page_title: Carl Sagan
section_title: Scientific and critical thinking advocacy
hierarchical_section_title: Carl Sagan / Career and research / Scientific and critical thinking advocacy
caption_attribution_description: A U.S. Navy Grumman F-14A Tomcat from Fighter Squadron 114 (VF-114) Aardvarks flies over an oil well set ablaze by Iraqi troops during the 1991 Gulf War. VF-114 was assigned to Carrier Air Wing 11 (CVW-11) aboard the aircraft carrier USS Abraham Lincoln for a deployment to the Western Pacific and the Indian Ocean from 28 May to 25 November 1991. This was VF-114's last deployment before being disestablished on 30 April 1993.
context_page_description: Carl Edward Sagan was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space: the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the now-accepted hypothesis that the high surface temperatures of Venus can be attributed to and calculated using the greenhouse effect.
  Initially an associate professor at Harvard and later at Cornell, from 1976 to his death, he was the David Duncan Professor of Astronomy and Space Sciences at the latter. Sagan published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He wrote many popular science books, such as The Dragons of Eden, Broca's Brain and Pale Blue Dot, and narrated and co-wrote the award-winning 1980 television series Cosmos: A Personal Voyage.
context_section_description: Sagan's ability to convey his ideas allowed many people to understand the cosmos better—simultaneously emphasizing the value and worthiness of the human race, and the relative insignificance of the Earth in comparison to the Universe. He delivered the 1977 series of Royal Institution Christmas Lectures in London.
  Sagan was a proponent of the search for extraterrestrial life. He urged the scientific community to listen with radio telescopes for signals from potential intelligent extraterrestrial life-forms. Sagan was so persuasive that by 1982 he was able to get a petition advocating SETI published in the journal Science, signed by 70 scientists, including seven Nobel Prize winners. This signaled a tremendous increase in the respectability of a then-controversial field. Sagan also helped Frank Drake write the Arecibo message, a radio message beamed into space from the Arecibo radio telescope on November 16, 1974, aimed at informing potential extraterrestrials about Earth.
  Sagan was chief technology officer of the professional planetary research journal Icarus for 12 years. He co-founded The Planetary Society and was a member of the SETI Institute Board of Trustees. Sagan served as Chairman of the Division for Planetary Science of the American Astronomical Society, as President of the Planetology Section of the American Geophysical Union, and as Chairman of the Astronomy Section of the American Association for the Advancement of Science (AAAS).
  At the height of the Cold War, Sagan became involved in nuclear disarmament efforts by promoting hypotheses on the effects of nuclear war, when Paul Crutzen's "Twilight at Noon" concept suggested that a substantial nuclear exchange could trigger a nuclear twilight and upset the delicate balance of life on Earth by cooling the surface. In 1983 he was one of five authors—the "S"—in the follow-up "TTAPS" model (as the research article came to be known), which contained the first use of the term "nuclear winter", which his colleague Richard P. Turco had coined. In 1984 he co-authored the book The Cold and the Dark: The World after Nuclear War and in 1990 the book A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race, which explains the nuclear-winter hypothesis and advocates nuclear disarmament. Sagan received a great deal of skepticism and disdain for the use of media to disseminate a very uncertain hypothesis. A personal correspondence with nuclear physicist Edward Teller around 1983 began amicably, with Teller expressing support for continued research to ascertain the credibility of the winter hypothesis. However, Sagan and Teller's correspondence would ultimately result in Teller writing: "A propagandist is one who uses incomplete information to produce maximum persuasion. I can compliment you on being, indeed, an excellent propagandist, remembering that a propagandist is the better the less he appears to be one".  Biographers of Sagan would also comment that from a scientific viewpoint, nuclear winter was a low point for Sagan, although, politically speaking, it popularized his image amongst the public.
  The adult Sagan remained a fan of science fiction, although disliking stories that were not realistic (such as ignoring the inverse-square law) or, he said, did not include "thoughtful pursuit of alternative futures". He wrote books to popularize science, such as Cosmos, which reflected and expanded upon some of the themes of A Personal Voyage and became the best-selling science book ever published in English; The Dragons of Eden: Speculations on the Evolution of Human Intelligence, which won a Pulitzer Prize; and Broca's Brain: Reflections on the Romance of Science. Sagan also wrote the best-selling science fiction novel Contact in 1985, based on a film treatment he wrote with his wife, Ann Druyan, in 1979, but he did not live to see the book's 1997 motion-picture adaptation, which starred Jodie Foster and won the 1998 Hugo Award for Best Dramatic Presentation.
  Sagan wrote a sequel to Cosmos, Pale Blue Dot: A Vision of the Human Future in Space, which was selecte
caption: Sagan admitted that he had overestimated the danger posed by the 1991 Kuwaiti oil fires.
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