The Day-Night Effect in SNO: Beyond the Solar Neutrino Problem

Results from the Sudbury Neutrino Observatory (SNO) experiment have demonstrated that electron neutrinos produced in the solar interior change flavor prior to reaching the earth, thus resolving the long-standing ``Solar Neutrino Problem.'' Far from being the end of the story, these and other recent neutrino physics results have opened up a rich field of fundamental questions to be probed by current and future experiments. The day-night asymmetry measurement performed during the second phase of the SNO experiment will be described, emphasizing the role that solar neutrino experiments play in exploring fundamental neutrino physics.