Ukuvela Kwamaplanethi Esimisweni Selanga
Ukuvela kwamaplanethi ohlelweni lwethu lwelanga kuyindaba ende yokuthi izinto ezilula—igesi yendawo yonke kanye nothuli—kwaguquka kanjani kwaba imihlaba ehlukahlukene: amaplanethi anamatshe aminyene, amagesi amakhulu anezingqimba, kanye namaplanethi abandayo, abandayo emaphethelweni. Lolu hambo lwenzeka eminyakeni eyizigidigidi, luthonywe amandla adonsela phansi, ukushayisana, ukushisa kwangaphakathi kweLanga, imisebe, kanye nokuguquguquka kwesimo sezulu okushintsha njalo. Ukuqonda ukuvela kwamaplanethi akugcini nje ngokusinika ukuqonda ngemvelaphi yoMhlaba kodwa futhi kusiza ososayensi ukuthi bachaze indlela amaplanethi azungeze ezinye izinkanyezi akha ngayo.
1. Isiqalo: I-Solar Nebula kanye Nokuzalwa Kwelanga
Eminyakeni engaba yizigidigidi ezingu-4,6 edlule, uhlelo lwelanga lwavela efwini elikhulu lama-molecule elicebile nge-hydrogen, i-helium, nezinye izakhi ezisindayo ezaphinde zasetshenziswa ekuqhumeni kwezinkanyezi zezizukulwane zangaphambilini. Leli fu lawa ngaphansi kwamandla adonsela phansi—mhlawumbe libangelwe yigagasi lokushaqeka elivela ku-supernova—futhi laqala ukujikeleza ngokushesha nangokushesha. Njengoba ifu lijikeleza, lacaba lakha idiski ye-protoplanetary: idiski yegesi nothuli oluzungeza isikhungo salo.
Enkabeni yediski, iningi lezinto zahlangana ukuze zakhe i-protosun. Ukucindezela kanye nokushisa kwanda, kwaze kwaba yilapho ukusabela kwe-fusion kuvutha futhi iLanga elincane laqala ukukhipha amandla. Kulesi sigaba, idiski elizungezile lalisaqinile, ligcwele izinhlayiya zothuli ezincane ezazizoba izakhi zamaplanethi.
2. Ukusuka Othulini Kuya Edwaleni: Ukukhula Kokusanhlamvu kanye Nezilwane Eziphilayo
Isigaba esibalulekile ekuziphendukeleni kwemvelo kwamaplanethi inqubo yokwanda—ukuhlangana kwezinhlayiya ezincane zibe yimizimba emikhulu. Izinhlayiya zothuli oluncane ziyahlangana futhi zinamathele ndawonye, zakha izinhlayiya ezinkulu. Ngokuhamba kwesikhathi, lezi zinhlayiya zikhula zibe amatshe amancane, amatshe amakhulu, futhi ekugcineni zibe amaplanethi (izinto ezinobukhulu obungamakhilomitha).
Ngaphakathi kwediski, ukukhanga kwamandla adonsela phansi kanye nomphumela wokuhudula kwegesi kubangela ukuthi izinhlayiya zihambe, zishayisane, futhi zigxile ezindaweni ezithile. Njengoba amaplanethi akhiwa, amandla adonsela phansi aqala ukudlala indima ebaluleke kakhulu: adonsela izinto ezizungezile, kanti amanye ashayisana ukuze akhe ama-embryo eplanethi.
Nokho, lokhu kukhula akufani. Isici esiyinhloko esinquma ukuvela kweplanethi yibanga layo ukusuka eLangeni, njengoba izinga lokushisa kudiski lehla njengoba ibanga likhula.
3. Umugqa Weqhwa Nomehluko Womhlaba Wangaphakathi Nangaphandle
Umqondo owodwa oyinhloko “umugqa weqhwa,” ibanga elivela eLangeni lapho amazinga okushisa ephansi ngokwanele ukuba amanzi nezinye izinto eziguquguqukayo ziqine khona. Ngaphakathi komugqa weqhwa (isifunda esiseduze neLanga), izinto ezingamelana nokushisa kuphela njengezinto eziqinile njenge-silicates nezinsimbi ezingasinda njengeziqinile. Yingakho amaplanethi angaphakathi—iMercury, iVenus, uMhlaba, neMars—engamaplanethi anamatshe anesisindo esiphansi kakhulu.
