Content deleted Content added
No edit summary Tags: Visual edit Mobile edit Mobile web edit |
m Post-split cleanup of a wikilink according to WP:SPLIT#Step 6: Clean up so that it points to a section United States security clearance, not to any section in Security clearance |
||
| (8 intermediate revisions by 8 users not shown) | |||
Line 1:
{{Use American English|date=September 2024}}▼
{{Short description|American astrophysicist, cosmologist and author (1934–1996)}}
{{
▲{{Use American English|date=September 2024}}
{{Use mdy dates|date=September 2024}}
{{Infobox scientist
Line 70:
}}
'''Carl Edward Sagan''' ({{IPAc-en|ˈ|s|eɪ|ɡ|ən}}; {{respell|SAY|gən}};<!-- Location of birth; please add here. --> November 9, 1934{{spaced ndash}}<!-- Location of death; please add here. -->December 20, 1996) was an American [[astronomer]], [[planetary scientist]]
Initially an assistant professor at [[Harvard University|Harvard]], Sagan later moved to [[Cornell University]], where he spent most of his career. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books.<ref name="scholar"/> He wrote many [[popular science]] books, such as ''[[The Dragons of Eden]]'', ''[[Broca's Brain]]'', ''[[Pale Blue Dot (book)|Pale Blue Dot]]'' and ''[[The Demon-Haunted World]]''. He also co-wrote and narrated the award-winning 1980 television series ''[[Cosmos: A Personal Voyage]]'', which became the most widely watched series in the history of American [[public television]]: ''Cosmos'' has been seen by at least 500 million people in 60 countries.<ref name =Starchild>{{cite web |url=http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/sagan.html |title=StarChild: Dr. Carl Sagan |work=StarChild |publisher=[[NASA]] |access-date=October 8, 2009 |archive-date=February 7, 2012 |archive-url=https://web.archive.org/web/20120207191139/http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/sagan.html |url-status=live}}</ref> A book, also called ''[[Cosmos (Carl Sagan book)|Cosmos]]'', was published to accompany the series. Sagan also wrote a science-fiction novel, published in 1985, called ''[[Contact (novel)|Contact]]'', which became the basis for the 1997 film ''[[Contact (1997 American film)|Contact]]''. His papers, comprising 595,000 items,<ref>{{cite book |title=The Seth MacFarlane Collection of the Carl Sagan and Ann Druyan Archive: A Finding Aid to the Collection in the Library of Congress |date=2013 |publisher=Manuscript Division, Library of Congress |url=http://rs5.loc.gov/service/mss/eadxmlmss/eadpdfmss/2013/ms013113.pdf |access-date=January 17, 2016 |archive-date=March 8, 2016 |archive-url=https://web.archive.org/web/20160308005013/http://rs5.loc.gov/service/mss/eadxmlmss/eadpdfmss/2013/ms013113.pdf |url-status=live}}</ref> are archived in the [[Library of Congress]].<ref>{{cite web |last1=Lowensohn |first1=Josh |title=Massive Carl Sagan archive posted by Library of Congress |url=https://www.theverge.com/2014/2/4/5379446/massive-carl-sagan-archive-posted-by-library-of-congress |access-date=January 16, 2016 |website=The Verge |date=February 4, 2014 |archive-date=January 12, 2020 |archive-url=https://web.archive.org/web/20200112204114/https://www.theverge.com/2014/2/4/5379446/massive-carl-sagan-archive-posted-by-library-of-congress |url-status=live}}</ref>
Line 79:
===Childhood===
[[File:Carl Sagan in 1951 Allegarooter.jpg|thumb|upright|left|Sagan in [[Rahway High School]]'s 1951 yearbook]]
Carl Edward Sagan was born on November 9, 1934, in the [[Bensonhurst, Brooklyn|Bensonhurst]] neighborhood of New York City's [[Brooklyn]] borough.<ref name=poundstone>[[#Poundstone|Poundstone 1999]], pp. 363–364, 374–375.</ref><ref name="nyt"/> His mother, Rachel Molly Gruber (1906–1982), was a housewife from New York City; his father, Samuel Sagan (1905–1979), was a Ukrainian-born garment worker who had emigrated from [[Kamianets-Podilskyi]] (then in the [[Russian Empire]]).