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Waarom het Uranus en Neptunus meer metaan as Jupiter en Saturnus?

Waarom het Uranus en Neptunus meer metaan as Jupiter en Saturnus?


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Die standaardteorie van die sonnevel is dus dat ys en gesteente in die omgewing van die gasplanete kan saamtrek tot planeetdiere, wat dan waterstof en helium kan akkretreer om die gasreuse te vorm. Die reuse-planete is almal meestal waterstof en helium, maar Uranus en Neptunus bevat relatief groot hoeveelhede waterstofverbindings soos metaan (dit is wat hulle kleur gee).

My vraag is: waarom het dit gebeur? Hoe het Uranus en Neptunus hul metaan gekry? My indruk is dat al die gasreuse ver genoeg was om metaan in ys te kondenseer, so hoe het Uranus en Neptunus by voorkeur met metaan beland?


Waarom het Uranus en Neptunus meer metaan as Jupiter en Saturnus?

Dit is 'n kombinasie van toestandsvergelykings (EOS), serpentinisering en vermenging (rotasie en konvektief) wat die voorkeur vir sommige reaksies (en resulterende verbindings) bo ander verkies.

Sien die verwysings hieronder.

Die reuse-planete is almal meestal waterstof en helium, maar Uranus en Neptunus bevat relatief groot hoeveelhede waterstofverbindings soos metaan (dit is wat hulle kleur gee).

Jupiter en Saturnus is gasreuse, Uranus en Neptunus is ysreuse.

My vraag is waarom dit gebeur het? Hoe het Uranus en Neptunus hul metaan gekry? My indruk is dat al die gasreuse ver genoeg was om metaan in ys te kondenseer, so hoe het Uranus en Neptunus by voorkeur met metaan beland?

Sien Wikipedia se "Buiteaardse atmosfeer":

Grafieke van ontsnap snelheid teen oppervlaktemperatuur van sommige voorwerpe van die Sonnestelsel wat wys watter gasse behoue ​​bly. Die voorwerpe word volgens skaal geteken en hul datapunte is by die swart kolletjies in die middel. Die gegewens is gebaseer op "Lesing 5: oorsig van die sonnestelsel, materie in Thermodynamc-ewewig" en "Stargazer se vrae - hoe presies word atmosfeer gehou?".

Wikipedia sê weinig oor die atmosfeer van hierdie planete, en die minste oor Uranus en Neptunus:

  • Atmosfeer van Jupiter:

    "Daar is geen metaanwolke nie, want die temperatuur is te hoog om te kondenseer." - Bron: "Jupiter's ammoniakwolke - gelokaliseerd of alomteenwoordig?" (9 April 2004), deur SK Atreya, AS Wong, KH Baines, M. H. Wong en TC Owen.

    Aanhalings uit die vraestel:

    Bladsy 502: "Vir die produksie van polisikliese aromatiese koolwaterstowwe (PAH's), begin chemie met die vernietiging van metaan (CH $ _4 $) deur UV-sonkragfotone teen $ lambda le $ 160 nm, wat uiteindelik lei tot die vorming van benseen ($ c $ -C $ _6 $ H $ _6 $, oftewel A $ _1 $) en ander komplekse koolwaterstowwe (Fig. 3). In die polêre aurorale gebiede waar energieke deeltjies ook metaan afbreek, word ioonchemie dominant in die produksie van benseen en swaar koolwaterstowwe (Wong et al., 2003, en Fig. 3). ".

  • Atmosfeer van Saturnus:

    "Ultravioletstraling van die son veroorsaak metaanfotolise in die boonste atmosfeer, wat lei tot 'n reeks chemiese koolwaterstofreaksies, met die gevolglike produkte wat afwaarts gedra word deur wervels en diffusie. Hierdie fotochemiese siklus word gemoduleer deur Saturnus se jaarlikse seisoenale siklus.". - Bron: "Etaan-, asetileen- en propaanverspreiding in Saturnus se stratosfeer vanaf waarnemings van Cassini / CIRS-ledemate" (Nov. 2008), deur S. Guerlet, T. Fouchet en B. Bézard.

    Aanhalings uit die vraestel:

    Bladsy 406: "3 Metode

    Ons het 'n lyn-vir-lyn-stralingsoordragmodel gebruik om sintetiese spektra te bereken. Dit het dekking van CH $ _4 $, CH $ _3 $ D, C $ _2 $ H $ _6 $, C $ _2 $ H $ _2 $, C $ _3 $ H $ _8 $, C $ _3 $ H $ _4, C $ _4 $ H $ _2 en botsing-geïnduseerde dekking van H2-He en H2-H2. Die atmosferiese rooster bestaan ​​uit [van] 360 lae van 10 bar tot 10−8 bar. Dit is gekoppel aan 'n iteratiewe inversie-algoritme wat aangepas is van Conrath et al. (1998), om die atmosferiese toestand (temperatuur, koolwaterstof vertikale profiele) uit die gemete spektra te haal.

    Aangesien 'n molekulêre emissie-intensiteit afhang van die hoeveelheid en temperatuur, het ons in twee stappe voortgegaan. Eerstens het ons die vertikale temperatuurprofiel van die metaan ν4-emissieband op 1305 m $ ^ {- 1} $ gehaal (as ons aanvaar dat dit eenvormig gemeng is met 'n vmr van 4,5 x10 $ ^ {- 3} $ (Flasar et al. 2005) ), wat inligting verskaf in die 1 mbar - 2 $ mu $ bar-streek.

    Figuur 1 toon 'n voorbeeld van 'n vergelyking tussen sintetiese en waargenome emissiebande van etaan, asetileen en propaan by twee gegewe drukvlakke (al die verskillende drukvlakke wat deur CIRS ondersoek word, is nie vir die duidelikheid geteken nie) en Fig. 3 die ooreenstemmende herwin profiele.

Wat dit beteken, is dat meer ingewikkelde verbindings as metaan deur die voorwaardes bevoordeel word.

  • Atmosfeer van Uranus en Neptunus:

    "Die gasvormige buitenste lae van die ysreuse het verskillende ooreenkomste met dié van die gasreuse. Dit sluit langlewende, hoëspoed-ekwatoriale winde in, polêre draaikolke, grootskaalse sirkulasiepatrone en komplekse chemiese prosesse wat deur ultravioletstraling van bo af aangedryf word. en meng met die onderste atmosfeer.

    Die bestudering van die atmosfeerpatroon van die ysreuse gee ook insig in die atmosferiese fisika. Hul samestellings bevorder verskillende chemiese prosesse en hulle kry baie minder sonlig in hul verre wentelbane as enige ander planete in die Sonnestelsel (wat die relevansie van interne verhitting op weerpatrone verhoog). "

NASA Factsheets - Atmosferiese samestelling (volgens volume, onsekerheid tussen hakies):

  • Jupiter

    • Hoofvak: Molekulêre waterstof (H $ _2 $) - 89,8% (2,0%); Helium (He) - 10,2% (2,0%)

    • Gering (dpm): Metaan (CH $ _4 $) - 3000 (1000); Ammoniak (NH $ _3 $) - 260 (40); Waterstofdeuteride (HD) - 28 (10); Etaan (C $ _2 $ H $ _6 $) - 5,8 (1,5); Water (H $ _2 $ O) - 4 (wissel met druk)

    • Aërosols: Ammoniakys, waterys, ammoniakhidrosulfied

  • Saturnus

    • Hoofvak: Molekulêre waterstof (H $ _2 $) - 96,3% (2,4%); Helium (He) - 3,25% (2,4%)

    • Gering (dpm): metaan (CH $ _4 $) - 4500 (2000); Ammoniak (NH $ _3 $) - 125 (75); Waterstofdeuteride (HD) - 110 (58); Etaan (C $ _2 $ H $ _6 $) - 7 (1,5)

    • Aërosols: Ammoniakys, waterys, ammoniakhidrosulfied

  • Uranus

    • Hoofvak: Molekulêre waterstof (H $ _2 $) - 82,5% (3,3%); Helium (He) - 15,2% (3,3%) Metaan (CH $ _4 $) - 2,3%

    • Gering (dpm): Waterstofdeuteride (HD) - 148

    • Aërosols: Ammoniakys, waterys, ammoniakhidrosulfied, metaanys (?)

