We learned today that astronomer Professor John Bahcall died Wednesday, August 17 due to a blood disorder. His obituary is given here.
John Bahcall was famous for helping in our understanding of how the sun works, especially in regard to the mystery of neutrinos, nearly-massless particles that are created during nuclear reactions. The detection of neutrinos coming from the sun proved that nuclear reactions provide the sun's power. But, under the early thought that neutrinos were massless particles, we only detected 1/3 the expected number. Recently it has been shown that neutrinos do have a small mass, and complex physics then explains why we only see 1/3 the number (in short, neutrinos can change into other types of neutrinos due to quantum mechanics).
Due in a large part to Professor Bahcall's work, we now understand the interior of the sun to very high precision. His contributions are enormous, and he and his mind will be missed greatly.