Carl Sagan

Carl Sagan was an American astronomer and planetary scientist who made significant contributions to the study of other planets while also becoming one of the most widely known popularizers of science of the twentieth century. As a researcher, Sagan helped explain the extreme surface temperature of Venus as the result of a runaway greenhouse effect trapping heat in its thick carbon dioxide atmosphere, contributed to the analysis of data returned by numerous NASA robotic missions exploring the solar system, and was an early and persistent advocate for the scientific search for extraterrestrial life, helping design experiments carried on the Viking Mars landers intended to test for microbial life in Martian soil. Sagan led the effort to design physical messages intended for any intelligent life that might one day encounter them in deep space, including the plaques carried aboard the Pioneer 10 and 11 spacecraft and the Voyager Golden Record, a phonograph disc carried aboard the Voyager 1 and Voyager 2 probes containing sounds, images, spoken greetings in dozens of languages and music intended to represent life and culture on Earth. Sagan spent most of his research career as a professor at Cornell University, where he directed the Laboratory for Planetary Studies, and he reached an enormous global audience through his 1980 television series Cosmos: A Personal Voyage and its accompanying book, which did more than perhaps any other single work to popularize astronomy and the scientific method for a general public audience.