An Etymological Dictionary of Astronomy and Astrophysics

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.

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