Understanding the Sun: Borexino

Solar neutrinos have been detected over the past 40 years providing the first evidence of physics beyond the Standard Model for elementary particle interactions. The hypothesis of neutrino oscillations has offered a solution to the long-standing solar neutrino problem (missing solar neutrinos). The Solar Standard Model is a fundamental ingredient in the interpretation of the solar neutrino measurements. New determinations of solar metal abundances caused the Solar Standard Model predictions to be in conflict with helioseismological measurements. The direct measurement of 7 Be solar neutrinos performed by the Borexino experiment at the Gran Sasso Underground Laboratory allows to probe the Solar Standard Model assuming the neutrino oscillation scenario. At present Borexino has measured 7 Be solar neutrinos at the level of 10%. In the near future a measurement at the level of 5-3% could be achieved. This accuracy could allow to determine the metal abundances at the center of the Sun. In this framework solar neutrinos offer an independent method to determine the source of the conflict between Solar Standard Model and helioseismology. The Borexino results are presented and discussed in the framework of the Solar Standard Model and neutrino oscillations.