LOKACIN DA TSAKIYAR DUNIYA TA HAƊIYE SARARINTA

Sararin Duniya baƙon abu ne a cikin duniyoyin dutse. Venus da Mars, duk da matsi da suka bambanta ƙwarai, dukansu suna da iska da aka yi da kusan kashi 95% na carbon dioxide da ’yan kashi kaɗan na nitrogen. Na Duniya yana da ƙarancin carbon dioxide kuma yana da yawan oxygen. Wani ɓangare na bambancin ya samo asali ne daga biliyoyin shekaru na ilimin ƙasa da rayuwa. Amma watakila duniyoyin ma sun fara ne da wadatar sinadarai daban-daban da ke samar da sararin sama da halittu masu rai: hydrogen, carbon da nitrogen.

Vera Sparrman, ta Jami’ar Copenhagen, da Anders Johansen, na Copenhagen da Jami’ar Lund a Sweden, sun koma farkon farko: lokacin da Duniya ke ci gaba da girma, a cikin faifan iskar gas da ƙura da ke kewaye da matashin Rana.

Ruwan saman ƙarfe ta cikin tekun magma

A wancan mataki, zafin da kayan da ke shigowa ke fitarwa ya sa mantle na duniyar ya ci gaba da narkewa. Duniya da ke girma tana lulluɓe da tekun magma na duniya baki ɗaya. Kowane sabon yanki na kaya ya kawo dutse, wanda ya haɗu da magma, da ƙarfe-nickel, wanda ya nutse ta cikinsa a cikin ɗigo — yana faɗuwa kusan mita ɗaya a cikin daƙiƙa — don gina tsakiyar duniya. Iskar gas daga sararin sama sun narke cikin magma, kuma wasu daga cikinsu sun narke a cikin ƙarfen da ke faɗuwa. Ta haka ruwan saman ƙarfe zai iya ɗauke su har ƙasa.

Marubutan sun yi samfurin wannan musanya tsakanin sararin sama, tekun magma da tsakiyar duniya mataki-mataki, daga iri mai nauyin kashi 2% na nauyin Duniya har zuwa 64% — kusan Duniyar farko kafin babban karo da ya samar da Wata. An daidaita jimillar adadin hydrogen, carbon da nitrogen don su dace da ƙiyasin Duniya ta yau, har da waɗanda ake tunanin suna ɓoye a tsakiyarta.

Hanyoyi biyu na gina duniya

Sun kwatanta hanyoyi biyu na girma:

• Tara tsakuwoyi (pebble accretion): Duniya tana share tsakuwoyi masu girman milimita zuwa santimita. Yayin da kewayen duniyar ke ɗumama, waɗannan ƙananan ƙwayoyi suna rasa sinadaransu masu saurin tashi kafin su iso. Hydrogen yana daina zuwa kusan nan take; carbon da nitrogen suna daina zuwa a kusan nauyin Mars. Sinadarai masu saurin tashi suna zuwa da wuri.
• Tara planetesimals (planetesimal accretion): Duniya tana girma daga jikkuna masu faɗin ɗaruruwan mita ko fiye, waɗanda ke kare sinadaransu masu saurin tashi a ciki. Isarwa tana ci gaba.

Zuwa da wuri, binnewa mai zurfi

Lokaci ya zama yana da muhimmanci ƙwarai. Idan isarwa ta zo da wuri, kowane ɗan ƙarfe da ke faɗuwa daga baya yana ci gaba da wanke magma. A hanyar tsakuwoyi, kusan kashi 70% na hydrogen da kashi 69% na carbon suna ƙarewa a tsakiyar duniya. Idan isarwa tana ci gaba, tsakiyar duniya tana ɗaukar kusan rabi a mafi yawa, kuma mantle da sararin sama suna riƙe kusan ninki biyu. Waɗannan rabo sun fito daga rukunin ma’aunin dakin gwaji da marubutan suka ɗauka a matsayin tushensu; kamar yadda za mu gani, wani rukuni yana ba da lambobi mabambanta ƙwarai.

Inda hydrogen, carbon da nitrogen ke ƙarewa yayin da Duniyar farko da aka gina da tsakuwoyi ke girma daga nauyin Duniya 0.02 zuwa 0.64: tsakiyar duniya (ja mai duhu), tekun magma (ruwan lemu), sararin sama (shuɗi). — Figure 4 (layin sama), Sparrman and Johansen (2026), arXiv:2610.27788.