<ref name="Internet Accuracy Project">{{cite web |title=Carl Sagan |url=http://www.accuracyproject.org/cbe-Sagan,Carl.html |website=Internet Accuracy Project |location=Grandville, MI |access-date=August 22, 2012 |archive-date=March 8, 2012 |archive-url=https://web.archive.org/web/20120308095615/http://www.accuracyproject.org/cbe-Sagan,Carl.html |url-status=live}}</ref> Sagan was named in honor of his maternal grandmother, Chaiya Clara, who had died while giving birth to her second child; she was, in Sagan's words, "the mother she [Rachel] never knew."<!-- note: "she" is correct, refers to Rachel. Please do not turn this into "he" --><ref name="Davidson">[[#CITEREFDavidson1999|Davidson 1999]].</ref> Sagan's maternal grandfather later married a woman named Rose, who Sagan's sister, Carol, would later say, was "never accepted" as Rachel's mother because Rachel "knew she [Rose] wasn't her birth mother."<ref>{{Cite web |title=Carl Sagan |url=https://archive.nytimes.com/www.nytimes.com/books/first/d/davidson-sagan.html |access-date=May 7, 2021 |website=The New York Times |archive-date=July 14, 2021 |archive-url=https://web.archive.org/web/20210714153902/https://archive.nytimes.com/www.nytimes.com/books/first/d/davidson-sagan.html |url-status=live}}</ref> Sagan's family lived in a modest apartment in Bensonhurst. He later described his family as [[Reform Judaism|Reform Jews]], the most [[Religious liberalism|liberal]] of Judaism's four main branches. He and his sister agreed that their father was not especially religious, but that their mother "definitely believed in God, and was active in the [[Synagogue|temple]] [...] and served only [[Kosher foods|kosher]] meat."{{Sfn|Davidson|1999|p=12}} During the worst years of the [[Great Depression|Depression]], his father worked as a movie theater usher.{{Sfn|Davidson|1999|p=12}}
According to biographer Keay Davidson, Sagan experienced a kind of "inner war" as a result of his close relationship with both his parents, who were in many ways "opposites." He traced his analytical inclinations to his mother, who had been extremely poor as a child in New York City during [[World War I]] and the 1920s,{{Sfn|Davidson|1999|p=2}} and whose later intellectual ambitions were sabotaged by her poverty, status as a woman and wife, and [[Jewish ethnicity]]. Davidson suggested she "worshipped her only son, Carl" because "he would fulfill her unfulfilled dreams."{{Sfn|Davidson|1999|p=2}} Sagan believed that he had inherited his sense of wonder from his father, who spent his free time giving apples to the poor or helping soothe tensions between workers and management within New York City's garment industry.{{Sfn|Davidson|1999|p=2}} Although awed by his son's intellectual abilities, Sagan's father also took his inquisitiveness in stride, viewing it as part of growing up.{{Sfn|Davidson|1999|p=2}} Later, during his career, Sagan would draw on his childhood memories to illustrate scientific points, as he did in his book ''[[Shadows of Forgotten Ancestors (book)|Shadows of Forgotten Ancestors]]''.{{Sfn|Davidson|1999|p=9}}
Line 85:
Describing his parents' influence on his later thinking, Sagan said: "My parents were not scientists. They knew almost nothing about science. But in introducing me simultaneously to skepticism and to wonder, they taught me the two uneasily cohabiting modes of thought that are central to the scientific method."<ref name="Spangenburg">[[#Spangenburg & Moser|Spangenburg & Moser 2004]], pp. 2–5.</ref> He recalled that a defining moment in his development came when his parents took him, at age four, to the [[1939 New York World's Fair]]. He later described his vivid memories of several exhibits there. One, titled ''[[Futurama (New York World's Fair)|America of Tomorrow]]'', included a moving map, which, as he recalled, "showed beautiful highways and [[Cloverleaf interchange|cloverleaves]] and little [[General Motors]] cars all carrying people to skyscrapers, buildings with lovely spires, flying buttresses—and it looked great!"{{Sfn|Davidson|1999|p=14}} Another involved a flashlight shining on a [[Solar cell|photoelectric cell]], which created a crackling sound, and another showed how the sound from a [[tuning fork]] became a wave on an [[oscilloscope]]. He also saw an exhibit of the then-nascent medium known as television. Remembering it, he later wrote: "Plainly, the world held wonders of a kind I had never guessed. How could a tone become a picture and light become a noise?"{{Sfn|Davidson|1999|p=14}}
