The Online Encyclopedia and Dictionary






Carl Sagan

 A respected astronomer and dogged critic of pseudoscience, Carl Sagan is best known for his enthusiastic efforts at popularizing science.
A respected astronomer and dogged critic of pseudoscience, Carl Sagan is best known for his enthusiastic efforts at popularizing science.

Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer and science popularizer. He pioneered exobiology and promoted the Search for Extraterrestrial Intelligence (SETI). He is world-famous for his popular science books and the television series Cosmos, which he co-wrote and presented. In his works he frequently advocated the scientific method.


Education and scientific career

Carl Sagan was born in Brooklyn, New York. His father, Sam Sagan, was a Jewish garment worker and his mother, Rachel Molly Gruber, was a housewife. Sagan attended the University of Chicago, where he received a bachelor's degree (1955) and a master's degree (1956) in physics, before earning his doctorate (1960) in astronomy and astrophysics. He taught at Harvard University until 1968, when he moved to Cornell University.

Sagan became a full professor at Cornell in 1971 and directed a lab there. He contributed to most of the unmanned space missions that explored our solar system. He conceived the idea of adding an unalterable and universal message on spacecraft destined to leave the solar system, that could be understood by any extraterrestrial intelligence that might find it. The first message that was actually sent into space was a gold-anodized plaque attached to the space probe Pioneer 10. He continued to refine his designs and the most elaborate such message he helped to develop was the Voyager Golden Record that was sent out with the Voyager space probes.

Scientific achievements

He was well known as a coauthor of the scientific paper that warned of the dangers of nuclear winter. He furthered insights regarding the atmosphere of Venus, seasonal changes on Mars, and Saturn's moon Titan. Sagan established that the atmosphere of Venus is extremely hot and dense. He also perceived global warming as a growing, man-made danger and likened it to the natural development of Venus into a hot life-hostile planet through greenhouse gases. He suggested that the seasonal changes on Mars were due to windblown dust, not to vegetation changes, as others had proposed.

Sagan was among the first to hypothesize that Titan and Jupiter's moon Europa may possess oceans (a subsurface ocean in the case of Europa) or lakes, making them habitable for life. Europa's subsurface ocean was later indirectly confirmed by the spacecraft Galileo.

Scientific advocacy

Sagan was a proponent of the search for extraterrestrial life. He urged the scientific community to listen with large radio telescopes for signals from intelligent extraterrestrial lifeforms. He advocated sending probes to other planets. Sagan was Editor in Chief of Icarus (a professional journal concerning planetary research) for 12 years. He cofounded the Planetary Society and was a member of the SETI Institute Board of Trustees.

Social concerns

Sagan believed that the Drake equation suggested that a large number of extraterrestrial civilizations would form, but that the lack of evidence of such civilizations (the Fermi paradox) suggests that technological civilizations tend to destroy themselves rather quickly. This stimulated his interest in identifying and publicizing ways that humanity could destroy itself, with the hope of avoiding such destruction and eventually becoming a space-faring species.

Carl Sagan was an avid user of marijuana, although he never publicly admitted it during his life. Under the pseudonym "Mr. X," he wrote an essay concerning cannabis smoking in the 1971 book Marihuana Reconsidered, whose editor was Lester Grinspoon . In the essay Sagan commented that marijuana encouraged some of his works and enhanced experiences. After Sagan's death, Grinspoon disclosed this to Sagan's biographer Keay Davidson. When the biography, entitled Sagan: A Life, was published in 1999, the marijuana exposure stirred some media attention.

Popularization of science

Sagan with a model of the Viking Lander probes which would land on Mars.
Sagan with a model of the Viking Lander probes which would land on Mars.

Sagan's capability to convey his ideas allowed many people to better understand the cosmos. He delivered the 1977/1978 Christmas Lectures for Young People at the Royal Institution. He wrote (with Ann Druyan, eventually his third wife) and narrated the highly popular thirteen part PBS television series Cosmos; he also wrote books to popularize science (The Dragons of Eden, which won a Pulitzer Prize, Broca's Brain, etc.) and a novel, Contact, that was a best-seller and had a film adaptation starring Jodie Foster in 1997. The film won the 1998 Hugo Award.

