Meghnad Saha (6.10.1894-16.02.1956) — Indian physicist and astrophysicist, a member of the National Academy of Sciences. Born in Shaoratoli (now Bangladesh). Graduated from the University of Calcutta (1915), where he worked in 1916 — 23 (a professor from 1921). In 1923 —38 he was a professor at Allahabad University, and in 1938 —55 at Calcutta. Founder (1951) and director of the Institute of Nuclear Physics in Calcutta.
His work was in thermodynamics, statistical mechanics, astrophysics, cosmic-ray physics, ionospheric radiation, geophysics, the theory of radiation and nuclear physics. He developed the ionisation theory (the Saha theory), which became the basis for the study of stellar atmospheres. In 1920 he proposed the formula that determines the degree of thermal ionisation in a gas (the Saha formula). He wrote the equation that establishes how the degree of surface ionisation depends on the temperature of a metal surface, its work function and the ionisation potential of the ionised atoms (the Langmuir–Saha equation).
Founder of various Indian scientific organisations and an active public figure. A Fellow of the Royal Society.