Chaka Chowala

Pali nyenyezi 33 mkati mwa zaka 12.5 zowala kuchokera ku Sun

Chaka chowala ndilo gawo la kutalika komwe limagwiritsidwa ntchito pofotokoza kutalika kwa zakuthambo ndi makilomita 9,5 trillion kapena 5,9 trillion mailosi. Monga momwe tafotokozera ndi International Astronomical Union (IAU), chaka chowunika ndilo mtunda umene kuwala kumayenda mu chingwe chimodzi cha Julian (masiku 365.25). Chifukwa limaphatikizapo mawu oti "chaka", mawu akuti chaka chowala nthawi zina amamasuliridwa mofanana ngati gawo limodzi.

Chaka chowala nthawi zambiri chimagwiritsidwa ntchito pofotokozera kutalika kwa nyenyezi ndi kutalika kwina pamagalactic, makamaka m'mabuku a sayansi ndi odziwika bwino. Chipangizo chomwe chimagwiritsidwa ntchito kwambiri mu katswiri wa astrometry ndi parchik (chizindikiro: pc, pafupifupi 3.26 zaka-kuwala; mtunda womwe umodzi wa zakuthambo umagwiritsa ntchito mphindi imodzi ya arc).

Mbiri

Chigawo cha chaka chowonekera chinaonekera zaka zingapo pambuyo poyesa kupambana kwa mtunda wa nyenyezi osati Sun, mwa 1838 Friedrich Bessel. Nyenyeziyi inali 61 Cygni, ndipo adagwiritsa ntchito heliometer ya mamita 160 mm ndi Joseph von Fraunhofer. Chigawo chachikulu kwambiri chofotokozera kutalika kwa danga panthawiyo chinali chigawo cha astronomical unit, chofanana ndi chigawo cha dziko lapansi. Momwemo, mawerengero a trigonometric opangidwa ndi 61 Cygni's parallax of 0.314 arcseconds, adawonetsera kutalika kwa nyenyezi kuti akhale 660000 zakuthambo. Bessel anawonjezera kuti kuwala kumagwiritsa ntchito zaka 10.3 kuti apite mtunda umenewu. Anadziŵa kuti owerenga ake amasangalala ndi nthawi yeniyeni ya kuwala, komatu sanagwiritse ntchito chaka chowala ngati chigwirizano. Angakhale atakhumudwa kufotokoza kutalika kwake kwa zaka zochepa chifukwa zikhoza kuwonongera kuti mbiri yake ya parallax ikuwonjezeka chifukwa cha kuchulukitsa ndi kuthamanga kwapadera. Kufikira kwa kuwala kunalibekudziwika bwino mu 1838; mtengo wake unasintha mu 1849 (Fizeau) ndi 1862 (Foucault). Sichidawonekere kukhala chinthu chokhazikika chokhazikika, ndipo kufalikira kwa kuwala kupyolera mu malo ozungulira kapena malo anali akadakalibe. Komabe, chaka cha 1851 chinaonekera m'chaka cha 1851 m'nkhani ina yotchuka ya zakuthambo yotchedwa Otto Ule. Chododometsa cha dzina lokhala ndi mtunda wamtunda wotsirizira pa "chaka" 'adafotokozedwa ndi Ule pochiyerekezera ndi ola la msewu wodutsa (Wegstunde). Buku lina la ku Germany lotchuka kwambiri la zakuthambo linanenanso kuti chaka chowala ndi dzina losamvetsetseka. Mu 1868 magazini ya Chingerezi inalembetsa chaka chowala ngati umodzi wogwiritsidwa ntchito ndi Ajeremani. Eddington adatcha chaka choyera kukhala chinthu chosasokonekera komanso chosagwirizana, chomwe nthawi zina chimachokera ku ntchito yotchuka kupita ku kufufuza zamakono.

Ngakhale kuti akatswiri aza zakuthambo amakono amakonda kugwiritsa ntchito parsec, zaka zowala zimagwiritsidwanso ntchito kuti zizindikire malo osokoneza bongo ndi intergalactic danga.