  • Neptunus

    • Hoofvak: Molekulêre waterstof (H $ _2 $) - 80,0% (3,2%); Helium (He) - 19,0% (3,2%); Metaan (CH $ _4 $) 1,5% (0,5%)

    • Gering (dpm): Waterstofdeuteride (HD) - 192; Etaan (C $ _2 $ H $ _6 $) - 1.5

    • Aërosols: Ammoniakys, waterys, ammoniakhidrosulfied, metaanys (?)

Bykomende verwysings:

"Metaan in die sonnestelsel" in Engels, (Bol. Soc. Geol. Mex [aanlyn]. 2015, vol.67, n.3, pp.377-385.), Deur Andrés Guzmán-Marmolejo en Antígona Segura.

"Abiotiese produksie van metaan in aardse planete" (Astrobiologie. 2013 Jun; 13 (6): 550-559), deur Andrés Guzmán-Marmolejo, Antígona Segura en Elva Escobar-Briones.

"Metaan-klatrate in die sonnestelsel" (Astrobiology. 2015 Apr; 15 (4): 308-26), deur Mousis O, Chassefière E, Holm NG, Bouquet A, Waite JH, et al.

NASA - "Scientists Model a Cornucopia of Earth-sized Planets" (24 September 2007).


Wat het Saturnus Jupiter Uranus en Neptunus rondom hulle?

Die Joviese planete is ook kenmerkend omdat hulle baie mane het. Saturnus en Jupiter elkeen het meer as 60 mane, Uranus het meer as 20, en Neptunus het meer as 10. Die planete ook het hewige winde en storms, en 'n vinnige rotasie. In vergelyking met die aarde is die Joviese planete enorm.

Vervolgens is die vraag, watter planeet het 'n soliede oppervlak Venus Jupiter Saturnus Uranus Neptunus? Oorspronklik beantwoord: Is Jupiter, Saturnus, Uranus en Neptunus het 'n soliede oppervlak? Nee, absoluut nie. Bogenoemde planete het 'n alternatiewe naam gasreuse, wat verwys na planete geheel en al van gasse gemaak. Hierdie groot planeet het groot swaartekrag as gevolg van groot massa met minder digtheid.

Buitendien, waarom het Jupiter Saturnus Uranus en Neptunus almal ringe?

Showalter (SETI Instituut). Jupiter se ringe bestaan ​​uit baie klein stofdeeltjies, en die struktuur daarvan hang af van Jupiter s’n magnetiese velde. Neptunus het donker ringe gemaak van metaan- en ammoniakys. Uranus' ringe word oorheers deur dik rotse en kan hoofsaaklik uit rots bestaan.

Is dit waar dat Saturnus die enigste planeet is met ringe van rots en ys rondom?

Saturnus is 'n snaakse voorkoms planeet. Waar, dit is nie die enigste planeet met ringe. Jupiter, Uranus en Neptunus het ringe, ook. Maar Saturnus se ringe is die grootste en helderste.


Sterrekunde Hoofstuk 8 Oefenvrae

Watter van die volgende is nie 'n algemene kenmerk van die vier joviese planete in ons sonnestelsel nie?

Die gemiddelde digtheid is hoër as die aardplanete.

Watter van die volgende beskryf die interne gelaagdheid van Jupiter, vanaf die middel na buite, die beste?

Kern van gesteente, metaal en waterstofverbindings, dik laag metaalwaterstoflaag van vloeibare waterstoflaag, gasvormige waterstofwolklaag

Watter van die volgende stellings wat die Joviese interieur vergelyk, word nie as waar beskou nie?

Hulle het almal dieselfde presiese stel interne lae, alhoewel hierdie lae in grootte verskil.

Oor die algemeen lyk die samestelling van Jupiter en die meeste soos _________.

Jupiter se kleure kom gedeeltelik uit sy drie lae wolke. Watter van die volgende is nie die primêre bestanddeel van een van die wolklae van Jupiter nie?

Hoe vergelyk tipiese windspoed in die atmosfeer van Jupiter met tipiese windspoed op aarde?

Dit is baie vinniger as orkaanwinde op die aarde.

Wat is die Groot Rooi Vlek?

'n langlewende, hoëdrukstorm op Jupiter

Watter atmosferiese bestanddeel is verantwoordelik vir die blou kleur van Uranus en Neptunus?

Hoe vergelyk die sterkte van Jupiter se magneetveld met dié van die Aarde se magneetveld?

Jupiter se magneetveld is ongeveer 20 000 keer so sterk soos die aarde.

Watter van die volgende stellings oor die mane van die Joviese planete is nie waar nie?

Die meeste mane is groot genoeg om bolvormig te wees, maar 'n paar het die meer aartappelagtige vorms van asteroïdes.

Watter stelling oor Io is waar?

Dit is die vulkanies aktiefste liggaam in ons sonnestelsel.

Watter maan het 'n dik atmosfeer wat meestal uit stikstof bestaan?

Die Huygens-sonde het talle foto's geneem toe dit afdaal na die oppervlak van Titan in 2005. Wat het die foto's getoon?

kenmerke of erosie, insluitend droë riviervalleie en meerbekke

Watter maan word beskou as 'n diep, ondergrondse oseaan van vloeibare water?

Watter groot Joviaanse maan is vermoedelik in sy huidige baan gevang?

Gestel jy kan net 'n paar meter bo Saturnus se ringe in die ruimte dryf. Wat sou jy sien as jy neerkyk op die ringe?

ontelbare ysige deeltjies, wat wissel van stofkorrels tot groot rotse

Watter stelling oor planetêre ringe is nie waar nie?

Saturnus se ringe is 4,6 miljard jaar gelede saam met sy mane gevorm.

Watter van die volgende gasse is nie 'n belangrike bestanddeel van die Joviese planeetatmosfeer nie?

Jupiter en die ander Joviese planete word soms & quotgas-reuse genoem. & Quot In watter sin is hierdie term misleidend?

Hulle bevat eintlik relatief min materiaal in 'n gasvormige toestand.

Wat sou met Jupiter gebeur as ons die massa op een of ander manier kon verdubbel?

Die digtheid daarvan sal toeneem, maar die deursnee daarvan sal skaars verander.

Waarom het Uranus en Neptunus volgens ons teorie van die vorming van sonnestelsels baie minder groot geword as Jupiter en Saturnus?

