What spectral property reveals the chemical makeup of stars?

• A. Fingerprint
• B. Barcode
• C. Signature
• D. Code

Answer: (A)

Spectroscopy reveals what stars are made of because atoms absorb and emit light at very specific wavelengths, producing a pattern of lines that is unique to each element. This pattern acts like a fingerprint for the elements present in a star. By comparing the observed spectral lines with laboratory spectra, astronomers can identify which elements are in the star and estimate how much of each element there is. That distinctive, element-by-element pattern is why we describe the spectral property as a fingerprint of stellar chemistry. The other ideas—barcodes, signatures, or codes—don’t capture this precise, element-specific pattern scientists use to read a star’s composition.