LYOT, BERNARD(-FERDINAND)

born Feb. 27, 1897, Paris, Fr. died April 2, 1952, Cairo, Egypt French astronomer who invented the coronagraph (1930), an instrument which allows the observation of the solar corona when the Sun is not in eclipse. Before Lyot's coronagraph, observing the corona had been possible only during a solar eclipse, but this was unsatisfactory because total eclipses occur only rarely and the duration of such eclipses is too short (no more than seven minutes) to allow prolonged scientific observation of the corona. Merely blocking out the Sun's radiant disk was insufficient to view the comparatively dim corona because of the diffusion of the Sun's light by the atmosphere, whose brightness rendered the delicate corona invisible. But by going to the Pic du Midi Observatory high in the French Pyrenees, where the high altitude resulted in less atmospheric diffusion, and by equipping his coronagraph with an improved lens and a monochromatic filter that he had developed, Lyot succeeded in making daily photographs of the Sun's corona. In 1939, using his coronagraph and filters, he shot the first motion pictures of the solar prominences. Lyot was elected to the Academy of Sciences in 1939 and was also awarded the Gold Medal of the Royal Astronomical Society in that year.