The atoms and molecules in a gas will absorb only certain wavelengths of light. The pattern of absorption is unique to each element and tells us what elements make up the composition of a star. The presence of dark lines are caused by gaseous elements in the star's composition absorbing light at these wavelengths. Study the spectroscopy of the four elements and a mystery star. Take note of the dark bands in the spectra, comparing the absorption spectrum of each element with the mystery star. What can you conclude about this mystery star by studying the spectroscopy?