light crosses sphere trajectory captured black hole light reaches outside observer sphere emitted objects sphere event horizon compact objects stars spheres follows fact field external object governed metric depends object mass radius object object radius smaller times radius sphere rotating black holes surrounded region impossible stand called result process known frame dragging general rotating mass tend slightly drag immediately surrounding object near rotating mass tend start moving direction rotation rotating black hole effect strong near event horizon object faster speed light opposite direction stand black hole volume inner boundary black hole event horizon outer boundary event horizon poles noticeably wider equator outer boundary called objects radiation escape normally process objects emerge energy entered energy taken energy black hole causing slow stable circular orbit gravity test particles orbit arbitrary distances central object general exists stable circular orbit called inside circular orbit lead black hole location depends spin black hole case black hole spin zero formula decreases increasing spin formation evolution considering exotic nature black holes natural question bizarre objects exist nature suggest merely solutions thought black holes form held angular momentum collapsing particles stabilize motion radius led general community dismiss results contrary years minority continued contend black holes physical objects end 1960s persuaded majority researchers field obstacle formation event horizon event horizon forms proved general quantum mechanics requires form shortly showed solutions describe big bang fields exotic matter solution hair laws black hole showed physical properties black holes simple making respectable subjects research primary formation process black holes expected collapse heavy objects stars exotic processes lead production black holes collapse collapse occurs object internal pressure insufficient resist object gravity stars usually occurs star little fuel left maintain temperature stellar star stable receives extra matter way raise core temperature case star temperature longer high prevent collapsing weight collapse stopped pressure star constituents allowing matter exotic state result types compact star type compact star formed depends mass remnant original star left outer layers blown away explosions lead mass substantially original star remnants exceeding produced stars collapse mass remnant exceeds limit original star heavy remnant collected additional mass matter pressure insufficient stop collapse known mechanism possibly pressure star powerful stop object inevitably collapse form black hole collapse heavy stars assumed responsible formation stellar mass black holes star formation early universe resulted massive stars collapse produced black holes black holes seeds black holes found centers suggested black holes typical masses formed direct collapse gas clouds young universe candidates objects found observations young universe energy released collapse emitted quickly outside observer actually end process collapse takes finite time reference frame matter distant observer material slow halt event horizon time light collapsing material takes longer longer reach observer light emitted event horizon forms delayed infinite time external observer sees formation event horizon instead collapsing material increasingly red shifted eventually fading away black holes big bang collapse requires great density current universe high found stars early universe shortly big bang greater possibly allowing creation black holes high density allow formation black holes uniform mass distribution allow mass bunch order black holes form dense medium initial density grow gravity different models early universe vary widely predictions size models predict creation black holes ranging mass hundreds thousands solar masses black holes account creation type black hole high energy collisions collapse process create black holes principle black holes formed high energy collisions achieve sufficient density events detected directly indirectly mass balance particle experiments suggests lower limit mass black holes theoretically boundary expected lie mass quantum effects expected predictions general creation black holes firmly reach high energy process occurring near earth certain developments quantum gravity suggest mass lower scenarios example boundary low micro black holes created high energy collisions occur cosmic rays hit earth atmosphere possibly large theories speculative creation black holes processes deemed unlikely specialists micro black holes formed expected seconds posing threat earth growth black hole formed continue grow absorbing additional matter black hole continually absorb gas dust surroundings cosmic background radiation primary process black holes grown similar process suggested formation intermediate mass black holes found clusters possibility black hole growth black hole merge objects stars black holes necessary growth thought important especially early development black holes formed smaller objects process proposed origin intermediate mass black holes predicted black holes entirely black small amounts thermal radiation effect known radiation applying quantum field theory static black hole background determined black hole particles display perfect black body spectrum publication verified result approaches theory black hole radiation correct black holes expected shrink time lose mass particles temperature thermal spectrum temperature proportional surface gravity black hole black hole proportional mass large black holes radiation small black holes stellar black hole temperature far temperature cosmic microwave background radiation stellar mass larger black holes receive mass cosmic microwave background radiation grow instead shrink temperature larger able black hole need mass moon black hole diameter tenth millimeter black hole small radiation effects expected strong black hole heavy compared human instant black hole mass car diameter time briefly times sun lower mass black holes expected faster example black hole mass seconds completely small black hole quantum effects expected play important role small black hole stable current developments quantum gravity indicate radiation black hole predicted weak difficult detect earth possible exception burst gamma rays emitted stage black holes searches flashes proven unsuccessful provide stringent limits possibility existence low mass black holes nasa gamma ray space launched continue search flashes evidence nature black holes directly electromagnetic radiation hypothetical radiation searching black holes generally rely indirect observations example black hole existence observing interactions surroundings event horizon run mit observatory attempt directly observe immediate environment event horizon black hole centre way image event horizon appear early existence magnetic fields outside event horizon predicted theoretical studies black holes confirmed detection waves merging black holes september wave observatory successful observation waves signal consistent theoretical predictions waves produced merger black holes solar masses solar masses observation provides concrete evidence existence black holes date instance wave signal suggests separation object prior merger roughly times radius corresponding masses objects extremely compact leaving black holes plausible interpretation importantly signal observed included start post merger signal produced newly formed compact object stationary state arguably direct way observing black hole signal possible extract frequency time dominant mode possible mass angular momentum final object match independent predictions numerical merger frequency decay time dominant mode determined geometry sphere observation mode confirms presence sphere exclude possible exotic alternatives black holes compact sphere observation provides evidence existence stellar mass black hole furthermore evidence stellar mass black holes weighing solar masses proper motions stars proper motions stars near center way provide strong evidence stars black hole tracked motions stars invisible object radio source fitting motions able million object contained volume radius light years cause motions stars stars called completed orbit data able calculations mass million radius object causing motion stars upper limit object size large test smaller radius observations strongly suggest central object black hole plausible scenarios invisible mass small volume additionally evidence object possess event horizon feature unique black