small solar system body passing close sun heats begins displaying visible atmosphere coma tail phenomena effects solar radiation solar wind nucleus range metres tens kilometres composed loose collections ice dust small rocky particles coma tail larger sufficiently bright seen earth aid observed recorded ancient times cultures usually highly eccentric elliptical wide range periods ranging years potentially millions years short period originate belt associated scattered disc lie orbit neptune long period thought originate cloud spherical cloud bodies extending outside belt halfway nearest star long period directed sun cloud caused passing stars tide pass inner solar system space distinguished presence extended atmosphere surrounding central nucleus atmosphere parts termed coma central immediately surrounding nucleus tail typically linear section consisting dust gas blown coma sun light pressure solar wind extinct passed close sun times lost nearly volatile dust come resemble small thought different origin having formed inside orbit outer solar system discovery main belt active blurred distinction november known number steadily increasing represents tiny fraction total potential population reservoir like bodies outer solar system cloud estimated roughly year visible naked eye faint particularly bright examples called great visited european space agency land robotic spacecraft nasa deep impact crater study interior etymology word derives old english latin turn greek wearing long hair oxford english dictionary notes term meant long haired star greek derived wear hair long derived hair head mean tail astronomical symbol consisting small disc extensions physical characteristics nucleus solid core structure known nucleus composed amalgamation rock dust water ice frozen gases carbon dioxide carbon popularly described dirty fred model higher dust content leading called research conducted suggests like deep fried ice cream surfaces formed dense ice mixed organic compounds interior ice colder dense surface nucleus generally dry dusty rocky suggesting hidden beneath surface crust metres thick addition gases mentioned contain variety organic compounds include hydrogen complex molecules long chain confirmed acid found dust recovered nasa mission august report based nasa studies found earth published suggesting dna components related organic molecules formed outer surfaces low making reflective objects found solar system space probe found nucleus reflects percent light falls deep space discovered surface reflects light falls comparison asphalt reflects seven percent light falls dark surface material nucleus consist complex organic compounds solar heating drives lighter volatile compounds leaving larger organic compounds tend dark like tar crude oil low surfaces enables absorb heat necessary drive processes kilometres observed exact size difficult nucleus probably metres diameter lack smaller detected despite increased sensitivity instruments led suggest real lack smaller metres known estimated average density low mass spherical gravity irregular shapes roughly percent near earth thought extinct longer experience including don results spacecraft nucleus magnetic field suggests played role early formation alice determined nucleus produced water molecules solar radiation sun thought earlier responsible degradation water carbon dioxide molecules released nucleus coma instruments found sixteen organic compounds surface detected time coma streams dust gas released form huge extremely thin atmosphere called coma force exerted coma sun radiation pressure solar wind cause enormous tail form pointing away sun coma generally dust water making outflow nucleus astronomical units sun parent destroyed primarily smaller extent solar wind playing minor role destruction water compared larger dust particles left path smaller particles pushed away sun tail light pressure solid nucleus generally kilometres coma thousands millions kilometres larger sun example month october holmes briefly dust atmosphere larger sun great coma roughly diameter sun coma large size decrease time crosses orbit mars astronomical units sun distance solar wind strong blow gas dust away coma tail tails observed extend astronomical unit million coma tail illuminated sun visible passes inner solar system dust reflecting sunlight directly gases glowing faint visible aid decade bright visible naked eye occasionally experience huge sudden gas dust size coma greatly increases period time happened holmes found rays greatly surprised ray usually associated high temperature bodies rays generated interaction solar wind highly charged solar wind fly atmosphere molecules stealing process called charge exchange exchange transfer electron solar wind followed ground state leading rays far tails outer solar system remain frozen inactive extremely difficult impossible detect earth small size statistical inactive belt reported observations space questioned approaches inner solar system solar radiation causes volatile materials stream nucleus carrying dust away streams dust gas form distinct tail pointing slightly different directions tail dust left orbit manner forms curved tail called type dust tail time type tail gases points directly away sun gas strongly affected solar wind dust following magnetic field lines trajectory occasions earth passes plane track edge tail pointing opposite direction dust tails seen observation contributed significantly discovery solar wind tail formed result solar ultra violet radiation particles coma particles attain net positive electrical charge turn gives rise induced induced magnetic field form obstacle outward flowing solar wind particles relative speed solar wind bow shock formed upstream flow direction solar wind bow shock large concentrations called pick act load solar magnetic field field lines forming tail tail loading sufficient magnetic field lines point distance tail magnetic occurs leads tail event observed number occasions notable event recorded april tail completely severed passed mass event observed stereo space probe scientists reported planet venus streams manner similar tail seen streaming similar conditions jets uneven heating cause newly generated gases break weak spot surface nucleus like streams gas dust cause nucleus spin split apart revealed dry ice frozen carbon dioxide power jets material flowing nucleus known spacecraft got close jets coming measure infrared spectrum point shows materials characteristics small solar system bodies elongated elliptical close sun orbit reaches solar system remainder classified according length periods longer period elongated short period periodic short period generally defined having periods years usually orbit plane direction planets typically region outer planets example little orbit neptune near major planet orbit called family families thought arise planet capturing long period shorter shorter extreme orbit reach orbit known type short period periods shorter years low degrees called family like periods years extending zero degrees called type observed compared identified recently discovered main belt form distinct class circular belt elliptical frequently close giant planets subject short period tendency coincide giant planet semi major axis largest group clear coming cloud strongly influenced gravity giant planets result close encounter source greatest twice massive planets combined long period shorter periods based characteristics short period thought originate belt scattered disc disk objects trans region source long period thought far distant spherical cloud dutch jan existence vast like bodies thought orbit sun distant regions roughly circular occasionally influence outer planets case belt objects nearby stars case cloud objects throw bodies elliptical orbit takes sun form visible unlike return periodic established previous observations appearance new mechanism unpredictable long period long period highly eccentric periods ranging years thousands years greater near necessarily mean leave solar system example near passage january bound sun roughly year orbit drops moves sun future orbit long period properly obtained orbit leaving region calculated respect center mass solar system definition long period remain bound sun ejected solar system close passes major planets longer properly considered having periods long period far outer planets plane need lie near long period west distances nearly periods estimated million years single non periodic similar long period slightly near inner solar system giant planets cause change single orbit allows permanently exit solar system single pass sun sun hill sphere unstable maximum boundary light years seen reach orbit near body best fit suggests escape solar system significantly greater observed confirmed observations likely originated outside solar system period roughly million years passage encounter accelerated giving largest known expected return inner solar system include neat authorities use term periodic refer periodic orbit short period plus long period use mean exclusively short period similarly literal meaning non periodic single use mean periodic second sense include period greater years early observations revealed genuinely non periodic accounted space moving order relative stars near sun tens second objects entered solar system positive specific energy observed genuinely rough calculation shows century orbit orders magnitude cloud hills cloud cloud thought occupy vast space far sun estimates place outer edge region subdivided spherical outer cloud shaped inner cloud outer cloud weakly bound sun supplies long period possibly type inside orbit neptune inner cloud known hills cloud named hills proposed existence models predict inner cloud tens hundreds times outer halo seen possible source new resupply relatively outer cloud numbers gradually depleted hills cloud explains continued existence cloud years solar system detected common way system detected beta young type main sequence star total systems identified absorption spectrum caused large clouds gas emitted passing close star effects connection showers result leave wake trail solid debris large swept away radiation pressure solar wind path crosses path earth follows orbit sun point likely showers earth passes trail debris shower example occurs year august earth passes orbit swift source shower october impact life collided earth early stages scientists think bombarding young earth billion years ago brought vast quantities water fill earth oceans significant portion researchers cast doubt idea detection organic molecules including significant quantities led speculate brought life life earth suggested impacts rocky surfaces potential create proteins shock synthesis scientists found significant amounts molecular oxygen indicator presence occur naturally thought strong indicator alien life supposed suspected impacts long delivered significant quantities water earth moon survived lunar ice impacts thought responsible existence fate departure solar system traveling fast leave solar system case date known ejected interacting object solar system example thought shifted predicted orbit million years sun trajectory encounter planet exhausted family long period appear follow different fading laws active lifetime years long period fade faster long period survive passages small survive passages eventually volatile material contained nucleus away small dark rock rubble resemble elliptical identified extinct roughly percent near earth thought extinct longer gas breakup collisions nucleus fragile conclusion supported observation splitting apart significant disruption levy discovered close encounter july broken pieces period days july pieces fell atmosphere time observed collision objects solar system splitting include greek historian reported split apart far winter suspected splitting thermal stress internal gas pressure impact van appear fragments parent numerical shown close approach january nearly identical observed break passage including great west significant example broke pieces passage seen separately afterward instead spectacular showers seen visible minor shower occurs annually november caused earth crosses orbit meet spectacular end falling sun smashing planet body collisions planets common early solar system moon example caused recent collision planet occurred july levy broke pieces collided nomenclature names given followed different conventions past centuries prior early 20th century simply referred year appeared additional particularly bright great great great january demonstrated body successfully predicted return calculating orbit known similarly second known periodic named calculated original later periodic usually named appeared continued referred year early 20th century convention naming common remains today named instrument program helped find history study early observations thought ancient sources chinese bones known appearances noticed humans sixteenth century usually considered bad deaths kings noble men coming interpreted attacks heavenly beings terrestrial inhabitants aristotle believed atmospheric phenomena fact appear outside vary course days elder believed connected political unrest death 16th century demonstrated exist outside earth atmosphere measuring great observations collected geographically separated observers precision measurements implied times distant earth moon studies newton proved object moving influence square law universal trace orbit shaped like sections demonstrated fit path sky orbit example applied newton method occurred noted similar elements able account slight differences terms saturn confident appearances predicted appear predicted return date later refined team french joseph predicted date month accuracy returned predicted known day designation appear studies physical characteristics newton described compact solid bodies moving oblique orbit tails thin streams emitted ignited heated sun newton suspected origin life supporting component air early 18th century scientists correct physical composition composed volatile substance gives rise brilliant displays near german mathematician friedrich observing streams appearance proposed jet forces material great significantly alter orbit argued non movements resulted phenomenon fred lawrence proposed rocky objects containing ice objects containing dust rock dirty model soon accepted appeared supported observations spacecraft including european space agency probe soviet_union flew coma photographed nucleus observed jets material january scientists reported detection definitive time water dwarf planet largest object belt detection far infrared abilities space observatory finding unexpected typically considered jets according scientists lines blurred august released studies large millimeter array alma time detailed distribution dust inside spacecraft missions describes collection spacecraft missions visited observations 1980s deep impact debate continues ice deep space spacecraft obtained high resolution images surface found surface hot dry temperature extremely dark suggesting ice removed solar heating maturation hidden like material covers july deep impact probe crater study interior mission yielded results suggesting majority water ice surface feed jets water form coma renamed november data mission materials retrieved tail wild born fire extremely high temperatures formed outer solar system radial mixing material early formation solar system thought material disk contain grains formed hot inner solar system seen sample return missions recent materials retrieved demonstrate dust resembles materials new results forced scientists nature distinction probe presently erratic orbit november successfully landed surface time spacecraft landed object history great approximately decade bright noticed casual observer leading designated great predicting great difficult factors cause depart drastically predictions broadly speaking large active nucleus pass close sun obscured sun seen earth chance great fulfilled criteria expected spectacular failed west appeared years later lower expectations extremely impressive late 20th century saw lengthy gap appearance great followed arrival quick succession followed reached maximum having discovered years earlier great 21st century visible naked eye observers january years passes extremely close sun generally million kilometres small completely close approach sun larger survive passages strong tidal forces experience lead observed members group originate giant broke smaller passage inner solar system remainder contains sporadic related groups identified groups groups appear related parent streams unusual thousands known exhibit unusual properties outside belt inside orbit planet mercury currently travels nearly circular orbit entirely saturn unstable orbit saturn originally classified faint coma noticed similarly levy originally designated fate typically behave characteristics classified neat neat discovered exhibited coma classified despite orbit discovered coma later active classified plan involved sending nasa decided destroy instead observation discovered wide field visually access optical equipment possible amateur discover online images accumulated satellite discovered polish amateur december amateur equipment amateur lost number periodic discovered earlier decades previous centuries lost known predict future appearances occasionally new discovered calculation orbit shows old lost example swift linear discovered found accidentally rediscovered linear fit category gallery videos popular culture depiction popular culture firmly rooted long western tradition seeing doom world altering change caused publications sorts especially noted birth death notable persons coincided separate appearances writers mark correctly speculated life mary carpenter dedicated song came jackson times past bright inspired panic general population thought bad recently passage earth passed tail erroneous newspaper reports inspired fear tail poison millions appearance triggered mass suicide heaven gate cult science fiction impact depicted threat overcome technology heroism deep impact armageddon trigger global apocalypse hammer zombies night group people stranded sun large manned space expedition visits sir arthur clarke novel odyssey


