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dark grey star（第1页）

darkgreystar

darkgreystar

Theageoftheuniverseis13。8billionyears，andthediameterisabout93billionlight-years

ThePisces-CetusSuperclustercomplexis1billionlight-yearslongand150millionlight-yearswide。

TheLaniakeasupergalaxyhasadiameterof520millionlight-yearsandcontains100，000galaxies。

TheVirgoSuperclusteris100millionlight-yearsindiameterandcontains47，000galaxies。

TheLocalGroupofGalaxiesis10millionlight-yearsindiameterandcontains50galaxies

TheAndromedaGalaxyis220，000light-yearsindiameterandhas1trillionstars。

TheMilkyWayis180，000light-yearsindiameterandhas400billionstars。

Whatistheconceptoflightyear

Commonlyusedunitsinastronomyareparsecs，astronomicalunitsandlightseconds

Anastronomicalunitis149，597，870，700meters

Alightsecondisthedistancetraveledbylightinonesecondandis299，792，458meters。

Alight-yearis9，460，528，177，426。821meters。

Oneparsecequals3。26lightyears

Thespeedoftheearth'smovementaroundthesunis29。79kilometerspersecond，

ThespeedofthesunintheMilkyWayis240kilometerspersecond，

ThespeedoftheMilkyWayintheuniverseis600kilometerspersecond，

TheJunospaceprobehasatopspeedof265，000kilometersperhour，

Itwouldtakeabout4075Earthyearstotraveladistanceof1light-yearwithJuno，

IfJunoweretoflytotheclosesthabitableplanettoEarth，

Ittakes17115EarthyearstoreachProximab，4。2light-yearsaway，

Ittakes48512EarthyearstoreachTiancang5e，whichis11。905light-yearsaway，

Ittakes56，235EarthyearstoreachWolf1061c，whichis13。8light-yearsaway，

Ittakes65199EarthyearstoreachGris832c，whichis16lightyearsaway，

Ittakes83536EarthyearstoreachGris581g，whichis20。5light-yearsaway，

Ittakes92502EarthyearstoreachGris667，whichis22。7light-yearsaway，

ToreachGliese667Ccat24lightyears，itwouldtake97800Earthyears，

ToreachTrapp-1at39。13light-years，itwouldtake159，454Earthyears，

ToHD40307gat42lightyears，itwouldtake171149Earthyears，

Ittakes199，674EarthyearstoreachGris163c，whichis49light-yearsaway，

Ittakes452，325EarthyearstoreachK2-18binLeo，whichis111light-yearsaway，

ToreachKepler438b，whichis470lightyearsaway，itwilltake1915250Earthyears，

ToreachKepler186f，whichis500light-yearsaway，itwilltake2，037，500Earthyears，

Ittakes2，445，000EarthyearstoreachKepler22b，whichis600light-yearsaway，

KOI-4878。01to1075light-years，requires4380624Earth

ToreachKepler62fat1，200light-years，itwouldtake4，890，000Earthyears，

Ittakes5，705，000EarthyearstoreachKepler452b，whichis1，400light-yearsaway，

ToreachKepler69cat2700lightyears，itwilltake11002500Earthyears，

65millionyearsbeforeEarth'sGregorianEra，