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{{Infobox_Person
| name = Carl Sagan
| image = Sagan_large3.jpg
| birth_date = [[November 9]] [[1934]]
| birth_place = [[Brooklyn, New York|Brooklyn]], [[New York]]
| death_date = [[December 20]] [[1996]]
| death_place = [[Seattle, Washington]]
}}
'''Carl Edward Sagan''' ([[November 9]] [[1934]] – [[December 20]] [[1996]]) was an [[United States|American]] [[astronomer]], [[Astrobiology|astrobiologist]], and highly successful science popularizer. He pioneered [[Astrobiology|exobiology]] and promoted the Search for Extra-Terrestrial Intelligence ([[SETI]]). He is world-famous for writing [[popular science]] books and for co-writing and presenting the award-winning 1980 television series ''[[Cosmos: A Personal Voyage]]'', then the most-watched [[Public Broadcasting Service|PBS]] program of all time<ref> According to [http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/sagan.html nasa.gov], [http://www.infoplease.com/ipa/A0187957.html], [http://www.seasky.org/spacexp/sky5e08.html] and [http://www.mnsu.edu/emuseum/information/biography/pqrst/sagan_carl.html]</ref> until 1990's [[The Civil War (documentary)|''The Civil War'']]. A [[Cosmos (book)|book]] to accompany the program was also published. He also wrote the novel [[Contact (novel)|''Contact'']], the basis for the 1997 [[Contact (film)|film of the same name]] starring [[Jodie Foster]]. During his lifetime, Sagan published more than 600 scientific papers and popular articles and was author, co-author, or editor of more than 20 books. In his works, he frequently advocated [[scientific skepticism]], [[humanism]], and the [[scientific method]].
==Education and scientific career==
[[Image:Sagan of Cornell.jpg|left|thumb|Sagan of Astronomy Department, Cornell University, 1969]]
Carl Sagan was born in [[Brooklyn, New York|Brooklyn]], [[New York]].<ref>For biographical information see ''[[Carl Sagan: A Life in the Cosmos]]'' by [[William Poundstone]]. Henry Holt & Company ([[October 1]] [[1999]]) ISBN 0-8050-5766-8</ref> His parents were [[Jew]]ish; his father, Sam Sagan, was a garment worker and his mother, Rachel Molly Gruber, was a housewife. Carl was named in honor of Rachel's biological mother, Chaiya/ Clara, "the mother she never knew," in Sagan's words. Sagan graduated from Rahway ([[New Jersey|NJ]]) High School in 1951.<ref>''[[Carl Sagan: A Life]]'' by Keay Davidson, pages 33-41. John Wiley & Sons ([[August 30]] [[1999]]) ISBN 0-471-25286-7</ref> He 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]]. During his time as an undergraduate, Sagan spent some time working in the laboratory of the [[geneticist]] [[Hermann Joseph Muller|H. J. Muller]]. From 1962 to 1968, he worked at the [[Smithsonian Astrophysical Observatory]].
[[Image:YoungSagan60s.jpg|right|thumb|Sagan, chairman of the Voyager Golden Record committee in 1977]]
Sagan taught at [[Harvard University]] until 1968, when he moved to [[Cornell University]]. He became a full professor at Cornell in 1971 and directed the Laboratory for [[Planetary science|Planetary Studies]] there. From 1972 to 1981 he was Associate Director of the Center for Radio Physics and Space Research at Cornell.
Sagan was a leader in the U.S. [[space program]] since its inception and worked as an adviser to [[NASA]] since the 1950s. (One of his many duties during his tenure at the space agency included briefing the [[Project Apollo|Apollo]] [[astronaut]]s before their flights to the [[Moon]].) Sagan contributed to most of the [[unmanned space mission|unmanned missions]] that explored the [[solar system]], placing experiments on many robotic space expeditions. 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. Sagan assembled the first physical message that was sent into [[outer space|space]]: a [[gold]]-[[anodized]] [[Pioneer plaque|plaque]], attached to the space probe [[Pioneer 10]], launched in 1972. [[Pioneer 11]], also containing the plaque, was launched the following year. He continued to refine his designs and the most elaborate such message he helped to develop and assemble was the [[Voyager Golden Record]] that was sent out with the [[Voyager program|Voyager]] space probes in 1977.
Sagan taught at Cornell a course on [[critical thinking]] until his death in 1996 from a rare bone marrow disease. The course had only a limited number of seats, although hundreds of students tried to attend. He chose about 20 students who were allowed to enroll by reading huge piles of application essays. The course was discontinued after his death.
==Scientific achievements==
[[Image:Sagan telescope1.jpg|thumb|125px|left|A still from ''Cosmos'']]
Sagan was central to the discovery of the high surface temperatures of the planet [[Venus]]. In the early 1960s, no one knew for certain the basic conditions of Venus' surface and Sagan listed the possibilities in a report (which were later depicted for popularization in a [[Time-Life]] book, ''Planets'') — his own view was that the planet was dry and very hot, as opposed to the balmy paradise others had imagined. He had investigated radio emissions from Venus and concluded that there was a surface temperature of 900°F (500°C). As a visiting scientist to NASA's [[Jet Propulsion Laboratory]], he contributed to the first [[Mariner program|Mariner]] missions to Venus, working on the design and management of the project. [[Mariner 2]] confirmed his views on the conditions of Venus in 1962.
Sagan was among the first to hypothesize that [[Saturn]]'s moon [[Titan (moon)|Titan]]<ref>Much of Sagan's research in the field of planetary science is outlined by William Poundstone (see reference #2, above). Poundstone's biography of Sagan includes an eight page list of Sagan's scientific articles published from 1957 to 1998. Detailed information about Sagan's scientific work comes from the primary research articles. Example: Sagan, C., Thompson, W. R., and Khare, B. N. ''[[Titan: A Laboratory for Prebiological Organic Chemistry]]'', Accounts of Chemical Research, volume 25, page 286 (1992). There is commentary on this research article about Titan at [http://www.daviddarling.info/encyclopedia/T/Titanprebiotic.html The Encyclopedia of Astrobiology, Astronomy, and Spaceflight].</ref> and [[Jupiter]]'s moon [[Europa (moon)|Europa]] may possess oceans (a subsurface ocean, in the case of Europa) or lakes, thus making the hypothesized water ocean on Europa potentially habitable for [[life]]. Europa's subsurface ocean was later indirectly confirmed by the spacecraft [[Galileo probe|Galileo]]. Sagan also helped solve the mystery of the reddish haze seen on Titan, revealing that it is composed of complex [[organic molecules]] constantly raining down to the moon's surface.
He furthered insights regarding the atmospheres of Venus and Jupiter as well as seasonal changes on [[Mars (planet)|Mars]]. Sagan established that the atmosphere of Venus is extremely hot and dense with crushing pressures. 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 gas|greenhouse gasses]]. Sagan speculated (along with his Cornell colleague [[Edwin Ernest Salpeter]]) about [[Jupiter#Life on Jupiter|life in Jupiter's clouds]], given the planet's dense atmospheric composition rich in organic molecules. He studied the observed color variations on Mars’ surface, concluding that they were not seasonal or vegetation changes as most believed, but shifts in surface dust caused by [[dust storm#on other planets|windstorms]].
Sagan is best known, however, for his research on the possibilities of [[exobiology|extraterrestrial life]], including experimental demonstration of the production of [[amino acid]]s from basic chemicals by [[radiation]].<ref>According to [http://www.bartelby.com/65/sa/Sagan-Ca.html The Columbia Encyclopedia, Sixth Edition].</ref>
==Scientific advocacy==
[[Image:Planetary society.jpg|thumb|right|300px|Planetary Society members at the organization's founding. Carl Sagan seated, right]]
Sagan was a proponent of the search for extraterrestrial life. He urged the scientific community to listen with [[radio telescope]]s for signals from intelligent extraterrestrial lifeforms. So persuasive was he 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 was a tremendous turnaround in the respectability of this controversial field. Sagan also advocated sending [[Space probe|probes]] to explore the solar system.
He was editor-in-chief of [[Icarus (journal)|''Icarus'']] (a professional journal concerning planetary research) for 12 years. He cofounded the ''[[Planetary Society]]'', the largest space-interest group in the world, with over 100,000 members in more than 140 countries, 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]].
[[Image:2Sagan 1972.jpg|left|thumb|150px|[[Communication with Extraterrestrial Intelligence|CETI]] conference, 1972]]
Sagan helped Dr. [[Frank Drake]] write the [[Arecibo message]], a radio message beamed into space from the [[Arecibo radio telescope]] on November 16, 1974, aimed at informing extraterrestrials about Earth.