moon inner moon discovered december voyager spacecraft follows convention naming characters shakespeare orbit lies rings large approximately spherical shape diameter dark heavily surface shows signs water ice discovery naming largest inner moon discovered images taken voyager december given temporary designation moon later named character appears shakespeare night dream little travels globe night celtic mythology english folklore imagined evil demon christians designated physical characteristics largest small inner moon inside orbit intermediate size second largest inner moon smallest large classical orbit located rings little known aside orbit radius geometric visible light approximately discovered voyager imaging team discovered early probe programmed image detail images showed shape slightly ratio axes surface heavily grey color named surface largest diameter observations space large terrestrial found water ice absorption features spectrum known internal structure probably mixture water ice dark material similar found rings dark material probably rocks radiation processed absence bright rays implies differentiated meaning ice non ice components separated core mantle


largest discovered january group objects found orbit planet names derive lovers largest objects solar system exception sun planets larger dwarf planets largest moon solar system bigger planet mercury inner resonance discovered improvements enabled observe bodies distinctly discovery showed importance tool proving objects space seen naked eye importantly discovery bodies earth dealt blow accepted world system theory earth initially named discovery stars names eventually prevailed chosen simon discovered independently time gave present names suggested published history discovery result improvements capability able bodies distinctly possible allowed discover december january came known january wrote letter containing mention time saw believed fixed stars near continued observe january march observations discovered fourth body observed fixed stars discovery proved importance tool showing objects space discovered remained unseen naked eye importantly discovery bodies earth dealt blow accepted world system held earth center universe bodies revolved messenger announced observations explicitly mention theory placed sun center universe accepted theory chinese historian astronomy claimed small reddish star observed near bce chinese discovery dedication employed mathematics tutor grand duke seeking patronage wealthy student powerful family discovery gain february wrote grand duke secretary god able singular sign reveal lord devotion desire glorious live equal stars new planets wish imitation great placed excellent heroes age stars grand duke asked stars stars honor brothers clan secretary replied best march wrote letter duke day sent copy grand duke hoping obtain grand duke support quickly possible march sent view grand duke official copy messenger following secretary advice named stars introduction wrote scarcely immortal soul begun shine forth earth bright stars offer heavens like speak celebrate excellent virtues time stars reserved journeys speed star like children family appears maker stars clear arguments new planets initially called discovery stars honour suggestion changed stars brothers discovery announced messenger published venice march months observations names forward include prince iii duke disciple author satellites latin meaning escorts names eventually prevailed chosen simon discovered independently time named suggestion lovers god greek equivalent published refused use names invented result numbering scheme parallel proper moon names numbers run outward iii respectively system actually published numbered names mid-20th century inner discovered names widely determination able develop method determining based timing times precisely calculated advance compared local observations land ship determine local time main problem technique difficult observe moving ship problem tried solve invention method map france members models predict generations satellites early history generation formed destroyed tidal interactions satellite disk new forming remaining debris time present generation formed gas satellite disk point longer greatly interfered models suggest satellites formed satellite disk formation comparable shorter migration likely interior rock metal thought contain ice water mass remainder rock increasing order distance diameter kilometers fourth largest moon solar system named lovers simply referred satellite mid-20th century active active object solar system surface mountains taller earth mount unlike satellites outer solar system thick coating ice primarily composed rock surrounding iron iron core proven recent data indicate magnetic field extremely thin atmosphere dioxide surface data collection vessel land future extremely tough similar tank like bodies soviet survive radiation magnetic fields originate second second closest smallest kilometers diameter slightly smaller moon comes mythical courted queen crete widely mid-20th century objects solar system layer water surrounding mantle planet thought kilometers thick smooth surface includes layer ice ice liquid water apparent youth surface led hypothesis water ocean exists beneath serve extraterrestrial life heat energy tidal ensures ocean remains liquid drives geological activity life exist ice ocean environment similar earth deep ocean lake life ocean possibly similar life earth deep ocean far evidence life exists likely presence liquid water spurred calls send probe prominent markings cross moon mainly features emphasize low topography surface active young theories suggest gravity causing markings constantly facing volcanic water splitting surface considered cause color markings reddish brown caused scientists confirm data collection devices sent primarily rock likely iron core atmosphere composed primarily oxygen moon named mythological greek gods beloved largest natural satellite solar system kilometers diameter makes larger planet mercury half mass world satellite solar system known possess likely created convection liquid iron core composed primarily rock water ice salt water ocean believed exist nearly surface layers ice metallic core suggests greater heat time past previously proposed surface mix types terrain highly dark regions younger ancient regions large array grooves ridges high number gone barely visible crust forming satellite thin oxygen atmosphere includes possibly atomic hydrogen fourth moon second largest kilometers diameter largest moon solar system daughter king hunting companion goddess form resonance affects inner satellites experience tidal heating composed approximately equal amounts rock makes dense heavily satellites solar system major feature basin wide called surrounded extremely thin atmosphere composed carbon dioxide probably molecular oxygen investigation revealed possibly ocean liquid water depths greater kilometers likely presence ocean indicates harbor life likely nearby long considered suitable place human base future exploration system intense radiation comparative structure fluctuations indicate mean density decreases distance dense density intermediate ice rock moon density intermediate rock iron ancient heavily ice surface way indicates density equally distributed suggesting rocky metallic core consists mix rock ice original structure rotation inner contrast indicates interiors matter core lighter matter reveal significant alteration surface reveals past movement ice surface required partial melting layers reveals dynamic recent movement nature suggesting thinner ice crust finally moon surface active sign ice evidence suggests nearer moon interior current model experience tidal heating result field proportion square distance giant planet melted interior ice allowing rock iron sink interior water cover surface thick solid ice crust formed warmer thinner easily broken crust formed heating extreme rock melted water long ago boiled space size latest origin evolution regular satellites believed formed disk ring gas solid debris analogous disk remnants score mass satellites formed early history suggest disk relatively high mass given moment time substantial fraction tenths percent mass captured solar processed disk mass required explain existing satellites generations mass satellites early history generation drag disk new forming new debris captured solar time present possibly fifth generation formed disk point longer greatly interfered current affected falling partially protected resonance exists larger mass means migrated inward faster rate visibility bright sighted earth farther away easily visible low powered apparent opposition sun unit magnitude conjunction main difficulty observing earth proximity obscured maximum angular minutes arc close limit human visual maximum separation targets potential naked eye observation