holes matter conservation angular momentum gas falling created massive object typically form disc like structure object artists impressions accompanying representation black hole commonly depict black hole flat space material body hiding disc detailed mathematical modelling shows image disc actually distorted bending light originated black hole way upper disc entirely visible partially visible secondary image underside disk disc friction cause angular momentum transported outward allowing matter fall inward releasing potential energy increasing temperature gas object star black hole gas inner disc high speeds proximity compact object resulting friction significant heats inner disc temperatures vast amounts electromagnetic radiation mainly rays bright ray sources detected process efficient energy producing processes known rest mass material emitted radiation nuclear fusion rest mass emitted energy cases discs accompanied jets emitted poles carry away energy mechanism creation jets currently understood universe energetic phenomena attributed matter black holes particular active believed discs black holes similarly ray generally accepted star systems stars compact object matter companion suggested ray sources intermediate mass black holes november direct observation disk black hole reported ray ray star systems majority radiation ray spectrum ray emissions generally thought result stars compact object matter regular star presence ordinary star system provides unique opportunity studying central object determine black hole system signals directly traced compact object black hole absence signal exclude possibility compact object star studying companion star possible obtain parameters system obtain estimate mass compact object larger limit maximum mass star collapses object star generally expected black hole strong candidate black hole discovered way charles thomas paul doubt remained result companion star heavier candidate black hole currently better candidates black holes found class ray called soft ray class system companion star relatively low mass allowing accurate estimates black hole mass systems actively rays months years period low ray called disc extremely faint allowing detailed observation companion star period best candidates dominated flow disc ray suspected caused flow mass entering mode called dominated flow mode energy generated friction disc swept flow instead away model correct forms strong evidence presence event horizon object center disc solid surface large amounts radiation highly energetic gas hits surface effect observed stars similar state quasi periodic ray emissions certain frequencies signals called quasi periodic thought caused material moving inner edge disk stable circular orbit frequency linked mass compact object alternative way determine mass candidate black holes use term active galaxy describe unusual characteristics unusual line strong radio theoretical studies shown activity active explained presence black holes millions times massive stellar ones models consist central black hole millions times massive sun disk gas dust called disk jets perpendicular disk black holes expected found carefully studied attempts identify measure actual masses central black hole candidates notable black hole candidates include galaxy galaxy widely accepted center nearly galaxy active ones contains black hole close mass hole velocity host galaxy known relation strongly suggests connection formation black hole galaxy proposed way black hole nature object tested future observation effects caused strong field vicinity effect massive object causes light rays light passing lens observations weak light rays directly observed black hole possibility observing black hole observe stars orbit black hole candidates observation orbit alternatives evidence stellar black holes strongly relies existence upper limit mass star size limit heavily depends assumptions properties dense matter new exotic phases matter push bound phase free high density allow existence dense stars models predict existence stars extensions standard model existence fundamental building blocks form stars hypothetical models potentially explain number observations stellar black hole candidates shown arguments general object maximum mass average density black hole inside radius proportional square mass black holes dense stellar black holes average density black hole comparable water consequently physics matter forming black hole better understood possible alternative explanations black hole observations mundane example black hole modelled large cluster dark objects alternatives typically stable explain black hole candidates evidence existence stellar black holes implies order black holes form general fail theory gravity onset quantum mechanical anticipated feature theory quantum gravity feature event black holes real artifacts attention drawn model string theory based calculations specific situations string theory proposal suggests individual states black hole solution event horizon classical semi classical observer statistical average states appears ordinary black hole general open questions showed general conditions total area event collection classical black holes decrease merge result known second law black hole mechanics remarkably similar second law states total system decrease classical objects absolute zero temperature assumed black holes zero case second law violated laden matter entering black hole resulting decrease total universe proposed black hole proportional horizon area link laws strengthened discovery quantum field theory black hole radiation constant temperature seemingly causes violation second law black hole mechanics radiation carry away energy black hole causing shrink radiation carries away proven general assumptions sum matter surrounding black hole quarter area horizon measured units fact increasing allows law black hole mechanics law mass acting energy surface gravity temperature area feature black hole scales area volume normally extensive quantity scales volume system odd property led propose principle suggests happens volume described data boundary volume general perform semi classical calculation black hole situation theoretically statistical mechanics understood counting number microscopic configurations system qualities mass charge pressure etc satisfactory theory quantum gravity perform black holes progress approaches quantum gravity andrew showed counting specific black hole string theory reproduced similar results reported different black holes string theory approaches quantum gravity like loop quantum gravity information loss black hole internal parameters information matter went forming black hole lost regardless type matter goes black hole appears information concerning total mass charge angular momentum long black holes thought persist forever information loss problematic information thought existing inside black hole inaccessible outside black holes slowly radiation radiation appear carry additional information matter formed black hole meaning information appears gone forever question information truly lost black holes black hole information divided theoretical physics community bet quantum mechanics loss information corresponds violation vital property called conservation probability argued loss imply violation conservation energy recent years evidence building information preserved quantum treatment problem popular reading university textbooks review papers