Ngale komugqa weqhwa, iqhwa lamanzi kanye nezinye iqhwa ezishintshashintshayo (njenge-ammonia ne-methane) zaqina, okwenza izinto ezitholakalayo zokwakha amaplanethi zaba zinkulu kakhulu. Lokhu kwavumela ukwakheka kwama-core amakhulu amaplanethi, abe esebamba igesi ye-hydrogen ne-helium kudiski. Lokhu kwazala uJupiter noSaturn, amagesi amakhulu, kanye ne-Uranus neNeptune, amaqhwa amakhulu, anokwakheka kweqhwa negesi okuyinhloko.
4. Ukwakheka Komkhathi: Kusukela “Ekuthathweni” Kuya “Ekukhululweni”
Izimo zeplanethi nazo ziyashintsha. Kuma-gas giants, umoya oyinhloko owakhiwa ngokubamba ngqo igesi e-nebular ngaphambi kokuba idiski yegesi ishabalale. Emaplanethini anamadwala, umoya wokuqala wawungavela emithonjeni emibili: ukubamba igesi encane kudiski kanye nokukhipha igesi (ukukhishwa kwegesi) ngaphakathi kweplanethi ngomsebenzi wentaba-mlilo.
Isibonelo, uMhlaba wakuqala cishe wawunesimo sezulu esihluke kakhulu kunesanamuhla—ucebile nge-carbon dioxide, umhwamuko wamanzi, i-nitrogen, kanye namanye amagesi avela emisebenzini yezintaba-mlilo. Ngokuhamba kwesikhathi, amazinga okushisa omhlaba ehla, umhwamuko wamanzi wahlangana nolwandle, futhi izinqubo zamakhemikhali nezebhayoloji zashintsha ukwakheka komkhathi. Ukuba khona kokuphila, ikakhulukazi i-photosynthesis, kwakuyimbangela enkulu yokuvela komkhathi woMhlaba ngokwandisa amazinga omoya-mpilo.
I-Venus ne-Mars balandela izindlela ezahlukene. I-Venus yabhekana nomphumela wokushisa okungekho emthethweni, yashisa kakhulu. I-Mars, enobunzima bayo obuncane kanye ne-magnetic field ebuthakathaka, yalahlekelwa umkhathi wayo omningi ngenxa yokusebenzisana nomoya welanga kanye namandla ayo adonsela phansi aphansi, ayengakwazi ukubamba amagesi kanye noMhlaba.
5. Isikhathi Somthelela Omkhulu: Ukwakha Ubuso NamaSathelayithi
Esikhathini sokuqala sesimiso selanga, ukushayisana kwezinto ezinkulu kwakuvame kakhulu. Lokhu kushayisana kwadlala indima ekwakheni ubuso bamaplanethi, ekufudumaleni kwangaphakathi kwawo, ngisho nasekushintsheni indlela yokujikeleza kwawo. Esinye sezibonelo ezidumile kakhulu yi-"giant impact" ethint of the creation of the Moon: into enobukhulu obufana ne-Mars kucatshangwa ukuthi yashaya uMhlaba omncane, yaphonsa izinto ezizungezayo kamuva ezahlangana ndawonye ukuze zakhe iNyanga.
Imithelela emikhulu nayo ibangela ukuhlukahluka kwangaphakathi: njengoba iplanethi ishisa, izinto ezisindayo njengensimbi ziyacwila ziye enkabeni ukuze zakhe umongo, kuyilapho ama-silicates alula akha i-mantle kanye noqweqwe. Lokhu kuhlukahluka kubalulekile ngoba umongo wensimbi owuketshezi ungakhiqiza insimu yamagnetic ngokusebenzisa amandla oketshezi (geodynamo), njengoba nje kwenza eMhlabeni.
6. Ukufuduka Kweplanethi kanye Nokwakhiwa Kwesistimu Yelanga
Ososayensi bake bacabanga ukuthi amaplanethi akheka futhi ahlala emizuliswaneni yawo. Manje, ukufuduka kwamaplanethi kubhekwa njengenqubo evamile. Kuma-gas disk, ukusebenzisana kwamandla adonsela phansi phakathi kwamaplanethi amancane ne-disk kungashintsha imizuliswano yawo, okubangela ukuba asondele noma aqhelelane neLanga.