moon greek known moon discovered images taken voyager named wife additional observations early september spacecraft allowed surface locked shape strongly twice large smallest known orbit length day main ring thought major contributor material rings discovery observations discovered stephen images taken voyager probe designated officially named mythological wife greek equivalent photographs taken voyager showed dot knowledge limited arrival spacecraft surface constraints composition physical characteristics irregular shape measures makes second smallest inner satellites rough estimate surface area placed square kilometers bulk composition mass known assuming mean density like mass estimated density imply composed water ice surface heavily dark appears reddish color substantial leading trailing leading hemisphere times brighter trailing probably caused higher velocity frequency impacts leading hemisphere bright material presumably ice interior orbit rotation small inner distance main ring orbit small relative equator tidal locking period longest axis aligned lies inside orbit radius result tidal forces slowly cause orbit decay density similar orbit lies fluid limit broken lie outside rigid limit close appears gigantic sphere diameter largest angular diameter viewed reason surface visible time limited view fastest moving relationship rings orbit lies main ring wide gap notch ring gap clearly related moon origin connection established supplies significant main ring dust material appears consist primarily material ejected surfaces small inner satellites impacts easy impact lost satellites space satellites surfaces lie fairly close edge spheres low density


apparent path sun sphere basis coordinate system refers plane path orbit earth sun apparent orbit sun earth path sun normally noticeable earth surface earth carrying observer cycles sunrise sunset apparent motion sun respect stars sun apparent motion motions described movement earth earth moon center mass apparent path sun slightly period month planets solar system earth moon slightly mean position complex fashion actually apparent path sun course year earth takes year orbit sun apparent position sun takes length time complete circuit slightly days year sun moves little eastward day small difference sun position stars causes particular spot earth surface catch stand directly north south sun minutes later day earth orbit day earth hours long approximately hour minute day based hypothetical earth uniform speed sun actual speed earth sun varies slightly year speed sun varies example sun north equator days year south days variation speed accounts equation time relationship equator earth axis perpendicular plane earth plane plane inclined angle known equator projected outward sphere forming equator crosses points known sun apparent motion crosses equator points south north north south crossing south north known known point ascending equator crossing north south descending orientation earth axis equator fixed space rotate poles period years process known effect moon sun earth likewise fixed bodies solar system cause smaller motion plane earth orbit known combined action motions called general changes position arc seconds year periodic motions moon apparent periodic motions sun actually earth orbit cause short term small periodic earth axis equator known adds periodic component position positions equator fully updated called true equator positions mean equator term earth equator respect earth rotation axis perpendicular currently decreasing degrees years angular value found observation motions earth planets years produce new fundamental accuracy observation improves understanding dynamics increases astronomical values including derived date calculated work analyzed positions planets tropical centuries date question jet propulsion laboratory series computer generated took fundamental astronomical based analyzed observations calculated julian centuries fundamental continually updated astronomical expressions intended high precision relatively short time span centuries expression order good years years expressions mean equator included true includes plane solar system major bodies solar system orbit sun nearly plane likely way solar system formed disk probably closest current representation disk known plane solar system earth orbit inclined little plane major planets solar system bodies appear close sky defined motion sun plane defined angular momentum entire solar system essentially motions bodies system somewhat uncertain value requires precise knowledge object system reasons reference plane solar system convenience reference plane forms fundamental planes reference positions sphere equator perpendicular poles north pole pole north equator fundamental planes closer background stars motion roughly equator spherical coordinates known latitude latitude specify positions bodies sphere respect measured positively eastward direction sun appears latitude measured perpendicular northward southward poles latitude complete spherical position distance necessary different distance units different objects solar system astronomical units objects near earth earth kilometers corresponding right handed rectangular coordinate system occasionally axis directed axis east axis north pole astronomical unit unit measure symbols coordinates somewhat standardized table coordinates convenient positions solar system objects planets small appear relatively close sky earth orbit moves little relatively fixed reference respect stars motion coordinates objects sphere continuously changing position coordinates requires particular particular date known coordinates referred direction date instance astronomical lists position mars terrestrial time jan latitude true distance mean date mean jan addition orbit moon inclined sun near occur near moon orbit occur conjunction opposition sun moon moon near ascending descending time conjunction opposition named noted occurred moon crossed exact times apparent including effects sun earth orbit calendar dates fixed currently passes following forms center band wide called sun moon planets seen traditionally region divided signs sun motion month ancient times signs corresponded roughly signs terminology today point named actually moved


crater named greek prominent lunar impact crater lies northwest moon near considered large formations lunar surface nearly double lunar features feature bright visible naked eye dazzling large readily identified lunar surface illuminated crater larger grand canyon crater located southeastern edge plateau elevated area contains number volcanic features area noted large number reported lunar phenomena recent emissions gas measured lunar spacecraft located elevated rocky rise known plateau midst large lunar mare block rises maximum elevation mare southeastern section east crater south system narrow named bright young formation approximately million years old solar wind time excavated material process space impact occurred following creation ray crater appearance prominent rays mapped system feature crater steep central peak sections interior floor appear relatively level lunar photographs reveal surface covered small hills minor crater outer wall roughly shape covered bright blanket spread bright rays south south east suggesting likely formed oblique impact northeast composition includes material plateau lunar mare november lunar reconnaissance passed crater spans miles kilometers miles kilometers deep plateau diverse places moon mysterious raised flat plateau giant carved enormous lava fields explosive volcanic ash surrounded massive flood said mark robinson principal investigator lunar reconnaissance camera arizona state university nasa released photos crater december remote sensing professor robert wood photography images crater area discovered plateau appearance area north appeared indications deposit colorful area referred wood spot alternate plateau taken crater mission perform mineral mapping data indicated central peak type rock called slow cooling form rock composed contrast outer wall rock composed equal parts region space study investigating presence oxygen rich soils form mineral measurements apollo apollo landing sites chemistry known compared advanced camera surveys photograph crater visual light crater determined especially rich concentrations mineral potentially future lunar settlement oxygen lunar phenomena region plateau site reported lunar phenomena total reports highest recorded lunar feature events include temporary surface reliable come apollo passed kilometers plateau significant rise alpha particles detected particles believed caused decay radioactive gas half life days lunar mission later confirmed emissions crater observations explained slow visually gas surface explosive events names named greek like moon near given nomenclature system standardized earlier lunar given feature different names michael van map calls charles heir apparent kingdoms spain called mountains near egypt particular region low called wood spot robert wood satellite surrounding smaller probably secondary secondary form large blocks ejected primary crater surface high convention features identified lunar maps placing letter crater closest primary crater following renamed


