Ama-Interplanetary Projectiles
Lokha nawuqala phezulu esibhakabhakeni ebusuku, koke kubonakala kuthulile. Iinkwekwezi ziyameruza esibhakabhakeni esinzima esikhulu ngaphezulu kwehloko yakho. Kodwana iqiniso lihlukile. Isibhakabhaka sizele umlanjana we-space matter, esikhathini esinengi sidoseleka kusukela kuma-asteroid belt hlangana ne-Mars kunye ne-Jupiter. Isenzo lesi sikatelekekile begodu, kusaqatjangwa bona ama-interplanetary projectiles ambalwa mancani khulu namhlanjesi kunalokha iPhasi lisabumbeka, kulinganiswa bona i- 30 000 yamathani yama-interplanetary debris isangenelela emoyeni wethu qobe nyaka.
Inengi leenquntu ziyatjha nazisangenelela emoyeni, zifuthumale ukudlula izinga lelo zincibilika ngalo ngokwala umoya. Umkhanyo ovezwa ziintwezi uzenza zibonakale njengama-meteors, nofana ama-shooting stars. Nangabe i-meteor yikulu ngokulingeneko, igcenye yayo ingarhona ukuphila emtjhisweni ibese iwela ephasini njenge-meteorite. Ukukunikela ilwazi/ For Your Information (FYI), i-meteorite ekulu ekheyatholwa kufikela ngalesi isikhathi yi-Hoba meteorite, eyatholwa ngo 1920. Yawela phasi eduze ne-Grootfontein, kwetlhagwini ye-Namibia, eminyakeni engaphazulu kuka 80 000 eyadlulako begodu akhenge kheyisikinyiswe kusukela lokho. I-Hoba yisiquntu esiqinileko setiriga ne-nickel, enobukhulu obungaba mamitha amathathu isikwere nemitha yinye ukuyaphezulu.
Ukubethana Ngamandla Okukhulu
Kodwana kungenzekani nakungenzeka into ekulu yehle ngebelo eliphezulu iza ephasini? kungenzekani nange i-bolide enobukhulu obungaba yi 10 nofana i-100 khilomitha ububanzi ingawela phasi? Irhubhululo elenziweko laphambilini lezehlakalo zebethano ngamandla azitjengisi isithombe esihle ngalokhu.
Izehlakalo zokubethana ngamandla okukhulu zibonakala zinerhono lokubhubhusa ingasi yindawo ezenzeka kizo kwaphela, kodwana iphasi loke mazombe. Ukudengezela komhlaba okuthusa khulu, ama-titanic tsunamis neenkhukhula zokunyakaza kwentaba evutha umlilo okumphumela webethano ngamandla kungabhubhisa ipilo esephasini.
Ukuya phambili, ubukhulu bethuli nama-debris aphephukela emoyeni angavimbela ilanga, enze bona iphasi mazombe lihlale lisesikhathi sebusuka esingadosa iinyanga nofana iminyaka. Ngokufitjhani, ku-kuliqiniso bona izehlakalo zebethano ngamandla zingabangela bona kufe yoke into ephilako ephasini loke.
Ukubhubhisa
Ukubhubhisa/bulawa kuyigcenye yekambiso yokusombuluka kwendalo. Eminyakeni engaphezulu kwamabhiliyoni, imihlobo eminengi engeze yabalwa yezinto egade ziphila zabhujiswa ngonobangela wokutjhuguluka kwetlayimethi, iinhlekelele zemvelo nokuphalisana okuhlangana nezinto eziphilako.
Lokhu kuthathwa njengokubhubhisa okujayelekileko begodu kusaragela phambili nanamhlanjesi- kurheletjwe nababantu abaphila esikhathini sanje njengombana beba izinto abazithole ephasini. Kulinganiswa bona, ngaphasi kwesimo esijayelekileko, hlangana kwemibili nemihlanu imindeni e-taxonomic izokubhubha iphele qobe eminyakeni eyimiliyoni, kodwana ngokukhula kwenani labantu singarhona ukubuyisela i-avaregi leyo phezulu.
Nomakunjalo, amarekhodi wama-fossil atjengisa bona, esikhathini esithileko kade, kwabanokubhujiswa okukhulu lapho amaphesenti amanengi wayoyoke into ephilako ephasini atjhabalala ngokuphazima kwelihlo. Lokhu kwesinye isikhathi kubizwa ngama-boundry events begodu abonakala ngokuphela kwamatje nama-fossils athileko, lapho umhlobo munye wepilo ujanyiselwa ngomunye. Ama-boundry events lawa esikhathini esinengi abonakala kuma-contemporary rock layers eendaweni ezihlukahlukenolo, ephasini loke.