Narkewa — yawan iskar gas da magma zai iya narkarwa a wani matsi — ce ke yanke wanda zai tsira: abin da ya narke a cikin magma kawai ne ɗigon ƙarfen da ke faɗuwa ta cikinsa zai iya ɗauka. Ruwa yana narkewa cikin sauƙi, don haka hydrogen yana fuskantar ruwan saman ƙarfe kuma yana nutsewa da inganci. Carbon monoxide yana narkewa da ƙyar ƙwarai, don haka a kowane lokaci galibin carbon yana zama a sama a cikin iska; amma dukkan ƙarfen da ke zuwa daga baya yana ci gaba da zuba ɓangaren da ya narke, wanda sararin sama ke sake cika nan take, don haka a ƙarshe kashi 69% na carbon ya sauka duk da haka. Nitrogen shi ne misalin akasin haka: yana da ƙaunar ƙarfe fiye da hydrogen, duk da haka kashi 4% kawai nasa ke isa tsakiyar duniya — yana narkewa da ƙyar har ba ya kusan taɓa kasancewa a wurin da ruwan saman ƙarfe ke wucewa, kuma kashi 93% yana zama a sararin sama. Rashin narkewa yana kariya.

Sararin sama mai nauyi na carbon monoxide

Abin da ya rage a ƙarshen hanyar tsakuwoyi shi ne sararin farko mai kauri na kusan bar 760 — iskar da muke shaka tana da nauyin bar 1 a matakin teku, kuma iskar Venus bar 92. Carbon ne ke mamaye shi, galibi a matsayin carbon monoxide (kusan bar 710), tare da kusan bar 39 na hydrogen da bar 1.7 na nitrogen. Carbon da ya tsere daga tsakiyar duniya kuma ya ƙare a cikin wannan sararin sama ya kai kusan ninki 15 na carbon dioxide da ke cikin sararin Venus a yau; nitrogen ɗin kuwa ya kai kusan adadin nitrogen na Venus. Hanyar planetesimals tana ba da sararin sama mafi nauyi ma, kusan bar 1,350, mai irin wannan haɗi.

Sararin Duniyar farko da aka gina da tsakuwoyi yayin da take girma: da zarar isarwa ta tsaya, ruwan saman ƙarfe yana ci gaba da zubar da hydrogen da carbon, kuma carbon monoxide (layukan ja masu yankewa) ne ke mamayewa. — Figure 7 (sama), Sparrman and Johansen (2026), arXiv:2610.27788.

Bayan tarawa ta ƙare, marubutan suna sa ran mantle zai yi oxidation kuma sararin sama ya koma zuwa ruwa da carbon dioxide, tare da tekuna suna tattaruwa. Idan aka faɗaɗa zuwa nauyin Venus, samfurin yana ba da farawa iri ɗaya, kusan bar 500 na carbon monoxide; marubutan suna nuna cewa motsin faranti (plate tectonics) na Duniya, ta hanyar binne carbon, maimakon haihuwa daban, zai iya bayyana dalilin da ya sa duniyoyin biyu suka rabu.

Ta wace hanya Duniya ta girma?

A ƙa’ida, adadin da ya rage zai iya bayyana yadda Duniya ta samu. Samfurin tsakuwoyi tare da bayanan tunani (reference data) shi kaɗai ne ya dace da ƙiyasin da aka wallafa na dukkan sinadarai uku a mantle na yau. Amma waɗannan ƙiyasi suna saɓa wa juna kusan yadda samfuran ke yi, kuma ma’aunin dakin gwaji na yadda waɗannan sinadarai ke rabuwa tsakanin ƙarfe da dutse sun bambanta da matakan girma (orders of magnitude) da dama — da wani rukunin bayanai, duk hydrogen yana ƙarewa a tsakiyar duniya. Narkewar carbon monoxide a cikin magma ita ce shigarwa mafi tasiri kuma mafi ƙarancin sani. Ingantattun gwaje-gwaje, marubutan sun kammala, za su iya mayar da haɗin cikin Duniya zuwa rubutaccen tarihin yadda aka gina duniyar.