At the height of the [[Cold War]], Sagan deliberately ignored the "extraordinary claims" test for evidence when a mathematical climate model suggested that a substantial nuclear exchange could upset the delicate balance of life on [[Earth]]. He was the last of five authors — the "S" of the [[Nuclear winter#history|"TTAPS"]] report as the research paper came to be known. He eventually co-authored the scientific paper that predicted [[nuclear winter]]<ref>Turco RP, Toon OB, Ackerman TP, Pollack JB, Sagan C. ''[[Climate and smoke: an appraisal of nuclear winter]],'' [[Science (journal)|Science]], volume 247, pages 166-176 (1990). [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11538069&dopt=Abstract PubMed abstract]|[http://links.jstor.org/sici?sici=0036-8075%2819900112%293%3A247%3A4939%3C166%3ACASAAO%3E2.0.CO%3B2-V JSTORE] link to full text article. Carl Sagan discussed his involvement in the political nuclear winter debates and his erroneous global cooling prediction for the Gulf War fires in his book, ''[[The Demon-Haunted World]]''.</ref> would follow [[Nuclear warfare|nuclear war]]. He also co-authored the book ''A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race'', a comprehensive examination of the phenomenon of nuclear winter.
Sagan famously predicted on [[American Broadcasting Company|ABC]]'s ''[[Nightline]]'' in 1991 that smoky [[Kuwaiti oil fires|oil fires]] in Kuwait (set by [[Saddam Hussein]]'s army during the first [[Gulf War]]) would cause a worldwide ecological disaster of black clouds resulting in [[global cooling]]. Retired [[atmospheric physics|atmospheric physicist]] and climate change skeptic [[Fred Singer]] dismissed Sagan's prediction as nonsense, predicting that the smoke would dissipate in a matter of days. In his book ''[[The Demon-Haunted World]]'' (see below), 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 tentative, a self-correcting process.
Sagan is also known for being involved as a researcher in [[Project A119]], a secret [[United States Air Force|US Air Force]] operation whose purpose was to explode an [[nuclear weapon|atomic bomb]] on Earth's Moon.
==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.
[[Image:Sagan young2.jpg|right|thumb|150px|Sagan in the early 1970s]]
Sagan became more politically active after marrying novelist [[Ann Druyan]], performing acts of [[civil disobedience]] at the [[Nevada Test Site|Nevada Nuclear Weapons Test Site]] during the [[Nuclear freeze]] era, for which he was publicly arrested twice, along with [[Daniel Ellsberg]], [[Philip Zimmermann]] and [[Martin Sheen]]. He was also arrested for participating in an anti-war protest during the [[Vietnam war|Vietnam]] era. He spoke out against President [[Ronald Reagan]]'s [[Strategic Defense Initiative]], or the "Star Wars" program, which he felt was technically impossible to build and perfect, far more expensive to create than for an enemy to defeat through decoys and other means, and destabilizing to Cold War [[Nuclear disarmament|nuclear weapons disarmament]] progress.
Carl Sagan was an avid user of [[Cannabis (drug)|marijuana]], although he never admitted this publicly during his life. Under the [[pseudonym]] "Mr. X," he wrote an essay concerning cannabis smoking in the 1971 book ''Marihuana Reconsidered''<!-- That's the spelling (with an "H") used by the US version of Amazon, BTW -->, whose editor was [[Lester Grinspoon]].<ref>''[[Marihuana Reconsidered]]'' by Lester, M.D. Grinspoon. Publisher: Quick American Archives (2nd edition; [[April 1]] [[1994]]) ISBN 0-932551-13-0. Sagan's [http://www.marijuana-uses.com/essays/002.html essay] is available online.</ref> In his 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 ''Carl Sagan: A Life'', was published in 1999, the marijuana exposure stirred some media attention.<ref>[http://news.bbc.co.uk/1/hi/sci/tech/475954.stm BBC news story] that includes mention of Sagan's marijuana use.</ref><ref>[http://www.druglibrary.org/think/~jnr/sagan.htm San Francisco Examiner article] on Sagan's marijuana use. Also includes an article by Lester Grinspoon.</ref><ref>[http://cannabisculture.com/articles/63.html Carl Sagan: Toking Astronomer] – article in Cannabis Culture magazine.</ref>
==Popularization of science==
[[Image:2Sagan 1980.jpg|thumb|150px|left|Sagan in 1980]]
Sagan's capability to convey his ideas allowed many people to better understand the cosmos. He delivered the 1977/1978 [[Royal Institution Christmas Lectures|Christmas Lectures for Young People]] at the [[Royal Institution]]. He hosted and, with Ann Druyan, co-wrote and co-produced the highly popular thirteen-part [[PBS]] television series [[Cosmos: A Personal Voyage|''Cosmos: A Personal Voyage'']] (modeled on [[Jacob Bronowski]]'s ''[[The Ascent of Man]]'').
[[Image:Sagan Viking.jpg|thumb|250px|right|Sagan with a model of the [[Viking Lander]] probes which would land on [[Mars (planet)|Mars]]. Sagan examined possible landing sites for Viking along with Mike Carr and Hal Masursky.]]
''Cosmos'' covered a wide range of scientific subjects including the [[origin of life]] and a perspective of our place in the [[universe]]. The series was first broadcast by the [[Public Broadcasting Service]] in 1980. It won an [[Emmy Award|Emmy]] and a [[Peabody Award]]; according to the NASA Office of Space Science, it has been since broadcast in more than 60 countries and seen by over 600 million people.
Sagan also wrote books to popularize science, such as ''[[Cosmos (book)|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,<ref>According to [http://science.discovery.com/convergence/cosmos/bio/bio.html?clik=fsmain_feat3 The Science Channel].</ref> ''[[The Dragons of Eden|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 (novel)|''Contact'']], but did not live to see the book's 1997 [[Contact (film)|motion picture adaptation]], which starred [[Jodie Foster]] and 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'',<ref>Refuted by Carl Sagan himself in his book ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium|Billions and Billions]]'', pages 3-4. Ballantine Books, [[June]] [[1997]], ISBN 0-345-37918-7</ref> but his distinctive delivery and frequent use of ''billions'' (with noted emphasis on the opening "b") made this a favorite phrase of [[Johnny Carson]], [[Gary Kroeger]], [[Mike Myers (actor)|Mike Myers]], [[Bronson Pinchot]], [[Harry Shearer]] and others, doing many affectionate impressions of him. Sagan took this in good humor, and his final book was entitled ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium|Billions and Billions]]'' (see below) and opened with a tongue-in-cheek discussion of this catch phrase.) A humorous unit of measurement, the ''[[Sagan (unit of measurement)|Sagan]]'', has now been coined to stand for any count of at least 4,000,000,000.
He wrote a sequel to ''Cosmos,'' [[Pale Blue Dot|''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 bestselling 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 [[China|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 [[scientific skepticism]] and against [[pseudoscience]]; most notably his thorough [[Debunker|debunking]] of the book ''[[Worlds in Collision]]'' by [[Immanuel Velikovsky]]. 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. Sagan's arguments against Velikovsky's [[catastrophism]] have been criticized by some of his colleagues. [[Robert Jastrow]] of NASA's [[Goddard Institute for Space Studies]] wrote: "Professor Sagan's calculations, in effect, ignore the law of gravity. Here, Dr. Velikovsky was the better astronomer."
Late in his life, Sagan's books developed his skeptical, [[naturalism (philosophy)|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 critical thinking and the [[scientific method]]. The compilation, ''Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium'', published in 1997 after Sagan's death, contains essays written by Sagan, such as his views on [[abortion]], and his widow Ann Druyan's account of his death as a [[skepticism|skeptic]], [[agnosticism|agnostic]], and [[freethought|freethinker]].
In 2006, Ann Druyan edited Sagan's 1985 ''Gifford Lectures in Natural Theology'' into a new book, ''The Varieties of Scientific Experience: A Personal View of the Search for God,'' in which he elaborates on his views of divinity in the [[nature|natural world]].
==Personality==
In 1966, Sagan was asked to contribute an interview about the possibility of extraterrestrials to a proposed introduction to the film ''[[2001: A Space Odyssey (film)|2001: A Space Odyssey]]''. According to an unsourced anecdote in ''The Independent'', Sagan "responded by saying that he wanted editorial control and a percentage of the film's takings, which was rejected."<ref>[http://enjoyment.independent.co.uk/film/news/article321643.ece 2001: The secrets of Kubrick's classic]" by Anthony Barnes ([[October 23]] [[2005]]).</ref>
In 1994, [[Apple Computer]] began developing the [[Power Macintosh 7100]]. They chose the internal code name "Carl Sagan," the joke being that the mid-range PowerMac 7100 would make Apple "billions and billions".<ref>An account of this lawsuit is given in ''[[Carl Sagan: A Life in the Cosmos]]'', pages 363-364 and 374-375.</ref> Though the project name was strictly internal and never used in public marketing, when Sagan learned of this internal usage, he sued Apple Computer to use a different project name — other projects had names like "[[Cold fusion]]" and "[[Piltdown Man]]", and he was displeased at being associated with what he considered pseudoscience. Though Sagan lost the suit, Apple engineers complied with his demands anyway, renaming the project "BHA" ([[Notable litigation of Apple Computer#Libel dispute with Carl Sagan|Butt-Head Astronomer]]). Sagan sued Apple for libel over the new name, claiming that it subjected him to contempt and ridicule. Sagan lost this lawsuit as well; still, the 7100 saw another name change: it was lastly called "LAW" (Lawyers Are Wimps).
