Izinto Zomthetho KaKepler
Uyakhumbula ukuthi okokuqala ugibele imoto (hhayi ngesikhathi useyingane)? Ngesikhathi usemotweni ehambayo, wawubona sengathi imithi noma izakhiwo ziyahamba. Ngaleso sikhathi, kungenzeka ukuthi wawucabanga ukuthi imithi noma izakhiwo ziyahamba, kuyilapho wena nemoto nisamile. Eqinisweni, wena nemoto benihamba, kuyilapho imithi noma izakhiwo zimile. Empeleni sibona lokhu kunyakaza okubonakalayo noma ukunyakaza okungamanga nsuku zonke. Njalo ekuseni ilanga “liphuma” emkhathizwe osempumalanga, bese lihamba entshonalanga bese “lishona” emkhathizwe osentshonalanga ntambama. Ngokufanayo, ebusuku, uvame ukubona inyanga isuka empumalanga iye entshonalanga. Wake wacabanga noma wasola ukuthi ilanga nenyanga zihamba zizungeze umhlaba, kuyilapho umhlaba usamile?
Abantu basendulo (ekuqaleni kwe-AD) nabo babekholelwa ukuthi ilanga, inyanga, nezinye izidalwa zasezulwini zazijikeleza uMhlaba, kuyilapho uMhlaba uhlala umile. Ngamanye amazwi, uMhlaba wawubhekwa njengesikhungo sendawo yonke (i-geocentric). Lokhu kucabanga kwakusekelwe kokuhlangenwe nakho okulinganiselwe komuntu, okwakubona ilanga, inyanga, nezinkanyezi zihamba nsuku zonke, kuyilapho uMhlaba wawubhekwa njengomile. Kufana nalapho usemotweni ehambayo, ubona sengathi izihlahla noma izakhiwo ziyahamba. Lo mbono wokuthi uMhlaba uyindawo ephakathi nendawo yonke wacwaningwa futhi wathuthukiswa yisazi sezinkanyezi esingumGreki uClaudius Ptolemy (100-170 AD) ngekhulu lesibili AD futhi wakholelwa eminyakeni eyi-1400 eyalandela.
Ngokusho kukaPtolemy, uMhlaba uphakathi nendawo yesimiso sonozungezilanga. Ilanga namaplanethi ajikeleza ngendilinga (ukujikeleza), kanti isikhungo salendilinga sijikeleza uMhlaba ngendlela eyindilinga (ukuguquka).
Ngo-1543, isazi sezinkanyezi sasePoland uNicolaus Copernicus (1473–1543) waphakamisa imodeli ye-heliocentric, lapho ilanga liphakathi nendawo yesimiso selanga. Amaplanethi, okuhlanganisa noMhlaba, azungeza indilinga (ukujikeleza), kanti isikhungo salesi siyingi sizungeza ilanga ngendlela eyindilinga (uguquko). UCopernicus wayenokuqonda okuthuthukile kunoPtolemy, ebeka ilanga phakathi nendawo yesimiso selanga. Kodwa-ke, uCopernicus wayesasebenzisa izindilinga njengesibonelo semijikelezo yamaplanethi.
Isazi sezinkanyezi esidumile saseDenmark okuthiwa uTycho Brahe (1546 - 1601) saba yisazi sezinkanyezi sokugcina ukubona izinto zasezulwini sisebenzisa iso kuphela. Ngemva kokwenza ukuqaphela kusukela ngo-1576 kuya ku-1599, uTycho Brahe wabe esesebenzisana nesazi sezinkanyezi saseJalimane, uJohannes Kepler (1571 - 1630), owayeyisazi sezibalo futhi. UKepler wayengumsizi kaTycho Brahe. Ukubambisana phakathi kukaTycho Brahe noKepler akuzange kuhlale isikhathi eside ngoba uTycho Brahe washona. Ngemva kokufa kukaTycho Brahe, uKepler wasebenzisa idatha yezinkanyezi etholwe nguthisha wakhe futhi wachitha iminyaka engaba amashumi amabili yokuphila kwakhe edala imodeli yezibalo ukuchaza ukunyakaza kwamaplanethi.
Umsebenzi wokuqala kaKepler kwezesayensi yezinkanyezi, i-The Mysteries of the Universe, wanyatheliswa ngo-1596. Kuwo, wazama ukuthola ukuvumelana phakathi kwemizila yeplanethi kaCopernicus kanye nokubonwa kukaTycho Brahe. Kodwa-ke, uKepler wehluleka ukuthola ukuvumelana phakathi kwamamodeli athuthukiswe ukubonwa kukaCopernicus noPtolemy kanye noTycho Brahe. Ngakho-ke, washiya amamodeli kaPtolemaic noCopernican wazama ukuthola imodeli entsha. Ngo-1609, uKepler wathola ukuthi i-ellipse yayifanelana kahle nokubonwa kukaTycho Brahe. UKepler wayengasasebenzisi iziyingi njengesimo semizila yezidalwa zasezulwini, kodwa kunalokho ama-ellipse.
Lo mthetho wabekwa phambili nguKepler iminyaka engamashumi amahlanu ngaphambi kokuba u-Isaac Newton abeke phambili imithetho yakhe emithathu yokuhamba kanye nomthetho wendawo yonke wamandla adonsela phansi.
Umthetho Wokuqala KaKepler
Indlela yeplanethi ngayinye njengoba ijikeleza ilangai, ngesimo se-elliptical, lapho ilanga litholakala khona kwenye yezindawo ezigxile kuzo.
Umthetho Wesibili KaKepler
Umugqa ongokomfanekiso oxhumanisa ilanga neplanethi ususa izindawo ezilinganayo ngezikhawu ezilinganayo zesikhathi.
Umthetho Wesithathu KaKepler
Isilinganiso sesikwele sesikhathi kuya ku-cube yebanga elimaphakathi leplanethi ukusuka elangeni (T2/r3) ayiguquguquki futhi inani layo liyafana kuwo wonke amaplanethi.
