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利鼎娱乐:Twelve new moons of Jupiter discovered, with risks of collision

更新时间:2018-9-9 7:00:11    来源:http://www.toolib.cn/    浏览次数:283作者:利鼎娱乐 字号:TT

WASHINGTON,July17--AstronomersfoundadozenofnewmoonsorbitingJupiter,11normaloutermoonsandone"oddball"addingtheplanetstotalnumberofknownmoonsto79,ttheInternationalAstronomicalUnionsMinorPlanetCenterusedtheteamsobservationstocalculateorbitsforthenewlyfoundmoons."IttakesseveralobservationstoconfirmanobjectactuallyorbitsaroundJupiter"Williamssaid."So,thewholeprocesstookayear."AccordingtoCarnegieInstitutionforSciencesnewsreleaseonTuesday,nineofthenewmoonsarepartofadistantouterswarmofmoonsthatorbititintheretrograde,oroppositedirectionofJupiterbitalgroupingsandarethoughttobetheremnantsofthreeonce-largerparentbodiesthatbrokeapartduringcollisionswithasteroids,comets,innergroupofmoonsthatorbitintheprograde,orsamedirectionastheplanetfinclinationsaroundJupiterundJupiter."OurotherdiscoveryisarealoddballandhasanorbitlikenootherknownJovianmoon"saidSheppard."ItsalsolikelyJupiterssmallestknownmoon,beinglessthanonekilometerindiameter."Thenew"oddball"moonismoredistantandmoreinclinedthanthe,thisnewoddballprogrademoonhasanorbitthatcrossestheouterretrogrademoons,head-oncollisionsaremuchmorelikelytooccurbetweenthe"oddball"progradeandtheretrogrademoons,whicharemovinginoppositedirections."Thisisanunstablesituation"saidSheppard."Head-oncollisionswouldquicklybreakapartandgrindtheobjectsdowntodust."Theteamnamedtheoddball"Valetudo"aftertheRomangodJupitersgreat-granddaughter,andsuggestedthatitcouldbethelast-remainingremnantofaonce-largerprograde-orbitingmoonthatfo,onlyonetothreekilometers,iftheserawmaterialshadstillbeenpresentwhenJupitersfirstgenerationofmoonscollidedtoformitscurrentclusteredgroupingsofmoons,thedragexertedbyanyremaininggasanddustonthesmallermoondissipated,theresearcherssaid.。

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