Final answer:
The absorption of light in stars' atmospheres helps scientists determine their chemical composition through unique spectral signatures.
Explanation:
The scientific phenomenon that helps scientists determine the chemical composition of some stars is the absorption of light. When light from an astronomical source passes through elements in a star's atmosphere, certain wavelengths are absorbed, leaving a unique spectral signature that indicates the elements present. This process is key in spectroscopy to identify the chemical makeup of celestial bodies.
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