type type type occurs systems stars stars white dwarf star giant star smaller white dwarf white common carbon oxygen variety capable fusion reactions release great deal energy temperatures rise high physically carbon oxygen white low rate rotation limited solar masses cases trigger explosion somewhat limit referred mass despite marginally different absolute limit electron pressure unable prevent catastrophic collapse white dwarf gradually mass companion general hypothesis core reach temperature carbon fusion approaches limit white dwarf merges white dwarf rare event momentarily exceed limit begin collapse raising temperature past nuclear fusion point seconds initiation nuclear fusion substantial fraction matter white dwarf undergoes runaway reaction releasing energy star explosion type category produces consistent peak uniform mass white explode mechanism stability value allows explosions standard candles measure distance host visual magnitude depends primarily distance nasa reported space observatory observed type process exploding details pre nova moments help scientists better understand dark energy consensus model type sub category classification scheme devised american swiss means type form share common underlying mechanism theoretical long believed star type white dwarf evidence found type observed galaxy slowly rotating carbon oxygen white dwarf matter companion exceed limit longer support weight electron pressure absence process white dwarf collapse form star induced non process normally occurs case white dwarf primarily composed neon oxygen current view model type explosions limit actually attained collapse initiated instead increase pressure density increasing weight raises temperature core white dwarf approaches limit period convection lasting approximately years point phase flame born powered carbon fusion details unknown including location number points flame begins oxygen fusion initiated shortly fuel consumed completely carbon fusion begun temperature white dwarf starts rise main sequence star supported thermal pressure expand cool automatically increase thermal energy pressure independent temperature white dwarf unable regulate fusion process manner normal stars vulnerable runaway fusion reaction flame dramatically taylor instability interactions matter considerable debate flame transforms regardless exact details nuclear fusion generally accepted substantial fraction carbon oxygen white dwarf converted heavier elements period seconds raising internal temperature degrees energy release fusion star individual particles making white dwarf gain energy fly apart star explodes violently releases shock wave matter typically ejected speeds order roughly speed light energy released explosion causes extreme increase typical visual absolute magnitude type billion times brighter sun little variation theory type similar white dwarf matter slowly approach limit case nova falling matter causes hydrogen fusion surface explosion disrupt star type differs core collapse caused explosion outer layers massive star core formation single model formation category close star system system consists main sequence stars primary possessing mass secondary greater mass primary pair evolve giant branch star envelope expands considerably stars share common envelope system lose significant amounts mass reducing angular momentum radius period primary degenerated white dwarf secondary star later red giant stage set mass primary final shared envelope phase stars spiral closer angular momentum lost resulting orbit period brief hours continues long white dwarf eventually approach limit white dwarf companion matter types companions including orbit sufficiently close main sequence star actual evolutionary process stage remains uncertain depend rate transfer angular momentum white dwarf companion estimated single account type double second possible mechanism triggering type merger white combined mass exceeds limit resulting merger called super mass white dwarf case total mass constrained limit collisions solitary stars way occur years far frequently appearance collisions occur greater frequency dense core regions clusters blue likely scenario collision star system systems containing white collision leave close system white orbit merge shared envelope study based found double systems white tested implying double white dwarf merger years way rate matches number type detected neighborhood double scenario explanations proposed massive possible explanation possible models white dwarf ruled strongly suggested given companion star remnant found observations nasa swift space ruled existing giant companion stars type studied companion blown outer shell rays glow detected swift ray closest remnants type observed days explosion satellite optical showed radiation originating heated companion star surface hit shock wave meaning red giants larger stars case companion star smaller sun existed ray observatory revealed ray radiation elliptical galaxy times expected ray radiation emitted discs type missing radiation indicates white possess discs ruling common based model inward white dwarf pairs strong sources waves detected double scenarios raise questions type standard candles total mass merging white varies significantly meaning varies type proposed group sub occur white dwarf classified type type completely destroy white dwarf observation unlike types type generally occur types including preference regions current stellar formation white dwarf stars form end star main sequence evolutionary period long lived star system far region originally formed close system spend million years mass transfer stage possibly forming persistent nova conditions type occur long standing problem astronomy identification direct observation provide useful constraints models search ongoing longer century observation provided useful constraints previous observations space star position event excluding red giant source expanding explosion found contain carbon oxygen making likely white dwarf primarily composed elements similarly observations nearby discovered january factory lead conclusion explosion arises single red giant companion suggesting single path direct observations reported august edition science support conclusion star experienced periodic nova surprising discovery later analysis revealed material massive single scenario fits better core scenario light curve type characteristic light curve function time explosion near time maximum spectrum contains lines intermediate mass elements oxygen calcium main constituents outer layers star months explosion outer layers expanded point transparency spectrum dominated light emitted material near core star heavy elements synthesized explosion prominently close mass iron iron peak elements radioactive decay produces high energy dominate energy output intermediate late times use type measure precise distances pioneered collaboration chilean survey series papers 1990s survey showed type reach peak single measured light curve correct type standard values original correction standard value known phillips relationship shown group able measure relative distances accuracy cause peak related produced white presumably exploding near limit similarity absolute profiles nearly known type led use secondary standard astronomy improved variable distance scale direct geometric distance measurements dynamics combined type distances led improved value constant observations distant type indicated unexpected result universe undergo accelerating expansion members teams subsequently awarded nobel prizes discovery distinct types recently discovered type considered fact different form type relatively today far common earlier history universe far reaching significance lead revision rate expansion universe prevalence dark energy research needed


astronomy astronomy natural science study objects stars planets processes explosions gamma ray bursts cosmic microwave background radiation physics chemistry evolution objects processes generally phenomena originate outside atmosphere earth related distinct subject physical concerned studying universe astronomy oldest sciences early recorded history greeks indians chinese maya performed observations night sky historically astronomy included disciplines diverse navigation astronomy making professional astronomy considered synonymous 20th century field professional astronomy split theoretical branches astronomy focused acquiring data observations astronomical objects analyzed basic principles physics theoretical astronomy oriented development computer models describe astronomical objects phenomena fields complement theoretical astronomy seeking explain results observations confirm theoretical results astronomy sciences play active role especially discovery observation phenomena amateur contributed important astronomical discoveries etymology astronomy greek star law culture means law stars culture stars depending translation astronomy confused belief system claims human affairs positions objects fields share common origin entirely distinct use terms astronomy generally term astronomy refer subject based strict dictionary definitions astronomy refers study objects matter outside earth atmosphere physical chemical properties refers branch astronomy dealing behavior physical properties dynamic processes objects phenomena cases introduction introductory textbook physical universe frank astronomy describe study subject describe physics oriented version subject modern astronomical research deals subjects related physics modern astronomy actually called fields purely astronomy departments scientists carry research subject use astronomy partly depending department historically affiliated physics department professional physics