  We examine the maximal $\nu_e \to \nu_s$ solution to the solar neutrino
problem. This solution can be motivated by the exact parity model and other
theories. The $\nu_e$ survival probability exhibits one of three qualitatively
different behaviours depending on the value of $\Delta m^2$, viz. approximately
energy independent, just-so or MSW. By the last of these we mean an enhanced
night-time event rate due to regeneration in the Earth. We study all of these
possibilities in the context of the recent SuperKamiokande data.

High Energy Physics - Phenomenology