Ukulinganisa Umhlaba Ngenduku

WAKE wezwa yini ngesazi sezibalo nezinkanyezi esingumGreki u-Eratosthenes? Cishe igama laso laziwa kakhulu izazi zezinkanyezi. Kungani sihlonishwa kangaka?

U-Eratosthenes wazalwa cishe ngo-276 B.C.E. futhi wathola ingxenye yemfundo yakhe e-Athene, eGrisi. Nokho, wachitha ingxenye enkulu yokuphila kwakhe e-Aleksandriya, eGibhithe, ngaleso sikhathi eyayibuswa amaGreki. Cishe ngo-200 B.C.E, u-Eratosthenes wanquma ukuthola ubukhulu bomhlaba ngokusebenzisa induku. Ungase uthi, ‘Akunakwenzeka.’ Wakwenza kanjani?

Emzini waseSiyene (manje obizwa ngokuthi i-Aswân), u-Eratosthenes waphawula ukuthi emini bebade ngosuku lokuqala lwehlobo, ilanga lalihlaba okhakhayini. Lokhu wakwazi ngoba kwakungabi nathunzi lapho imisebe yelanga ihlaba ekujuleni kwemithombo ejulile. Nokho, emini ngosuku olufanayo emzini wase-Aleksandriya, ongamastadiyua angu-5 000 enyakatho yeSiyene, laliba khona ithunzi. Lokho kwanika u-Eratosthenes icebo.

U-Eratosthenes wahloma induku phansi. Lapho sekusemini bebade, walinganisa i-engela yethunzi lenduku e-Aleksandriya. Wathola ukuthi le engela yayingama-degree angu-7,2 ukusuka endukwini ayeyihlome phansi.

U-Eratosthenes wayekholelwa ukuthi umhlaba uyisiyingi, futhi wayazi ukuthi kunama-degree angu-360 esiyingini. Ngakho wahlukanisa u-360 nge-engela ayeyitholile, u-7,2. Waba yini umphumela? I-engela ayeyitholile yayiyingxenye yesihlanu yesiyingi esiphelele. Wabe esephetha ngokuthi ibanga lokusuka eSiyene uye e-Aleksandriya, noma amastadiyu angu-5 000, kumelwe ukuba alingana nengxenye yesihlanu yobukhulu bomhlaba. Ngokuphindaphinda u-50 ngo-5 000, u-Eratosthenes wafinyelela esibalweni esingamastadiyu angu-250 000 athi siwubukhulu bomhlaba.

Isibalo asithola sasisondele kangakanani ezibalweni zanamuhla? Amastadiyu angu-250 000 alingana nebanga eliphakathi kwamakhilomitha angu-40 000 nangu-46 000 ngokwezibalo zamanje. Zisebenzisa imikhumbi-mkhathi ezungeza umhlaba, izazi zezinkanyezi zalinganisa ubukhulu bomhlaba ukusuka enyakatho ukuya eningizimu futhi zathola inani elingamakhilomitha angu-40 008. Ngakho, eminyakeni engaphezu kuka-2 000 edlule, u-Eratosthenes wasondela ngendlela ephawulekayo esibalweni sanamuhla. Ukunemba kwakhe kuyingqayizivele nakakhulu uma ucabangela ukuthi le ndoda yasebenzisa nje induku nolwazi lwayo lwezibalo! Namuhla, izazi zezinkanyezi zisebenzisa le ndlela yokubala njengesisekelo sokubala ibanga lezinto eziqhelile esimisweni sethu sonozungezilanga.

Abanye bangase bakuthole kuyinto ephawuleka kakhulu ukuthi u-Eratosthenes wayazi ukuthi umhlaba uyisiyingi. Phela, ngisho nabanye abantu abahlakaniphile ababehileleke kwezesayensi babekholelwa ukuthi umhlaba uyisicaba, kwaze kwaba semakhulwini ambalwa nje eminyaka adlule. AmaGreki asendulo ayethole isimo sokwakheka komhlaba ngokucwaninga kwawo kwezesayensi. Nokho, eminyakeni engaba ngu-500 ngaphambi kuka-Eratosthenes, umprofethi ongumHebheru waphefumulelwa ukuba abhale: “Ukhona Lowo [uNkulunkulu] ohlala ngaphezu kwesiyingi somhlaba.” (Isaya 40:22) U-Isaya wayengeyena usosayensi. Wázi kanjani ukuthi umhlaba uyisiyingi? Leli qiniso walembulelwa ngokuphefumulelwa uNkulunkulu.

[Umbhalo waphansi]

[Umdwebo ekhasini 10]

(Ukuze ubone ukuthi indaba ihlelwe kanjani, bheka encwadini)

Umsebe welanga

ISiyene

7,2°

I-Aleksandriya

7,2°