[[Image:Sagan Druyan.jpg|right|thumb|150px|Sagan with Druyan]]
Sagan wrote about [[religion]] and the relationship between religion and science, observing statements such as: "The idea that [[God]] is an oversized white male with a flowing beard, who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by 'God,' one means the set of [[physical laws]] that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to [[prayer|pray]] to the law of [[gravity]]."<ref>A similar quote can be found in Chapter 23 of Sagan's book ''[[Broca's Brain: Reflections on the Romance of Science|Broca's Brain]]''. "Some people think God is an outsized, light-skinned male with a long white beard, sitting on a throne somewhere up there in the sky, busily tallying the fall of every sparrow. Others — for example [[Baruch Spinoza]] and [[Albert Einstein]] — considered God to be essentially the sum total of the physical laws which describe the universe. I do not know of any compelling evidence for anthropomorphic patriarchs controlling human destiny from some hidden celestial vantage point, but it would be madness to deny the existence of physical laws."</ref> Sagan is also widely regarded as a freethinker or skeptic, one of his most famous quotations (as seen in ''Cosmos'') being, "Extraordinary claims require extraordinary evidence." (This is also known, under different wording, as the principle of [[Pierre-Simon Laplace|Laplace]] — attributed to Pierre-Simon Marquis de Laplace (March 23, [[1749]] – March 5, [[1827]]), a [[France|French]] [[mathematician]] and astronomer: "The weight of evidence for an extraordinary claim must be proportioned to its strangeness.")
Sagan married three times; the famous biologist, [[Lynn Margulis]] (mother of [[Dorion Sagan]] and [[Jeremy Sagan]]) in 1957, artist [[Linda Salzman Sagan|Linda Salzman]] (mother of [[Nick Sagan]]) in 1968, and author Ann Druyan (mother of Sasha and Sam) in 1981, with whom he remained married until his death.
[[Isaac Asimov]] described Sagan as one of the only two people he ever met who were just plain smarter than Asimov himself. The other was [[Computer science|computer scientist]] and expert on [[artificial intelligence]], [[Marvin Minsky]].
==Sagan and UFOs==
Sagan had some interest in [[UFO]] reports from at least 1964, when he had several conversations on the subject with [[Jacques Vallee]] (Westrum 37). Though quite skeptical of any extraordinary answer to the UFO question, Sagan thought that science should study the phenomenon, at least because there was widespread public interest in UFO reports.
[[Stuart Appelle]] notes that Sagan "wrote frequently on what he perceived as the [[logic|logical]] and [[empiricism|empirical]] [[fallacy|fallacies]] regarding UFOs and the [[abduction phenomenon|abduction experience]]. Sagan rejected an [[extraterrestrial hypothesis|extraterrestrial explanation]] for the phenomenon but felt there were both empirical and [[pedagogical]] benefits for examining UFO reports and that the subject was, therefore, a legitimate topic of study" (Appelle 22).
In 1966, Sagan was a member of the Ad Hoc Committee to Review [[Project Blue Book]]. The committee concluded that the U.S. Air Force's [[Project Blue Book]] had been lacking as a scientific study, and recommended a university-based project to give the UFO phenomenon closer scientific scrutiny. The [[Condon Committee]] (1966-1968), led by physicist [[Edward Condon]], and their still-controversial final report, formally concluded that there was nothing anomalous about UFO reports.
[[Ron Westrum]] writes that "The high point of Sagan's treatment of the UFO question was the [[American Association for the Advancement of Science|AAAS]]'s symposium in 1969. A wide range of educated opinions on the subject were offered by participants, including not only proponents as [[James E. McDonald|James McDonald]] and [[J. Allen Hynek]] but also skeptics like astronomers [[William Hartmann]] and [[Donald Menzel]]. The roster of speakers was balanced, and it is to Sagan's credit that this event was presented in spite of pressure from [[Edward Condon]]" (Westrum 37-38). With physicist [[Thornton Page]], Sagan edited the lectures and discussions given at the symposium; these were published in 1972 as ''UFO's: A Scientific Debate''.
[[Jerome Clark]] writes that Sagan's perspective on UFO's irked Condon: "... though a skeptic, [Sagan] was too soft on UFOs for Condon's taste. In 1971, he considered blackballing Sagan from the prestigious [[Cosmos Club]]" (Clark 603).
Some of Sagan's many books examine UFOs (as did one episode of ''Cosmos'') and he recognized a religious undercurrent to the phenomenon. However, Westrum writes that "Sagan spent very little time researching UFOs ... he thought that little evidence existed to show that the UFO phenomenon represented alien spacecraft and that the motivation for interpreting UFO observations as spacecraft was emotional" (Westrum 37).
It is sometimes noted that Sagan's generally skeptical attitude to UFOs conflicted sharply with his views in a 1966 book he wrote with Russian astronomer and astrophysicist [[Iosif Samuilovich Shklovsky|I.S. Shklovskii]], ''Intelligent Life in the Universe''. Here Sagan instead argued that technologically advanced alien civilizations were common and he considered it very probable that Earth had been visited many times in the past.
Yet only a few years later in ''UFO's: A Scientific Debate'', Sagan was now highly skeptical of interstellar visitation. As to the physical possibility of [[interstellar travel]], Sagan brought up the proposed [[Bussard ramjet]] as an interstellar vehicle. While not terribly practical, Sagan thought such proposed propulsion systems were nevertheless important because they demonstrated that there were conceivable ways of accomplishing interstellar travel "without bumping into fundamental physical constraints. And this suggests that it is premature to say that interstellar space flight is out of the question." But to this Sagan added, "I believe the numbers work out in such a way that UFO's as interstellar vehicles is extremely unlikely, but I think it is an equally bad mistake to say that interstellar space flight is impossible."
Sagan again revealed his views on interstellar travel in his 1980 ''Cosmos'' series. He scoffed at the idea that UFOs are visiting Earth, maintaining that the chances any alien spacecraft would visit the Earth are vanishingly small. However, in another episode he said the stars would "beckon" to humanity, and described the Bussard ramjet as one way humans might achieve interstellar travel. In one of his last written works, Sagan again claimed that there was no evidence that aliens have actually visited the Earth, either in the past or present (Sagan, 1996: 81-96, 99-104).
==Legacy==
[[Image:Sagan1996.jpg|left|frame|Sagan in 1996, shortly before his death]]
After a long and difficult fight with [[Myelodysplastic syndrome|myelodysplasia]], Sagan died of [[pneumonia]] 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 popularization of the [[Natural science#Natural sciences|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 ''[[Mars Pathfinder#End of the mission|Carl Sagan Memorial Station]]'' on [[July 5]] [[1997]]. [[2709 Sagan|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, ends with the dedication "For Carl."
On November 9, 2001, on what would have been Sagan’s 67th birthday, the [[NASA Ames Research Center]] dedicated the site for the Carl Sagan Center for the Study of Life in the Cosmos. "Carl was an incredible visionary, and now his legacy can be preserved and advanced by a 21st century research and education laboratory committed to enhancing our understanding of life in the universe and furthering the cause of space exploration for all time," said NASA Administrator [[Daniel Goldin]]. Ann Druyan was at the center as it opened its doors on October 22, 2006.
Sagan's son, Nick Sagan, wrote several episodes in the ''[[Star Trek]]'' franchise. In an episode of ''[[Star Trek: Enterprise]]'' entitled "Terra Prime," a quick shot is shown of the relic rover [[Mars Pathfinder|Sojourner]], part of the Mars Pathfinder mission, placed by a historical marker at Carl Sagan Memorial Station on the Martian surface. The marker displays a quote from Sagan: "Whatever the reason you're on Mars, I'm glad you're there, and I wish I was with you."
Sagan's student, [[Steve Squyres]], would lead the team that landed the [[Spirit Rover]] and [[Opportunity Rover]] successfully on Mars in 2004.
==Awards and medals==
* Annual Award for Television Excellence - 1981 - [[Ohio State University]] - PBS series ''[[Cosmos: A Personal Voyage|Cosmos]]''
* [[Apollo Achievement Award]] - [[NASA|National Aeronautics and Space Administration]]
* [[Chicken Little Award|Chicken Little]] Honorable Mention - 1991 - National Anxiety Center; a ''dubious achievement award'' from an organization which is skeptical about many pessimistic appraisals of the state of the environment
* [[NASA Distinguished Service Medal#NASA Distinguished Public Service Medal|NASA Distinguished Public Service Medal]] - National Aeronautics and Space Administration (twice)
* [[Emmy]] - Outstanding Individual Achievement - 1981 - PBS series ''Cosmos''
* Emmy - [[Primetime Emmy Award for Outstanding Informational Series|Outstanding Informational Series]] - 1981 - PBS series ''Cosmos''
* [[NASA Exceptional Achievement Medal|Exceptional Scientific Achievement Medal]] - National Aeronautics and Space Administration
* [[Helen Caldicott Leadership Award]] - Women's Action for Nuclear Disarmament
* [[Homer Award]] - 1997 - ''[[Contact (novel)|Contact]]''
* [[Hugo Award]] - 1981 - ''Cosmos''
* [[American Humanist Association#AHA's Humanists of the Year|Humanist of the Year]] - 1981 - Awarded by the [[American Humanist Association]]
* [[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 - ''[[Cosmic Connection: An Extraterrestrial Perspective]]''
* [[Joseph Priestley|Joseph Priestley Award]] - "For distinguished contributions to the welfare of mankind"
* [[Klumpke-Roberts Award]] of the [[Astronomical Society of the Pacific]] - 1974
* [[Konstantin Tsiolkovsky Medal]] - Awarded by the Soviet Cosmonauts Federation
* [[Locus Award]] 1986 - ''Contact''
* [[Lowell Thomas Award]] - [[Explorers Club]] - 75th Anniversary
* [[Masursky Award]] - [[American Astronomical Society]]
* [[Oersted Medal]] - 1990 - American Association of Physics Teachers
* [[Peabody Award]] - 1980 - PBS series ''Cosmos''
* [[Prix Galbert]] - The international prize of [[Astronautics]]
* [[Public Welfare Medal]] - 1994 - [[National Academy of Sciences]]
* [[Pulitzer Prize|Pulitzer Prize for General Non-Fiction]] - 1978 - ''[[The Dragons of Eden]]''
* [[The San Francisco Chronicle#Awards given by the Chronicle|SF Chronicle Award]] - 1998 - ''[[Contact (film)|Contact]]''
* [[Carl Sagan Memorial Award]] - Named in his honor
* Named 99th "[[Greatest American]]" on the [[June 5]] [[2005]] "Greatest American" show on the [[Discovery Channel]].