minor planet designation second discovered largest solar system estimated mass belt massive massive kilometers diameter somewhat smaller likely remnant discovered german march counted planet early 19th century discovery eventually led surface likely composed material spectrum estimated density resemble orbit unusually highly inclined plane belt nearly large making relatively inaccessible spacecraft considered possible dwarf planet size longer considered having significant departures ellipsoid history discovery discovered object initially believed shortly announced observations object noting slow uniform motion suggesting different type object lost sight months recovered later year baron von preliminary orbit friedrich object came named discovered months later attempting locate noticed moving object vicinity coincidentally passing near time discovery object created interest astronomy community point speculated planet gap mars unexpectedly second body found discovered estimates size high diameter recently estimated diameter greater currently accepted value orbit determined found period years similar period relatively high plane later observations japanese began study motions plotting mean motion set discovered distinct later paper reported group associated named family largest member group members family identified semi major axes validity grouping confirmed comparison observed stars times including best observed events careful timing measurements taken observers resulted accurate measurements diameter discovery possible tiny satellite diameter reported confirmed reported indicating larger satellite diameter existence later refuted radio signals spacecraft orbit mars surface estimate mass tiny induced motion mars dawn team granted viewing time space september year opportunity view closest approach obtain comparative data naming named ancient greek alternate goddess killed adopted friend mourning male characters greek mythology invariably given female names greek languages use variant versions italian russian spanish arabic example chinese different means wisdom god star chinese goddess greek iron connected instead named german naturalist peter simon chemical element hand named discovered element astronomical symbol disk discovery number older iconic symbol orbit rotation unusual dynamic parameters large body orbit highly inclined moderately eccentric despite distance sun central belt furthermore high tilt north pole pointing coordinates uncertainty reference frame means summer winter large parts surface constant sunlight constant darkness time order earth year areas near poles experiencing continuous sunlight long years near likely resonance resonance year period approximate resonance year period planets mercury venus mars earth occasionally appear transit pass sun earth transit mercury october venus mars physical characteristics assumed title second largest time time diameter slightly smaller mass moon farther earth lower seen earth smaller iris marginally exceeds mean opposition magnitude mean opposition magnitude range unlike require powerful optical aid view small magnitude drop low rare reach magnitude right edge naked eye visibility late february magnitude based observations primary component material surface containing little iron water minerals type include found surface composition similar lower minerals type discovered italy primitive known visible near infrared spectrum flat slightly brighter blue clear absorption band suggests component mixed like little known surface features images resolution kilometres variation placed features lower end little obtained visible light infrared filters significant suggesting large surface features near west rotation appears thought undergone degree thermal alteration partial suggests remnant formation stage solar system objects grew size process approximately size objects incorporated larger bodies planets destroyed collisions likely survivors early stage formation objects possibly meeting provisional definition planet early draft definition planet satellites suggested moon moon kilometer diameter suggested based data separated kilometers kilometers diameter suggested later shown incorrect observations considering level studied observed discovered unlikely large exploration visited spacecraft plans exploration spacecraft dawn probe visits discussed possible


moon greek known second distance smallest inner discovered photographs taken voyager making natural satellite discovered images taken spacecraft officially named mythological foster mother greek god equivalent roman god solar system known orbit planet length planet day edge main ring thought main contributor material rings despite observations 1990s spacecraft little known moon physical characteristics size fact locked discovery observations discovered david edward voyager probe photographs taken july received designation appeared dot moon discovered spacecraft soon discovery inner observed images taken months earlier voyager spacecraft able determine moon shape images remain poor officially named greek daughter lover physical characteristics irregular shape measures surface area estimate km2 makes smallest inner bulk composition mass known assuming mean density like mass estimated density implies moon composed water ice similar surface details known low resolution available images orbit smallest second closest member inner satellite family radius exterior edge planet main ring solar system known orbit planet length planet day moon mars moon orbit small respectively relative equator tidal locking period keeping face looking planet long axis aligned lowest energy configuration orbit lies inside orbit radius result tidal forces slowly causing orbit decay day impact density similar orbit actually lie fluid limit breaking lie outside rigid limit second fastest moving speed relationship rings largest contributor material rings appears consist primarily material ejected surfaces small inner satellites impacts easy impact lost satellites space satellites low density surfaces lying close edge spheres source ring material evidenced ring main ring located orbit precisely orbit lies near outer edge main ring exact extent visible ring material depends phase angle images forward scattered light firmly outside main ring scattered light reveals bigger particles appears narrow outside orbit


detached object detached objects class minor planets outer reaches solar system belong broader family trans objects objects points closest approach sun sufficiently distant influence neptune moderately affected neptune known planets makes appear detached solar system way detached objects differ substantially known form loosely defined set populations varying degrees current orbit encounters giant planets predominantly neptune detached objects larger populations including objects resonance neptune classical belt objects non scattered disk objects like detached objects referred scientific literature extended scattered disc objects distant detached objects scattered extended formal classification deep survey reflects exist parameters scattered disk detached population bodies identified largest distant best known greater termed known detached objects larger neptune highly elliptical large semi major axes astronomical units radius earth orbit created scattering giant planets particular neptune instead number explanations forward including encounter passing star distant planet sized object neptune eccentric orbit objects current orbit ejected planets present early solar system ejected classification suggested deep survey team introduces formal distinction scattered near objects scattered neptune scattered extended objects value planet hypothesis suggests detached objects explained influence large planet sun influence neptune classification detached objects distinct classes classes classical belt objects objects scattered disc objects detached objects generally distance greater strong interactions neptune approximately circular orbit sun clear boundaries scattered detached regions intermediate region distance intermediate body determined orbit discovery objects discovered time motivated discussion category distant objects inner cloud objects likely transitional objects scattered disc inner cloud officially considered scattered disc object michael brown suggested distance distant affected attraction outer planets considered inner cloud object member scattered disc classification detached object accepted recent publications line thinking suggests lack significant interaction outer planets creates extended outer group starting conventional like listed scattered near object deep survey influence neptune problems defining extended category weak exist difficult prove chaotic current lack knowledge distant objects periods years observed short observation arc couple years great distance slow movement background stars decades distant determined confirm rule resonance improvement orbit potential resonance objects help understand migration giant planets formation solar system example distant objects resonance neptune likelihood resonance likelihood resonance likelihood resonance likely dwarf planet appears likelihood resonance influence hypothetical planet neptune mike brown planet hypothesis makes observation known distant objects pulled little bit away influence hypothetical planet specifically objects axis calculated significant compatible planet hypothesis particular number objects trapped mean motion planet axis possible detached objects list known objects decreasing easily scattered neptune current orbit likely detached objects lie inside gap defines


fourth largest solar system volume mass located belt somewhat kilometres miles mass estimated total mass belt largest class dark type surface observation despite size appears dim observed earth dark surface larger average distance sun reason smaller observed discovered april magnitude observing typically requires millimetre opposition observed discovery april naples italy age discovered discoveries director naples observatory named chose honor ruling family kingdom naples located john russell hind wrote universally termed unnecessary dropped final favor comes greek goddess health daughter romans occasionally 19th century example monthly notices royal astronomical society physical characteristics based evidence surface thought consist primitive materials similar found alteration products detected surface indicate presence water ice past heated sufficiently melt primitive present surface composition indicate melted early period solar system formation contrast large like main member family contains mass family largest class dark type dominant outer belt lie gap appears noticeably shape average diameter axis ratio objects big dwarf planet aside smallest like relatively low density comparable satellites saturn terrestrial planets largest body region dark surface larger average distance sun appears dim observed earth fact discovered having lower mean opposition magnitude orders observation calls inch resolve opposition reach unlike largest belt visibility stellar tracked earth based independent observers little learned shape space resolved ruled presence companions larger kilometres diameter orbit rotation generally properties poorly known big objects belt orbit closer plane circular similar ascending descending opposite corresponding ones objects extremely close mean distance collision larger companions impossible distance opposite sides pass pass reaches extreme edge belt family resonance minor planet center unusually slow taking hours minutes revolution hours typical large direction rotation certain present ambiguity data exacerbated long rotation period makes single night observations span best fraction rotation believed analysis indicates pole points coordinates uncertainty gives tilt cases gallery


