| Citation | Distinguished for his theoretical work on helioseismology, which has given the first accurate determination of the depth of the solar convection zone and the first determination of the internal rotation of the sun. He has played a major role in designing suitable measurements of solar oscillations from spacecraft. In astrophysical fluid dynamics he has made inventive calculations of convective instabilities. He made the first calculation of the interaction of stellar pulsation with convection and showed how convection might limit the red extension of the instability strip in the HR diagram. He demonstrated that one possible explanation of the solar neutrino problem envolves a turnover of the core predicted from an instability of the standard solar model. |