This lesson serves as an introduction to color and to both line spectra and continuous spectra, with applications to sunlight. It also explains how a glass prism resolves light into its rainbow components and the difference between spectral colors and the colors perceived by the eye. Students will learn that hot solids (or dense gases) radiate a continuous spectrum, related to their temperature. But the colors of a glowing rarefied gas are characteristic of the atoms emitting them. They also learn that cold atoms in a gas absorb the same colors as the ones they emit when hot, and that such absorption causes dark lines in the Sun’s spectrum. Lastly, the students learn that light is a wave with a very short wavelength on the order of a few microns (0.001 millimeter), spreading through space.