==Books and media==
===By Sagan===
* Sagan, Carl, Jonathon Norton Leonard and editors of Life, ''[[Planets]]''. Time, Inc., 1966
*[[Iosif Samuilovich Shklovskii|I.S. Shklovskii]] coauthor, ''[[Intelligent Life in the Universe]]''. Random House, 1966, 509 pgs
*''UFO's: A Scientific Debate''. Cornell University Press, 1972, 310 pgs
*''[[Communication with Extraterrestrial Intelligence]]''. MIT Press, 1973, 428 pgs
* Sagan, Carl, et. al. ''[[Mars and the Mind of Man]]''. Harper & Row, 1973, 143 pgs
*Jerome Agel coauthor, ''[[Cosmic Connection: An Extraterrestrial Perspective]]''. Anchor Press, 1973, ISBN 0-521-78303-8, 301 pgs
*''[[Broca's Brain: Reflections on the Romance of Science]]''. Ballantine Books, 1974, ISBN 0-345-33689-5, 416 pgs
*''[[Other Worlds]]''. Bantam Books, 1975
* Sagan, Carl, et. al. ''[[Murmurs of Earth: The Voyager Interstellar Record]]''. Random House, 1977
*''[[The Dragons of Eden|The Dragons of Eden: Speculations on the Evolution of Human Intelligence]]''. Ballantine Books, 1978, ISBN 0-345-34629-7, 288 pgs
*''[[Cosmos (book)|Cosmos]]''. Random house, 1980. Random House New Edition, [[May 7]] [[2002]], ISBN 0-375-50832-5, 384 pgs
* Sagan, Carl et. al. ''[[The Nuclear Winter: The World After Nuclear War]]''. Sidgwick & Jackson, 1985
*Ann Druyan coauthor, ''[[Comet]]''. Ballantine Books, 1985, ISBN 0-345-41222-2, 496 pgs
*''[[Contact (novel)|Contact]]''. Simon and Schuster, 1985; Reissued August 1997 by Doubleday Books, ISBN 1-56865-424-3, 352 pgs
*Richard Turco coauthor, ''[[A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race]]''. Random House, 1990, 499 pgs
*Ann Druyan coauthor, ''[[Shadows of Forgotten Ancestors: A Search for Who We Are]]''. Ballantine Books, October 1993, ISBN 0-345-38472-5, 528 pgs
*''[[Pale Blue Dot: A Vision of the Human Future in Space]]''. Random House, November 1994, ISBN 0-679-43841-6, 429 pgs
*''[[The Demon-Haunted World|The Demon-Haunted World: Science as a Candle in the Dark]]''. Ballantine Books, March 1996, ISBN 0-345-40946-9, 480 pgs
*Ann Druyan coauthor, ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium]]''. Ballantine Books, June 1997, ISBN 0-345-37918-7, 320 pgs
*''The Varieties of Scientific Experience: A Personal View of the Search for God''. 1985 [[Gifford lectures]], Penguin Press, 2006, ISBN 1-59420-107-2, 304 pgs
===About Sagan===
* Appelle, Stuart, "[[Ufology]] and [[Academia]]: The UFO Phenomenon as a Scholarly Discipline" (pages 7-30 in ''UFOs and Abductions: Challenging the Borders of Knowledge'', David M. Jacobs, editor; University Press of Kansas, 2000; ISBN)
* Clark, Jeromne, ''The UFO Book''. Visible Ink Press, 1998, 750 pgs
* Davidson, Keay, ''[[Carl Sagan: A Life]]''. John Wiley & Sons, [[August 30]] [[1999]], ISBN 0-471-39536-6, 560 pgs
* Head, Tom (editor), ''[[Conversations with Carl Sagan]]''. University Press of Mississippi, 2005, ISBN 1-57806-736-7, 170 pgs
* Poundstone, William, ''[[Carl Sagan: A Life in the Cosmos]]''. Henry Holt & Company, [[October 1]] [[1999]], ISBN 0-8050-5766-8, 473 pgs
*Westrum, Ron, "Limited Access: Six Natural Scientists and the UFO Phenomenon" (pages 30-55 in Jacobs)
* Zemeckis, Robert, ''[[Contact (film)|Contact]]''. Warner Studios, 1997, [http://us.imdb.com/Title?0118884 IMDB]
==Footnotes==
<div class="references-small">
<references />
</div>
==External links==
* [http://www.carlsagan.com/ CarlSagan.com] - homepage of ''Cosmos Studios'', which sells the ''Cosmos'' series on DVD.
*[http://www.marijuana-uses.com/essays/002.html "Mr. X"] - Sagan's anonymous 1969 essay in Lester Grinspoon's ''Marihuana Reconsidered'', 1971.
*[http://video.google.com/videoplay?docid=-8949469271181885482&q=Carl+Sagan Life Beyond Earth and the Mind of Man 1975] - a symposium held at [[Boston University]] that explores the implications of the possible existence of extraterrestrial life within the galaxy and the universe, with Sagan as a panel member.
*[http://www.bigear.org/vol1no2/sagan.htm "The Quest for Extraterrestrial Intelligence"] - 1978 essay by Carl Sagan.
*[http://www.stephenjaygould.org/ctrl/sagan_science.html "Can We Know the Universe?"] - 1979 essay by Carl Sagan, taken from his book ''Broca's Brain''.
*[http://spider.ipac.caltech.edu/staff/jarrett/sagan/dmaps.html "Dreams are Maps"] - 1987 essay by Sagan.
*[http://www.detwiler.us/sagan.html Carl Sagan's Religion of Science] - an analysis of Sagan's view of religion as expressed in his writings.
*[http://www.asa3.org/asa/PSCF/1993/PSCF3-93McKim.html The Cosmos According to Carl Sagan] - Review and critique of Sagan's criticism toward religion.
*[http://www.csicop.org/si/2005-07/sagan.html "Carl Sagan Takes Questions"] - from Sagan's 1994 "Wonder and Skepticism" keynote address delivered in Seattle June 23–26.
*[http://video.google.com/videoplay?docid=-1127834163386485385&q=Carl+Sagan ''Charlie Rose'' January 5, 1995] - interview with Sagan on his book ''Pale Blue Dot: A Vision of the Human Future in Space''.
*[http://www.npr.org/templates/story/story.php?storyId=1011828 ''Talk of the Nation'' May 3, 1996] - Ira Flatow interviews Sagan on his book ''The Demon-Haunted World: Science as a Candle in the Dark''.
*[http://video.google.com/videoplay?docid=2181165206611526024 ''Charlie Rose'' May 27, 1996] - interview with Sagan on his book ''The Demon-Haunted World''.
*[http://web.archive.org/web/20050322090707/http://www.news.cornell.edu/general/Dec96/saganobit.ltb.html "Carl Sagan, Cornell astronomer, dies today (Dec. 20) in Seattle"] - Cornell University press release.
* [http://home.austarnet.com.au/stear/carl-sagan-tribute.htm "In Memory of Carl Sagan"] ''Skeptic'' remembers Carl, with tributes from Tom McDonough, [[James Randi]], [[Michael Shermer]], and others. Also includes quotations from selected works of Sagan.
*[http://www.sciencenter.org/SaganPW/ The Sagan Planet Walk] - New York planetary exhibit created in memory of Carl Sagan.
*[http://www.coseti.org/klaescnt.htm ''Contact'' Film Review] - an analysis of the film and novel, by Larry Klaes.
*[http://www.2think.org/sagan.shtml Carl Sagan editorials] - reviews of his books; includes some of his articles (including the one on abortion).
*[http://www.donaldedavis.com/PARTS/SAGAN.html "Carl Sagan, Cosmos, and the Space Artists"] - recollections by artist and friend of Carl, Donald Davis.
