The solar-neutrino problem, 1995.

The status of the Solar-Neutrino Problem (SNP), as is seen in 1995, is reviewed. Basically, there are two principal solutions to the SNP: i) with standard neutrino (neutrino of SM of electroweak interactions) and ii) with non-standard neutrino (neutrino beyond the SM). Actually, one can distinguish three solar-neutrino problems: the deficit of B-8 neutrinos, the deficit of Be-7 neutrinos and the HOMESTAKE/KAMIOKANDE conflict. The first problem probably can be solved with small correlated changes of nuclear cross-sections and the change of the central temperature of the Sun. The deficit of Be-7 neutrinos looks like the key problem. The HOMESTAKE/KAMIOKANDE conflict strongly disfavours or excludes the standard neutrino (nuclear/astrophysical solution to the SNP). MSW conversion gives a most plausible explanation to the SNP.