Deeltjies in die sonnevel was meer verspreid op groter afstande, sodat die aanwas langer geneem het en daar minder tyd was om gas in te trek voordat die sonwind die newel skoongemaak het.

Waarom het Jupiter drie verskillende wolklae?

Die drie lae stel wolke voor van gasse wat by verskillende temperature kondenseer.

Watter van die volgende is die beste redes waarom ons horisontale & quotstrips & quot sien op foto's van Jupiter en Saturnus?

Die ligte strepe is streke met hoë wolke, en die donker strepe is streke waar ons kan sien tot dieper, donker wolke.

Uranus en Neptunus het metaanwolke, maar Jupiter en Saturnus nie. Watter faktor verklaar waarom?

Die temperatuur op Jupiter en Saturnus is te hoog vir metaan om te kondenseer.

Watter Joviese planeet moet die mees ekstreme seisoenale veranderinge hê?

Waarom is die bestraling so intens in die streek wat die baan van Jupiter (die Io torus) opspoor?

Die streek is vol gasse wat geïoniseer word nadat dit uit vulkane op Io vrygestel word.

Watter van die volgende verklaar die beste redes waarom baie Joviese mane meer geologies aktief was as die Maan of Mercurius?

Joviese mane bestaan ​​meestal uit ys wat kan smelt of vervorm by laer temperature as die rots en metaal waaruit die maan en kwik bestaan.

Al die volgende stellings is waar. Watter een is die belangrikste om die geweldige getyverhitting op Io te verklaar?

Io wentel om Jupiter op 'n elliptiese baan as gevolg van baanresonansies met ander satelliete.

Watter van die volgende is nie 'n bewys wat ondersteun die idee dat Europa 'n oseaan in die oppervlak kan hê nie?

Sterrekundiges het klein mere vloeibare water op die oppervlak van Europa opgespoor.

Watter van die volgende is waarskynlik nie op Titan te vinde nie?

mere vloeibare water in die warmer ekwatoriale streke

Waarom glo sterrekundiges dat Triton 'n gevange maan is?

Triton wentel om Neptunus in 'n teenoorgestelde rigting van die rotasie van Neptunus.

Watter stelling oor Saturnus se ringe is nie waar nie?

Die ringe moet vandag baie dieselfde lyk as kort nadat Saturnus gevorm het.

Volgens die huidige begrip, watter van die volgende is nodig om 'n planeet ringe te hê?

Die planeet moet baie klein mane hê wat in sy ekwatoriale vlak relatief naby die planeet wentel.


Waarom Neptunus en Uranus verskil

Uranus (links) en Neptunus (regs). Alhoewel die twee ysreusplanete ooreenkomste het, het hulle ook beduidende verskille, wat verklaar kan word deur die impak van ander groot liggame in die vroeë sonnestelsel. Beeld via NASA / JPL / PlanetS.

Ons is geneig om Uranus en Neptunus in ons gedagtes saam te smelt, amper asof hulle 'n tweelingwêreld is. Hulle is byna ewe groot en is groter as die aarde, maar kleiner as Jupiter of Saturnus en albei is blou of blougroen, met diep atmosfeer en ysige interieurs. Alhoewel Uranus en Neptunus oppervlakkig soortgelyk is, verskil hulle regtig. Hulle & # 8217; re meer anders as wat die meeste mense dink. En alhoewel hul verskille nog nie volledig uiteengesit is nie, blyk dit dat magtige botsings met sorgsame planeetgrootte liggame & # 8211 vroeg in die geskiedenis van die sonnestelsel & # 8211 die sleutel kan wees.

Navorsers van die National Centre of Competence in Research PlanetS (PlanetS) aan die Universiteit van Zürich in Switserland het rekenaarsimulasies uitgevoer om die rol van botsings in die vorming van die verskille tussen Uranus en Neptunus te ondersoek. Die bevindinge is op 4 Februarie 2020 deur PlanetS aangekondig, met die gepaardgaande navorsingsartikel wat eers op 22 November 2019 gepubliseer is.

Uranus en Neptunus is die twee belangrikste planete in ons sonnestelsel. Albei word nou as ysreuse beskou. Albei verskil fundamenteel van die groter gasreuse Jupiter en Saturnus, en van kleiner rotsagtige wêrelde soos die Aarde. Uranus en Neptunus het soortgelyke massas en interne komposisies. Die buitenste atmosfeer is saamgestel uit waterstof, helium en metaan, terwyl hul mantels 'n kombinasie is van water-, ammoniak- en metaanys, en hul kern is 'n mengsel van rots en ys.

Uranus het 'n skitterende voorkoms as Neptunus en is meestal wolkloos. Die atmosfeer van die Neptunus het donkerder bande as die van Uranus, met strepe en wit wolke, sowel as 'n groot & # 8220donker plek. & # 8221

Maar daar is ook meer beduidende verskille tussen die twee wêrelde, en die navorsers wou weet waarom. Volgens 'n verklaring deur Christian Reinhardt, een van die PlanetS-lede:

& # 8230 is daar ook opvallende verskille tussen die twee planete wat verduideliking benodig.

Diagram wat die vorming van beide Uranus en Neptunus voorstel, en hoe dit anders ontwikkel het as gevolg van impak van ander groot voorwerpe in die vroeë sonnestelsel. Beeld via Reinhardt & amp Helled / ICS / Universiteit van Zürich / PlanetS.

'N Ander spanlid, Joachim Stadel, het daarop gewys dat, in teenstelling met Neptunus en die Aarde en die meeste ander groot planete in ons sonnestelsel, Uranus nie om 'n as draai wat byna loodreg lê ten opsigte van die vlak van sy baan nie. In plaas daarvan:

& # 8230 Uranus en sy belangrikste satelliete is ongeveer 97 grade in die sonvlak gekantel, en die planeet draai effektief retrograde ten opsigte van die son.

Nog 'n belangrike verskil is dat die groter mane van Uranus in stabiele wentelbane is wat in lyn is met die kanteling van die planeet. Maar die grootste maan van Neptunus, Triton, omring die planeet op 'n baie skuins baan.

Hierdie verskille dui daarop dat Uranus en # mane gevorm is uit dieselfde skyf stof en gas wat die planeet self gedoen het, terwyl Triton waarskynlik eens 'n aparte voorwerp was wat deur die swaartekrag van Neptunus gevang is.

Volgens die navorsers dui hierdie en ander verskille op verskillende soorte impakte wat die twee planete lank gelede beïnvloed het.

Grootte vergelyking van Aarde en Neptunus. Volgens die nuwe studie het voorwerpe met ongeveer 1 tot 3 aardmassas met Uranus en Neptunus gebots nadat dit gevorm het. Uranus is pas bewei, terwyl Neptunus 'n tromp-opslag gehad het. Beeld via NASA / Sky & amp Telescope.

Die navorsers het rekenaarsimulasies uitgevoer om 'n reeks verskillende moontlike botsings op albei planete te ondersoek. Uit die vraestel:

Ondanks baie ooreenkomste, is daar beduidende verskille waargeneem tussen Uranus en Neptunus: hoewel Uranus gekantel is en 'n gereelde stel satelliete het, wat daarop dui dat hulle vanaf 'n skyf toegeneem het, is Neptunus se mane onreëlmatig en is gevangene. Daarbenewens lyk dit of Neptunus 'n interne hittebron het, terwyl Uranus in ewewig is met son-isolasie. Laastens, struktuurmodelle wat gebaseer is op gravitasiedata, dui daarop dat Uranus meer sentraal is as Neptunus. Ons voer 'n groot reeks SPH-simulasies met 'n hoë resolusie uit om te ondersoek of hierdie verskille deur reuse-impakte verklaar kan word.

