Under Sydkorset
Billedet her er fra Ultra High Definition Expeditionen til ESOs La Silla Observatorium i Chile. Det viser det Danske 1,54-meter teleskop i færd med at studere den stjernebestrøede sydlige himmel. Sydkorset, som er et af de mest markante stjernebilleder, kan ses til venstre for teleskopets åbne kuppel - lige midt i Mælkevejens bånd.
Stjernebilledet Crux (Sydkorset) kendes ved den korsformede gruppe stjerner, fire i alt: Alpha, Beta, Gamma og Delta Crucis. Den nærmeste af stjernerne befinder sig blot 88 lysår fra Jorden, og den fjerneste er 364 lysår borte. Den blåhvide stjerne Alpha Crucis, som udgør bunden af korset (længst til venstre på billedet her), er himlens 13-klareste stjerne.
Den mørke udtværede blækklat lige over Sydkorset er støvtågen Kulsækken. Den er en af de bedst synlige af de mørke tåger, og den er tydelig med det blotte øje. Det er en uigennemsigtig sky af interstellart støv, som blokerer for lyset fra de fjernere stjerner i den retning. Derfor ser det ud, som om der er et stjernefrit hul midt i Mælkevejen. Den ildrøde emissionståge IC 2948 og den markante Carinatåge ses under Korset som to lysende pletter.
Sydkorset har stor betydning på den sydlige halvkugle af Jorden. I århundreder har den ligesom Karlsvognen på nordhimlen været brugt til navigation, fordi korsets stamme peger næsten eksakt imod Himlens Sydpol. Sydkorset har også haft en stor rolle i de religiøse ideer i mange af de sydlige kulturer, det indgår i bomærket for Det Europæiske Sydobservatorium, ESO, og det er med på en del af nationalflagene for stater på Jordens sydlige halvkugle.
Set med det blotte øje, er Sydkorset ikke særligt symmetrisk, blandt andet fordi den røde stjerne syner meget svagere end de andre. Mange turister, som tror, de har fået udpeget Sydkorset på himlen, har i virkeligheden set et langt større og mere symmetrisk kors af stjerner, som udgør en del af stjernebilledet Vela. Den stjernegruppe kaldes derfor ofte blandt kendere for Det falske Kors.
Kilde:ESO/B. Tafreshi
Om billedet
| Id: | potw1832a |
| Sprog: | da |
| Type: | Foto |
| Udgivelsesdato: | 6. august 2018 06:00 |
| Størrelse: | 6144 x 4096 px |
Om objektet
| Navn: | Danish 1.54-metre telescope |
| Type: | Unspecified : Technology : Observatory : Telescope |
Billedformater
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