Why do some stars appear red or orange instead of white or blue?

Stars behave roughly like blackbodies, so their color shifts with temperature. Cooler stars, such as many red dwarfs and red giants, emit more of their light at longer wavelengths and therefore look redder. Hotter stars emit more blue and ultraviolet light, so they appear white-blue to our eyes. The Sun, at about 5,800 kelvin, is close to white but can look yellowish from the ground because of atmospheric scattering. Color is a key clue to a star’s temperature and evolutionary stage.