Vir Uranus vind ons dat 'n skuins impak sy draai-as kan kantel en genoeg materiaal kan uitwerp om 'n skyf te skep waar die gewone satelliete gevorm word. Sommige van die skywe is massief en verleng genoeg, en bestaan ​​uit genoeg rotsagtige materiaal om die vorming van Uranus se gereelde satelliete te verklaar.

Vir Neptunus ondersoek ons ​​of 'n frontale botsing die binneland kan vermeng & # 8230 Ons vind dat massiewe en digte projektiele na die middelpunt kan binnedring en massa en energie in die diep binneste kan neersit, wat lei tot 'n minder sentraal gekonsentreerde binneland vir Neptunus.

Ons kom tot die gevolgtrekking dat die tweedeling tussen die ysreuse verklaar kan word deur gewelddadige gevolge na die vorming daarvan.

Soos 'n ander spanlid, Alice Chau, opgemerk het:

Daar word dikwels aanvaar dat albei planete op 'n soortgelyke manier gevorm het.

Maar hierdie resultate toon dat hul formasies, of ten minste hul baie vroeë geskiedenis, nie so gelyk het aan die eerste keer nie.

Neptunus en sy grootste maan, Triton, waarvan die baan baie geneig is. Triton se baan dui daarop dat dit deur Neptunus se swaartekrag gevang is. Intussen het die mane van Uranus waarskynlik in dieselfde skyf gas en stof gevorm wat Uranus gedoen het. Beeld via NASA / JPL / USGS / Astronomy.

In een scenario, waar Uranus en Neptunus meer ooreenstem, is gevind dat 'n impak met 'n liggaam van een tot drie aardmassas die verskille wat ons vandag sien, kan verklaar. As die voorwerp net Uranus bewei in plaas van 'n frontale botsing, sou die planeet en die binnekant nie geraak word nie, maar die impak sou steeds genoeg wees om die planeet te kantel.

Omgekeerd, as Neptunus 'n frontale impak gehad het, sou die botsing die binnekant van die planeet beïnvloed het, maar nie 'n skyf van rommel vorm nie. Dit sou verklaar waarom Neptunus geen groot mane in gereelde wentelbane het nie. 'N Groot hittevloei op Neptunus wys ook daarop dat die binnekant in 'n massiewe botsing gemeng word.

Die simulasies wys hoe die twee planete waarskynlik baie meer ooreenstem, maar die verskillende soorte botsings het hulle aansienlik verander. Soos Ravit Helled gesê het:

Ons toon duidelik dat 'n aanvanklik soortgelyke vormingsweg as Uranus en Neptunus kan lei tot die tweedeling wat waargeneem word in die eienskappe van hierdie boeiende buitenste planete.

Vergelyking van die binnestrukture van die twee gasreuse, Jupiter en Saturnus, en die 2 ysreuse, Uranus en Neptunus. Aarde is volgens skaal. Beeld via NASA / Lunar and Planetary Institute.

Die resultate van hierdie studie toon aan hoe ewekansige gebeure soos planetêre botsings met ander groot liggame in die vroeë sonnestelsel die toekomstige evolusie van 'n planeet beslis kan beïnvloed. Uranus en Neptunus is die wêrelde wat ons vandag sien as gevolg van sulke gebeure, lui hierdie studie. Wat as geen planeet getref is nie? Wat as Neptunus net bewei is in plaas van Uranus? Hoe sou hierdie ysreuse vandag in sulke omstandighede wees? Ons weet nie, maar om meer te weet oor hoe hulle kon gewees het beïnvloed, sal wetenskaplikes help om die vorming van hierdie soort planete, sowel as die gasreuse soos Jupiter en Saturnus, en rotsagtige wêrelde soos Aarde, Mars, Venus en Mercurius beter te verstaan.

Met 'n beter begrip van hoe die planete in ons eie sonnestelsel gevorm en ontwikkel het, kan ons die kennis ook toepas op die bestudering van wêrelde in verre sonnestelsels.

Kortom: 'n Nuwe studie deur navorsers van PlanetS werp lig op waarom Uranus en Neptunus op sommige maniere soortgelyk is, maar in ander radikaal verskil. Dit blyk dat botsings & # 8211 vroeg in die geskiedenis van die sonnestelsel & # 8211 die sleutel is.


Waarom het Uranus en Neptunus meer metaan as Jupiter en Saturnus? - Sterrekunde

Uranus is die sewende planeet vanaf die son. Dit het die derde grootste planetêre radius en die vierde grootste planetêre massa in die Sonnestelsel. Uranus is soortgelyk aan Neptunus, en albei het 'n ander chemiese samestelling as die groter gasreuse Jupiter en Saturnus. Om hierdie rede klassifiseer wetenskaplikes Uranus en Neptunus dikwels as 'ysreuse' om hulle van die gasreuse te onderskei. Uranus se atmosfeer is soortgelyk aan Jupiter en Saturnus in sy primêre samestelling van waterstof en helium, maar dit bevat meer "ys" soos water, ammoniak en metaan, tesame met spore van ander koolwaterstowwe. Dit is die koudste planeetatmosfeer in die sonnestelsel, met 'n minimum temperatuur van 49 K (224 C 371 F), en het 'n komplekse, gelaagde wolkestruktuur met water wat die laagste wolke vorm en methaan die hoogste wolklaag. Die binnekant van Uranus bestaan ​​hoofsaaklik uit ys en rots.

Uranus is die enigste planeet waarvan die naam afgelei is van 'n figuur uit die Griekse mitologie, uit die gelatiniseerde weergawe van die Griekse god van die hemel Ouranos. Soos die ander reuse-planete het Uranus 'n ringstelsel, 'n magnetosfeer en talle mane. Die Uraniese stelsel het 'n unieke konfigurasie onder die planete, omdat die rotasie-as sywaarts gekantel is tot by die vlak van sy sonbaan. Sy noord- en suidpool lê dus waar die meeste ander planete hul ewenaars het. In 1986 het beelde van Voyager 2 Uranus getoon as 'n byna kenmerkende planeet in sigbare lig, sonder die wolkbande of storms wat verband hou met die ander reuse-planete. Waarnemings vanaf die aarde het seisoenale veranderinge en verhoogde weeraktiwiteit getoon namate Uranus sy ewening in 2007 nader. Windsnelhede kan 250 meter per sekonde (900 km / h 560 mph) bereik.

Uranus wentel een keer in die 84 jaar om die Son. Die gemiddelde afstand vanaf die son is ongeveer 20 AU (3 miljard km 2 miljard myl). Die verskil tussen die minimum en maksimum afstand vanaf die son is 1,8 AE, groter as dié van enige ander planeet, hoewel nie so groot soos die van die dwergplaneet Pluto nie. Die intensiteit van sonlig wissel omgekeerd met die vierkant van die afstand, en so is Uranus (ongeveer 20 keer die afstand van die son af in vergelyking met die aarde) ongeveer 1/400 die intensiteit van die lig op die aarde. Uranus is 17 uur, 14 minute. Soos op al die reuseplanete, ervaar die boonste atmosfeer sterk winde in die rigting van rotasie. Op sommige breedtegrade, soos ongeveer 60 grade suid, beweeg die sigbare kenmerke van die atmosfeer baie vinniger, wat binne 14 uur 'n volle draai maak.

