Published online by Cambridge University Press: 23 May 2005
The atmosphere of Venus was discovered for the first time by the Russian scientist Mikhail V. Lomonosov at the St Petersburg Observatory in 1761. Lomonosov detected the refraction of solar rays while observing the transit of the planet across the disk of the Sun. From these observations he correctly inferred that only the presence of refraction in a sufficiently thick atmosphere could explain the appearance of a light (‘fire’) ring around the night disk of Venus during the initial phase of transit, on the side opposite from the direction of motion. Lomonosov described this phenomenon, which carries his name, as the appearance ‘of a hair-thin luminescence’, which encircled a portion of the planet's disk that had not yet contacted the solar disk. He also observed a bulge set up at the edge of the Sun during the egress phase of the Venus transit. ‘This bears witness to nothing less than the refraction of solar rays in the Venusian atmosphere’, he wrote. This paper is based on the original Lomonosov publications and describes historical approaches to the study involving procedure, drawings, and implications.