The world knew him as Chandra, a popular teacher among his students at the University of Chicago and "a beautiful and warm human being" among fellow scientists. But Subrahmanyan Chandrasekhar was far more. The Indian-American—whose familiar name means "luminous" or "moon" in Hindi—was one of the leading astrophysicists of the 20th century, so it's only fitting that NASA's third great observatory should be named for him.
Born in Lahore—at that time part of India—in 1910, Chandrasekhar came to the United States in 1937 and joined the faculty of the University of Chicago, where he continued his career until his death in 1995. He was one of the first scientists to combine the disciplines of astronomy and physics. Early on he demonstrated that there is an upper limit to the mass of a white dwarf star, the last stage in the life cycle of a star such as the sun. Chandrasekhar proved that when the nuclear energy source at a star's center is spent, it collapses to form a white dwarf. His discovery showed that stars with more mass than the sun must either explode or form black holes, now a commonly accepted idea in modern astrophysics.
Through the course of his career, Chandrasekhar published works on stellar structure, stellar dynamics, radiative transfer, hydrodynamic and hydromagnetic stability, ellipsoidal figures of equilibrium, and black holes. In 1983 he was awarded the Nobel Prize for his studies on the physical processes of the structure and evolution of stars.
The Chandra X-ray Observatory launched into orbit in July 1999 and has since enlightened astronomers about the nature of black holes, the formation of galaxies, and the life cycles of stars. It's only natural that the observatory should glide through space bearing the name of one who, as Great Britain's Astronomer Royal Sir Martin Rees put it, "probably thought longer and deeper about our universe than anyone since Einstein."