Uranus word gekenmerk deur die feit dat dit aan sy sy kantel met 'n rotasie-as wat 98 grade na die baan neig.

Die ongewone posisie daarvan word vermoedelik die gevolg van 'n botsing met 'n planeetgrootte liggaam vroeg in die geskiedenis van die sonnestelsel (let ook op dat die mane bewys lewer van 'n gewelddadige gebeurtenis in die verlede).

Let op dat hierdie ongewone aksiale kantel lei tot 'n eienaardige seisoenale en dagbeweging, gesien vanaf die 'oppervlak'. Byvoorbeeld, gedurende die somer op die noordelike halfrond sou 'n waarnemer sien hoe die son elke 17 uur sirkels in die lug maak. Namate die somer afneem, sal die son geleidelik suidwaarts beweeg. Uiteindelik sou die son opkom en 21 jaar na die somer-sonstilstand op die herfs-ewening van gelyke dag en nag sak. Dan sou die nagte langer word totdat die son eendag nie sou opgaan nie en 'n lang 21 jaar nag sou begin.

Aangesien Uranus meer as 19 AE van die son af lê, ontvang dit 360 keer minder lig en hitte van die son as die aarde. As gevolg hiervan is sy atmosfeer buitengewoon koud, met 'n temperatuur van ongeveer -214C op die druk van 1 bar (gelykstaande aan die gemiddelde lugdruk op seespieël op aarde).

Die atmosfeer van Uranus bestaan ​​uit 83% waterstof, 15% helium, 2% metaan en klein hoeveelhede asetileen en ander koolwaterstowwe. Metaan in die boonste atmosfeer absorbeer rooi lig en gee Uranus sy blou-groen kleur. In die innerlike Joviese wêrelde (Jupiter en Saturnus) oorheers ammoniumhidrosulfied die kleur van atmosfeer met sy rooi en geel. Maar as die temperatuur onder 70 K daal, vries ammoniakgas in yskristalle en val uit die atmosfeer. Metaan word meer oorheersend en omdat dit 'n blou gas is, gaan die buitenste Joviese wêrelde (Uranus en Neptunus) van blougroen tot diepblou in hul kleur. Let ook op dat metaan, CH 4 is 'n kweekhuisgas.

Die atmosfeer van Uranus is gerangskik in wolke wat op konstante breedtegrade loop, soortgelyk aan die oriëntasie van die meer lewendige breedtebande wat op Jupiter en Saturnus gesien word, hoewel hierdie wolke slegs in die infrarooi sigbaar is. Winde op die middelbreedte op Uranus beweeg in die rigting van die rotasie van die planeet. Hierdie winde waai teen snelhede tussen 90 en 360 myl per uur.

Uranus het nie 'n interne energiebron soos Jupiter en Saturnus nie, en daarom is sy atmosfeer se energiestelsel baie minder aktief, wat minder funksies tot gevolg het (dws storms, wervels, ens.). Wolkpatrone word slegs op die warmer, laer vlakke diep onder die atmosferiese waas gesien. Daarbenewens produseer die gekantelde as van Uranus ongelyke opwarming in die twee halfrond wat langtermyn-Noord-Suid-strome oor die breedtegraad sone lewer. Die kombinasie van hierdie effekte beteken dat die atmosfeer soos Saturnus uitgewas word.

Uranus interne struktuur:

Die standaardmodel van Uranus se struktuur is dat dit uit drie lae bestaan: 'n rotsagtige (silikaat / yster nikkel) kern in die middel, 'n ysige mantel in die middel en 'n buitenste gasvormige waterstof / heliumomhulsel. Die kern is relatief klein, met 'n massa van slegs 0,55 Aardmassas en 'n radius van minder as 20% van Uranus. Die mantel bestaan ​​uit sy grootste deel, met ongeveer 13,4 Aardmassas, en die boonste atmosfeer is relatief onbeduidend, met 'n gewig van ongeveer 0,5 Aardmassas en strek vir die laaste 20% van Uranus se radius. Uranus se kerndigtheid is ongeveer 9 g / cm3, met 'n druk in die middel van 8 miljoen bar (800 GPa) en 'n temperatuur van ongeveer 5000 K. Die ysmantel bestaan ​​nie uit ys in die konvensionele sin nie, maar uit 'n warm en digte vloeistof wat bestaan ​​uit water, ammoniak en ander vlugtige bestanddele. Hierdie vloeistof, wat 'n hoë elektriese geleidingsvermoë het, word soms 'n water-ammoniak oseaan genoem.

Die uiterste druk en temperatuur diep binne Uranus kan die metaanmolekules opbreek, met die koolstofatome wat kondenseer tot diamantkristalle wat soos haelkorrels deur die mantel reën. Baie hoëdruk-eksperimente by die Lawrence Livermore Nasionale Laboratorium dui daarop dat die basis van die mantel 'n oseaan van vloeibare diamant met drywende soliede 'diamantberge' kan bevat.

Die grootste samestelling van Uranus en Neptunus verskil van dié van Jupiter en Saturnus, met ys wat oor gasse heers, wat hul afsonderlike klassifikasie as ysreuse regverdig. Daar kan 'n laag ioniese water wees waar die watermolekules afbreek in 'n sop van waterstof- en suurstofione, en dieper van onder superioniese water waarin die suurstof kristalliseer, maar die waterstofione vrylik binne die suurstofrooster beweeg.

Alhoewel die bogenoemde model redelik standaard is, is dit nie uniek nie, maar ander modelle voldoen ook aan waarnemings. As daar byvoorbeeld groot hoeveelhede waterstof en rotsagtige materiaal in die ysmantel gemeng word, sal die totale massa ys in die binneland laer wees en die totale massa gesteentes en waterstof dienooreenkomstig hoër wees. Tans beskikbare data laat nie wetenskaplike vasstelling toe watter model korrek is nie. Die vloeibare binnestruktuur van Uranus beteken dat dit geen vaste oppervlak het nie. Die gasagtige atmosfeer gaan geleidelik oor in die interne vloeistoflae. Gerieflikheidshalwe word 'n draaiende oblate-sferoïde-stel op die punt waarop atmosferiese druk gelyk is aan 1 bar (100 kPa) voorwaardelik as 'n 'oppervlak' aangedui. Dit het ekwatoriale en poolstrale van onderskeidelik 25.559 km (15.881,6 mi) en 24.973 km (15.518 mi).

Uranus se interne hitte lyk in astronomiese opsig aansienlik laer as dié van die ander reuseplanete, dit het 'n lae termiese vloed. Waarom Uranus se interne temperatuur so laag is, word nog steeds nie verstaan ​​nie. Neptunus, wat die grootste tweeling van Uranus in grootte en samestelling is, straal 2,61 keer soveel energie in die ruimte uit as wat dit van die son af ontvang, maar Uranus straal amper geen oortollige hitte uit nie. Die totale krag wat Uranus in die verre infrarooi (dws hitte) deel van die spektrum uitstraal, is 1.060 keer die sonenergie wat in sy atmosfeer opgeneem word. Uranus se hittevloei is slegs 0,042 W / m2, wat laer is as die interne hittevloei van die Aarde van ongeveer 0,075 W / m2. Die laagste temperatuur wat in Uranus se tropopouse aangeteken is, is 49 K (224,2 C 371,5 F), wat Uranus die koudste planeet in die sonnestelsel maak.