astronomy degrees leading scientific journals field european journal named astronomy leading american journals journal astronomical journal history early times astronomy comprised observation predictions motions objects visible naked eye locations early cultures assembled massive artifacts possibly astronomical purpose addition ceremonial uses employed determine seasons important factor knowing plant crops understanding length year tools invented early study stars conducted naked eye developed notably greece india china egypt central_america astronomical assembled ideas nature universe began explored early astronomy actually consisted mapping positions stars planets science referred observations early ideas motions planets formed nature sun moon earth universe explored earth believed center universe sun moon stars rotating known model universe system named particularly important early development beginning mathematical scientific astronomy began laid foundations later astronomical traditions developed discovered lunar repeating cycle known following significant advances astronomy ancient greece world greek astronomy characterized start seeking rational physical explanation phenomena 3rd century estimated size distance moon sun propose model solar system 2nd century discovered calculated size distance moon invented earliest known astronomical devices created comprehensive catalog stars northern hemisphere derive greek astronomy mechanism early analog computer designed location sun moon planets given date technological artifacts similar complexity 14th century mechanical astronomical appeared europe middle ages astronomy medieval europe 13th century astronomy flourished islamic world parts world led emergence astronomical muslim world early 9th century galaxy largest galaxy local group discovered persian described book fixed stars apparent magnitude stellar event recorded history observed egyptian arabic ali ibn chinese prominent islamic persian arab significant contributions science include time introduced arabic names individual stars believed ruins great housed astronomical observatory europeans previously believed astronomical observation pre colonial middle ages sub africa modern discoveries roman_catholic_church gave financial social support study astronomy centuries recovery ancient learning late middle ages enlightenment probably institutions church motives finding date easter scientific revolution renaissance proposed model solar system work defended expanded corrected enhance observations system described correctly details motion planets sun center succeed theory laws wrote left newton invention dynamics law finally explain motions planets newton developed reflecting english john stars discoveries paralleled improvements size quality extensive star produced william detailed catalog clusters discovered planet new planet found distance star announced measured friedrich 19th centuries attention body problem led accurate predictions motions moon planets work refined allowing masses planets estimated significant advances astronomy came introduction new technology including photography discovered bands spectrum sun ascribed presence different elements stars proven similar earth sun wide range temperatures masses sizes existence earth galaxy way separate group stars proved 20th century existence external soon expansion universe seen recession modern astronomy discovered exotic objects radio observations develop physical theories describe objects terms equally exotic objects black holes stars physical huge advances 20th century model big bang heavily supported evidence provided astronomy physics cosmic microwave background radiation law elements space enabled measurements parts electromagnetic spectrum normally blocked blurred atmosphere recently february revealed project detected evidence waves september astronomy astronomy main source information bodies objects visible light generally electromagnetic radiation astronomy divided according observed region electromagnetic spectrum parts spectrum observed earth surface parts high altitudes outside earth atmosphere specific information given radio astronomy radio astronomy studies radiation greater approximately millimeter radio astronomy different forms astronomy observed radio waves treated waves relatively easier measure phase radio waves easily shorter radio waves produced astronomical objects form thermal radio observed earth result radiation produced orbit magnetic fields additionally number lines produced gas notably hydrogen line radio wide variety objects radio including gas active infrared astronomy infrared astronomy founded detection analysis infrared radiation longer red light infrared spectrum useful studying objects cold visible light planets light blocked dust longer infrared penetrate clouds dust block visible light allowing observation young stars molecular clouds observations wide field infrared survey explorer wise particularly effective unveiling numerous host star clusters exception close visible light infrared radiation heavily absorbed atmosphere masked atmosphere produces significant infrared consequently infrared located high dry places space molecules strongly infrared allows study chemistry space specifically detect water optical astronomy historically optical astronomy called visible light astronomy oldest form astronomy optical images observations originally drawn hand late 19th century 20th century images photographic equipment modern images digital particularly charge coupled devices recorded modern medium visible light extends approximately equipment observe near near infrared radiation astronomy astronomy refers observations approximately light absorbed earth atmosphere observations performed upper atmosphere space astronomy best suited study thermal radiation lines hot blue stars stars bright wave band includes blue stars targets surveys objects commonly observed light include remnants active light easily absorbed dust appropriate adjustment measurements necessary ray astronomy ray astronomy study astronomical objects ray typically ray radiation produced result magnetic field lines thermal thin gases million thermal thick gases rays absorbed earth atmosphere ray observations performed high altitude balloons rockets spacecraft notable ray sources include ray remnants elliptical clusters active gamma ray astronomy gamma ray astronomy study astronomical objects shortest electromagnetic spectrum gamma rays observed directly satellites gamma ray observatory specialized called atmospheric actually detect gamma rays directly instead detect flashes visible light produced gamma rays absorbed earth atmosphere gamma ray sources actually gamma ray bursts objects produce gamma radiation thousands seconds fading away gamma ray sources non sources steady gamma ray include stars black hole candidates active fields based electromagnetic spectrum addition electromagnetic radiation events originating great distances observed earth astronomy use heavily shielded underground facilities sage iii detection vast majority streaming earth originate sun detected cosmic rays consist high energy particles decay absorbed enter earth atmosphere result cascade particles detected current additionally future sensitive particles produced cosmic rays hit earth atmosphere wave astronomy emerging new field astronomy aims use wave collect data compact objects constructed laser observatory detection september observing waves black hole second wave detected december additional observations continue waves extremely difficult detect combining observations electromagnetic radiation waves different means shall information known multi messenger astronomy mechanics oldest fields astronomy science measurement positions objects historically accurate knowledge positions sun moon planets stars essential navigation use objects guide navigation making careful measurement positions planets led solid understanding ability determine past future positions planets great accuracy field known mechanics recently tracking near earth objects allow predictions close encounters potential collisions earth measurement stellar nearby stars provides fundamental cosmic distance ladder measure scale universe measurements nearby stars provide absolute properties distant stars properties compared measurements radial velocity proper motion plot movement systems way galaxy results basis distribution dark matter galaxy 1990s measurement stellar nearby stars detect large planets nearby stars theoretical astronomy theoretical use tools including models example approximate behaviors star