From Cosmos and his frequent appearances on The Tonight Show, Sagan became associated with the catch phrase "billions and billions." (He never actually used that phrase in Cosmos, but his distinctive delivery and frequent use of billions made this a favorite phrase of Johnny Carson and others doing the many affectionate impressions of him. Sagan took this in good humor, and his final book was entitled Billions and Billions - see below.) He wrote a sequel to Cosmos, Pale Blue Dot: A Vision of the Human Future in Space, which was selected as a notable book of 1995 by The New York Times. Carl Sagan also wrote an introduction for the best selling book by Stephen Hawking, A Brief History of Time.

Sagan presents a speculation concerning the origin of the swastika symbol in his book, Comet. Sagan hypothesized that a comet approached so close to Earth in antiquity that the jets of gas streaming out of it were visible, bent by the comet's rotation. The book Comet reproduces an ancient Chinese manuscript that shows comet tail varieties; most are variations on simple comet tails, but the last shows the comet nucleus with four bent arms extending from it, showing a swastika.

Sagan caused mixed reactions among other professional scientists. On the one hand, there was general support for his popularization of science, his efforts to increase scientific understanding among the general public, and his positions in favor of skepticism and against pseudoscience. On the other hand, there was some unease that the public would misunderstand some of the personal positions and interests that Sagan took as being part of the scientific consensus rather than his own personal views, and there was some unease, which some believe to have been motivated in part by professional jealousy, that scientific views contrary to those that Sagan took (such as on the severity of nuclear winter) were not being sufficiently presented to the public. His comments on the Kuwait oil well fires during the first Gulf War were shown later to be in error.

Late in his life, Sagan's books developed his skeptical, naturalistic view of the world. In The Demon-Haunted World: Science as a Candle in the Dark, he presented tools for testing arguments and detecting fallacious or fraudulent ones, essentially advocating wide use of the scientific method. In The Demon-Haunted World, Sagan gave a list of errors he had made (including his predictions about the effects of the Kuwaiti oil fires) as an example of how science is self-correcting. The compilation Billions and Billions: Thoughts on Life and Death at the End of the Millennium, published after Sagan's death, contains essays written by Sagan, such as his views on abortion, and Ann Druyan's account of his death as a non-believer.


After a long and difficult fight with myelodysplasia, Sagan died at the age of 62, on December 20, 1996, at the Fred Hutchinson Cancer Research Center in Seattle, Washington. Sagan was a significant figure, and his supporters credit his importance to his popularisation of the natural sciences, opposing both restraints on science and reactionary applications of science, defending democratic traditions, resisting nationalism, defending humanism, and arguing against geocentric and anthropocentric views.

The landing site of the unmanned Mars Pathfinder spacecraft was renamed the Carl Sagan Memorial Station in honor of Dr. Sagan on July 5, 1997. Asteroid 2709 Sagan is also named in his honor.

The 1997 movie Contact (see above), based on Sagan's novel of the same name, and finished after his death, movingly ends with the dedication "For Carl."

Awards and medals

  • Apollo Achievement Award - National Aeronautics and Space Administration
  • Chicken Little Honorable Mention - 1991 - National Anxiety Center
  • Distinguished Public Service - National Aeronautics and Space Administration
  • Emmy - Outstanding individual achievement - 1981 - PBS series Cosmos
  • Emmy - Outstanding Informational Series - 1981 - PBS series Cosmos
  • Exceptional Scientific Achievement Medal - National Aeronautics and Space Administration
  • Helen Caldicott Leadership Award - Women's Action for Nuclear Disarmament
  • Homer Award - 1997 - Contact
  • Hugo Award - 1998 - Contact
  • Hugo Award - 1981 - Cosmos
  • Hugo Award - 1997 - The Demon-Haunted World
  • In Praise of Reason Award - 1987 - Committee for the Scientific Investigation of Claims of the Paranormal
  • Isaac Asimov Award - 1994 - Committee for the Scientific Investigation of Claims of the Paranormal
  • John F. Kennedy Astronautics Award - American Astronautical Society
  • John W. Campbell Memorial Award - 1974 - The Cosmic Connection
  • Klumpke-Roberts Award of the Astronomical Society of the Pacific - 1974
  • Konstantin Tsiolkovsky Medal - Soviet Cosmonauts Federation
  • Locus Poll Award 1986 - Contact
  • Lowell Thomas Award - Explorers Club - 75th Anniversary
  • Masursky Award - American Astronomical Society
  • Peabody - 1980 - PBS series Cosmos
  • Public Welfare Medal - 1994 - National Academy of Sciences
  • Pulitzer Prize for Literature - 1978 - The Dragons of Eden
  • SF Chronicle Award - 1998 - Contact
  • Carl Sagan Memorial Award - Named in his honor