lunar phenomenon lunar phenomenon lunar phenomenon short lived light color change appearance surface moon claims short lived lunar phenomena years having observed independently multiple witnesses scientists majority lunar phenomenon reports possess adequate control experiments distinguish alternative explain origins lunar scientists acknowledge events impact occur time controversy lies frequency events term created patrick moore authorship nasa technical report chronological catalog reported lunar events published description events reports lunar phenomena range patches permanent changes lunar landscape cameron involving forms reddish green blue violet extensive lunar phenomena exist recent events going 6th century reliable events come vicinity plateau famous historical accounts phenomena include following june monks canterbury reported moon shortly sunset bright new moon usual phase horns east suddenly upper horn split division torch sprang considerable distance fire hot sparks body moon anxiety words reported saw eyes moon like wounded snake resumed proper state phenomenon repeated dozen times flame assuming twisting shapes random returning normal moon horn horn length took appearance start think monks crazy need look date happened describe seeing crash new moon jack proposed described formation crater recent studies suggest appears unlikely event related formation crater true lunar phenomenon millions tons lunar debris ejected impact large leave wide crater resulted intense week long storm earth accounts memorable storm found known historical records including astronomical archives world light suspected group monks event known witnesses saw atmospheric explosion directly oncoming chance alignment specific point far distant moon night april british sir william noticed red glowing spots dark moon informed king george iii observations attributed phenomena perceived greater discovered april observations aurora northern lights italy aurora activity far south arctic circle rare display observations happened days number peaked experienced lunar observer claimed crater changed appearance based drawings earlier personal observations drawings stated crater time oblique illumination seen emphasis high illumination visible bright spot based repeat observations stated seen illumination crater normal type local change taken place today visible normal young impact crater diameter miles november russian observed apparent half hour eruption took place central peak crater inch equipped time obtained showed evidence bright bands molecules exposing second noticed marked increase central region unusual white colour sudden started decrease resulting spectrum normal october chart information center james clarke edward observatory arizona manually recorded bright red orange pink colour phenomena southwest cobra head hill southeast lunar valley southwest interior rim crater event sparked major change attitude reports according reaction professional circles naturally surprise hard heels surprise followed attitude directed long dead great sir william cameron states event serial november observations started modern interest observing moon credibility findings stemmed reputation photographic evidence night november days event french thomas photographs wide area lunar article scientific american transformed widely publicized events like argued solar energetic particles cause phenomenon apollo mission houston apollo got observation time lunar events reported vicinity west_germany observed bright glow lunar surface sort eerie intrigued moon centuries report passed houston immediately michael collins reported hey houston looking north area considerably illuminated surrounding area slight paris reported features floor crater meter foot observations night december normal unusually high features recorded following night change appearance minutes data collection observations days later showed similar smaller vicinity viewing conditions region close argued observations consistent reflection sunlight favored hypothesis consequence light scattering clouds airborne particles resulting release gas fractured floor crater cited possible source gas explanations explanations lunar phenomena fall classes impact events phenomena unfavorable observation conditions caused gas escaping underground events purported display distinctive reddish appeared white clouds indistinct majority appear associated floor fractured edges lunar maria locations linked volcanic activity common targets viewing moon bias support hypothesis data lunar alpha particle indicate recent surface particular results gas vicinity time year mission observations explained slow visually gas surface explosive events support explosive suggested roughly diameter region lunar surface recently modified gas release event age feature believed million years old suggesting large phenomena occur impact events impact events continually occurring lunar surface common events associated encountered showers impact flashes events detected multiple simultaneous earth based observations tables impacts recorded video cameras exist years associated showers furthermore impact clouds detected following crash spacecraft india moon impact probe nasa impact events leave visible surface detected analyzing photos sufficiently high resolution impact formed global resolution metre selected areas metre resolution metre missions identified phenomena suggested effects related charging able account lunar phenomena possibility effects related near surface materials charge gases present solar wind daughter products occur surface subsequent discharge gas able rise phenomena visible earth alternatively proposed charging particles gas borne dust cloud rise visible earth finally dust near potentially rise form phenomenon visible earth unfavourable observation conditions possible phenomena associated moon result unfavourable observing conditions phenomena associated earth instance reported phenomena objects near resolution employed earth atmosphere rise significant temporal confused actual lunar phenomena effect known astronomical seeing non lunar explanations include viewing earth satellites error debated status significant problem faces reports lunar phenomena vast majority single observer single location earth multitude reports phenomena occurring place moon evidence supporting existence absence eyewitness reports multiple observers multiple locations earth event regarded caution discussed equally plausible hypothesis events caused terrestrial atmosphere event observed different places earth time evidence atmospheric origin attempt overcome problems phenomena reports mission network amateur events reported photographed afterward spacecraft careful analysis images shows differences sites necessarily imply reports result error possible events lunar surface leave visible marker encouraging hypothesis authentic lunar phenomena observations currently coordinated association lunar observers british astronomical association observe sites lunar phenomena reported past documenting appearance features illumination conditions possible judge reports simply observer regarded furthermore digital images possible simulate atmospheric astronomical seeing light scattering atmosphere determine phenomena explain original reports