Een van die hipoteses vir hierdie teenstrydigheid dui daarop dat wanneer Uranus deur 'n supermassiewe impak getref is, wat veroorsaak het dat dit die grootste deel van sy oormatige hitte verdryf het, dit met 'n uitgedunde kerntemperatuur gelaat is. Nog 'n hipotese is dat daar 'n vorm van versperring in Uranus se boonste lae bestaan ​​wat voorkom dat die kern se hitte die oppervlak bereik. For example, convection may take place in a set of compositionally different layers, which may inhibit the upward heat transport perhaps double diffusive convection is a limiting factor.

Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. It has an equatorial radius of 24,900 kilometers (about 1.4 Earth radii). If Neptune were hollow, it could contain nearly 60 Earths. It has a mean density of 1.7 gm/cc. Neptune orbits the Sun once every 164.8 years at an average distance of 30.1 astronomical units. It is named after the Roman god of the sea and has the astronomical symbol , a stylised version of the god Neptune's trident.

Neptune's composition can be compared and contrasted with the Solar System's other giant planets. Like Jupiter and Saturn, Neptune's atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, but it contains a higher proportion of "ices" such as water, ammonia, and methane. However, its interior, like that of Uranus, is primarily composed of ices and rock, which is why Uranus and Neptune are normally considered "ice giants" to emphasise this distinction. Traces of methane in the outermost regions in part account for the planet's blue appearance.

In contrast to the hazy, relatively featureless atmosphere of Uranus, Neptune's atmosphere has active and visible weather patterns. For example, at the time of the Voyager 2 flyby in 1989, the planet's southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter. These weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 kilometres per hour (580 m/s 1,300 mph). Because of its great distance from the Sun, Neptune's outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching 55 K (218 C). Temperatures at the planet's centre are approximately 5,400 K (5,100 C). Neptune has a faint and fragmented ring system (labelled "arcs"), which was first detected during the 1960s and confirmed by Voyager 2.

Neptune has eight moons, six of which were found by Voyager. A day on Neptune is 16 hours and 6.7 minutes long. Neptune was discovered on September 23, 1846 by Johann Gottfried Galle, of the Berlin Observatory, and Louis d'Arrest, an astronomy student, through mathematical predictions made by Urbain Jean Joseph Le Verrier.

At high altitudes, Neptune's atmosphere is 80% hydrogen and 19% helium. A trace amount of methane is also present. Prominent absorption bands of methane exist at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue, although Neptune's vivid azure differs from Uranus's milder cyan. Because Neptune's atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune's color.

Unlike Uranus with its lack of atmospheric features, Neptune is a dynamic planet with several large, dark spots reminiscent of Jupiter's hurricane-like storms. The largest spot, known as the Great Dark Spot, is about the size of the earth and is similar to the Great Red Spot on Jupiter.

Other dark spots display cyclone-like structure in their centers.

Just like the storms on Jupiter, the dark spots on Neptune ``tumble'' along the zones absorbing smaller storms to power themselves. The most surprising thing about these storms is that, unlike Jupiter, they are short-lived. Recent HST images do not show the Great Dark Spot.

Long bright clouds, similar to cirrus clouds on Earth, were seen high in Neptune's atmosphere. At low northern latitudes, Voyager captured images of cloud streaks casting their shadows on cloud decks below.

The strongest winds on any planet were measured on Neptune. Most of the winds there blow westward, opposite to the rotation of the planet. Near the Great Dark Spot, winds blow up to 1,200 miles an hour.

Neptune emits 2.7 times more energy than it receives from the Sun. This access energy powers the atmosphere to produce the storms that are not seen on its twin planet Uranus. The source of internal energy cannot be due solely to leftover energy from formation (i.e. Jupiter) since Neptune is smaller and would have radiated away the energy long ago. Nor is it due to an unusual chemical change, such as the helium rain for Saturn. Rather, it appears that Neptune is more efficient at trapping leftover formation heat due to the fact that methane is highly abundant in Neptune's atmosphere, and methane is an excellent insulator of heat (i.e. the greenhouse effect). Neptune has a sub-zero type greenhouse effect that is trapping formation heat that should have been radiated billions of years ago like Uranus.

The interiors of Uranus and Neptune are almost identical, due to the fact they are similar in mass and size. Both have rocky cores like Jupiter and Saturn. But at that point the similarity ends. The pressures are never sufficient to convert molecular hydrogen to metallic hydrogen in the interiors of Uranus and Neptune. Instead, a large mantle of icy water and ammonia forms about 20,000 km below the surface.

Uranus/Neptune magnetic field:

The magnetic fields for both Uranus and Neptune are unusual and are not well understood at this time. As the diagram below shows, the magnetic fields of the strongest three worlds, Jupiter, Saturn and the Earth, are all roughly aligned with the rotational axis of the planets. The generation of these magnetic fields occurs in liquid mantles around solid cores (liquid rock for the Earth, metallic hydrogen for Jupiter and Saturn).

Uranus and Neptune, on the other hand, have radically different magnetic fields. Not only are they not aligned with the rotational axis of the planet, but neither are they located at the center of the planet either. The magnetic fields are probably be generated by local events in the icy mantles of both planets and may be unstable.

The best theory for the origin of these magnetic fields involves the high concentration of ammonia, NH 3 in the planet's interiors. Ammonia, in solution, is high electrically conductive. This is due to a high amount of free ions (atoms missing electrons so that they have net positive charge). These free ions could form a conducting ionic layer in the mantle which would then produce a magnetic field with Uranus and Neptune's high rotation rates.


Uranus' Satellites

  • Unlike the other bodies in the solar system which have names from classical mythology, Uranus' moons take their names from the writings of Shakespeare and Pope.
  • They form three distinct classes: the 11 small very dark inner ones discovered by Voyager 2, the 5 large ones (right), and the newly discovered much more distant ones.
  • Most have nearly circular orbits in the plane of Uranus' equator (and hence at a large angle to the plane of the ecliptic) the outer 4 are much more elliptical.

Why do Uranus and Neptune appear blue quizlet?

Most of the mass of each planet is made up of heavier gases, such as methane, ammonia, and water. As gevolg daarvan, Uranus and Neptune are more dense than Jupiter. Uranus looks blue-green, and Neptune appears deep blue. The color comes from methane gas, which absorbs certain colors of light.

Similarly, what atmospheric constituent is responsible for the blue color of Uranus and Neptune? methane

Beside this, why is Neptune blue?

Neptune's atmosphere is made up of hydrogen, helium and methane. The methane in Neptune's upper atmosphere absorbs the red light from the sun but reflects the blue light from the Sun back into space. Dit is why Neptune appears blue.

Why Uranus and Neptune do not contain liquid metallic hydrogen?

the axis is nearly parallel to the plane of its orbit. Uranus and Neptune do not contain liquid metallic hydrogen because they a. are not massive enough. are not rich enough in hydrogen.


Other Ring Worlds

Jupiter&rsquos rings are made of very small dust particles, and their structure is dependent on Jupiter&rsquos magnetic fields. Neptune has dark rings made of methane and ammonia ice. Uranus&rsquo rings are dominated by chunky boulders and may consist primarily of rock.