numerical advantages models process generally better giving insight heart going numerical models reveal existence phenomena effects astronomy endeavor create theoretical models results predict consequences models observation phenomenon predicted model allows select alternate conflicting models try generate modify models account new data case general tendency try minimal modifications model produces results fit data cases large inconsistent data time lead total abandonment model topics studied theoretical include stellar dynamics evolution galaxy formation large scale structure matter universe origin cosmic rays general physical including string physics serves tool gauge properties large scale structures plays significant role physical phenomena investigated basis black hole physics study waves widely accepted studied theories models astronomy included model big bang cosmic inflation dark matter fundamental theories physics examples process dark matter dark energy current leading topics astronomy discovery controversy originated study specific solar astronomy distance light minutes frequently studied star sun typical main sequence dwarf star stellar class billion years old sun considered variable star undergo periodic changes activity known cycle year numbers regions lower average temperatures associated intense magnetic activity sun steadily increased course life increasing main sequence star sun undergone periodic changes significant impact earth minimum example believed caused little ice age phenomenon middle ages visible outer surface sun called layer thin region known surrounded transition region rapidly increasing temperatures finally super heated center sun core region volume sufficient temperature pressure nuclear fusion occur core radiation zone conveys energy means radiation outer layers form convection zone gas material transports energy primarily physical displacement gas believed convection zone creates magnetic activity generates solar wind particles constantly streams outward sun limit solar system reaches solar wind earth create van allen radiation belts earth aurora lines earth magnetic field descend atmosphere science science study planets dwarf planets bodies sun planets solar system relatively studied initially later spacecraft provided good overall understanding formation evolution system new discoveries solar system subdivided inner planets belt outer planets inner terrestrial planets consist mercury venus earth mars outer gas giant planets saturn neptune neptune lies belt finally cloud extend far light year planets formed disk surrounded early sun process included attraction collision disk formed matter time radiation pressure solar wind expelled matter planets sufficient mass retained atmosphere planets continued sweep remaining matter period intense bombardment evidenced impact moon period collided leading hypothesis moon formed planet reaches sufficient mass materials different process form metallic core surrounded mantle outer surface core include solid liquid regions generate magnetic field protect solar wind stripping planet moon interior heat produced collisions created body radioactive materials tidal heating planets accumulate heat drive processes accumulate retain atmosphere undergo surface erosion wind water smaller bodies tidal heating cool quickly geological activity exception impact stellar astronomy study stars stellar evolution fundamental understanding universe stars determined observation theoretical understanding computer interior star formation occurs dense regions dust gas known giant molecular clouds cloud fragments collapse influence gravity form sufficiently dense hot core region trigger nuclear fusion creating main sequence star elements heavier hydrogen created inside stars characteristics resulting star depend primarily starting mass massive star greater rapidly hydrogen fuel core time hydrogen fuel completely converted star begins evolve fusion requires higher core temperature star expands size increases core density resulting red giant enjoys brief life span fuel turn consumed massive stars undergo series decreasing evolutionary phases fuse increasingly heavier elements final fate star depends mass stars mass greater times sun core collapse smaller stars form white dwarf matter forms remnant dense star stellar mass times sun black hole close stars follow complex evolutionary paths mass transfer white dwarf companion potentially cause necessary distribution metals medium new stars systems formed hydrogen astronomy solar system way barred spiral galaxy prominent member local group rotating mass gas dust stars objects held mutual attraction earth located dusty outer arms large portions way obscured view center way core bar shaped believed black hole center surrounded primary arms spiral core region active star formation contains younger population stars disk surrounded halo older population stars relatively dense concentrations stars known clusters stars lies medium region sparse matter regions molecular clouds molecular hydrogen elements create star forming regions begin compact pre stellar core dark concentrate collapse volumes determined jeans length form compact massive stars appear transform cloud region atomic hydrogen glowing gas stellar wind explosions stars eventually cause cloud disperse leaving young open clusters stars clusters gradually disperse stars join population way studies matter way demonstrated mass accounted visible matter dark matter halo appears dominate mass nature dark matter remains astronomy study objects outside galaxy branch astronomy concerned formation evolution morphology description classification observation active larger scale groups clusters finally important understanding large scale structure organized distinct shapes allow classification schemes commonly divided spiral elliptical irregular suggests elliptical galaxy cross shape stars random preferred direction contain little dust star forming regions generally older stars elliptical commonly found core clusters formed large spiral galaxy organized flat rotating disk usually prominent bar center trailing bright arms spiral outward arms dusty regions star formation massive young stars produce blue spiral typically surrounded halo older stars way nearest galaxy neighbor galaxy spiral irregular chaotic appearance spiral elliptical quarter irregular peculiar shapes result interaction active galaxy formation significant energy source stars dust gas powered compact region core thought super massive black hole radiation falling material radio galaxy active galaxy radio portion spectrum immense gas active shorter frequency high energy radiation include believed consistently objects known universe large scale structure represented groups clusters structure organized hierarchy largest collective matter formed walls leaving large greek world universe word study literally logic considered study universe observations large scale structure universe branch known physical provided deep understanding formation evolution fundamental modern accepted theory big bang universe began single point time expanded course billion years present condition concept big bang traced discovery microwave background radiation course expansion universe underwent evolutionary stages early moments universe experienced rapid cosmic inflation starting conditions produced abundance early universe neutral formed sea space transparent radiation releasing energy viewed today microwave background radiation expanding universe underwent dark age lack stellar energy sources structure matter began form minute variations mass density space matter accumulated regions forming clouds gas earliest stars population iii stars massive stars triggered process believed created heavy elements early universe nuclear decay create lighter elements allowing cycle continue longer leaving gaps gradually organizations gas dust merged form primitive time pulled matter organized groups clusters larger scale fundamental structure universe existence dark matter dark energy thought dominant components forming mass universe reason effort expended trying understand physics components studies astronomy developed significant links major scientific fields study ancient traditional cultural context utilizing archaeological evidence study advent evolution biological systems universe particular emphasis possibility non terrestrial life application statistics analysis vast data study chemicals found space including formation interaction destruction called substances usually found molecular clouds appear low temperature stars brown planets study