Sagan also saw one of the fair's most publicized events: the burial at [[Flushing Meadows–Corona Park|Flushing Meadows]] of a [[time capsule]], which contained mementos from the 1930s to be recovered by Earth's descendants in a future millennium. Davidson wrote that this "thrilled Carl." As an adult, inspired by his memories of the World's Fair, Sagan and his colleagues would create similar time capsules to be sent out into the galaxy: the [[Pioneer plaque]] and the ''[[Voyager Golden Record]]'' précis.{{Sfn|Davidson|1999|p=15}}
During [[World War II]], Sagan's parents worried about the fate of their European relatives, but he was generally unaware of the details of the ongoing war. He wrote, "Sure, we had relatives who were caught up in the [[The Holocaust|Holocaust]]. [[Adolf Hitler|Hitler]] was not a popular fellow in our household... but on the other hand, I was fairly insulated from the horrors of the war." His sister, Carol, said that their mother "above all wanted to protect Carl... she had an extraordinarily difficult time dealing with World War II and the Holocaust."{{Sfn|Davidson|1999|p=15}} Sagan's book ''[[The Demon-Haunted World]]'' (1996) included his memories of this conflicted period, when his family dealt with the realities of the war in Europe, but tried to prevent it from undermining his optimistic spirit.<ref name="Spangenburg" />
Line 114:
{{quote box||align=left|width=25em|bgcolor = LightCyan|quote=Science is more than a body of knowledge; it is a way of thinking. I have a foreboding of an America in my children's or grandchildren's time – when the United States is a service and information economy; when nearly all the key manufacturing industries have slipped away to other countries; when awesome technological powers are in the hands of a very few, and no one representing the public interest can even grasp the issues; when the people have lost the ability to set their own agendas or knowledgeably question those in authority; when, clutching our crystals and nervously consulting our horoscopes, our critical faculties in decline, unable to distinguish between what feels good and what's true, we slide, almost without noticing, back into superstition and darkness... The dumbing down of America is most evident in the slow decay of substantive content in the enormously influential media, the 30 second sound bites (now down to 10 seconds or less), lowest common denominator programming, credulous presentations on pseudoscience and superstition, but especially a kind of celebration of ignorance.|source='''Carl Sagan''', from ''Demon-Haunted World'' (1995)<ref>Sagan, Carl. ''Demon-Haunted World: Science as a Candle in the Dark'' ([https://books.google.com/books?id=Yz8Y6KfXf9UC&q=foreboding%20of%20an%20America on Google Books], {{Web archive |url=https://web.archive.org/web/20221003060920/https://www.google.com/books/edition/The_Demon_Haunted_World/Yz8Y6KfXf9UC?gbpv=1&bsq=foreboding%20of%20an%20America |date=3 October 2022 }}), Ballantine Books (1996) p. 25.</ref>}}
Long before the ill-fated tenure process, Cornell University astronomer [[Thomas Gold]] had courted Sagan to move to [[Ithaca, New York]], and join the recently
Sagan was associated with the U.S. space program from its inception.{{Citation needed|date=November 2020}} From the 1950s onward, he worked as an advisor to [[NASA]], where one of his duties included briefing the [[Apollo program|Apollo]] [[astronaut]]s before their flights to the [[Moon]]. Sagan contributed to many of the [[robotic spacecraft]] missions that explored the [[Solar System]], arranging experiments on many of the expeditions. Sagan assembled the first physical message that was sent into space: a [[Gold plating|gold-plated]] [[Pioneer plaque|plaque]], attached to the space probe ''[[Pioneer 10]]'', launched in 1972. ''[[Pioneer 11]]'', also carrying another copy of the plaque, was launched the following year. He continued to refine his designs; the most elaborate message he helped to develop and assemble was the [[Voyager Golden Record]], which was sent out with the [[Voyager program|Voyager]] space probes in 1977. Sagan often challenged the decisions to fund the [[Space Shuttle]] and the [[International Space Station]] at the expense of further robotic missions.