Related books and media

  • Sagan, Carl and Jonathon Norton Leonard and editors of Life, Planets. Time, Inc., 1966
  • Sagan, Carl and I.S. Shklovskii, Intelligent Life in the Universe. Random House, 1966
  • Sagan, Carl, Communication with Extraterrestrial Intelligence. MIT Press, 1973
  • Sagan, Carl, et. al. Mars and the Mind of Man. Harper & Row, 1973
  • Sagan, Carl, Other Worlds. Bantam Books, 1975
  • Sagan, Carl, et. al. Murmurs of Earth: The Voyager Interstellar Record. Random House, 1977
  • Sagan, Carl et. al. The Nuclear Winter: The World After Nuclear War. Sidgwick & Jackson, 1985
  • Sagan, Carl, Contact. Simon and Schuster, 1985; Reissued August 1997 by Doubleday Books, ISBN 1568654243, 352 pgs
  • Sagan, Carl and Richard Turco, A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race. Random House, 1990
  • Sagan, Carl, The Dragons of Eden: Speculations on the Evolution of Human Intelligence. Ballantine Books, December 1989, ISBN 0345346297, 288 pgs
  • Sagan, Carl, Broca's Brain: Reflections on the Romance of Science. Ballantine Books, October 1993, ISBN 0345336895, 416 pgs
  • Sagan, Carl and Ann Druyan, Shadows of Forgotten Ancestors: A Search for Who We Are. Ballantine Books, October 1993, ISBN 0345384725, 528 pgs
  • Sagan, Carl and Ann Druyan, Comet. Ballantine Books, February 1997, ISBN 0345412222, 496 pgs
  • Sagan, Carl, Pale Blue Dot: A Vision of the Human Future in Space. Ballantine Books, September 1997, ISBN 0345376595, 384 pgs
  • Sagan, Carl and Ann Druyan, Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium. Ballantine Books, June 1998, ISBN 0345379187, 320 pgs
  • Sagan, Carl, The Demon-Haunted World: Science As a Candle in the Dark. Ballantine Books, March 1997, ISBN 0345409469, 480 pgs
  • Sagan, Carl and Jerome Agel, Cosmic Connection: An Extraterrestrial Perspective. Cambridge University Press, January 15, 2000, ISBN 0521783038, 301 pgs
  • Sagan, Carl, Cosmos. Random House, May 7, 2002, ISBN 0375508325, 384 pgs
  • Zemeckis, Robert, Contact. Warner Studios, 1997, ASIN 0790736330 IMDB
  • Davidson, Keay, Carl Sagan: A Life. John Wiley & Sons, August 31, 2000, ISBN 0471395366, 560 pgs

External links

Wikiquote has a collection of quotations by or about Carl Sagan
  • In Memory of Carl Sagan . Tributes by Tom McDonough , James Randi and Michael Shermer, and a selection of quotes from Sagan's works, published in Skeptic, Vol. 4, no. 4, 1996, pp. 10-17.
  • CarlSagan.Com . Homepage of Cosmos Studios, which sells the Cosmos series on DVD and VHS video tape.
  • Carl Sagan, Cornell astronomer, dies today (Dec. 20) in Seattle . Cornell University press release on Sagan's death.
  • Even in Death, Carl Sagan's Influence Is Still Cosmic by William J. Broad, The New York Times, November 30, 1998. Describes Sagan's legacy for space science.
  • Astronomy Picture of the Day: Carl Sagan . December 26, 1996.
  • Contact: A Eulogy to Carl Sagan , by Dr. Ray Bohlin , president of Probe Ministries . Dr. Bohlin suggests that the movie Contact can serve as a fitting eulogy for Carl Sagan. Sagan's scientific approach to the question, "was the universe created?" is critically analyzed by Bohlin from his Christian perspective.
  • Mr. X - Sagan's essay in the 1971 book Marihuana Reconsidered
  • Larry Klaes' in-depth analysis of the film and novel Contact
  • "Big Bang Bust" TIME magazine, December 14, 1981,10987,925115,00.html

Last updated: 02-05-2005 10:03:28
Last updated: 04-25-2005 03:06:01