atmosphere venus atmosphere venus layer gases surrounding venus composed primarily carbon dioxide earth temperature surface pressure bar atmosphere supports clouds acid making optical earth based observation surface impossible information topography obtained exclusively radar imaging aside carbon dioxide main component nitrogen chemical compounds present trace amounts person existence atmosphere venus based observation transit venus small observatory near house saint_petersburg russia atmosphere state vigorous circulation super rotation atmosphere circles planet earth days faster planet day days winds supporting super rotation blow fast mph winds times speed planet rotation earth fastest winds rotation speed hand wind speed increasingly slower elevation surface decreases breeze barely reaching speed surface near poles structures called polar vortex double eyed shows characteristic shaped pattern clouds unlike earth venus lacks magnetic field separates atmosphere outer space solar wind layer solar magnetic field giving venus distinct magnetic environment considered venus induced lighter gases including water continuously blown away solar wind induced speculated atmosphere venus billion years ago like earth liquid water surface runaway greenhouse effect caused surface water subsequent rise levels greenhouse gases despite harsh conditions surface atmospheric pressure temperature surface planet nearly earth making upper atmosphere earth like area solar system surface mars similarity pressure temperature fact air oxygen nitrogen lifting gas venus way lifting gas earth upper atmosphere proposed location exploration colonization january scientists reported planet venus streams manner similar tail seen streaming similar conditions structure composition composition atmosphere venus composed carbon dioxide nitrogen traces gases notably dioxide nitrogen atmosphere relatively small compared carbon dioxide atmosphere thicker earth total nitrogen content roughly times higher earth earth nitrogen makes atmosphere atmosphere contains range interesting compounds small quantities including based hydrogen hydrogen hydrogen carbon water molecular oxygen hydrogen relatively short supply atmosphere large planet hydrogen lost space remainder bound acid hydrogen loss significant amounts hydrogen proved high ratio measured atmosphere ratio times higher terrestrial value according measurements upper atmosphere venus ratio higher bulk atmosphere atmosphere divided number sections depending altitude atmosphere begins surface extends upwards like surface winds slow temperature pressure reaches earth like levels clouds pick speed atmospheric pressure surface venus times earth similar pressure found metres surface ocean atmosphere mass times mass earth total atmosphere density air surface liquid water earth pressure found venus surface high carbon dioxide technically longer gas fluid carbon dioxide forms kind sea covers entire surface venus sea carbon dioxide transfers heat efficiently temperature changes night day terrestrial days large atmosphere water dioxide create strong greenhouse effect trapping solar energy raising surface temperature planet solar system mercury despite located farther sun receiving solar energy unit area mercury average temperature surface melting points lead tin thick makes difference temperature day night small slow rotation planet causes single solar day earth days surface venus spends days darkness sun rises clouds venus contains atmosphere mass ninety percent atmosphere venus surface comparison atmosphere earth surface height atmospheric pressure approximately equal surface earth night venus clouds found surface altitude similar earth near boundary located slightly according measurements venus express altitude temperature altitude surface pressure earth sea level manned ships sent venus able compensate differences temperature certain extent surface easiest altitude base exploration colony temperature crucial liquid water range air pressure regions earth heavier air colony air nitrogen oxygen structure floating altitude like circulation circulation venus follows called roughly determined balance pressure gradient forces purely flow contrast circulation earth atmosphere governed balance venus directly measured upper altitude corresponds upper cloud deck cloud motion usually observed spectrum contrast clouds highest linear wind speeds level lower latitude sense blow direction rotation planet winds quickly decrease higher latitudes eventually reaching zero poles strong cloud winds cause phenomenon known super rotation atmosphere words high speed winds circle planet faster planet super rotation venus differential means super slowly winds strong vertical gradient decline deep rate winds near surface venus slower earth actually kilometres hour generally average high density atmosphere surface transport dust small stones surface like slow moving current water winds venus ultimately driven convection hot air rises zone solar heating concentrated flows poles called circulation air motions slower winds limit planet wide cell venus near latitudes air starts descend returns equator clouds interpretation supported distribution carbon concentrated vicinity latitudes cell different pattern circulation observed latitude range cold polar exist characterised temperatures lower upper nearby latitudes lower temperature probably caused air resulting cooling interpretation supported higher clouds clouds lie altitude higher poles low latitudes connection exist cold high speed jets winds blow fast jets natural consequence type circulation exist venus latitude odd structures known polar lie cold polar giant hurricane like storms times larger terrestrial vortex eyes centres rotation connected distinct shaped cloud structures double eyed structures called polar rotate period days direction general super rotation atmosphere linear wind speeds near outer edges zero poles temperature cloud tops polar higher nearby polar reaching conventional interpretation polar centre cold polar type circulation resembles winter polar earth especially found antarctica observations infrared atmospheric windows indicate circulation observed near poles penetrate deep altitude base clouds polar upper extremely dynamic large bright clouds appear disappear space hours event observed venus express january south polar region brighter event probably caused injection dioxide condensed forming bright eyes explained vortex venus discovered north pole pioneer venus mission discovery second large double eyed vortex south pole venus summer venus express came surprise upper atmosphere venus extends height begins eventually reaching upper limit atmosphere altitude atmosphere venus divided layers lower upper layer temperature nearly constant layer upper cloud deck second layer temperature starts decrease reaching altitude begins atmosphere serves boundary located temperature grows constant value prevalent contrast place venus temperature low called circulation patterns upper venus completely different lower atmosphere altitudes air moves planet hemisphere dark hemisphere causes heating air forms warm layer altitudes temperature layer far higher typical temperature found air circulated carries oxygen form excited molecules oxygen long lived state relax infrared radiation radiation altitude range observed ground spacecraft upper venus source non non local emissions molecules responsible low temperature venus express probe shown stellar atmospheric extends night day day cloud deck thickness extends night cloud deck form thick reaches altitude continuing transparent spacecraft discovered venus thin layer altitude venus extended located altitudes high levels maintained planet concentration zero venus consists layers additional layer near maximum electron volume density number unit volume reached layer near point upper boundary located altitudes separates origin induced main species layers layer consists observed motion solar processes mainly responsible accelerating observed flow appears sufficient maintain near observed median level induced venus known magnetic field reason absence clear probably related planet slow rotation lack convection mantle venus induced formed sun magnetic field carried solar wind process understood field lines wrapping obstacle venus case induced venus bow shock current sheet point bow shock stands radius venus surface venus distance measured near solar activity minimum near solar activity maximum times planet located altitude upper boundary near exists magnetic barrier local magnetic field prevents solar penetrating deeper atmosphere near solar activity minimum magnetic field barrier reaches continues planet active events particle acceleration tail energies respectively lack magnetic field venus solar wind relatively deep causes substantial atmosphere loss loss happens mainly currently main types lost ratio hydrogen oxygen losses indicating ongoing loss water clouds clouds thick composed dioxide acid clouds reflect sunlight falls surface venus optical imaging geometric common measure highest planet solar system high potentially enables probe exploring cloud tops sufficient solar energy solar cells fitted craft cloud cover typical surface light levels similar partly cloudy day earth equivalent visibility kilometers note likely vary prevailing wind conditions level little solar energy collected solar panels surface probe fact thick highly reflective cloud cover total solar energy received planet earth acid produced upper atmosphere sun action carbon dioxide dioxide water carbon dioxide carbon atomic oxygen atomic oxygen highly dioxide trace component atmosphere result combine water trace component venus atmosphere yield acid surface level humidity venus acid rain reaches ground heat reaching surface phenomenon known early volcanic activity released atmosphere high temperatures prevented trapped solid compounds surface earth clouds venus capable producing lightning like clouds earth existence lightning controversial outside soviet_union suspected bursts detected soviet venus express reported detect mode waves attributed lightning intermittent appearance indicates pattern associated weather activity lightning rate half earth prominent bright spot atmosphere noted amateur photographed venus express cause currently unknown surface advanced possible explanation possibility life harsh conditions surface little planet explored addition fact life currently understood necessarily parts universe extent life earth shown creatures known exist earth preferring extreme habitats thrive temperatures reaching boiling point water thrive level survive varied number extreme conditions types exist earth surface temperature venus far range extends tens degrees life exist cloud tops proposed life venus exist way bacteria found living clouds earth thick cloudy atmosphere protected solar radiation compounds air solar wind provide mechanism transfer venus earth atmosphere found sufficiently require investigation analysis data pioneer missions found chemicals hydrogen dioxide upper atmosphere gases react implying produce difficult produce present atmosphere noted presence accounted planet addition early detected large amounts toxic cloud deck proposed level light sun source energy possible explanation dark patches seen images planet large non spherical cloud particles detected cloud decks recently abundance vertical distribution unknown atmosphere investigated analysis venus monitoring camera images composition unknown evolution studies present cloud structure geology surface combined fact sun increased billion years ago thought atmosphere venus billion years ago like earth liquid water surface runaway greenhouse effect caused surface water rise levels greenhouse gases followed venus atmosphere received great deal attention studying climate change earth forms planet suggest presence water past billion years reason suppose venus exception processes formed earth gave water early history possibly original rocks formed planet later common view research scientists water existed million years surface david believe billion years plausible early earth believed scientists venus like atmosphere roughly bar surface temperature possibly acid clouds billion years ago time plate force early water oceans removed atmosphere early venus likely water oceans like earth plate ended venus lost oceans surface estimated million years old expected evidence plate observations measurement earth russian observed arc light surrounding venus sun disc beginning phase transit concluded venus atmosphere calculated atmosphere raise surface temperature boiling point water confirmed measurements temperature confirmed atmosphere consisted primarily carbon dioxide upper atmosphere venus measured earth planet crosses sun rare event known solar transit solar transit venus occurred astronomical scientists able sunlight passed planet atmosphere reveal chemicals technique light discover information planet atmosphere showed results opportunity gain conclusive results way atmosphere venus observation solar began solar transit rare opportunity considering lack information atmosphere solar transit enabled gather large data useful determining composition upper atmosphere venus techniques searching planets atmosphere near infrared radiation making easy observe transit absorption atmosphere function revealed properties gases altitude shift gases enabled wind patterns measured solar transit venus extremely rare event solar transit planet recent solar transit occur future exploration venus express spacecraft orbit planet deeper atmosphere infrared imaging range probe launched intended study planet period years including structure activity atmosphere failed enter venus orbit december second attempt achieve orbit succeeded december cameras known able measure atmosphere planet underneath thick clouds addition movement distribution trace components varied orbit able close photographs planet confirm presence active lightning venus explorer proposed nasa new program proposed probe aid understanding processes planet led climate change paving way later sample return mission craft called venus mobile explorer proposed venus exploration analysis group study composition measurements surface atmosphere days launch date set proposed missions missions discovered reality harsh nature planet surface attention shifted targets mars number proposed missions recently involve little known upper atmosphere soviet program dropped balloons atmosphere battery powered lasted earth days running power exploration upper atmosphere nasa contractor global proposed balloon capable staying upper atmosphere hundreds earth days opposed solar proposed place balloon idea featured time time early 2000s venus high reflects sunlight shines making surface dark upper atmosphere upward solar intensity meaning solar panels craft nearly equal efficiency addition slightly lower gravity high air pressure slow rotation allowing perpetual solar power planet ideal exploration proposed operate best altitude sunlight air pressure wind speed enable remain air slight lower altitudes hours time returning higher altitudes acid clouds height threat properly shielded craft called solar able measure area indefinitely long takes mechanical error problems cause fail proposed similar spirit opportunity possibly explore surface difference venus surface dumb controlled radio signals computers located requiring parts motors withstand surface conditions weaker parts involved resistant heat pressure acidic conditions russian space plan involves launch venus probe main scientific goals mission investigation structure chemical composition atmosphere investigation upper atmosphere electrical activity escape rate


moon thee greek moon order distance planet discovered september edward named greek mythology known close orbit outer edge ring formed dust ejected surface surface appear degrees diameter largest inner satellites irregularly shaped reddish color thought consist water ice unknown amounts materials surface features include large ridges photographed voyager spacecraft later detail 1990s history discovery discovered september edward inch observatory satellite discovered direct visual observation opposed new satellite discovery satellites named greek mythology infant greek equivalent goat milk roman designation formally adopted informal use decades initially suggested commonly known simply form orbit distance orbit relative equator values small unusual inner satellite explained influence satellite past passed mean motion excited mean motion resonance ratio periods bodies rational number like orbit lies near outer edge ring composed dust ejected satellite physical characteristics surface red increases green near infrared reddish color originating non ice material bright patches red appear major slopes nature color currently unknown surface slightly brighter surfaces inner satellites substantial leading trailing leading hemisphere times brighter trailing probably caused higher velocity frequency impacts leading hemisphere bright material presumably ice interior moon irregularly shaped best surface area likely square kilometers near like inner locked planet long axis pointing times surface heavily extremely large relative size moon pan largest crater measures deep crater measures likely twice deep pan prominent bright spots named width reaching located edge ridges irregular shape large size led past conclusion fairly strong rigid body argued body composed weak materials pulled spherical shape gravity november targeted came orbit moon mass volume calculated previously careful analysis extant images end density found low relatively body rubble pile likely recent measurements infrared suggest moon contains minerals organic materials indicating formed current position hot melted likely formed farther planet captured solar system body unfortunately images taken cameras radiation damage january resolution available images generally low slightly heat receives sun probably influence heat sunlight reflected planet charged particle bombardment trait shared different reasons named geological features named geological features bright spots located edge ridge anti relationship rings tidal force low density irregular shape escape velocity surface points closest dust easily escape impacts dust forms ring star detected flashes appear small near orbit sighted location true distances measured size gravel stadium sized origins unknown captured current orbit impacts final orbit hour destruction detected time planet probable particles form ring planet near orbit views surface appear bright shining magnitude similar venus earth disc barely period slightly longer parent planet day case means cross sky slowly time hours surface look enormous degrees appear roughly times larger moon rotation appear visible sun disappear bulk hour half revolution short rotation period gives hours daylight appear times brighter moon light spread area times greater look bright surface unit exploration voyager voyager space images resolved surface measured visible infrared surface temperature later completed imaging surface provided final satellite fly november distance moon center approximately height permitting moon mass accurately determined changing trajectory september having finished mission orbit refined new spacecraft instruments fiction setting works science fiction including stories arthur clarke james


