Colonization of Venus
Venus's atmosphere is made mostly out of carbon dioxide, which, after filtering from sulfuric acid, can be used to grow food. Because nitrogen and oxygen are lighter than the carbon-dioxide that makes the atmosphere, breathable-air-filled balloons will float at a height of about . At this height, the temperature is a manageable ; or if we could get higher (see ).
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.