chemicals found solar system including origins elements variations fields represent overlap disciplines astronomy chemistry forensic astronomy finally methods astronomy solve problems law history amateur astronomy astronomy sciences contribute collectively amateur observe variety objects phenomena equipment build common targets amateur include moon planets stars showers variety deep sky objects star clusters astronomy clubs located world programs help members set complete programs including observe objects objects points interest night sky branch amateur astronomy amateur involves taking photos night sky like observation particular objects types objects types events interest work visible small minority experiment outside visible spectrum includes use infrared filters conventional use radio pioneer amateur radio astronomy started observing sky radio 1930s number amateur use use radio originally built astronomy research available mile amateur continue scientific contributions field astronomy scientific disciplines significant contributions measurements minor planets discover perform regular observations variable stars improvements digital technology allowed impressive advances field problems astronomy scientific discipline astronomy tremendous understanding nature universe contents remain important unanswered questions answers require construction new space based instruments possibly new developments theoretical experimental physics origin stellar mass spectrum observe distribution stellar masses initial mass function apparently regardless initial conditions deeper understanding formation stars planets needed life universe especially intelligent life explanation existence life important scientific philosophical implications solar system normal caused universe form premise fine tuned universe hypothesis correct result natural selection caused cosmic inflation produced universe nature dark matter dark energy dominate evolution fate true nature remains unknown ultimate fate universe form black holes form creating ultra high energy cosmic rays abundance times lower predicted standard big bang model happens event horizon


lee array microwave background known array microwave background radio designed observe cosmic microwave background effect clusters located hawaii metres sea level originally element atop mount observations started october clusters effect announced upgraded elements capable expansion elements result collaboration institute astronomy national taiwan university australia national facility involves researchers universities design initially element dishes mounted carbon mount located hawaii observes minimize foreground non thermal sources retractable shelter seven steel fabric receivers based microwave integrated circuit technology low noise cooled provide signals mixed local reduce frequency prior analog system temperatures started funding years particle project taiwan ministry education element prototype set funding second years provided national science council mount arrived site platform installed elements installed light september observing dedicated october lee array upgraded thirteen dishes extensive testing scientific observations resumed elements observations primary goal observe temperature cosmic microwave background corresponding sky observing thermal effect clusters maximum initial configuration measures resolution observes night good weather planets clusters clusters largest comparisons ray weak data study cluster layout radial properties specifically mass profiles content predicted elements able detect clusters year effect collaboration result collaboration institute astronomy national taiwan university australia national facility involves researchers harvard center national radio astronomy observatory university hawaii university bristol nottingham trent university canadian institute theoretical university


sphere sphere hypothetical completely encompasses star captures power output concept described science fiction novel star maker later popularized freeman paper search artificial stellar sources infrared radiation speculated structures logical consequence escalating energy needs technological civilization necessity long term survival proposed searching structures lead detection advanced intelligent extraterrestrial life different types spheres energy harvesting ability correspond levels technological advancement scale variant designs involving building artificial structure series structures encompass star proposed engineering described science fiction sphere later proposals limited solar power stations involving industrial elements fictional depictions describe solid shell matter star considered plausible variant idea starship century san_diego repeated comments wished concept named origin concept concept sphere result thought experiment physicist mathematician freeman technological constantly increased demand energy reasoned human civilization expanded energy demands long come time demanded total energy output sun proposed system structures referred initially shell designed intercept collect energy produced sun proposal detail system constructed focused issues energy collection basis structure distinguished unusual spectrum comparison star paper search artificial stellar sources red radiation published journal science credited concept sphere advance idea inspired mention concept science fiction novel star maker possibly works rice explored similar concepts work feasibility theoretically possible plans build fixed place sphere currently far humanity engineering capacity parts technology like satellites solar sails developed deployment spacecraft satellites seen small steps building number craft required obtain transmit maintain complete sphere far exceeds present day industrial capabilities george advocated use self robots overcome limitation relatively near term suggested habitats built white variants fictional accounts sphere concept interpreted artificial hollow sphere matter star perception based literal interpretation original short paper introducing concept response letters prompted paper replied solid shell ring surrounding star impossible form envisaged consists loose collection objects traveling independent star variant closest original conception consists large number independent usually solar power satellites space habitats dense formation star construction approach advantages components sized appropriately constructed forms wireless energy transfer transfer energy components earth resulting nature mechanics arrangement extremely complex simplest arrangement ring structures share orbit complex patterns rings intercept star output result periodically overlap potential problem increasing loss stability adding elements increases probability noted cloud collectors alter light emitted star system disruption compared star overall natural emitted spectrum likely small noticed earth bubble second type sphere bubble similar composed independent usually solar power satellites space habitats likewise constructed unlike making orbit star satellites suspended use enormous light sails radiation pressure counteract star pull gravity danger collision totally stationary regard star independent ratio radiation pressure force gravity star constant regardless distance provided line sight surface star vary distance central star approach questionable modern material science ruled reflective deployed sun overall density grams square meter sail illustrate low mass required materials consider total mass bubble material radius mass illustration regular printing paper density material produced form working light sail carbon fiber light sail material currently produced density times heavy needed construct solar single sheet dimensional form carbon density square meter making single sheet possibly effective solar sail fabricated large sheets relatively high rate radiation absorption reflective frequencies upper lower range absorption rate high voltage bias ultra light carbon molecular manufacturing techniques time civilization ready use technology carbon manufacturing density lower necessary average sail density rigging kept spin stabilized light sail requires minimal additional mass rigging sail constructed density space habitat size society proposed cylinder km2 room million inhabitants tons supported circular light sail diameter combined sail habitat mass comparison slightly smaller diameter moon sail flat disc sphere distance san_francisco kansas_city structure mass lot construction massive gigantic undertaking required material science early stage engineering feats required