An Etymological Dictionary of Astronomy and Astrophysics
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An equation that gives the number of atoms of a given species in various stages of → ionization that exist in a gas in → thermal equilibrium as a function of the temperature, density, and ionization energies of the atoms.

Named after the Indian astrophysicist Megh Nad Saha (1894-1956), who first derived the equation in 1920; → equation.