We explore the earth matter effects on the energy spectra of neutrinos from a
supernova. We show that the observations of the energy spectra of νe and
νˉe from a galactic supernova may enable us to identify the solar
neutrino solution, to determine the sign of Δm322, and to probe the
mixing matrix element ∣Ue3∣2 to values as low as 10−3. We point out
scenarios in which the matter effects can even be established through the
observation of the spectrum at a single detector.Comment: 8 pages LaTeX, 2 eps figures, uses Rinton-P9x6.cls. Talk given at
CICHEP '2001, Cairo, Egypt, January 200