materials proposed sphere variants theory created deployed star compose non rigid version shell mentioned shell suffer massive pressure mass requirements shell high rigid form shell optical thermal properties rigid form detected similar fashion shell variant sphere depicted fiction shell uniform solid shell matter star structure completely alter emissions central star intercept star energy output structure provide immense surface surface spherical shell sphere solar system radius astronomical unit interior surface receive sunlight earth unit solid angle surface area approximately km2 million times surface area earth intercept sun output non shell designs intercept shell variant represents maximum possible energy captured solar system point sun evolution approximately times power consumption humanity theoretical difficulties solid shell variant sphere shell net interaction star shell drift relation central star movements went eventually result collision sphere star likely disastrous results structures need form propulsion counteract drift way repel surface sphere away star reason shell net interaction inside contents placed inner surface shell attracted sphere surface simply fall star proposed contained concentric spheres placed interior rotating sphere case force artificial gravity perpendicular axis rotation causing matter placed interior sphere pool equator effectively rendering sphere ring purposes fully effective energy collector placed outside sphere held place star gravity cases form illumination devised sphere partly transparent star light completely hidden assuming radius strength material forming sphere immense prevent star gravity selected point surface sphere viewed pressure base dome height sun gravity distance viewed base infinite number selected force arbitrary dome net force point immense finite known material strong withstand pressure form rigid static sphere star proposed paul birch relation smaller constructions large planet star possible support shell dynamic means similar space fountain masses travelling circular tracks inside sphere significantly greater velocity press magnetic force shell radius star mass sun mass travelling times velocity support times mass additional shell structure assuming radius sufficient building material solar system construct shell estimates easily usable building material solar system shell mass thick average depending density material includes hard access gas giants inner planets provide shell mass shell vulnerable impacts bodies material space currently sun bow shock protection theoretically provides cease exist types net possibility net web cables star power heat collection units cables net reduces special case shell bubble depending cables supported sun gravity artificial construct consists shell living space sphere hydrogen gas shell contains air people houses furniture etc idea conceived answer question largest space colony built volume power source theoretically gas giant enclosed solid shell certain radius surface gravity terrestrial energy provided tapping thermal energy planet concept explored novel short story curator incorporated novel chapter charles saturn converted human world stellar engine stellar engines class hypothetical purpose extract useful energy star specific purposes example brains extract energy purposes extract energy purposes propulsion proposed stellar engine designs based sphere black hole power source instead star order increase energy matter conversion efficiency black hole smaller star decrease communication distances important computer based societies described search original paper speculated sufficiently advanced extraterrestrial likely follow similar power consumption pattern humans eventually build sphere collectors constructing system civilization type civilization existence system collectors alter light emitted star system collectors absorb energy star radiation emitted collectors determined substances making temperature collectors likely collectors heavy elements normally found central star light relatively low energies compared energetic free stellar atmosphere light star type light spectrum emitted star system percentage star output filtered transformed absorption significant detected distances given energy available square meter distance sun possible known substances energy infrared electromagnetic spectrum sphere constructed life forms humans proximity sun like star materials similar available humans likely cause increase infrared radiation star system emitted spectrum selected title search artificial stellar sources infrared radiation published paper adopted assumptions search looking infrared heavy solar ongoing survey analyzing data infrared astronomical satellite identifying infrared sources sphere require improved techniques sphere natural sources discovered potential ambiguous candidates named amusing questionable searches resulted candidates unconfirmed october realization strange pattern light star observed space raised speculation sphere discovered fiction noted sphere originated fiction concept appeared science fiction fictional accounts spheres depicted shell engineering difficulties variant noted largely ignored


observatory observatory originally called students observatory observatory jointly operated university california berkeley san_francisco state university observatory built berkeley campus years directed observatory renamed relocated present home california approximately miles east berkeley campus physics astronomy department san_francisco state university partner presently observatory operating inch optical equipped observations visible light infrared infrared astronomy foot radio dish undergraduate radio astronomy course observatory perform professional astronomy research orbit determination small solar system bodies early 1900s surveys 1980s 1990s served primary tool education graduate undergraduate students berkeley history students observatory constructed berkeley campus original funds provided california legislature order observatory provide practical training civil engineers quickly students observatory seen training ground students studying astronomy better prepared use facilities observatory contributed separation departments civil engineering astronomy students observatory home berkeley astronomy department appointed director students observatory post held retirement time observatory center minor planets satellites simon said organized department observatory thorough school astronomy better stepped observatory directed series regarded including louis students observatory renamed observatory university california honor space sciences lab operates began operations observatory permanent home berkeley hills completed observatory relocated short distance east berkeley campus hills california acre km2 russell reservation observatory equipped new inch built laboratories observatory testing ground variety experiments instruments predecessor automatic imaging tested observatory early 1990s early 2000s prototype allen array unveiled observatory inch continues regularly undergraduate astronomical instruction inch decommissioned disrepair physics astronomy department san_francisco state university bought inch state berkeley staff jointly refurbished upgraded motors control system larger state installed remote observing station based frequently fog laden san_francisco campus instruments optical infrared observatory houses optical inch diameter inch diameter inch usable inch undergoing upgrades inch design equipped charge coupled device observations visible light infrared fabricated order create infrared laboratory course undergraduate students berkeley optical outfitted control systems allow automated meaning observations minimal human intervention radio observatory home single metre radio prototypes allen array tested undergraduate radio astronomy lab operates uses element resolution operating range allows observe hydrogen line lines research discoveries orbit determination research students observatory primarily focused performing order determine newly discovered clyde reported discovery began observing instruments students observatory determine orbit months discovery cast doubt status planet suggesting instead unclear large planet weeks observation students observatory students fred determined elements upper limit half mass earth mass meant massive planet thought cause predicted observed orbit neptune observatory time home automated surveys berkeley automated search led went head project inch scan skies nightly observatory search loss began berkeley automated imaging bait searched case alex testing grounds automated searches sites bait eventually succeeded automatic imaging located observatory loss operated discovered inch program called hands universe allows elementary high school students request observations late march high school students oil city pennsylvania requested observations galaxy discovered galaxy days later realized observations inch captured earliest images images provided earliest light curve data record observatory home optical experiment carried direction berkeley dan program consists targeted search bright short duration nearby stars automated inch similar efforts carried observatory italian reported observing strange objects graduate student berkeley inch observatory identification objects elliptical known objects named discover identifying nature objects realized nearby objects belonging local group eventually membership local group ruled recognized nearest major elliptical galaxy nemesis david jack suggested extinction events earth followed periodic trend richard professor physics berkeley team suggested sun unseen stellar companion caused hypothetical companion dubbed nemesis involved automated searches underway began search nemesis optical observatory


