Dr. Meghnad Saha’s most celebrated work was done in Kolkata. It led to his theory of high temperature ionization of atoms and its application to stellar atmospheres. His paper provided for the first time a straightforward interpretation of the different classes of stellar spectra in terms of the physical conditions, like temperature and pressure, prevailing in the stellar atmospheres. It thus acquired fundamental importance for all future work in astrophysics.

In 1919, the Premchand Raychand Scholarship took Saha to Europe for about two years. He spent five months in Imperial College, London, where he developed his theory further with the help of Professor A.Fowler. In November 1921 Saha returned to Kolkata as Khaira Professor of Physics, a new chair