type pistol type pistol type japanese pistol developed associates imperial japanese army development type pistol began final prototype tested officially adopted japanese army late japanese calendar type pistol entered production approximately pistols manufactured production ended type pistol designed popular japanese tank aircraft crews preferred smaller lightweight design japanese weapons experts subsequently criticized design elements type particular pistol fired unintentionally breech fully locked bar receiver loose pistol handled additionally process pistol overly complex awkward build quality type pistol declined production run ditch pistols manufactured history type pistol designed retired japanese army founded rifle manufacturing company design type pistol commenced goal reducing bulk price previous designs imperial japanese army felt smaller pistol domestic design accommodate standard cartridge needed substitute larger heavier official military pistol type demand officer increased result japan invasion second sino japanese war new design wanted japanese army include magazine safety prevent cleaning common japanese personnel naming type pistol reflects change japanese nomenclature mythical foundation japan year instead traditional emperor reign period type revolver type pistol final prototype type officially adopted japanese army late production began supervision army arsenal rifle manufacturing company later successor company ltd estimated pistols produced military exact quantity unknown production pistols pistols world war pistol preferred weapon tank crews required smaller convenient pistol type officially adopted imperial_japanese_navy available officers japanese officer union design type pistol operated different mechanism previous japanese unlike previously designed pistols type operates concealed hammer firing pin hammer according authors harry derby james brown firing pin inherently weak prone cut provided prone breaking point hammer firing mechanism developed included type replace poor type locking system rising block type independently underneath chamber end barrel single positioned barrel barrel instead rear barrel found pistols grip smaller japanese pistols finished smooth wood according author jeff comfortable use men smaller hands magazine holds maximum rounds smaller grip considered difficult weapon pressure bolt holding inside pistol magazine catch far occasionally pistol placed left hard surface magazine manual safety located left rear frame fire safe stamped frame blade sight muzzle type pistol rear fixed occasionally positioned making useless weapon aimed rear sight reduced shape simple notch blade left unchanged attention detail applied world war progressed final production quality type pistols decreased end world war japanese faced bombing raids allied forces material shortages increased drastic change quality late march onwards quality standards appearing disappear end june smooth wooden finished grip replaced pattern pistols serialized pistols reported bear july manufacture date pistols known exist include parts inspection marks loops small number pistols final production stages include earlier production dates appear salvaged previously discarded pistols minor defects type pistol considered difficult lead damage pistol clearing type operator draw slide magazine follower hold bolt rear pistol allow released firing pin depressed removal depressing firing pin damage firing pin removing complicated hands holding pistol depressing firing pin type pistol generally leather ranged color tan dark reddish brown faced degradation quality type pistol supplies leather exhausted japan manufactured fabricated olive fabric type pistol distinguishable japanese having pointed closure vertically positioned magazine tow narrow extension accommodate cleaning rod majority civilian owned ink stamped arsenal inspection marks belt loop shoulder rings provided rear brass steel plating firing poor design breech allowed type fired unintentionally bar type converts forward pull trigger lateral movement hammer bar outside pistol loose engagement pistol handled forward end bar need depressed approximately cause weapon fire ability fire type pulling trigger gave rise war stories japanese soldiers surrendering fire pistol earning pistol suicide special surrender pistol stories widely difficulty fire weapon bar safety engaged type impossible weapon discharge unintentionally

Weapons, military equipment and programs


motor carriage motor carriage united_states_army self propelled gun world war design based requirements assault gun issued armored force built interim solution fully tracked design complete produced white motor company vehicle simply pack mounted modified half track combat north african campaign november later served italy france possibly pacific later leased french forces type late war 1950s specifications based half track specifications similar parent vehicle long wide high weighed short tons suspension consisted vertical springs tracks leaf springs wheels vehicle fuel capacity gallons range speed mph powered white cylinder gasoline engine compression ratio power weight ratio ton gun specifications main armament short pack pack mounted degrees elevate degrees traverse degrees vehicle rounds ammunition designed anti tank use high explosive anti tank heat shell penetrate armor gun shield thick armor designed stop bullet yards away development originally conceived interim design armored force requirement assault gun equip tank armored reconnaissance units ordnance department design based half track order brought service quickly prototype vehicle authorized october armed pack mount designed fit simple box structure half track authorization production prototypes given january deliveries vehicle following month white motor company seen temporary solution given type classification september partially replaced motor carriage gun stuart declared limited standard total produced white motor company service history entered service november seeing action time north african campaign 1st armored division armored regiment issued battalion headquarters platoon regimental reconnaissance platoon addition 6th 41st armored infantry regiments issued allocated headquarters platoon armored infantry battalion infantry divisions north african campaign deployed cannon company equipped encounter north_africa attempt destroy german tanks fired german tanks barely damaged ordered retreat cover smoke prevent losses similar experiences forces ceased practice employing self propelled mortars direct combat tanks served allied invasion sicily war italy possibly pacific removed infantry division use march following changes organization infantry battalions replaced towed eventually replaced based stuart light tank began entering service time delivered original configuration converted half tracks delivered later leased french forces late war vehicle retired service 1950s


bomb bombs conventional aerial bombs developed manhattan_project united_states_army air forces japan world war bomb close fat man bomb handling characteristics non nuclear conventional high explosive mainly testing training purposes included combat missions flown bombs composite group bomb resulted large fat shape instead usual cylindrical shape bombs actual reference term official documents development bombs means providing realistic training composite group boeing crews assigned drop atomic bomb bomb close non nuclear fat man bomb handling characteristics specifications bomb required carried forward bomb bay bomber effective actual targets bombs produced high explosive variants versions filled cement plaster sand mixture combined water grams cubic density composition high explosive versions filler variants weight weight distribution inner sphere bomb concept high explosive bomb originated december navy captain william parsons head ordnance division manhattan_project los laboratory united_states_army air forces lieutenant colonel paul commander composite group prior testing carried version bomb given training bombs parsons charles california institute technology managed development team official meetings documents probably referred large shape sources attribute naming bombs painting color bombs actually painted olive photographs indicate units delivered painted color yellow worn fat man manhattan scientists expected development means delivery atomic bomb straightforward parsons experience proximity program expected involve considerable effort test program initiated august naval proving ground virginia scale model fat man bomb developed march testing moved army air field california initial tests demonstrated fat man assembly unstable flight work properly production shells bomb manufactured los_angeles firms consolidated steel corporation western pipe steel company tail assembly produced centerline company detroit initial development management program turned navy bureau ordnance total live training bombs eventually delivered cost apiece versions went manufacturers directly army air field utah rail base unit flight testing bomb test drop missions flown composite group bombardment squadron training exercises bombs intended live ordnance shipped naval ammunition depot oklahoma filling explosives composition poured solidified drying facility hours sealed shipped railroad port chicago naval magazine california shipment sea description bombs externally similar fat man bomb size shape inch california parachute square tail assembly single point attachment bomb contact arranged triangle nose bomb atomic bomb fuse atomic bomb shell sections bombs inches hole filling shell fat man external mounting points radar antennae bombs bombs feet inches length inches maximum diameter weighed long tons consisting pounds shell pounds tail assembly pounds composition filler shells inch steel plate tail assemblies inch aluminum plate combat missions combat missions flown composite group july august bombs individual targets japanese cities total bombs dropped targets bomb ocean aboard aircraft aborted missions mission parameters similar actual atomic bomb missions targets located vicinity cities designated atomic attack bombs released altitude feet aircraft went sharp turn required nuclear mission war strategic bombing survey concluded bombs reasonably effective weapon japanese plants direct hits scored vital areas near miss sufficiently close important buildings cause severe structural damage