*[http://science.discovery.com/convergence/cosmos/cosmos.html 25th anniversary rebroadcast of ''Cosmos'' on The Science Channel] - includes a brief biography of Sagan.
| name = Carl Sagan
| image = Sagan_large3.jpg
| birth_date = [[November 9]] [[1934]]
| birth_place = [[Brooklyn, New York|Brooklyn]], [[New York]]
| death_date = [[December 20]] [[1996]]
| death_place = [[Seattle, Washington]]
}}
'''Carl Edward Sagan''' ([[November 9]] [[1934]] – [[December 20]] [[1996]]) was an [[United States|American]] [[astronomer]], [[Astrobiology|astrobiologist]], and highly successful science popularizer. He pioneered [[Astrobiology|exobiology]] and promoted the Search for Extra-Terrestrial Intelligence ([[SETI]]). He is world-famous for writing [[popular science]] books and for co-writing and presenting the award-winning 1980 television series ''[[Cosmos: A Personal Voyage]]'', then the most-watched [[Public Broadcasting Service|PBS]] program of all time<ref> According to [http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/sagan.html nasa.gov], [http://www.infoplease.com/ipa/A0187957.html], [http://www.seasky.org/spacexp/sky5e08.html] and [http://www.mnsu.edu/emuseum/information/biography/pqrst/sagan_carl.html]</ref> until 1990's [[The Civil War (documentary)|''The Civil War'']]. A [[Cosmos (book)|book]] to accompany the program was also published. He also wrote the novel [[Contact (novel)|''Contact'']], the basis for the 1997 [[Contact (film)|film of the same name]] starring [[Jodie Foster]]. During his lifetime, Sagan published more than 600 scientific papers and popular articles and was author, co-author, or editor of more than 20 books. In his works, he frequently advocated [[scientific skepticism]], [[humanism]], and the [[scientific method]].
==Education and scientific career==
[[Image:Sagan of Cornell.jpg|left|thumb|Sagan of Astronomy Department, Cornell University, 1969]]
Carl Sagan was born in [[Brooklyn, New York|Brooklyn]], [[New York]].<ref>For biographical information see ''[[Carl Sagan: A Life in the Cosmos]]'' by [[William Poundstone]]. Henry Holt & Company ([[October 1]] [[1999]]) ISBN 0-8050-5766-8</ref> His parents were [[Jew]]ish; his father, Sam Sagan, was a garment worker and his mother, Rachel Molly Gruber, was a housewife. Carl was named in honor of Rachel's biological mother, Chaiya/ Clara, "the mother she never knew," in Sagan's words. Sagan graduated from Rahway ([[New Jersey|NJ]]) High School in 1951.<ref>''[[Carl Sagan: A Life]]'' by Keay Davidson, pages 33-41. John Wiley & Sons ([[August 30]] [[1999]]) ISBN 0-471-25286-7</ref> He 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]]. During his time as an undergraduate, Sagan spent some time working in the laboratory of the [[geneticist]] [[Hermann Joseph Muller|H. J. Muller]]. From 1962 to 1968, he worked at the [[Smithsonian Astrophysical Observatory]].
[[Image:YoungSagan60s.jpg|right|thumb|Sagan, chairman of the Voyager Golden Record committee in 1977]]
Sagan taught at [[Harvard University]] until 1968, when he moved to [[Cornell University]]. He became a full professor at Cornell in 1971 and directed the Laboratory for [[Planetary science|Planetary Studies]] there. From 1972 to 1981 he was Associate Director of the Center for Radio Physics and Space Research at Cornell.
Sagan was a leader in the U.S. [[space program]] since its inception and worked as an adviser to [[NASA]] since the 1950s. (One of his many duties during his tenure at the space agency included briefing the [[Project Apollo|Apollo]] [[astronaut]]s before their flights to the [[Moon]].) Sagan contributed to most of the [[unmanned space mission|unmanned missions]] that explored the [[solar system]], placing experiments on many robotic space expeditions. 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. Sagan assembled the first physical message that was sent into [[outer space|space]]: a [[gold]]-[[anodized]] [[Pioneer plaque|plaque]], attached to the space probe [[Pioneer 10]], launched in 1972. [[Pioneer 11]], also containing the plaque, was launched the following year. He continued to refine his designs and the most elaborate such message he helped to develop and assemble was the [[Voyager Golden Record]] that was sent out with the [[Voyager program|Voyager]] space probes in 1977.
Sagan taught at Cornell a course on [[critical thinking]] until his death in 1996 from a rare bone marrow disease. The course had only a limited number of seats, although hundreds of students tried to attend. He chose about 20 students who were allowed to enroll by reading huge piles of application essays. The course was discontinued after his death.
==Scientific achievements==
[[Image:Sagan telescope1.jpg|thumb|125px|left|A still from ''Cosmos'']]
Sagan was central to the discovery of the high surface temperatures of the planet [[Venus]]. In the early 1960s, no one knew for certain the basic conditions of Venus' surface and Sagan listed the possibilities in a report (which were later depicted for popularization in a [[Time-Life]] book, ''Planets'') — his own view was that the planet was dry and very hot, as opposed to the balmy paradise others had imagined. He had investigated radio emissions from Venus and concluded that there was a surface temperature of 900°F (500°C). As a visiting scientist to NASA's [[Jet Propulsion Laboratory]], he contributed to the first [[Mariner program|Mariner]] missions to Venus, working on the design and management of the project. [[Mariner 2]] confirmed his views on the conditions of Venus in 1962.
Sagan was among the first to hypothesize that [[Saturn]]'s moon [[Titan (moon)|Titan]]<ref>Much of Sagan's research in the field of planetary science is outlined by William Poundstone (see reference #2, above). Poundstone's biography of Sagan includes an eight page list of Sagan's scientific articles published from 1957 to 1998. Detailed information about Sagan's scientific work comes from the primary research articles. Example: Sagan, C., Thompson, W. R., and Khare, B. N. ''[[Titan: A Laboratory for Prebiological Organic Chemistry]]'', Accounts of Chemical Research, volume 25, page 286 (1992). There is commentary on this research article about Titan at [http://www.daviddarling.info/encyclopedia/T/Titanprebiotic.html The Encyclopedia of Astrobiology, Astronomy, and Spaceflight].</ref> and [[Jupiter]]'s moon [[Europa (moon)|Europa]] may possess oceans (a subsurface ocean, in the case of Europa) or lakes, thus making the hypothesized water ocean on Europa potentially habitable for [[life]]. Europa's subsurface ocean was later indirectly confirmed by the spacecraft [[Galileo probe|Galileo]]. Sagan also helped solve the mystery of the reddish haze seen on Titan, revealing that it is composed of complex [[organic molecules]] constantly raining down to the moon's surface.
He furthered insights regarding the atmospheres of Venus and Jupiter as well as seasonal changes on [[Mars (planet)|Mars]]. Sagan established that the atmosphere of Venus is extremely hot and dense with crushing pressures. 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 gas|greenhouse gasses]]. Sagan speculated (along with his Cornell colleague [[Edwin Ernest Salpeter]]) about [[Jupiter#Life on Jupiter|life in Jupiter's clouds]], given the planet's dense atmospheric composition rich in organic molecules. He studied the observed color variations on Mars’ surface, concluding that they were not seasonal or vegetation changes as most believed, but shifts in surface dust caused by [[dust storm#on other planets|windstorms]].
Sagan is best known, however, for his research on the possibilities of [[exobiology|extraterrestrial life]], including experimental demonstration of the production of [[amino acid]]s from basic chemicals by [[radiation]].<ref>According to [http://www.bartelby.com/65/sa/Sagan-Ca.html The Columbia Encyclopedia, Sixth Edition].</ref>
==Scientific advocacy==
[[Image:Planetary society.jpg|thumb|right|300px|Planetary Society members at the organization's founding. Carl Sagan seated, right]]
Sagan was a proponent of the search for extraterrestrial life. He urged the scientific community to listen with [[radio telescope]]s for signals from intelligent extraterrestrial lifeforms. So persuasive was he 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 was a tremendous turnaround in the respectability of this controversial field. Sagan also advocated sending [[Space probe|probes]] to explore the solar system.
He was editor-in-chief of [[Icarus (journal)|''Icarus'']] (a professional journal concerning planetary research) for 12 years. He cofounded the ''[[Planetary Society]]'', the largest space-interest group in the world, with over 100,000 members in more than 140 countries, 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]].
[[Image:2Sagan 1972.jpg|left|thumb|150px|[[Communication with Extraterrestrial Intelligence|CETI]] conference, 1972]]
Sagan helped Dr. [[Frank Drake]] write the [[Arecibo message]], a radio message beamed into space from the [[Arecibo radio telescope]] on November 16, 1974, aimed at informing extraterrestrials about Earth.
