Atmosphere of Venus
In 1761, Russian polymath Mikhail Lomonosov observed an arc of light surrounding the part of Venus off the Sun's disc at the beginning of the egress phase of the transit and concluded that Venus has an atmosphere. In 1940, Rupert Wildt calculated that the amount of CO in the Venusian atmosphere would raise surface temperature above the boiling point for water. This was confirmed when Mariner 2 made radiometer measurements of the temperature in 1962. In 1967, Venera 4 confirmed that the atmosphere consisted primarily of carbon dioxide.
Venus in fiction
Others expected that the planet would have land masses, but not dry ones. In 1918, chemist and Nobel Prize winner Svante Arrhenius, deciding that Venus's cloud cover was necessarily water, decreed in "The Destinies of the Stars" that "A very great part of the surface of Venus is no doubt covered with swamps" and compared Venus' humidity to the tropical rain forests of the Congo. Because of what he assumed was constantly uniform climatic conditions all over the planet, the life of Venus lived under very stable conditions and did not have to adapt to changing environments like life on Earth. As a result of this lack of selection pressure, it would be covered in prehistoric swamps. Venus thus became, until the early 1960s, a place for science fiction writers to place all manner of unusual life forms, from quasi-dinosaurs to intelligent carnivorous plants. Comparisons often referred to Earth in the Carboniferous period.