On this day in 1910 – October 19th – Indian-American astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar was born in Lahore [now part of Pakistan].

He's known for his work in stellar evolution including black holes. The Chandrasekhar Limit is the dividing line between the mass of a star that has spent its nuclear fuel and will collapse into a white dwarf and one massive enough to go out with a bang - a supernova. It's about 1.4 times the Sun's mass.