The Sudbury Neutrino Observatory (SNO) in Ontario is designed to solve the solar neutrino problem that cropped up in 1967. Nuclear physicists and astrophysicists have predicted the number of neutrinos produced in solar fusion that should arrive on Earth -- but experimentalists detect only about a third as many. The solution of the mystery may require that neutrinos have mass, and avoid detection by changing character on their way to Earth. The experiment illustrates the interdependence of the atomic and the cosmic realms in a particularly compelling way.
The solar neutrino puzzle may be solved.