Ngomongo wesimiso sonozungezilanga, amamodeli afana ne-“Grand Tack” aphakamisa ukuthi iJupiter kungenzeka ukuthi yathuthela eLangeni, yabe isibuyela emuva ngenxa yokusebenzisana neSaturn. Ukufuduka okunjalo kungachaza ubukhulu obuncane beMars kanye nokwakheka okuxubile kwebhande le-asteroid. Ngaphezu kwalokho, ukufuduka kwezilwane ezinkulu zegesi kungaba nokuhlakaza amaplanethi, kuthumele izinto ezicebile ngamanzi ngaphakathi—inqubo okungenzeka ukuthi inegalelo ekuhlinzekweni kwamanzi eMhlabeni.
7. Ukupholisa, Umsebenzi Wezemvelo, kanye Nokuvela Kwesikhathi Eside
Ngemva kwesigaba sokwakheka okuphithizelayo, amaplanethi angena ekuguqukeni kwesikhathi eside okunqunywa ukupholisa kwangaphakathi, i-radioactivity, kanye ne-mantle dynamics. Amaplanethi amakhulu avame ukugcina ukushisa isikhathi eside, okuvumela umsebenzi we-geological ohlala isikhathi eside. EMhlabeni, i-plate tectonics isiza ukuphinda kusetshenziswe uqweqwe, kuzinzise isimo sezulu ngomjikelezo wekhabhoni, futhi isekele ukusimama kolwandle.
Ngakolunye uhlangothi, ubukhulu obuncane beMars buyivumela ukuthi iphole ngokushesha, kunciphisa umsebenzi wentaba-mlilo futhi kwenze buthaka amandla ayo kazibuthe. I-Mercury inomgogodla omkhulu uma kuqhathaniswa nobukhulu bayo, kodwa isancipha njengoba iphola. I-Venus, nakuba ifana noMhlaba ngobukhulu, kucatshangwa ukuthi inesitayela se-tectonic esihlukile—mhlawumbe ibhekana “nokuvuselelwa kwendawo” ngezikhathi ezithile kunokuba ibe yi-plate tectonics eqhubekayo.
Ezindaweni ezinkulu zegesi neqhwa, ukuziphendukela kwemvelo kubonakala ngokupholisa komoya, ukuguquguquka kwesiphepho, kanye noshintsho esakhiweni sangaphakathi. I-Jupiter ne-Saturn zikhipha amandla amaningi kunalawo atholakala eLangeni, okubonisa ukuthi zisakhipha ukushisa ekwakhekeni kwazo. I-Saturn ingase ifudunyezwe “yimvula ye-helium” ngaphakathi kwayo—inqubo yokukhipha amandla yokuhlukanisa i-helium ne-hydrogen.
8. Ikusasa Lesimiso Selanga: Ukuvela Okungaqediwe
Ukuvela kweplanethi akukapheli. Ukujikeleza kweplanethi kungashintsha kancane ngenxa yokukhanya okunamandla adonsela phansi. Ama-asteroid nama-comet asengashayisana namaplanethi, nakuba kungavamile kakhulu. Ngezikhathi ezinde kakhulu, iLanga ngokwalo lizoshintsha: eminyakeni eyizigidigidi ezimbalwa, ukukhanya kwalo kuzokwanda ngokwanele ukuthinta isimo sezulu soMhlaba. Esikhathini esizayo, iLanga lizoba yi-giant ebomvu—mhlawumbe ligwinye iMercury neVenus, lishintshe kakhulu izimo kumaplanethi asele.
Ekugcineni, ukuqonda ukuvela kwamaplanethi kumayelana nokuqonda izinhlelo eziguquguqukayo: umphumela wokwakheka kokuqala okunobudlova, okulandelwa isikhathi eside sokuqondana kwe-orbital, ukwakheka komkhathi, kanye nezinguquko ze-geological nezesimo sezulu. Uhlelo lwelanga lusebenza “njengelebhu yemvelo” ekhombisa iziphetho ezahlukahlukene zamaplanethi. Kulokhu, sifunda ukuthi uMhlaba awuyona nje iplanethi yesithathu enamatshe evela eLangeni, kodwa kunalokho uwumkhiqizo wochungechunge oluyinkimbinkimbi lwezehlakalo zasemkhathini—oluqhubeka nokuvela kuze kube namuhla.
