Det falske daggry
Himlen er fuld af optiske fænomener, som kan gøre det besværligt at se uforstyrret på det store kosmos. Det er især astronomerne, som ofte bliver frustrerede, men hvis man er astrofotograf kan himmelfænomenter være med til virkelig at gøre billederne ekstra lækre. Billedet her viser centeret af e Mælkevejen, med et spøgelsesagtigt skær tværs over; det, som kaldes zodiakallyset. Det lysskær er stopfyldt med effekter fra det støv, som det består af, og det forstyrrer så afgjort videnskabelige observationer - men det er så pænt, at det er svært at være utilfreds.
Mælkevejens centralområder ser på billedet ud til at være fyldt med blæksort gas. Faktisk er de mørke hvirvler blot områder, hvor der mangler lys i det synlige område, fordi enorme støvskyer spærrer for lyset fra de fjernere stjerner. På samme måde som støvet kan få noget til at se mørkt ud, kan det så også under andre omstændigheder være lysende. Det er netop det, der er tilfældet med zodiakallyset. Det er en sløret stribe lys, som vi kan se langs med det område på himlen, hvor dyrekredsens stjernebilleder. befinder sig. Når sollys bliver spredt af den skive af støv, som befinder sig i det indre solsystem, ser vi den effekt. Øvede observatører kan endog se detaljer i selve det lysende spor, og en af de mere markante detaljer er det, som kaldes Gegenschein. Det er en svagtlysende elliptisk plet, som kan ses i punktet lige modsat der, hvor Solen befinder sig - på billedet er det ude til venstre. Til højre i billedet ser man zodiakallyset som en lyssøjle; det, som også kaldes "det falske daggry" fra horisonten og opefter på himlen.
Billedet er optaget i løbet af en hel nat, og det er ESOs fotoambassadør Petr Horálek, som har stået for billedebehandlingen. Det helt enestående billede er optaget ved ESOs La Silla Observatorium i Chile.
Kilde:
ESO/P. Horálek
Om billedet
| Id: | potw1707a |
| Sprog: | da |
| Type: | Foto |
| Udgivelsesdato: | 13. februar 2017 06:00 |
| Størrelse: | 18510 x 4757 px |
Om objektet
| Type: | Unspecified : Sky Phenomenon : Night Sky : Zodiacal Light |
Billedformater
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