At the height of the [[Cold War]], Sagan deliberately ignored the "extraordinary claims" test for evidence when a mathematical climate model suggested that a substantial nuclear exchange could upset the delicate balance of life on [[Earth]]. He was the last of five authors — the "S" of the [[Nuclear winter#history|"TTAPS"]] report as the research paper came to be known. He eventually co-authored the scientific paper that predicted [[nuclear winter]]<ref>Turco RP, Toon OB, Ackerman TP, Pollack JB, Sagan C. ''[[Climate and smoke: an appraisal of nuclear winter]],'' [[Science (journal)|Science]], volume 247, pages 166-176 (1990). [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11538069&dopt=Abstract PubMed abstract]|[http://links.jstor.org/sici?sici=0036-8075%2819900112%293%3A247%3A4939%3C166%3ACASAAO%3E2.0.CO%3B2-V JSTORE] link to full text article. Carl Sagan discussed his involvement in the political nuclear winter debates and his erroneous global cooling prediction for the Gulf War fires in his book, ''[[The Demon-Haunted World]]''.</ref> would follow [[Nuclear warfare|nuclear war]]. He also co-authored the book ''A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race'', a comprehensive examination of the phenomenon of nuclear winter.
Sagan famously predicted on [[American Broadcasting Company|ABC]]'s ''[[Nightline]]'' in 1991 that smoky [[Kuwaiti oil fires|oil fires]] in Kuwait (set by [[Saddam Hussein]]'s army during the first [[Gulf War]]) would cause a worldwide ecological disaster of black clouds resulting in [[global cooling]]. Retired [[atmospheric physics|atmospheric physicist]] and climate change skeptic [[Fred Singer]] dismissed Sagan's prediction as nonsense, predicting that the smoke would dissipate in a matter of days. In his book ''[[The Demon-Haunted World]]'' (see below), 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 tentative, a self-correcting process.
Sagan is also known for being involved as a researcher in [[Project A119]], a secret [[United States Air Force|US Air Force]] operation whose purpose was to explode an [[nuclear weapon|atomic bomb]] on Earth's Moon.
==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.
[[Image:Sagan young2.jpg|right|thumb|150px|Sagan in the early 1970s]]
Sagan became more politically active after marrying novelist [[Ann Druyan]], performing acts of [[civil disobedience]] at the [[Nevada Test Site|Nevada Nuclear Weapons Test Site]] during the [[Nuclear freeze]] era, for which he was publicly arrested twice, along with [[Daniel Ellsberg]], [[Philip Zimmermann]] and [[Martin Sheen]]. He was also arrested for participating in an anti-war protest during the [[Vietnam war|Vietnam]] era. He spoke out against President [[Ronald Reagan]]'s [[Strategic Defense Initiative]], or the "Star Wars" program, which he felt was technically impossible to build and perfect, far more expensive to create than for an enemy to defeat through decoys and other means, and destabilizing to Cold War [[Nuclear disarmament|nuclear weapons disarmament]] progress.
Carl Sagan was an avid user of [[Cannabis (drug)|marijuana]], although he never admitted this publicly during his life. Under the [[pseudonym]] "Mr. X," he wrote an essay concerning cannabis smoking in the 1971 book ''Marihuana Reconsidered''<!-- That's the spelling (with an "H") used by the US version of Amazon, BTW -->, whose editor was [[Lester Grinspoon]].<ref>''[[Marihuana Reconsidered]]'' by Lester, M.D. Grinspoon. Publisher: Quick American Archives (2nd edition; [[April 1]] [[1994]]) ISBN 0-932551-13-0. Sagan's [http://www.marijuana-uses.com/essays/002.html essay] is available online.</ref> In his 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 ''Carl Sagan: A Life'', was published in 1999, the marijuana exposure stirred some media attention.<ref>[http://news.bbc.co.uk/1/hi/sci/tech/475954.stm BBC news story] that includes mention of Sagan's marijuana use.</ref><ref>[http://www.druglibrary.org/think/~jnr/sagan.htm San Francisco Examiner article] on Sagan's marijuana use. Also includes an article by Lester Grinspoon.</ref><ref>[http://cannabisculture.com/articles/63.html Carl Sagan: Toking Astronomer] – article in Cannabis Culture magazine.</ref>
==Popularization of science==
[[Image:2Sagan 1980.jpg|thumb|150px|left|Sagan in 1980]]
Sagan's capability to convey his ideas allowed many people to better understand the cosmos. He delivered the 1977/1978 [[Royal Institution Christmas Lectures|Christmas Lectures for Young People]] at the [[Royal Institution]]. He hosted and, with Ann Druyan, co-wrote and co-produced the highly popular thirteen-part [[PBS]] television series [[Cosmos: A Personal Voyage|''Cosmos: A Personal Voyage'']] (modeled on [[Jacob Bronowski]]'s ''[[The Ascent of Man]]'').
[[Image:Sagan Viking.jpg|thumb|250px|right|Sagan with a model of the [[Viking Lander]] probes which would land on [[Mars (planet)|Mars]]. Sagan examined possible landing sites for Viking along with Mike Carr and Hal Masursky.]]
''Cosmos'' covered a wide range of scientific subjects including the [[origin of life]] and a perspective of our place in the [[universe]]. The series was first broadcast by the [[Public Broadcasting Service]] in 1980. It won an [[Emmy Award|Emmy]] and a [[Peabody Award]]; according to the NASA Office of Space Science, it has been since broadcast in more than 60 countries and seen by over 600 million people.
Sagan also wrote books to popularize science, such as ''[[Cosmos (book)|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,<ref>According to [http://science.discovery.com/convergence/cosmos/bio/bio.html?clik=fsmain_feat3 The Science Channel].</ref> ''[[The Dragons of Eden|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 (novel)|''Contact'']], but did not live to see the book's 1997 [[Contact (film)|motion picture adaptation]], which starred [[Jodie Foster]] and 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'',<ref>Refuted by Carl Sagan himself in his book ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium|Billions and Billions]]'', pages 3-4. Ballantine Books, [[June]] [[1997]], ISBN 0-345-37918-7</ref> but his distinctive delivery and frequent use of ''billions'' (with noted emphasis on the opening "b") made this a favorite phrase of [[Johnny Carson]], [[Gary Kroeger]], [[Mike Myers (actor)|Mike Myers]], [[Bronson Pinchot]], [[Harry Shearer]] and others, doing many affectionate impressions of him. Sagan took this in good humor, and his final book was entitled ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium|Billions and Billions]]'' (see below) and opened with a tongue-in-cheek discussion of this catch phrase.) A humorous unit of measurement, the ''[[Sagan (unit of measurement)|Sagan]]'', has now been coined to stand for any count of at least 4,000,000,000.
He wrote a sequel to ''Cosmos,'' [[Pale Blue Dot|''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 bestselling 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 [[China|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 [[scientific skepticism]] and against [[pseudoscience]]; most notably his thorough [[Debunker|debunking]] of the book ''[[Worlds in Collision]]'' by [[Immanuel Velikovsky]]. 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. Sagan's arguments against Velikovsky's [[catastrophism]] have been criticized by some of his colleagues. [[Robert Jastrow]] of NASA's [[Goddard Institute for Space Studies]] wrote: "Professor Sagan's calculations, in effect, ignore the law of gravity. Here, Dr. Velikovsky was the better astronomer."
Late in his life, Sagan's books developed his skeptical, [[naturalism (philosophy)|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 critical thinking and the [[scientific method]]. The compilation, ''Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium'', published in 1997 after Sagan's death, contains essays written by Sagan, such as his views on [[abortion]], and his widow Ann Druyan's account of his death as a [[skepticism|skeptic]], [[agnosticism|agnostic]], and [[freethought|freethinker]].
In 2006, Ann Druyan edited Sagan's 1985 ''Gifford Lectures in Natural Theology'' into a new book, ''The Varieties of Scientific Experience: A Personal View of the Search for God,'' in which he elaborates on his views of divinity in the [[nature|natural world]].
==Personality==
In 1966, Sagan was asked to contribute an interview about the possibility of extraterrestrials to a proposed introduction to the film ''[[2001: A Space Odyssey (film)|2001: A Space Odyssey]]''. According to an unsourced anecdote in ''The Independent'', Sagan "responded by saying that he wanted editorial control and a percentage of the film's takings, which was rejected."<ref>[http://enjoyment.independent.co.uk/film/news/article321643.ece 2001: The secrets of Kubrick's classic]" by Anthony Barnes ([[October 23]] [[2005]]).</ref>
In 1994, [[Apple Computer]] began developing the [[Power Macintosh 7100]]. They chose the internal code name "Carl Sagan," the joke being that the mid-range PowerMac 7100 would make Apple "billions and billions".<ref>An account of this lawsuit is given in ''[[Carl Sagan: A Life in the Cosmos]]'', pages 363-364 and 374-375.</ref> Though the project name was strictly internal and never used in public marketing, when Sagan learned of this internal usage, he sued Apple Computer to use a different project name — other projects had names like "[[Cold fusion]]" and "[[Piltdown Man]]", and he was displeased at being associated with what he considered pseudoscience. Though Sagan lost the suit, Apple engineers complied with his demands anyway, renaming the project "BHA" ([[Notable litigation of Apple Computer#Libel dispute with Carl Sagan|Butt-Head Astronomer]]). Sagan sued Apple for libel over the new name, claiming that it subjected him to contempt and ridicule. Sagan lost this lawsuit as well; still, the 7100 saw another name change: it was lastly called "LAW" (Lawyers Are Wimps).