Ukubhubhisa Ngobunengi
Njengombana sithembele emarekhodini ukubona ama-boundries lawa, ukuya ngokukhula kweenhlekelele zokubhubhisa ngobunengi kubonakala lula ngemva kokukhula kwenani lepilo ngesikhathi se-Cambrian, eminyakeni angaba yi 550 miliyoni eyadlulako (Ma). Kusukela lapho, kwaba nokubhujisa okukhulu amahlandla angaba yi 5 okuthiwa yi: the End-Ordovician transition (444 Ma: 84% imihlobo eyalahlekako), i-Late Devonian (360 Ma: 79% imihlobo eyalahlekako), i-End-Permian (250 Ma, 95% imihlobo eyalahlekako – okukubhubhisa okumbi khulu okwakhe kwenzeka ephasini), End-Triassic (200 Ma, 79% imihlobo eyalahlekako) kunye ne-End-Cretaceous (65 Ma, 70% imihlobo eyalahlekako.).
Abarhubhululi besikhathini sanje baragela phambili ngokuveza bona sekuseduze kobana kufike isikhathi sokubhubhisa esinye, esizobe kungesokuthoma esenzeke msinya khulu esingarikhodiwa. Esizobe sirheletjwe kuphathwa kumbi kwethu kwebhoduluko, isehlakalwesi esibizwa nge-Holocene extinction singatjho bona imihlobo yabantu neenlwane ezingaba siquntu sazozoke eziphilako ephasini sizokubhujiswa eminyakeni engaba yi 100 elandelako (ngokuya kososayentsi munye othusako)
Wiped Out! Ukususa Koke!
Unobangela wokwenzeka kweenhlekelele lezi zokubhubhisa kunzima bona buzwisiseke. Yinye kwaphela i- (the End-Cretaceous, nofana i- K-T Boundary) eyahlotjaniswa nesehlakalo sebethano ngamandla. Ezinye akwaziwa kuhle bona zivelaphi, njengombana kunganamakhiwo yebethano ngamandla lazo ekheyatholwa kufikela kwanjesi.
Ngaphandle kwezehlakalo zokubethana ngamandla, abonobangela abaqatjangwako bafaka hlangana: ukutjhuguluka kwebhoduko (okufana ne-ice ages), izehlakalo ze-mammoth volcanic events (ezithela itjhefu emoyeni), ukuthuthumba kwama-gamma-ray (okufraya yoke into ephilako ephasi) nama-plate tectonics (okungahlanganisa amakhontinendi begodu kuhlanganise imihlobo yepilo egade ihlukene, ukwenza imihlobo emitjha yepilo).
Kodwana, kuqatjangwa bona amathuba mancani wokobana izehlakalo lezi zingabangela iinhlekelele zokubhubhisa ngobunengi zizodwa kwaphela, ngalokho kufanele kuhlangiswe namanye amafekthara ukuze lokhu kwenzeke.
Esikhathini esinengi, irhubhululo livezile bona ukubhubhisa ngobunengi kwenzeka ngeenkhathi ezithileko, mhlambe kungaba kanye qobe eminyakeni eyi 30 ukuya ku 60 miliyoni. Kufanele godi kutjhejwe bona nanoma singanabufakazi obuzwakalako besehlakalo sokubhubhisa ngobunengi ngaphambili kwe 500 Ma, akutjho bonyana akhange senzeke.
Ngaphambili kwesikhathi se-Cambrian, ipilo beyilula khulu, bufaka hlangana izinto ezilula ezifana ililwane, brachiopods kunye nama-trilobites. Ama-organisimu amancani lawa akatjhiyi ngemuva ama-fossils, begodu nenomboro yawo kubanzima bona uyilandelele. Ukuyaphambili, amatje weminyakeni angaba yi 600 miliyoni eyadlulako akatholakali lula, njengombana abuyela asetjenziswa godu ehlelweni le-tectonic. Lokhu kususa ubufakazi bama-boundry layers obungaveza iinkhathi zemiraro yephasi. Kuncono sithi, nangabe bekunobuphilo egade burarene ephasini ngesikhathi sebethano ngamandla kwe-Vredefort, ngabe sebasuswa boke.
Translated by Busisiwe Skhosana