Kuva turi abana, iyo dushushanya ikirere ntabwo dushidikanya cyane ku ibara ry’izuba; hafi buri gihe turishushanya mu ibara ry’umuhondo.
Iyo dushaka ko riboneka cyane mu mabara, wenda twongeraho imirasire ya orange cyangwa umutuku.
Kandi iyo icyo dushushanya ari izuba rirasa cyangwa rirenga, akenshi izuba n’ikirere tubishushanya mu ibara rya orange cyangwa umutuku.
Nyamara, iyi nyenyeri umubumbe wacu uzungurukaho si umuhondo, si orange, yewe si umutuku.
Nk’ikintu cyose kimurika, iyi nyenyeri nini itunga urumuri mu isanzure ririmo amabara.
Kandi iyo urebye izuba ukoresheje ikinyampande cya prisme, ushobora kubona ko urumuri rw’izuba rwicamo; umutuku, orange, umuhondo, icyatsi kibisi, ubururu, umwura (violet) na indigo.
Mu yandi magambo, izuba ryaba rifite amabara nk’ay’umukororombya!
Mu by’ukuri, imikororombya nta kindi uretse urumuri rw’izuba runyuze mu bitonyanga by’amazi biri mu kirere biba bimeze nka prisme ntoya.
Gusa, mbere yo gutangira umukino wo gushushanya izuba rifite amabara menshi, ni byiza ko tubanza gusobanura ko iki gishushanyo nacyo kidasobanuye ko ari gutyo izuba risa.
Iyo urumuri rw’aya mabara yose avanze rurekuwe n’izuba, tubona urumuri rw’ibara rimwe, kandi muratangazwa no kumenya iryo ari ryo.
Murashaka ikimenyetso?
Nimurebe ibicu, iyo bimuritsweho n’izuba. Ntabwo biba ari umuhondo cyangwa bifite amabara menshi. Biba ari umweru, kuko ari ryo bara mu by’ukuri izuba rirekura.
Kuki turibona ari umuhondo?
Kuri buri hantu izuba riri kugeza imirasire, iyo mirasire iba ifite uburebure butandukanye.
Imiremire kurusha indi ni iy’ibara ry’umutuku. Iyo mirasire igenda yegerana yivanga... kuva ku miremire ya orange ijya mu muhondo, mu cyatsi kibisi, mu bururu, muri indigo kugeza mu mwura ari wo murasire mugufi.
Uduce tw’amabara agize imirasire migufi nitwo dukwirakwira cyane kurusha utw’imirasire miremire.
Ariko kuko urumuri rugenda mu kirere nta kirukoma imbere, nta kintu gishobora guhindura utwo duce tugize amarabara.
Kubera iyo mpamvu, iyo urebye izuba uri mu kirere, uduce tugize ayo mabara yose tugera icyarimwe ku gace k’ubwonko bwacu kitwa ’visual cortex’ gashinzwe gutunganya ibyo tubona,maze tukabona ni urumuri rw’umweru.
Iryo niryo bara "ry’ukuri" ry’izuba.
Ku rundi ruhande, iyo imirasire y’izuba iciye mu kirere cy’isi yacu, uduce tugize umwuka duhindura ibigize imirasire migufi bigatuma imirasire miremire ariyo itugeraho mbere.
Ángel Molina umuhanga mu by’ikirere ati: "Atmosphere itangira igice gifite imbaraga kurusha ibindi cy’iyo mirasire, icyo ni ikigize imirasire migufi ya ultraviolet n’igice cy’ubururu.
"Nuko, mu gufata icyo gice cy’imirasire, twebwe ibyo tubona turi ku isi ni ibara rigana cyane cyane ku muhondo."
None kuki tubona izuba rijya kuba umuhondo aho kuribona muri ya mabara y’imirasire miremire y’umutuku na orange?
Umuhanga mu by’ikirere Gonzalo Tancredi wo muri Université de la République muri Uruguay, yabwiye BBC Mundo ko mu gutangira/guhagarika kubera mu kirere ahanini amabara y’imirasire migufi kuva ku mwura kugera ku cyatsi kubisi asigara, igikomeza hagati mu kirere ari umuhondo.
Izuba ry’icyatsi ?
Tancredi asobanura kandi impamvu imbuga nyinshi kuri internet zivuga ko izuba mu by’ukuri ari icyatsi kibisi.
Ati: "Iyo ukoze ishusho y’aho imirasire y’izuba iva ikagera (solar spectrum), iboneka nk’umusozi kandi ku gasongero kawo haba hari agace k’icyatsi."
Mu yandi magambo, kuko amaso ya muntu atabasha gutandukanya amabara y’imirasire y’izuba, iyo uyirebesheje ibikoresho byabugenewe, ubona ko imirasire y’icyatsi ari yo yiganje.
Ibyo bifasha gusobanura impamvu ku isi tubona izuba ari umuhondo, nk’uko uyu muhanga abisobanura.
Ati: "Iyo ukuyeho igice cy’ubururu n’igice cy’imirasire migufi kuri uwo musozi, agasongero gasigara ari umuhondo."
None ko iyo rirenga riba ritukura?
Ubu tumaze kumenya impamvu tubona izuba ari umuhondo, nubwo rirekura urumuri rwera. Ariko se ni kuki rihindura ibara iyo rirasa mu gitondo n’iyo rirenga nimugoroba?
Uwabonye wese izuba rirasa n’iyo rirenga abona amabara atangaje iyi nyenyeri iba irekura, ahindura ikirere mo orange n’umutuku.
Nanone, ni amabara aboneka gutyo kubera guhura kw’imirasire y’izuba n’ibiri mu kirere cy’isi yacu.
Mu kuri, iyo rirasa cyangwa rirenga, izuba riba riri ku mpera (horizon) bityo imirasire yaryo ikanyura mu duce (molécules) twinshi tw’ikirere, ku buryo gutangira/guhagarika imirasire y’ubururu biba ifite imbaraga.
Ubwo buryo bwo "gusiga" ikirere cyacu amabara atandukanye bitewe n’aho izuba riri ugereranyije n’isi byahawe izina rya: Rayleigh scattering.
Mu buryo bugaragara neza kuri benshi mu gitondo kare no kuri ’kiberinka’ (rirenga), niho haboneka imirasire miremire kurusha iyindi; umutuku na orange.
Twizeye ko iyi nkuru ibafashije kugira icyo mumenya kuri iyi nyenyeri yacu itangaje.
Birumvikana ko tutasoza tutabibukije ko ari bibi cyane kurebesha amaso yanyu mu zuba, yewe no gukoresha indebakure nka télescope na jumelles, kuko bitera ibibazo bikomeye ku maso byavamo n’ubuhumbyi.
BBC