[[Image:Sagan Druyan.jpg|right|thumb|150px|Sagan with Druyan]]
Sagan wrote about [[religion]] and the relationship between religion and science, observing statements such as: "The idea that [[God]] is an oversized white male with a flowing beard, who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by 'God,' one means the set of [[physical laws]] that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to [[prayer|pray]] to the law of [[gravity]]."<ref>A similar quote can be found in Chapter 23 of Sagan's book ''[[Broca's Brain: Reflections on the Romance of Science|Broca's Brain]]''. "Some people think God is an outsized, light-skinned male with a long white beard, sitting on a throne somewhere up there in the sky, busily tallying the fall of every sparrow. Others — for example [[Baruch Spinoza]] and [[Albert Einstein]] — considered God to be essentially the sum total of the physical laws which describe the universe. I do not know of any compelling evidence for anthropomorphic patriarchs controlling human destiny from some hidden celestial vantage point, but it would be madness to deny the existence of physical laws."</ref> Sagan is also widely regarded as a freethinker or skeptic, one of his most famous quotations (as seen in ''Cosmos'') being, "Extraordinary claims require extraordinary evidence." (This is also known, under different wording, as the principle of [[Pierre-Simon Laplace|Laplace]] — attributed to Pierre-Simon Marquis de Laplace (March 23, [[1749]] – March 5, [[1827]]), a [[France|French]] [[mathematician]] and astronomer: "The weight of evidence for an extraordinary claim must be proportioned to its strangeness.")
Sagan married three times; the famous biologist, [[Lynn Margulis]] (mother of [[Dorion Sagan]] and [[Jeremy Sagan]]) in 1957, artist [[Linda Salzman Sagan|Linda Salzman]] (mother of [[Nick Sagan]]) in 1968, and author Ann Druyan (mother of Sasha and Sam) in 1981, with whom he remained married until his death.
[[Isaac Asimov]] described Sagan as one of the only two people he ever met who were just plain smarter than Asimov himself. The other was [[Computer science|computer scientist]] and expert on [[artificial intelligence]], [[Marvin Minsky]].
==Sagan and UFOs==
Sagan had some interest in [[UFO]] reports from at least 1964, when he had several conversations on the subject with [[Jacques Vallee]] (Westrum 37). Though quite skeptical of any extraordinary answer to the UFO question, Sagan thought that science should study the phenomenon, at least because there was widespread public interest in UFO reports.
[[Stuart Appelle]] notes that Sagan "wrote frequently on what he perceived as the [[logic|logical]] and [[empiricism|empirical]] [[fallacy|fallacies]] regarding UFOs and the [[abduction phenomenon|abduction experience]]. Sagan rejected an [[extraterrestrial hypothesis|extraterrestrial explanation]] for the phenomenon but felt there were both empirical and [[pedagogical]] benefits for examining UFO reports and that the subject was, therefore, a legitimate topic of study" (Appelle 22).
In 1966, Sagan was a member of the Ad Hoc Committee to Review [[Project Blue Book]]. The committee concluded that the U.S. Air Force's [[Project Blue Book]] had been lacking as a scientific study, and recommended a university-based project to give the UFO phenomenon closer scientific scrutiny. The [[Condon Committee]] (1966-1968), led by physicist [[Edward Condon]], and their still-controversial final report, formally concluded that there was nothing anomalous about UFO reports.
[[Ron Westrum]] writes that "The high point of Sagan's treatment of the UFO question was the [[American Association for the Advancement of Science|AAAS]]'s symposium in 1969. A wide range of educated opinions on the subject were offered by participants, including not only proponents as [[James E. McDonald|James McDonald]] and [[J. Allen Hynek]] but also skeptics like astronomers [[William Hartmann]] and [[Donald Menzel]]. The roster of speakers was balanced, and it is to Sagan's credit that this event was presented in spite of pressure from [[Edward Condon]]" (Westrum 37-38). With physicist [[Thornton Page]], Sagan edited the lectures and discussions given at the symposium; these were published in 1972 as ''UFO's: A Scientific Debate''.
[[Jerome Clark]] writes that Sagan's perspective on UFO's irked Condon: "... though a skeptic, [Sagan] was too soft on UFOs for Condon's taste. In 1971, he considered blackballing Sagan from the prestigious [[Cosmos Club]]" (Clark 603).
Some of Sagan's many books examine UFOs (as did one episode of ''Cosmos'') and he recognized a religious undercurrent to the phenomenon. However, Westrum writes that "Sagan spent very little time researching UFOs ... he thought that little evidence existed to show that the UFO phenomenon represented alien spacecraft and that the motivation for interpreting UFO observations as spacecraft was emotional" (Westrum 37).
It is sometimes noted that Sagan's generally skeptical attitude to UFOs conflicted sharply with his views in a 1966 book he wrote with Russian astronomer and astrophysicist [[Iosif Samuilovich Shklovsky|I.S. Shklovskii]], ''Intelligent Life in the Universe''. Here Sagan instead argued that technologically advanced alien civilizations were common and he considered it very probable that Earth had been visited many times in the past.
Yet only a few years later in ''UFO's: A Scientific Debate'', Sagan was now highly skeptical of interstellar visitation. As to the physical possibility of [[interstellar travel]], Sagan brought up the proposed [[Bussard ramjet]] as an interstellar vehicle. While not terribly practical, Sagan thought such proposed propulsion systems were nevertheless important because they demonstrated that there were conceivable ways of accomplishing interstellar travel "without bumping into fundamental physical constraints. And this suggests that it is premature to say that interstellar space flight is out of the question." But to this Sagan added, "I believe the numbers work out in such a way that UFO's as interstellar vehicles is extremely unlikely, but I think it is an equally bad mistake to say that interstellar space flight is impossible."
Sagan again revealed his views on interstellar travel in his 1980 ''Cosmos'' series. He scoffed at the idea that UFOs are visiting Earth, maintaining that the chances any alien spacecraft would visit the Earth are vanishingly small. However, in another episode he said the stars would "beckon" to humanity, and described the Bussard ramjet as one way humans might achieve interstellar travel. In one of his last written works, Sagan again claimed that there was no evidence that aliens have actually visited the Earth, either in the past or present (Sagan, 1996: 81-96, 99-104).
==Legacy==
[[Image:Sagan1996.jpg|left|frame|Sagan in 1996, shortly before his death]]
After a long and difficult fight with [[Myelodysplastic syndrome|myelodysplasia]], Sagan died of [[pneumonia]] 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 popularization of the [[Natural science#Natural sciences|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 ''[[Mars Pathfinder#End of the mission|Carl Sagan Memorial Station]]'' on [[July 5]] [[1997]]. [[2709 Sagan|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, ends with the dedication "For Carl."
On November 9, 2001, on what would have been Sagan’s 67th birthday, the [[NASA Ames Research Center]] dedicated the site for the Carl Sagan Center for the Study of Life in the Cosmos. "Carl was an incredible visionary, and now his legacy can be preserved and advanced by a 21st century research and education laboratory committed to enhancing our understanding of life in the universe and furthering the cause of space exploration for all time," said NASA Administrator [[Daniel Goldin]]. Ann Druyan was at the center as it opened its doors on October 22, 2006.
Sagan's son, Nick Sagan, wrote several episodes in the ''[[Star Trek]]'' franchise. In an episode of ''[[Star Trek: Enterprise]]'' entitled "Terra Prime," a quick shot is shown of the relic rover [[Mars Pathfinder|Sojourner]], part of the Mars Pathfinder mission, placed by a historical marker at Carl Sagan Memorial Station on the Martian surface. The marker displays a quote from Sagan: "Whatever the reason you're on Mars, I'm glad you're there, and I wish I was with you."
Sagan's student, [[Steve Squyres]], would lead the team that landed the [[Spirit Rover]] and [[Opportunity Rover]] successfully on Mars in 2004.
==Awards and medals==
* Annual Award for Television Excellence - 1981 - [[Ohio State University]] - PBS series ''[[Cosmos: A Personal Voyage|Cosmos]]''
* [[Apollo Achievement Award]] - [[NASA|National Aeronautics and Space Administration]]
* [[Chicken Little Award|Chicken Little]] Honorable Mention - 1991 - National Anxiety Center; a ''dubious achievement award'' from an organization which is skeptical about many pessimistic appraisals of the state of the environment
* [[NASA Distinguished Service Medal#NASA Distinguished Public Service Medal|NASA Distinguished Public Service Medal]] - National Aeronautics and Space Administration (twice)
* [[Emmy]] - Outstanding Individual Achievement - 1981 - PBS series ''Cosmos''
* Emmy - [[Primetime Emmy Award for Outstanding Informational Series|Outstanding Informational Series]] - 1981 - PBS series ''Cosmos''
* [[NASA Exceptional Achievement Medal|Exceptional Scientific Achievement Medal]] - National Aeronautics and Space Administration
* [[Helen Caldicott Leadership Award]] - Women's Action for Nuclear Disarmament
* [[Homer Award]] - 1997 - ''[[Contact (novel)|Contact]]''
* [[Hugo Award]] - 1981 - ''Cosmos''
* [[American Humanist Association#AHA's Humanists of the Year|Humanist of the Year]] - 1981 - Awarded by the [[American Humanist Association]]
* [[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 - ''[[Cosmic Connection: An Extraterrestrial Perspective]]''
* [[Joseph Priestley|Joseph Priestley Award]] - "For distinguished contributions to the welfare of mankind"
* [[Klumpke-Roberts Award]] of the [[Astronomical Society of the Pacific]] - 1974
* [[Konstantin Tsiolkovsky Medal]] - Awarded by the Soviet Cosmonauts Federation
* [[Locus Award]] 1986 - ''Contact''
* [[Lowell Thomas Award]] - [[Explorers Club]] - 75th Anniversary
* [[Masursky Award]] - [[American Astronomical Society]]
* [[Oersted Medal]] - 1990 - American Association of Physics Teachers
* [[Peabody Award]] - 1980 - PBS series ''Cosmos''
* [[Prix Galbert]] - The international prize of [[Astronautics]]
* [[Public Welfare Medal]] - 1994 - [[National Academy of Sciences]]
* [[Pulitzer Prize|Pulitzer Prize for General Non-Fiction]] - 1978 - ''[[The Dragons of Eden]]''
* [[The San Francisco Chronicle#Awards given by the Chronicle|SF Chronicle Award]] - 1998 - ''[[Contact (film)|Contact]]''
* [[Carl Sagan Memorial Award]] - Named in his honor
* Named 99th "[[Greatest American]]" on the [[June 5]] [[2005]] "Greatest American" show on the [[Discovery Channel]].
