Lyot, Bernard Ferdinand
French astronomer. He also designed and constructed optical instruments. He concentrated on the study of the solar corona, for which he devised the coronagraph and the photoelectric polarimeter, and he proved that some of the Fraunhofer lines in the solar spectrum represent ionized forms of known metals rather than undiscovered elements.
Lyot was born in Paris and graduated from the Ecole Supérieure d'Electricité. From 1920 he worked at the Meudon Observatory, becoming chief astronomer 1943.
Study of Moon
Most of Lyot's research during the 1920s was devoted to the study of polarized light, reflected to the Earth from the Moon and from other planets. In addition to designing a polariscope of greatly improved sensitivity, Lyot reported 1924 that the Moon was probably covered by a layer of volcanic ash and that duststorms were a common feature of the Martian surface.
Study of Sun
His most striking achievement was the observation of the Sun's corona in full daylight 1931, using a coronagraph he designed 1930. By making it possible to observe the Sun's corona in broad daylight rather than only during eclipses, the instrument also permitted the observation of continuous changes in the corona. This meant that the corona could be filmed, as Lyot demonstrated for the first time 1935. He also reported the rotation of the corona in synchrony with the Sun.
In addition he developed the Lyot filter for observing the Sun's disc in the light of a single spectral line. He continued solar and planetary observations at the Pic du Midi observatory, and died suddenly in Egypt shortly after observing the total solar eclipse 1952.
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