The-Beauty-of-Space3

Outerspace

However,theKármánline,at analtitudeof100kmabove sealevel,sconventionaly usedasthestartofouter spaceinspacetreatiesand foraerospacerecords keeping.Theframeworkfor internationalspacelawwas establishedbytheOuter SpaceTreaty,whichentered intoforceon10Oct.1967. Thistreatyprecludesany claimsofnational sovereigntyandpermitsal statestofreelyexploreouter space.Despitethedrafting ofUNresolutionsforthe peacefulusesofouter space,anti-satelite weaponshavebeentested inEarthorbit.

Outerspace,orjustspace,istheexpansethatexistsbeyondthe Earth and between celestialbodies.Outerspace is not completelyempty—itisahardvacuumcontainingalowdensity ofparticles,predominantlyaplasmaofhydrogenandheliumas welaselectromagneticradiation,magneticfields,neutrinos, dust,andcosmicrays. Thebaselinetemperature,assetbythebackgroundradiation fromtheBigBang,is2.7kelvins(−270.45°C;−454.81°F).The plasmabetweengalaxiesacountsforabouthalfofthebaryonic (ordinary)materintheuniverse;ithasanumberdensityofles thanonehydrogenatompercubicmetreandatemperatureof milionsofkelvins;localconcentrationsofthisplasmahave condensedintostarsandgalaxies.Studiesindicatethat90%of themas inmostgalaxiesisinanunknownform,caleddark mater,whichinteractswithothermaterthroughgravitational but notelectromagneticforces. Observationssuggestthatthemajorityofthemas-energyinthe observableuniverseisapoorlyunderstoodvacuumenergyof space,whichastronomerslabel darkenergy.Intergalacticspace takesupmostofthevolumeoftheUniverse,butevengalaxies andstarsystemsconsistalmostentirelyofemptyspace.Outer spacedoesnotbeginatadefinitealtitudeabovetheEarth's surface.However,theKármánline,atanaltitudeof100km(62 mi)abovesealevel,isconventionalyusedasthestartofouter spaceinspacetreatiesandforaerospacerecordskeeping.

Outerinterstelarspace TheSpacePortal

Discovery Humansbeganthephysicalexplorationofspaceduringthe20thcenturywiththeadventof high-altitudebaloonflights,folowedbymannedrocketlaunches. EarthorbitwasfirstachievedbyYuriGagarinoftheSovietUnionin1961,andunmanned spacecrafthavesincereachedaloftheknownplanetsintheSolarSystem.Duetothehighcost ofgetingintospace,mannedspaceflighthasbeenlimitedtolowEarthorbitandtheMoon. Outerspacerepresentsachalengingenvironmentforhumanexplorationbecauseofthedual hazardsofvacuumandradiation.Microgravityalsohasanegativeefectonhumanphysiology thatcausesbothmuscleatrophyandboneloss.Inadditiontothesehealthandenvironmental isues,theeconomiccostofputingobjects,includinghumans,intospaceisveryhigh. Spaceisapartialvacuum:itsdiferentregionsaredefinedbythevariousatmospheresand "winds"thatdominatewithinthem,andextendtothepointatwhichthosewindsgivewayto thosebeyond.Geospaceextendsfrom Earth'satmospheretotheouterreachesofEarth's magneticfield,whereuponitgiveswaytothesolarwindofinterplanetaryspace.

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