==Books and media==
===By Sagan===
* Sagan, Carl, Jonathon Norton Leonard and editors of Life, ''[[Planets]]''. Time, Inc., 1966
*[[Iosif Samuilovich Shklovskii|I.S. Shklovskii]] coauthor, ''[[Intelligent Life in the Universe]]''. Random House, 1966, 509 pgs
*''UFO's: A Scientific Debate''. Cornell University Press, 1972, 310 pgs
*''[[Communication with Extraterrestrial Intelligence]]''. MIT Press, 1973, 428 pgs
* Sagan, Carl, et. al. ''[[Mars and the Mind of Man]]''. Harper & Row, 1973, 143 pgs
*Jerome Agel coauthor, ''[[Cosmic Connection: An Extraterrestrial Perspective]]''. Anchor Press, 1973, ISBN 0-521-78303-8, 301 pgs
*''[[Broca's Brain: Reflections on the Romance of Science]]''. Ballantine Books, 1974, ISBN 0-345-33689-5, 416 pgs
*''[[Other Worlds]]''. Bantam Books, 1975
* Sagan, Carl, et. al. ''[[Murmurs of Earth: The Voyager Interstellar Record]]''. Random House, 1977
*''[[The Dragons of Eden|The Dragons of Eden: Speculations on the Evolution of Human Intelligence]]''. Ballantine Books, 1978, ISBN 0-345-34629-7, 288 pgs
*''[[Cosmos (book)|Cosmos]]''. Random house, 1980. Random House New Edition, [[May 7]] [[2002]], ISBN 0-375-50832-5, 384 pgs
* Sagan, Carl et. al. ''[[The Nuclear Winter: The World After Nuclear War]]''. Sidgwick & Jackson, 1985
*Ann Druyan coauthor, ''[[Comet]]''. Ballantine Books, 1985, ISBN 0-345-41222-2, 496 pgs
*''[[Contact (novel)|Contact]]''. Simon and Schuster, 1985; Reissued August 1997 by Doubleday Books, ISBN 1-56865-424-3, 352 pgs
*Richard Turco coauthor, ''[[A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race]]''. Random House, 1990, 499 pgs
*Ann Druyan coauthor, ''[[Shadows of Forgotten Ancestors: A Search for Who We Are]]''. Ballantine Books, October 1993, ISBN 0-345-38472-5, 528 pgs
*''[[Pale Blue Dot: A Vision of the Human Future in Space]]''. Random House, November 1994, ISBN 0-679-43841-6, 429 pgs
*''[[The Demon-Haunted World|The Demon-Haunted World: Science as a Candle in the Dark]]''. Ballantine Books, March 1996, ISBN 0-345-40946-9, 480 pgs
*Ann Druyan coauthor, ''[[Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium]]''. Ballantine Books, June 1997, ISBN 0-345-37918-7, 320 pgs
*''The Varieties of Scientific Experience: A Personal View of the Search for God''. 1985 [[Gifford lectures]], Penguin Press, 2006, ISBN 1-59420-107-2, 304 pgs
===About Sagan===
* Appelle, Stuart, "[[Ufology]] and [[Academia]]: The UFO Phenomenon as a Scholarly Discipline" (pages 7-30 in ''UFOs and Abductions: Challenging the Borders of Knowledge'', David M. Jacobs, editor; University Press of Kansas, 2000; ISBN)
* Clark, Jeromne, ''The UFO Book''. Visible Ink Press, 1998, 750 pgs
* Davidson, Keay, ''[[Carl Sagan: A Life]]''. John Wiley & Sons, [[August 30]] [[1999]], ISBN 0-471-39536-6, 560 pgs
* Head, Tom (editor), ''[[Conversations with Carl Sagan]]''. University Press of Mississippi, 2005, ISBN 1-57806-736-7, 170 pgs
* Poundstone, William, ''[[Carl Sagan: A Life in the Cosmos]]''. Henry Holt & Company, [[October 1]] [[1999]], ISBN 0-8050-5766-8, 473 pgs
*Westrum, Ron, "Limited Access: Six Natural Scientists and the UFO Phenomenon" (pages 30-55 in Jacobs)
* Zemeckis, Robert, ''[[Contact (film)|Contact]]''. Warner Studios, 1997, [http://us.imdb.com/Title?0118884 IMDB]
==Footnotes==
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==External links==
* [http://www.carlsagan.com/ CarlSagan.com] - homepage of ''Cosmos Studios'', which sells the ''Cosmos'' series on DVD.
*[http://www.marijuana-uses.com/essays/002.html "Mr. X"] - Sagan's anonymous 1969 essay in Lester Grinspoon's ''Marihuana Reconsidered'', 1971.
*[http://video.google.com/videoplay?docid=-8949469271181885482&q=Carl+Sagan Life Beyond Earth and the Mind of Man 1975] - a symposium held at [[Boston University]] that explores the implications of the possible existence of extraterrestrial life within the galaxy and the universe, with Sagan as a panel member.
*[http://www.bigear.org/vol1no2/sagan.htm "The Quest for Extraterrestrial Intelligence"] - 1978 essay by Carl Sagan.
*[http://www.stephenjaygould.org/ctrl/sagan_science.html "Can We Know the Universe?"] - 1979 essay by Carl Sagan, taken from his book ''Broca's Brain''.
*[http://spider.ipac.caltech.edu/staff/jarrett/sagan/dmaps.html "Dreams are Maps"] - 1987 essay by Sagan.
*[http://www.detwiler.us/sagan.html Carl Sagan's Religion of Science] - an analysis of Sagan's view of religion as expressed in his writings.
*[http://www.asa3.org/asa/PSCF/1993/PSCF3-93McKim.html The Cosmos According to Carl Sagan] - Review and critique of Sagan's criticism toward religion.
*[http://www.csicop.org/si/2005-07/sagan.html "Carl Sagan Takes Questions"] - from Sagan's 1994 "Wonder and Skepticism" keynote address delivered in Seattle June 23–26.
*[http://video.google.com/videoplay?docid=-1127834163386485385&q=Carl+Sagan ''Charlie Rose'' January 5, 1995] - interview with Sagan on his book ''Pale Blue Dot: A Vision of the Human Future in Space''.
*[http://www.npr.org/templates/story/story.php?storyId=1011828 ''Talk of the Nation'' May 3, 1996] - Ira Flatow interviews Sagan on his book ''The Demon-Haunted World: Science as a Candle in the Dark''.
*[http://video.google.com/videoplay?docid=2181165206611526024 ''Charlie Rose'' May 27, 1996] - interview with Sagan on his book ''The Demon-Haunted World''.
*[http://web.archive.org/web/20050322090707/http://www.news.cornell.edu/general/Dec96/saganobit.ltb.html "Carl Sagan, Cornell astronomer, dies today (Dec. 20) in Seattle"] - Cornell University press release.
* [http://home.austarnet.com.au/stear/carl-sagan-tribute.htm "In Memory of Carl Sagan"] ''Skeptic'' remembers Carl, with tributes from Tom McDonough, [[James Randi]], [[Michael Shermer]], and others. Also includes quotations from selected works of Sagan.
*[http://www.sciencenter.org/SaganPW/ The Sagan Planet Walk] - New York planetary exhibit created in memory of Carl Sagan.
*[http://www.coseti.org/klaescnt.htm ''Contact'' Film Review] - an analysis of the film and novel, by Larry Klaes.
*[http://www.2think.org/sagan.shtml Carl Sagan editorials] - reviews of his books; includes some of his articles (including the one on abortion).
*[http://www.donaldedavis.com/PARTS/SAGAN.html "Carl Sagan, Cosmos, and the Space Artists"] - recollections by artist and friend of Carl, Donald Davis.
*[http://science.discovery.com/convergence/cosmos/cosmos.html 25th anniversary rebroadcast of ''Cosmos'' on The Science Channel] - includes a brief biography of Sagan.
