wanted to know more. father held from iraq wants to know. how do scientists determine the chemical composition of faraway stars. by the one thing i met split into its color components light forms a continuous spectrum. when light impinges on atoms or molecules a portion of it is absorbed that create black lines a distinct frequency. in some ways it's like a fingerprint. all the elements in a store leave their fingerprint in the light spectrum that it emits. these spectra can differ greatly that's because the cocktail of elements that make up a star changes. over time. this is what the spectrum produced