rhamphotheca:

The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars’ absolute magnitudes or luminosities versus their spectral types or classifications and effective temperatures. Hertzsprung–Russell diagrams are not pictures or maps of the locations of the stars. Rather, they plot each star on a graph measuring the star’s absolute magnitude or brightness against its temperature and color… (read more: Wikipedia)

(via scientificillustration)