Carl Sagan is a well known scientist from the 70s/80s and also a controversial part of ufology history. This is in part because of some of the contradictory statements he had made about UFOs, extraterrestrials, and surrounding subjects, and how he became somewhat of a mouthpiece for some anti-ufo propaganda.
However, he was also outspoken in favor of nuclear disarmament (coincidentally, this is in alignment with what seems to be UFO/ET interests in the same goal), and a big part of both conversations in mainstream media. People also wonder if this was in part one of his connections to the government as well. Either way, he became a known face and personality for the subjects of planetary science, Ugology, and his name will forever be synonymous with the 70s/80s Ufology community and a part of the mainstream media covering the topic during his time on television.
One thing is for sure, a lot of controversy remains around Carl and his motivations for some of his statements. Read into his full story and decide for yourself.
From his wiki:
Carl Edward Sagan (/ˈseɪɡən/; November 9, 1934 – December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, poet, 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. The most widely watched series in the history of American public television, Cosmos has been seen by at least 500 million people across 60 different countries. The book Cosmos was published to accompany the series. He also wrote the science fiction novel Contact, the basis for a 1997 film of the same name. His papers, containing 595,000 items, are archived at The Library of Congress.
Sagan advocated scientific skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI). He spent most of his career as a professor of astronomy at Cornell University, where he directed the Laboratory for Planetary Studies. Sagan and his works received numerous awards and honors, including the NASA Distinguished Public Service Medal, the National Academy of Sciences Public Welfare Medal, the Pulitzer Prize for General Non-Fiction for his book The Dragons of Eden, and, regarding Cosmos: A Personal Voyage, two Emmy Awards, the Peabody Award, and the Hugo Award. He married three times and had five children. After suffering from myelodysplasia, Sagan died of pneumonia at the age of 62, on December 20, 1996.