L’Atmosphere du Soleil et des Etoiles

Summary

The Sun is a very pleasant star to study: it is the closest, by far, and we can study all the details of its surface. Actually, the number of photons reaching the Earth from the Sun is tremendously bigger than the number of photons from the rest of the Universe, meaning that we have much more information from our star Sun than from the rest of the Universe.

This lecture was given at rather short notice, in place of the lecture which was prepared on the same subject by Professor Vainu Bappu, and because of his bad health. A few days later, we all learnt of the untimely death of our friend Vainu Bappu, President of the International Astronomical Union. In spite of the lack of originality of this talk, which has been using many of the slides prepared for it by Vainu, and which has been, in many respects, a reiteration of ideas given at some recent occasions, the author wishes to dedicate this paper to the memory of a fine scientist, and of an old friend, to the memory of Vainu Bappu, whose personal contribution has been so important in the field covered (as seen hereafter). (The lecture was delivered in French, slides being commented in English).