Webb will observe how the rings change around their planets, and look for small moons, new rings, and other material around the giant planets. Webb will watch as the planets move in front of stars and observe how the rings block starlight. This will show whether the rings are dense or porous, and how their structures change over time. Most importantly, Webb will conduct spectroscopic observations of the rings, examining the light they emit for clues to their chemical composition. Spectroscopy will also tell astronomers the age of the ice in the rings. These clues will assist astronomers in determining whether the rings&rsquo origins are planetary moons that broke up, or objects from the distant Kuiper Belt that were drawn to the planet by gravity and then torn apart. Gaps in our understanding of Solar System evolution will be filled in.

Finally, Webb will look at some puzzling features of rings that astronomers are still working to understand. The spoke-like structures that appear in Saturn&rsquos rings and have rarely been observed by Cassini or the Hubble Space Telescope. Around Neptune, intermittent regions of thickly clustered particles, known as ring arcs, have been seen to split and evolve, but astronomers need more data to truly understand the processes taking place. Webb will provide a much clearer understanding of how the Solar System works, and likely open up new areas of study we haven&rsquot yet imagined.


The Outer Planets of the Solar System

Jupiter is the fifth planet from the sun and the largest in our solar system. It has 1 400 times the volume of our Earth, but is only 300 times as heavy because the planet must be made up of gas rather than rocks or metal.

It takes Jupiter almost 12 years to orbit the sun. But it rotates on its own axis very quickly &ndash it completes one full turn every 10 hours. If you look at Jupiter closely, you can see stripes , probably clouds that are created by fast-moving winds.

We don't know very much about Jupiter because not very many spaceships have visited it. In 1979 two American Voyager spacecraft flew past Jupiter and gave us lots of new information. Today we know that most of the planet consists of gases - hydrogen en helium - and does not have a hard core , like the Earth. In 1994 a big comet crashed into Jupiter and stirred up the planet's atmosphere. Scientists could find out what kind of gases Jupiter's atmosphere is made up of.

In 1989 NASA launched an unmanned spacecraft to Jupiter - Galileo. After 6 years, Galileo reached the planet and went into orbit. It sent a small probe through the clouds of Jupiter to find out more about the atmosphere. It turned out to be very dense and filled with sulphur and other poisonous gases, impossible to breathe .

One of Jupiter's main features is a great red spot on the planet, probably a big storm about the size of our earth.

Jupiter has four large moons and many other smaller ones &ndash over 60 moons have been found so far. Galileo discovered the four biggest moons in the 17th eeu. They are also called the Galilean moons. Ganymede, the biggest moon in the solar system is even larger than Mercury and would be an own planet if it didn't travel around Jupiter. Callisto is as big as Mercury. Both these moons have an icy surface. Io is a rocky, volcanic moon from which lava and sulphur come out. It is about as big as our moon and the innermost of Jupiter's moons. Europa is the smallest of the Galilean moons. It has a very smooth surface and a lot of lines and dots on it that may be frozen rivers or seas. Maybe there is even water underneath die surface of Europa.

Scientists discovered that, not only Saturn, but also Jupiter has a system of rings. They do not reflect the light from the sun because they are made of dark dust and pieces of rock. That's why they are not visible.

Saturn

Saturn is the sixth planet from the sun and the second-largest in our solar system. It is different from the other planets because of its rings, which were first seen by the Italian astronomer Galileo in 1610.

You can see Saturn without using a telescope, but you need one if you want to see its rings. Saturn has a diameter about 10 times larger than the Earth and about 760 Earths could fit into the planet.

Saturn compared to our Earth

Because it spins so quickly, Saturn looks a bit flat, with a longer diameter through the equator than through the poles. Saturn is a very light planet - the only one that would float in a big body of water.

One Saturnian day lasts about 10 hours and it takes the planet almost 30 years to orbit the sun once. Because it moves so quickly around its axis there are strong winds that sweep the whole planet. By die equator they probably have a speed of up to 1700 km an hour. Because it is very far away from the sun, temperatures on the surface are abut -175 ° C.

Saturn's rings are the most fascinating feature about the planet. They are extremely wide, but very flat. They stretch to a afstand of over 130,000 km from the planet&rsquos centre, but most of them are only very few meters thick. There are probably over 100,000 separate rings - made of icy rock and frozen gases. This makes them shine in the sunlight.

More than 50 moons have been discovered around Saturn. Some of them are only 20 km wide others are bigger than our moon. Saturn's largest moon is Titan- even larger than Mercury. Not very much is known about this moon because it has a very thick orange-colored atmosphere made up of nitrogen and other gases. Underneath thick clouds there might be some form of water on Titan.

In 1997 NASA launched a spacecraft from Cape Canaveral, Florida with the aim van reaching Saturn. After a 7-year trip Cassini went into orbit around Saturn and sent a small probe to the surface of Saturn's biggest moon, Titan. In the past few years it has sent important data about Titan back to Earth. It also found out that liquid methane rains down on the surface of Titan, forming rivers and lakes of hydrocarbon.

Uranus

Uranus is the seventh planet from the sun. It is sixth in size and just visible to the human eye. It was discovered by accident by the British astronomer William Herschel in the 18th century.

Uranus has a diameter of over 50,000 km - about 4 times that of the Earth and it is 3 billion km away from the sun. It takes Uranus 84 years for one single orbit around the sun and 17 hours for one rotation around its axis. Die unusual thing about Uranus is that its poles are pointed directly at the sun. This means that it orbits the sun on its side. Each pole gets 42 years of sunlight and then 42 years of darkness.

Uranus belongs to the "gas giants". Its atmosphere consists mostly of hydrogen en helium and a bit of methane, which gives the planet a bluish-green color. Die surface of Uranus is probably made up of frozen gas. Underneath this crust, there is a layer van poisonous water. Die core is ice and rock.

In 1977 an American astronomer discovered that Uranus also has a system of rings. 10 of the 17 moons were discovered when Voyager 2 flew by the planet in 1986.

Neptune

When Neptune was discovered 1846 astronomers thought it was a star. It is the eighth planet from the sun. It does not shine so brightly, so it is only visible when you use a telescope. It appears as a green - bluish disc, like Uranus.

It takes Neptune, which is almost 4.5 billion km away from Earth, almost 165 years to travel around the sun once . Neptune's day is shorter than an Earth day - only 16 hours.

Image of Neptune taken from Voyager 2

Neptune has a few dark spots. Scientists think that these spots are tremendous hurricanes that travel across the frozen planet. Strong and icy winds of up to 1000 km an hour blow on this planet. They are the fastest winds ever measured in our solar system. Neptune's atmosphere can change very quickly. When Voyager 2 flew past the planet in 1989 the dark spots were gone

Like the other giant planets, Neptune is a ball of gas. The atmosphere is made up of frozen methane , which gives the planet its blue color. The planet has 8 known satellites. The biggest moon is Triton - about the same size as our own moon. It has active ice volcanoes. When they erupt, they shoot frozen nitrogen and gas about 20 km high.


