Published online by Cambridge University Press: 12 April 2016
As it is impossible to approach all the problems concerning the inside of the Sun, a number of questions will not be taken into consideration during the meeting. In this brief overview of the presently unsolved questions I shall insist on some special aspects of the solar properties: the variations of the solar radius, the generation of the solar wind, some interesting effects due to the presence of a strong gradient of 3He, the history of the rotating Sun. The presence of the planetary system suggests that the Sun might have been a T Tauri star, with an accretion disc and may have started on the mains sequence as a fast rotating star. A sketch is given of the possible consequences.