gun motor carriage gun motor carriage united_states_army tank destroyer equipped gun produced fall france army decided self propelled artillery piece gun chassis designated improvement came production gun motor carriage supply gun shields insufficient production needs new gun shield designated served philippines campaign provisional field artillery brigade anti tank fire support role served north_africa tank destroyer battalions battle pass engagements success battle served allied invasion sicily eventually superseded tank destroyer total produced converted half tracks served pacific theater starting battle proved effective japanese type type tanks later served battle okinawa battle island battles specifications feet long feet wide feet high including gun shield weighed pounds suspension consisted semi elliptical leaf springs wheels vertical springs tracks transmission consisted constant ground clearance inches white horsepower cubic inch cylinder engine compression ratio mile range gal fuel tank speed mph power weight ratio ton armed rounds armor crew consisting commander gunner driver mount traverse left right elevate mount traverse directions development fall france army studied reasons effectiveness german campaign french british forces aspect highlighted study use self propelled artillery little available army arsenal role army number guns sufficient mass production weapon half track coming production debate army decided place guns half track chassis designated gun originally adapted chassis placing box chassis driver compartment accepted army october batch testing built transported philippines improved multiple ways improvements included inclusion mount raised gun shield replacement original gun shield gun shield addition machine gun later removed final improvements finished prototype vehicles sent company production existing supply gun shields insufficient meet requirements production ordnance department developed gun shield replaced new design designated gun motor carriage service history american use saw action army philippines months designed battalions provisional field artillery brigade operated japanese invaded philippines early campaign vehicle provide direct covering fire anti tank support japanese captured vehicles defense philippines tank destroyer battalions north african campaign consisted designed tanks proved inadequate task battles pass mainly poor tactics later battle success claiming german tanks including possibly tiger tanks cost saw service allied invasion sicily operation time tank destroyer replaced army total converted half tracks served marines pacific theater operations invasion proved highly effective type type fight japanese 9th tank regiment served battle battle okinawa conflicts pacific allied use saw limited service countries widely supplied lend lease program small batch vehicles supplied britain armored car regiments campaign royal sicily italy later france gradually retired free french army training receiving tank destroyers production total produced vehicles produced increased examples came production lines completed production stopped release better tank destroyers like


project project research development project larger manhattan_project build atomic bombs world war founded frank iowa state college iowa laboratory university_of_chicago devoted chemistry separate project right project developed process method preparing pure metal manhattan_project needed atomic bombs nuclear produced short tons metal developed methods preparing casting october iowa state college received army navy award excellence production award usually given industrial organisations laboratory national laboratory atomic energy commission background discovery james followed nuclear german theoretical explanation naming soon opened possibility controlled nuclear chain reaction december soon japanese attack pearl harbor brought united_states world war nobel prize winning physicist arthur placed charge project objective produce convert find ways separate ultimately design build atomic bomb manhattan_project successful built scientists produced different promising design concepts established laboratory university_of_chicago february mission build nuclear create atomic bombs advice assembling laboratory chemistry division physicist turned considerable experience radioactive elements recommended frank iowa state college iowa expert rare earth elements similar series included asked head laboratory chemistry division lack space university_of_chicago proposed organise chemistry division iowa state college colleagues willing help agreed spend half week half chicago intention staff eventually chicago space available happened success project ensured separate laboratory manhattan_project organization started recruiting fellow scientists iowa state college associate directors expert head project division head division section chiefs project grew scientific staff total number staff eventually exceeded senior staff meet sunday review previous week work set goals week ahead process came called depart chicago soon meeting early succeeded head chemistry division laboratory james allowing spend times remained associate director laboratory fortunate having support charles president iowa state college nature work disclosed security checks complete complete brought dean science project administrator united_states_army corps engineers took control manhattan_project june project late process item agenda find nuclear proposing build ore readily available short tons high grade ore belgian storage warehouse port richmond island short tons mined port great bear lake near arctic circle canada northwest territories company operated port hope ontario canadian belgian ore refined manhattan_project estimated requirements short tons required short tons proposed nuclear major problem act prevent nuclear chain reaction presence references published typically listed melting point pure metal actually peter alexander metal incorporated gave indications melting point low somewhat lower effective way laboratory advantage fact scaling process industrial production dangerous proposition explosive factory large quantities likely blow burn turned saint louis missouri experience went details chemical engineers henry john april months tons highly pure produced metal available commercially produced electric manufacturing company process reacted potassium large roof plant new_jersey produced size quarter sold edward head laboratory group responsible wanted metal sphere size orange experiments process cost taken year produce process developed peter alexander calcium reducing agent conversion ore metal means metal plant massachusetts managed produce pounds metal unfortunately calcium contained unacceptable amounts poison making metal unsuitable use months pass national bureau standards union figured means produce sufficiently pure calcium began looking ways create metal time produced form powder highly pressed stored cans useful needed melted cast casting presented difficulty produce metal tried reducing hydrogen work neighboring elements periodic table reduced form pure metal behave way june tried reducing carbon hydrogen atmosphere moderate success tried aluminum calcium unsuccessful following month team found cast container known react managed formed touched time manhattan_project berkeley radiation laboratory brought inch cube compound laboratory discuss possibility began wondering possible produce metal salt bypassing problems oxygen took cube asked investigate task assigned associate wayne investigated process known process originally developed university new_hampshire involved mixing calcium metal calcium lined steel pressure vessel known bomb heating able reproduce results august creating button pure metal process scaled september bombs prepared inch steel pipes inches long lined lime prevent containing kilograms gray took cast inch pure production september took laboratory chicago presented reaction disbelief thought hollow cut open hollow days later laboratory director richard went drew office scientific research development contract project produce pounds pure metal day pilot plant process eventually transferred industry contract superseded manhattan_project contract november initial contract december face value contracts let project totalled work carried found old wooden building southeastern edge campus home economics building served women gymnasium new built mainly storage building handed project wooden floor replaced concrete disappointment university architect trying years place torn building officially known physical chemistry annex local people called little nearby town iowa ordnance plant looking machine tools found machine shop sale owner bill tools longer obtain metal needed wartime bought laboratory supplied large reduction project supplied tons metal laboratory construction chicago world nuclear achieved december project later supply percent clinton engineer works oak ridge tennessee project producing ton highly pure metal day production rose pounds day december pounds day middle january production process changed use instead calcium cheaper readily available harder start reaction calcium requiring heating known green salt characteristic color supplied chemical ground arrival bombs normally inch pipes inch long inch inch long pipes produce pound heated minutes mixture spontaneously reacted reaching temperatures microphone detect bomb moved spray chamber cool worked metal produced bomb cooled opened separated resulting stamped sent cast casting shaped removed metal melted poured mold produced rods inches diameter inches long rods stamped number placed wooden boxes shipping laboratory sent oak ridge site july project producing pounds metal month cost pound metal fell dollar starting july began producing process phased production early project began program recovering metal scrap new building known physical chemistry annex constructed purpose washed dried passed remove iron pressed send job handed metal recovery plant site december time project recovered pounds scrap metal project produced short tons metal production ceased august metal leaving producer metal early post war period metals beginning production operations project conducted variety research related separation rare earth metals established bombarded transformed possible route atomic bomb especially turned easily separated pursued production required complete redesign april laboratory calculated nuclear containing produce sustain reaction adding interesting time thought scarce times plentiful july august project attempted create metal similar process unsuccessful higher melting point efforts continued found produce heating melt drawn left cast pounds pounds produced december sold war end project producing manhattan_project component firm produced commercially united_states brush ohio project began working production process december reducing bomb metallic main difficulty working high closed bomb possibility producing toxic dust process worked high temperatures pressures created meant potentially explosive alternative developed bomb metallic calcium lead metal cast vacuum research ongoing war ended project asked produce laboratories berkeley los cast bomb method time reduce calcium special dry room constructed drying hydrogen gas resulting metal contained calcium recast remove opportunity taken inch diameter rods inches long desired shape vacuum calcium shipment metal august laboratory produced pounds extremely pure august production ended metal scarce war little known manhattan_project interested properties particular water cooling speculation high thermal resistance project produced tested potential fuel instead metallic low capture cross section project produced tested point proposal table protect copper project studied copper occur interface practice aluminum studied tin cans tests carried calcium produced use project attempts separate exploiting greater affinity gold silver manhattan_project chose use process chemical separation method instead project studied carbon iron oxygen tin lead chemistry chemistry focus multiple studies project properties investigated particular interest point los laboratory considered atomic bomb instead metallic idea found inefficient shelved process developed recovery depleted metal left electromagnetic separation process left process operated pilot plant produced kilogram quantities turned manhattan_project sam laboratories implementation industrial scale oak ridge chemistry poorly understood practically unknown existed microscopic amounts samples began arriving manhattan_project investigations chemistry laboratory project investigated methods separating metal products post war major general director manhattan_project visited iowa state college october presented army navy award excellence production producing manhattan_project unprecedented college university receive award usually given industrial organisations award came form banner sporting white stars representing half years service war effort award display iowa state university hall iowa state board education created institute atomic research coordinating body research united_states november director manhattan_project continued fund activities project passage atomic energy act responsibility passed newly created atomic energy commission january awarded contract run laboratory status national laboratory iowa state college laboratory remained iowa state college campus faculty graduate students staff remained director retired administration delegated permanent buildings constructed opened subsequently named hall hall laboratory retained focus chemistry particularly rare earth metals