Carl Sagan was an astronomer and NASA consultant from the 1950s on. He played a major role in the US space program, and his scientific achievements included solving the mystery of Venus’s extremely high temperatures, and the unusual color of Titan, moon of Saturn. However, he is better known to the public due to his second career as an author and screenwriter.
Sagan was dedicated to the cause of popularizing science. He usually took a bi-partisan approach, but he directly grappled with contentious political issues where they related to or affected work in science. His last book, Billions and Billions, dealt with such topics as climate change denial, abortion, and social assistance. Airing in 1980, his enormously successful 13-part Cosmos television series (which was also a book) discussed the Solar System, the possibility of life on other planets, (then) current NASA projects, the history of science, and the general principles of scientific thinking. It remains the most-watched PBS series of all time.
Sagan tried hard to foster critical thinking in his readers and viewers, explaining the scientific approach to problems rather than focusing on the results. Perhaps his most significant advocacy for critical thinking can be found in The Demon-Haunted World: Science as a Candle in the Dark. It debunked both left- and right-wing myths, including conspiracy theories that aliens built the pyramids, or that the Earth is only a few thousand years old. Throughout, he carefully laid out the evidence for and against each proposal, and took the reader through each argument step-by-step.
Beyond the general cause of a more scientifically-literate populace, Sagan was a strong supporter of environmentalism, space exploration, and the SETI (Search for Extra-Terrestrial Intelligence) project. Sagan was awarded the NASA Medal for Exceptional Scientific Achievement, but he was also awarded the NASA Medal for Distinguished Public Service twice, in recognition of his advocacy of and public education on science.
He also wrote a screenplay for a movie, Contact, in the early 1980s. When production fell through, he adapted it into a novel. In 1997, the revived film was released, starring Jodie Foster and Matthew and McConaughey.
Sagan died from a recurring cancer in 1996. This year, a sequel to his Cosmos series has been announced. It will air in 2013, hosted by science popularizer and astrophysicist, Neil Degrasse Tyson. Appropriate to Sagan’s mission, the sequel program will air on FOX in prime-time, in order to reach as many people as possible.