Ilanga linenqwaba yezakhiwomkhathi
KUVAMILE ukuba uma sibuka izinto, siqale sibheke ngaphesheya sishiye eziseduze kwethu.
Sekukaningi sibhala ngezinto ezithinta umkhathi kodwa sithinte kakhulu izinto ezingaphandle kwesimonkanyezi ( star system) sethu, okuyilanga nezakhiwomkhathi ( celestial bodies) ezihambisana naso.
Kulokhu sithe ake sibheke ekhaya. Isimonkanyezi selanga sibanjwe ngontandozibuthe ( gravity), sihlanganisa ilanga nezakhiwomkhathi ezilizungezayo ngqo nezilizungeza ngokuhambisana nezakhiwomkhathi ezinkulu kunazo - njengenyanga.
Naso uqobo kasimile ngoba siyazungeza kumaxhobela ( galaxy) esikuwona, iMilky Way. Sizungeza ngesivinini esilinganiselwa ezi-828 000 km/hr. Yize lesi simonkanyezi sizungeza iMilky Way - ongumaxhobelasishingishane ( spiral galaxy) - ngalesi sivinini, kodwa kusithatha iminyaka eyizi-230 million ukuwuqeda nya umzungezo ( orbit) owodwa.
Sitholakala kwi-Orion Arm, okuyibanga eliyizi-26 000 light years ukusuka enkabeni yeMilky Way - okuyibanga okungaba yinkinga ukulibhala ngamakhilomitha.
Kwizakhiwomkhathi ezizungeza ilanga ngqo, kubalwa imihlaba eyisi-8 - okuyiMercury, iVenus, i-Earth, iMars, iJupiter, iSaturn, i-Uranus neNeptune - kuzokhumbuleka ukuthi uPluto akasabalwa njengomhlaba kwazise wehliselwe ekubeni wumhlabambumbulu ( dwarf planet) yi-International Astronomical Unit (IAU).
Kukhona-ke nemihlabambumbulu ezungeza ilanga, okuyiPluto, iCeres, i-Eris, iMakemake neHaumea kanti kukhona nezakhiwomkhathi ezincane njengezingamhlaba ( asteroids). Izakhiwomkhathi ezizungeza ilanga zibe zizungeza izakhiwomkhathi ezinkulu kunazo, yizinyanga - okukhona kuzona ezimbili ezinkulu ukudlula iMercury onomugqankaba ( diameter) oyizi-4,879 km.
Lezi zinyanga yiGanymede (umugqankaba - 5,268 km) ozungeza iJupiter noTitan (umugqankaba - 5,151 km) ozungeza iSaturn. Isimonkanyezi selanga sakheke eminyakeni eyizi-4.6 billion eyedlule emuva kokuba untandozibuthe udonsele ndawonye ifu elidalwe yizinkanyezi ezimbili. Ingxenye enkulu yalesi simonkanyezi iselangeni njengoba liwu-1.989 × 10^30 kg - okuyinto engaba wu- 1,98 9,100,000,000,000,000,000,000,000,000 kg kanti umugqankaba walo wu- 1.3914 million km.
I-Jupiter yiyona elandela ilanga ngobukhulu. Isimonkanyezi selanga sinezakhiwomkhathi okuyibhande lezingamhlaba ( asteroid belt) eliphakathi kweMars neJupiter, yiKuiper belt, iScattered Disc - okuwuvucu oluhlanganisa izakhiwomhlaba ezincane okubalwa kuzona izingamhlaba, uthuli, igesi nezinye izinhlayiya.
I-Kuiper belt neScattered Disc kutholakala emuva kweNeptune kanti igcwele iqhwa. Emuva kwakho kukhona izingamhlaba-mbumbulu ( Sednoids), ezisanda kutholakala. Kukhona nezinye izakhiwomkhathi kulesi simonkanyezi okungoshiyamsila ( comets), izingamhlaba-mbumbulu ezibizwa ngama- centaur, yifu lothuli okuzipepenyekelayo nje emkhathini.
Imihlaba eyisi-6 nemihlabambumbulu emine nenqwaba yezakhiwomkhathi, kuzungezwa yizinganyanga. Kuphele isikhathi eside abantu bengasiqondi isimonkanyezi selanga njengoba abebephila kusukela ngesikhathi esiphakathi kweminyaka ye-1301- 1500 nabebephila kwese-1500-1700, bebecabanga ukuthi umhlaba kawunyakazi, umile enkabeni kasakambo ( universe) futhi wehlukile kakhulu kwizakhiwomkhathi ezibonakala esibhakabhakeni.
Yize incithabuchopho yaseGreece, u-Aristarchus wasesiqhingini iSamos, ehlawumbisele ukuthi kungenzeka kube yilanga elizunge- zwa ngezinye izakhiwomkhathi kodwa nguNicolaus Copernicus obe ngowokuqala ngqa ukusebenzisa izibalo ukubheka lesi simo - ukuthi ilanga lizungezwa ngezinye izakhiwomkhathi.
Ngeminyaka ye-1700, uGalileo Galilei, uJohannes Kepler noDkt Isaac Newton basungule indlela yokuqonda ubuhlakanibemvelo ( physics) eholele ekubeni kwamukelwe ukuthi impela wumhlaba ozungeza ilanga nokuthi neminye imihlaba ilawulwa yimithetho yobuhlakanibemvelo efanayo nelawula umhlaba (i-Earth).
Ukusungulwa kukamabonemajukujukwini ( telescope) kuholele ekutholakaleni kweminye imihlaba nezinyanga. Ukuthuthukiswa komabonemajukujukwini nokusetshenziswa kweziphuphutheki ezingashayelwa muntu ( unmanned spacecraft), kusize ekutheni kube lula ukucubungula izimo ezifana nezintaba, yizinkambabeyibuza ( crater), amafu, wuthuli nokunye okukweminye imihlaba.
Iningi lezakhiwomkhathi ezimaphakathi nesimonkanyezi zigcwele kakhulu amadwala. I-Jupiter neSaturn kugcwele kakhulu amagesi.
Amabanga ngokwehlukana kwemihlaba ukusuka elangeni
* Mercury = 0.39 AU (57.9 million km. * Venus = 0.723 AU (108.2 million km. * Earth = 1 AU (150 000 000 km). * Mars = 1.524 AU (227.9 million km. * Jupiter = 5.2 AU (780 000 000km). * Saturn = 10.12 AU (1.51 billion km). * Uranus = 20.1 AU (3 billion km). * Neptune wu-30AU (4.5 billion km). Umthombo ngabe: universe today.com; en.wikipedia.org