Kayan Dokar Kepler
Shin ka tuna lokacin farko da ka hau mota (ba lokacin da kake jariri ba)? Lokacin da kake cikin mota mai motsi, ka ga kamar bishiyoyi ko gine-gine suna motsi. A lokacin, za ka iya tunanin bishiyoyi ko gine-gine suna motsi, yayin da kai da motar kake motsi. A zahiri, kai da motar kuna motsi, yayin da bishiyoyi ko gine-gine suke tsaye. A zahiri muna fuskantar wannan motsi ko motsi na ƙarya kowace rana. Kowace safiya rana tana "fitowa" a sararin sama na gabas, sannan ta motsa yamma ta "faɗi" a sararin sama na yamma da rana. Haka nan, da dare, sau da yawa kana ganin wata yana motsawa daga gabas zuwa yamma. Shin ka taɓa tunanin ko ka yi zargin cewa rana da wata suna motsawa a duniya, yayin da duniya take tsaye?
Tsoffin mutane (farkon AD) sun kuma yi imani da cewa rana, wata, da sauran halittun sama suna kewaye da Duniya, yayin da Duniya ta kasance a tsaye. A wata ma'anar, an ɗauke Duniya a matsayin cibiyar sararin samaniya (geocentric). Wannan zato ya dogara ne akan ƙarancin ƙwarewar motsin rai na ɗan adam, wanda ke lura da rana, wata, da taurari suna motsi kowace rana, yayin da ake ganin Duniya a matsayin a tsaye. Yana kama da lokacin da kake cikin mota mai motsi, ganin kamar bishiyoyi ko gine-gine suna motsi. Wannan ra'ayin cewa Duniya ita ce cibiyar sararin samaniya an yi bincike kuma an ƙirƙira shi ta masanin ilmin taurari na Girka Claudius Ptolemy (100-170 AD) a ƙarni na biyu AD kuma an yi imani da shi tsawon shekaru 1400 masu zuwa.
A cewar Ptolemy, Duniya tana tsakiyar tsarin hasken rana. Rana da taurari suna zagaye a cikin da'ira (juyawa), inda tsakiyar wannan da'irar ke zagaye Duniya a cikin hanyar da'ira (juyin juya hali).
A shekara ta 1543, masanin ilmin taurari ɗan ƙasar Poland Nicolaus Copernicus (1473–1543) ya gabatar da samfurin da ke tsakiyar sararin samaniya, wanda rana take tsakiyar tsarin hasken rana. Duniyoyin duniya, ciki har da Duniya, suna zagaye da'ira (juyawa), tare da tsakiyar wannan da'irar tana zagaye rana a cikin hanyar da'ira (juyin juya hali). Copernicus yana da fahimta mafi zurfi fiye da Ptolemy, yana sanya rana a tsakiyar tsarin hasken rana. Duk da haka, Copernicus har yanzu yana amfani da da'ira a matsayin samfurin kewayar taurari.
Wani shahararren masanin ilmin taurari ɗan Denmark mai suna Tycho Brahe (1546 - 1601) shi ne masanin ilmin taurari na ƙarshe da ya kalli abubuwan sama ta amfani da ido kawai. Bayan ya yi nazari daga 1576 zuwa 1599, Tycho Brahe ya yi aiki tare da wani masanin ilmin taurari ɗan Jamus, Johannes Kepler (1571 - 1630), wanda shi ma masanin lissafi ne. Kepler shi ne mataimakin Tycho Brahe. Haɗin gwiwar da ke tsakanin Tycho Brahe da Kepler bai daɗe ba saboda Tycho Brahe ya mutu. Bayan mutuwar Tycho Brahe, Kepler ya yi amfani da bayanan ilmin taurari da malaminsa ya samu kuma ya shafe kimanin shekaru ashirin na rayuwarsa yana ƙirƙirar samfurin lissafi don bayyana motsin duniyoyi.
An buga littafin Kepler na farko a fannin ilmin taurari, The Mysteries of the Universe, a shekarar 1596. A cikinsa, ya yi ƙoƙarin gano jituwa tsakanin kewayar taurarin Copernicus da kuma lurar Tycho Brahe. Duk da haka, Kepler ya kasa samun jituwa tsakanin samfuran da aka ƙirƙiro ta hanyar lurar Copernicus da Ptolemy da Tycho Brahe. Saboda haka, ya yi watsi da samfuran Ptolemaic da Copernican ya kuma yi ƙoƙarin nemo sabon samfuri. A shekarar 1609, Kepler ya gano cewa ellipse ɗin ya yi daidai da lurar Tycho Brahe. Kepler bai sake amfani da da'ira a matsayin siffar kewayar halittun sama ba, sai dai ellipses.
Kepler ya gabatar da wannan doka rabin ƙarni kafin Isaac Newton ya gabatar da dokokinsa guda uku na motsi da kuma dokar nauyi ta duniya.
Dokar Farko ta Kepler
Hanyar kowace duniya yayin da take kewaya ranai, siffar ellipse, inda rana take a ɗaya daga cikin wuraren da aka fi so.
Dokar Kepler ta Biyu
Layin tunani da ke haɗa rana da wata duniya yana share wurare daidai gwargwado a cikin tazara tsakanin lokaci.
Dokar Kepler ta Uku
Rabon murabba'in lokaci zuwa kubiyar matsakaicin nisan da duniya ke da shi daga rana (T)2/r3) yana da daidaito kuma ƙimarsa iri ɗaya ce ga dukkan duniyoyi.