Internal Heat Sources

Because of their large sizes, all the giant planets were strongly heated during their formation by the collapse of surrounding material onto their cores. Jupiter, being the largest, was the hottest. Some of this primordial heat can still remain inside such large planets. In addition, it is possible for giant, largely gaseous planets to generate heat after formation by slowly contracting. (With so large a mass, even a minuscule amount of shrinking can generate significant heat.) The effect of these internal energy sources is to raise the temperatures in the interiors and atmospheres of the planets higher than we would expect from the heating effect of the Sun alone.

Jupiter has the largest internal energy source, amounting to 4 × 10 17 watts that is, it is heated from inside with energy equivalent to 4 million billion 100-watt lightbulbs. This energy is about the same as the total solar energy absorbed by Jupiter. The atmosphere of Jupiter is therefore something of a cross between a normal planetary atmosphere (like Earth’s), which obtains most of its energy from the Sun, and the atmosphere of a star, which is entirely heated by an internal energy source. Most of the internal energy of Jupiter is primordial heat, left over from the formation of the planet 4.5 billon years ago.

Saturn has an internal energy source about half as large as that of Jupiter, which means (since its mass is only about one quarter as great) that it is producing twice as much energy per kilogram of material as does Jupiter. Since Saturn is expected to have much less primordial heat, there must be another source at work generating most of this 2 × 10 17 watts of power. This source is the separation of helium from hydrogen in Saturn’s interior. In the liquid hydrogen mantle, the heavier helium forms droplets that sink toward the core, releasing gravitational energy. In effect, Saturn is still differentiating—letting lighter material rise and heavier material fall.

Uranus en Neptune are different. Neptune has a small internal energy source, while Uranus does not emit a measurable amount of internal heat. As a result, these two planets have almost the same atmospheric temperature, in spite of Neptune’s greater distance from the Sun. No one knows why these two planets differ in their internal heat, but all this shows how nature can contrive to make each world a little bit different from its neighbors.


Recommended Reading

Jupiter Is the Best Planet

A Major Correction

When ‘the Aliens Are Us’

This strange posture is just one on Uranus’s list of mysteries, a list that also includes its temperature. While the other gas planets are still slowly radiating out the heat of their formation, Uranus generates hardly any internal heat at all. No one is sure why, but that lack of heat may be the underlying cause of the planet’s extreme atmospheric temperatures: Deeper cloud layers get as low as 360 degrees below zero, colder than any other planet in the solar system, and yet the outer-most layer can reach more than 500 degrees, far higher than any other gas giant.

Like Jupiter and Saturn, Uranus’s atmosphere is full of hydrogen and helium, but unlike its larger cousins, Uranus also holds an abundance of methane, ammonia, water, and hydrogen sulfide. Methane gas absorbs light on the red end of the spectrum, giving Uranus its blue-green hue. If you were to fly down through the layers of the atmosphere, the surrounding clouds would grow denser and denser, colder and colder, bluer and bluer as the gases absorbed more of the visible spectrum. And deep below the atmosphere you may find the answer to yet another one of Uranus’s big puzzles: Its unruly magnetic field is tilted 60 degrees from its rotational axis, much stronger on one pole than the other, and shifted a few thousand miles off-center. Some astronomers believe the warped field may be the result of vast oceans of ionic liquids hidden beneath the greenish clouds, full of water, ammonia, or even liquefied diamond.

Perhaps Uranus wouldn’t be quite so mysterious if more spacecraft stopped by—but while Mars, Jupiter, and Saturn seem to receive a constant stream of high-tech fan-mail from Earth, Uranus has only been visited once. In 1986, Voyager 2 swung by on its way into deep space. It was the first and so far the only mission to get an up-close view of Uranus, and what the probe saw was, at first glance, dull. Voyager 2 observed little atmospheric activity, and few cloud formations. For a moment, it seemed the icy clouds held little of interest. But it’s been 30 years since the Voyager fly-by, and we’re wiser now.

When Voyager visited, Uranus was just about at its solstice—the South Pole was almost directly facing the sun, and its North Pole was turned away. But as Uranus continued along its slow orbit, the seasons changed, and the northern hemisphere slowly came back into the light. In 2007, Uranus reached its equinox, the time when the equator faces the sun and the hemispheres receive equal sunlight. According to Imke de Pater, a professor of astronomy at the University of California, Berkeley, the earlier observations of Uranus were “nothing like what we’ve seen during the Equinox.” Over the past several years, astronomers have witnessed winds that blow hundreds of miles an hour, massive storm systems persisting for hours to years, bright cloud patches that migrate across the planet, and “dark spot” storms similar to the famous Neptunian version.

Uranus’s trips around the sun take just over eight decades, but it doesn’t travel alone. It is joined in its orbit by 27 known moons and 13 known rings, altogether every bit as bizarre as the planet itself. The rings of Uranus aren’t made of bright ice like Saturn’s—they’re more reserved, mostly rock and dust, and so dark they can be hard to spot (even Voyager 2 overlooked Uranus’s two outermost rings). But when Saturn’s rings have dissipated, as astronomers suspect will happen millions of years from now, Uranus’s surprisingly stable rings—which come in all sorts of strange flavors—will remain long into the future. One appears to be made entirely of dust knocked off the moon Mab by asteroid impacts another dusty ring seems to have disappeared sometime in the last few decades, while a different ring appeared elsewhere and perhaps most incredibly, one of the rings “breathes,” expanding and contracting around five kilometers once every several hours. According to Mark Showalter of the SETI Institute, these rings are “totally unlike anything else we’ve seen.”

And then there are the moons, which, like Uranus itself, bear unusual names—most moons in our solar system inherit their names from Greek mythology, but Uranus’s moons come from English literature. There’s Umbriel, strangely dark except for a mysterious bright band Oberon, covered in craters and one very large mountain Miranda, scarred by cracks and fissures so extreme they put the Grand Canyon to shame and two dozen more.

When describing the motion of Uranus’ moons, Showalter uses words like “random” and “unstable.” The moons are constantly pushing and pulling each other gravitationally, which makes their long-term orbits unpredictable, and over millions of years some are expected to crash into each other. In fact, at least one of Uranus’s rings is thought to be the result of such a collision.

An image from the Hubble Space Telescope of the planet and its rings (NASA)

Learn enough, and it’s impossible to not be entranced by the beautiful chaotic dance of Uranus’s ring and moon system. Hidden among those strange movements may be the keys to understanding the unusual gravitational interactions of bodies across the cosmos.

So why not take a closer look?

Astronomers have considered sending an orbiter to Uranus, but there are complications. For one, Uranus is incredibly far away, between 1.5 and 2 billion miles from Earth. Besides that, Uranus is hard to predict. We don’t know what to expect from the fluctuating temperatures of the planet’s upper atmosphere, and while the chaotic motion of the moons is too slow to threaten a spacecraft, there’s reason to suspect we haven’t yet spotted all of the moons and debris orbiting the planet.

“What I’d really like to do,” says Glenn Orton of NASA’s Jet Propulsion Laboratory, “is get a probe into the atmosphere.” There, astronomers might be able to start unraveling some of Uranus’ most enduring puzzles: the deep structure of its atmosphere, the cause of its off-kilter magnetic field, and perhaps the reason for its frigid internal temperatures.

Until then, we can only gaze at the planet across 2 billion miles of space, guessing at its secrets. The best questions in science are the unanswered ones, and the best planet in the solar system is seventh from the sun, shrouded in methane and in mystery.


Kyk die video: Kelas 6 Mars, Yupiter, Saturnus, Uranus, Neptunus (November 2022).