A simplified version of the Hertzsprung-Russell diagram of the original Hubble data, this graph schematically plots the brightness of the stars in globular cluster NGC 2808 (along the vertical axis) against stellar color and temperature (along the horizontal axis). The cooler a star is, the redder it appears, and it diminishes in brightness. The bluer stars are to the left; redder stars are to the right. The brightest stars are near the top. The three curves represent the three different populations of stars that are present in NGC 2808.