william william metre optical near infrared reflecting located del los island islands spain named william newton group funded research councils united_kingdom netherlands spain time construction largest single optical world currently second largest europe final constructed parsons year history equipped wide range instruments operating optical near infrared regimes professional conduct wide range astronomical research discovered evidence black hole centre way optical observation gamma ray burst history conceived late 1960s anglo australian designed british astronomical community saw need comparable power northern hemisphere particular need optical follow interesting sources radio surveys conducted bank located completed point british science engineering research council began planning group located northern hemisphere known newton group ing newton moved existing site castle class initially planned new site chosen altitude island islands del los project led royal observatory operated control passed independent ing closed verge scrapped budget whilst reduced panel known tiger team convened reduce cost design cut price tag savings primarily reducing focal length allowed use smaller dome relocating non essential functions outside dome simpler cheaper rectangular year newton moved los observatory newton group netherlands organization scientific research bought stake project allowing given ahead year anniversary discovery william decided honour construction parsons company produced year history work began workshop newcastle shipped newton group began operating saw light june largest optical world time total cost including dome initial suite instruments equivalent budget inflation taken account design consists primary mirror illinois zero expansion glass material ground parsons mirror blank produced set purchased years primary solid active system required despite weight tonnes long tons mirror support cell holds main mirror set cylinders extreme loading pointing horizon mirror vertical shape mirror changes normal operation smaller usual configuration secondary mirror form system field view additional flat fold mirror allows use platforms folded stations fields view operates wide field prime focus configuration case secondary removed element field lens inserted provides effective focus field view changing takes matter seconds night switching prime focus requires replacing secondary mirror prime focus assembly daytime mounted takes minutes focus planned later addition feed optical built secondary mirror planned infrared observations placed hold cost saving design implemented mount optical system weighs long tons mount total moving mass long tons plus instruments multi mirror demonstrated 1970s significant weight cost savings achieved design compared traditional mount large design requires continuous computer control compensation field rotation focus results degree radius blind spot drive motors motion drives maximum speed degree second axis mount smooth finely balanced drive motors installed possible long tons assembly hand closed loop guiding mount capable absolute pointing accuracy dome housed shaped steel dome internal diameter manufactured steel mount located cylindrical concrete pier centre rotation ground level lifts ground layer air better seeing conventional wide wind blind large fans thermal control long ton capacity crane moving primary mirror incorporated size shape allow observations horizon corresponds total moving mass dome tonnes long tons mounted storey cylindrical building dome designed wind stresses support weight ice weather dome rest separate sets foundations driven metres volcanic prevent vibrations caused dome rotation wind stresses building affecting pointing attached dome storey rectangular building houses control room computer room kitchen etc human presence required inside dome means environmental conditions kept stable result perfect dome seeing building houses laboratory plant largest single mirror del los plant vacuum vessel large accommodate mirrors mountain result observatory contract use plant exception plant operations operated newton group ing newton offices administration located hour drive away santa island capital funding provided science technology facilities council netherlands spain values time distributed proportion funding spain receives additional allocation return use observatory site percent observing time reserved competitive research heavily typically receiving applications times observing time actually available vast majority observations carried visitor mode investigating physically present shift service mode operations carried observatory staff behalf travel considered rejected scientific operational grounds instruments equipped wide range scientific instruments providing capabilities conduct large variety scientific investigations current common user instrumentation auxiliary port camera optical narrow band imaging field low resolution permanently mounted broken robot science field mounted prime focus wide field fed optical bench mounted optical fed located use focus isis intermediate imaging system medium resolution long dual beam optical mounted focus isis original generation instruments long intermediate resolution infrared near infrared imaging field resolutions long multi object masks mounted focus natural guide star multi purpose instrumentation feed operating entire optical near infrared regions permanently mounted ground layer laser system laser guide star optional use newton group red imaging device high spatial resolution near infrared camera use stellar high contrast optional use oasis system imaging optical integral field unit use prime focus imaging platform wide field optical camera narrow band imaging field mounted prime focus addition popular single purpose visitor instruments recent years included integral visitor instruments use focus common set lamps neon arc lamps flat field lamp permanently mounted broken instruments isis approximately thirds time awarded instruments scientific research use conduct scientific research branches astronomy including solar system science astronomy astronomy instruments designed useful range different research significant new discoveries notable include evidence black hole centre way optical observation gamma ray burst mid-1990s faced increasing competition newer wide range research continues recent years included project integral field survey nearby elliptical spectrum subsequently hit earth spectrum discovery bands originate confirmation planet high resolution known double future developments upcoming generation extremely large require sophisticated order capability advanced system operating receiving attention programs european southern observatory european project begun programme test bed system receive nights year sky testing project involves construction new optical experiments called demonstrate multi object required eagle instrument originally major financial contributor gradually reduced funding ing number years funding partners increasing contributions efficiency savings result shares observing time netherlands spain new development started development new wide field multi object facility developed led consortium involving major contributions netherlands spain france italy expected place end provide medium high resolution visible range simultaneous targets degree field view currently expected operate