In simple words, Subrahmanyan Chandrasekhar was the man who told us about the evolution of stars -- where they come from and how they will come to an end. Subrahmanyan Chandrasekhar explained this before he turned 20. The Chandrasekhar Limit is named after him.
Subrahmanyan Chandrasekhar's works included a wide variety of subject, from contemporary understanding of stellar structure and white dwarfs to mathematical theory of black holes and theory of colliding gravitational waves.
NASA in 1979 named the third of its four "Great Oservatories after Subrahmanyan Chandrasekhar. The Chandrasekhar Number is also named after him and so is 1958 Chandra, an asteroid.
"Today's Doodle illustrates one of the most important of all of S. Chandrasekhar's contributions to our understanding of stars and their evolution: The Chandrasekhar limit. The limit explains that when a star's mass is lighter than 1.4 times that of the sun, it eventually collapses into a denser stage called a "white dwarf." When heavier than 1.4, a white dwarf can continue to collapse and condense, evolving into a black hole or a supernova explosion," Google said on the Doodle.
Subrahmanyan Chandrasekhar studied at the Presidency College in Madras, currently Chennai and then went on to study at the University of Cambridge. However, most of Subrahmanyan Chandrasekhar's life was spent at the University of Chicago, where he served from 1934 to 1995, when he died of a heart-attack at the age of 84.
Subrahmanyan Chandrasekhar was married to his college time love Lalitha Doraiswamy. Interestingly, Subrahmanyan Chandrasekhar was the nephew of renowned scientist CV Raman.