Izinkanyezi Ezitshuzayo Zivelaphi?
“HAWU, AKE UBHEKE! Nansiyana enye!” “Kuphi? Kuphi?” Ingabe wake wawasho lamazwi lapho ubuka isibhakabhaka ebusuku ufuna ukubona izinkanyezi ezitshuzayo? Mhlawumbe okokuqala wabona eyodwa ngokungazelele ishiya umugqa onokukhanya unqamula isibhakabhaka phezu kwakho, kwabonakala sengathi enye yezinkanyezi ngokungazelele yayitshuze yanqamula isibhakabhaka. Yiqiniso, izinkanyezi ezitshuzayo azethiwanga kahle ngempela. “Zingatshuza,” kodwa azizona neze izinkanyezi.
Izazi zezinkanyezi zizibiza ngokuthi ama-meteor. Futhi nakuba inkanyezi nje evamile ingayigwinya yonke iplanethi yethu izikhathi eziphindwe kasigidi, yiplanethi yethu egwinya lama-meteor ngezigidi. Ayini ama-meteor, futhi avelaphi?
Ahlangene kakhulu nezinkanyezi ezinomsila. Isibonelo esaziwayo, esenkanyezi enomsila i-Halley’s comet, eyadlula ngokushesha emhlabeni ngo-1986 ohambweni lwayo olude lokuzungeza ilanga oluthatha iminyaka engu-76 ubude. Ngenxa yokuthi ngokusobala izinkanyezi ezinomsila zakhiwa ngokuyinhloko iqhwa nothuli, ngezinye izikhathi zibizwa ngokuthi amabhola eqhwa angcolile. Lapho inkanyezi enomsila isondela elangeni, ingaphandle layo liyafudumala, ikhiphe uthuli nesisi. Amandla amaza okukhanya kwelanga asunduzela izinto eziqinile emuva emsileni ovuthayo wothuli. Ngaleyondlela inkanyezi enomsila ishiya ngemuva kwayo umzila wemvithimvithi—izilongotsha okuthi lapho zisesemkhathini, zibizwe ngokuthi ama-meteoroid. Uthuli oluningi lwezinkanyezi ezinomsila luncane kakhulu ukuba lube ama-meteor abonakalayo. Izilongotsha ezincane zothuli zicishe zilingane nohlamvu lwesihlabathi, kuyilapho ezimbalwa zilingana nezimbokodo ezincane.
Ezimweni ezimbalwa, umzila wokujikeleza kwenkanyezi enomsila uhlangana nomzila womhlaba. Lokho kusho ukuthi umhlaba uhlangana nalomzila ofanayo wothuli isikhathi ngasinye lapho unqwamana nomzila wokujikeleza kwenkanyezi enomsila. Lapho lokhu kwenzeka ama-meteoroid amancane awela emkhathini ngezivinini ezinkulu—ezifinyelela emakhilomitheni angu-71 ngomzuzwana. Lapho ewa, amakhulu ayashisa futhi avuthe, enze imisho emhlophe eshisayo enqamula esibhakabhakeni ebizwa ngokuthi ama-meteor.
Lapho umhlaba unqamula umzila wenkanyezi enomsila, ama-meteor abonakala sengathi atshuzela kuzo zonke izinhlangothi esuka endaweni eyodwa esibhakabhakeni, ebizwa ngokuthi i-radiant. Esuka kulama-radiant, ukuwela emkhathini kwama-meteor kwenzeka njalo ngezikhathi ezithile ngonyaka. Omunye umbukwane othandwayo owokuwela emkhathini kwama-Perseid, abizwa ngalendlela ngoba i-radiant yawo itholakala ezinkanyezini ze-Perseus. Lapho ama-Perseid ewela kakhulu khona esibhakabhakeni ngomhla ka-12 no-13 ku-August unyaka ngamunye, kuba umbukwane okhazimulayo. Ama-meteor angaphezu kuka-60 angawa njalo ihora ngalinye.
Cishe ngo-October 21 ungase ubone ukuwela emkhathini kwama-Orionid, lawo njengokuwa kwama-Aquarid okwenzeka ngaphambili, kuthiwa abangelwa ama-meteoroid avela kuyi-Halley’s Comet. Ngokwephephabhuku i-Astronomy, izazi zesayensi zilinganisela ukuthi i-Halley’s comet “ingajikeleza izikhathi ezingu-100 000 ngaphambi kokuba ilahlekelwe yikho konke enakho.” Uma ukucabangela kwabo kuqondile, i-Halley’s comet iyobuya njalo ngemva kweminyaka engu-7 600 000! Futhi ngisho nakuba seyahamba kudala, akukho kungabaza ngokuthi umzila wayo wothuli uyoqhubeka iminyaka eminingi kamuva unikeza izakhamuzi zomhlaba izinkanyezi ezitshuzayo. Amaningi ama-meteor esiwabonayo manje ngokusobala avela ezinkanyezini ezinomsila ezafa kudala.
Izazi zesayensi zilinganisela ukuthi emhlabeni wonke, kunama-meteor abonakalayo ayizigidi ezingu-200 emkhathini wethu usuku ngalunye. Futhi ngokuphathelene nokuwela kwama-meteor emkhathini okuwumbukwane, kuhlala kunonyaka ozayo—kanye nezigidi ezengeziwe ezizofika!