Hertzsprung-Russell Diagram, HRD: Stellar Evolution

This Hertzsprung-Russell-diagram page and much of this entire 550-page website are excerpted from You and the Universe, a handmade, individualized fine art book on astrology, mythology and astronomy through which the recipient's complete astrological reading is woven.

A Hertzsprung-Russell (temperature-luminosity) diagram (HRD) plots stars’ absolute luminosity (intrinsic brightness) versus their spectral type (related to temperature), and indicates a star’s place in its evolution. Above is an HRD of 23,000 nearby stars. Most stars fall into the central "main sequence" where they fuse hydrogen in their cores, from hot and bright (upper left) to cooler and less bright (lower right). The Sun is on the main sequence at luminosity 1 and B-V color index 0.66 (5780° K, spectral type G2).