Modern forms plot luminosity versus temperature backwards on the axes, revealing clear trends among the stars.
It's namesake scientists, Ejnar and Henry Norris, independently used these in 1911 and 1913 to organize their stellar data. They originally plotted either color or spectral type on the horizontal axis, while distances from recent parallax measurements allowed absolute magnitude to be plotted vertically. Modern forms plot luminosity versus temperature backwards on the axes, revealing clear trends among the stars. FTP, name these graphs which revolutionized theories concerning stellar evolution, marked by the main sequence running across its diagonal.
It's namesake scientists, Ejnar and Henry Norris, independently used these in 1911 and 1913 to organize their stellar data.
{Hertzsprung-Russell} Diagram or {H-R} Diagram