• A star's apparent brightness depends on its luminosity and distance from Earth. Separately, Hertzsprung and Russell deduced that different types of stars had different characteristics. Hertzsprung-Russell (H-R) diagrams are a way of organizing their results. H-R diagram shows a narrow band of stars from the top left (bright, hot stars) to the lower right (dimmer, cooler stars) (dim, cool stars). The majority of stars, including the Sun, are located on the main sequence.