Figure 3-44 Solar Spectrum Starlight passing through a prism or diffraction grating spreads into its component colors. From such spectra we can learn an incredible amount about stars, including their masses, surface temperatures, diameters, chemical compositions, rotation rates, and motions toward or away from us. This image, called a spectrogram, shows the spectrum of the Sun sliced and stacked to fit on this page. In it you can see thousands of absorption lines. As you study spectra, also note the distinct differences between the intensities of the various colors emitted by each star and by different stars.