<ref name="CharlieRose">{{cite interview |last=Sagan |first=Carl |title=An Interview with Carl Sagan |url=https://www.youtube.com/watch?v=soF-aS169bw |work=[[Charlie Rose (TV series)|Charlie Rose]] |publisher=[[PBS]] |date=January 5, 1995 |access-date=August 30, 2013 |archive-date=July 14, 2015 |archive-url=https://web.archive.org/web/20150714182925/https://www.youtube.com/watch?v=soF-aS169bw |url-status=live}}</ref>
Line 139:
In 1980 Sagan co-wrote and narrated the award-winning 13-part [[PBS]] television series ''[[Cosmos: A Personal Voyage]]'', which became the most widely watched series in the history of American public television until 1990. The show has been seen by at least 500 million people across 60 countries.<ref name="Starchild" /><ref>{{cite web |url=http://www.mnsu.edu/emuseum/information/biography/pqrst/sagan_carl.html |title=Carl Sagan |work=EMuseum |publisher=[[Minnesota State University, Mankato]] |archive-url=https://web.archive.org/web/20100528213538/http://www.mnsu.edu/emuseum/information/biography/pqrst/sagan_carl.html |archive-date=May 28, 2010 |access-date=August 30, 2013}}</ref><ref>{{cite web |url=http://www.cosmolearning.com/documentaries/cosmos/ |title=CosmoLearning Astronomy |publisher=CosmoLearning |access-date=October 8, 2009 |archive-date=May 29, 2012 |archive-url=https://archive.today/20120529135421/http://www.cosmolearning.com/documentaries/cosmos/ |url-status=live}}</ref> The book, ''Cosmos'', written by Sagan, was published to accompany the series.<ref name="NationalGeo">{{cite web |url=http://news.nationalgeographic.com/news/2014/03/140316-carl-sagan-science-galaxies-space/ |title=Who Was Carl Sagan? |last=Vergano |first=Dan |date=March 16, 2014 |website=National Geographic Daily News |publisher=[[National Geographic Society]] |location=Washington, D.C. |access-date=May 13, 2014 |archive-date=May 13, 2014 |archive-url=https://web.archive.org/web/20140513032406/http://news.nationalgeographic.com/news/2014/03/140316-carl-sagan-science-galaxies-space/ |url-status=dead}}</ref>
Because of his earlier popularity as a science writer from his best-selling books, including ''The Dragons of Eden'', which won him a [[Pulitzer Prize]] in 1977, he was asked to write and narrate the show. It was targeted to a general audience of viewers,
Each of the 13 episodes was created to focus on a particular subject or person, thereby demonstrating the synergy of the universe.<ref name="Browne" /> They covered a wide range of scientific subjects including the [[Abiogenesis|origin of life]] and a perspective of humans' place on Earth.
Line 181:
Sagan wrote a sequel to ''Cosmos'', ''[[Pale Blue Dot (book)|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]]''. He appeared on PBS's ''[[Charlie Rose (TV series)|Charlie Rose]]'' program in January 1995.<ref name="CharlieRose" /> Sagan also wrote the introduction for [[Stephen Hawking]]'s bestseller ''[[A Brief History of Time]]''. Sagan was also known 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]], such as his [[Debunker|debunking]] of the [[Betty and Barney Hill abduction]]. To mark the tenth anniversary of Sagan's death, [[David Morrison (astrophysicist)|David Morrison]], a former student of Sagan, recalled "Sagan's immense contributions to planetary research, the public understanding of science, and the skeptical movement" in ''[[Skeptical Inquirer]]''.<ref name="morrison" />
Following [[Saddam Hussein]]'s threats to light [[Kuwait]]'s oil wells on fire in response to any physical challenge to Iraqi control of the oil assets, Sagan together with his "TTAPS" colleagues and [[Paul Crutzen]], warned in January 1991 in ''[[The Baltimore Sun]]'' and ''[[Wilmington Morning Star]]'' newspapers that if the fires were left to burn over a period of several months, enough smoke from the 600 or so 1991 [[Kuwaiti oil fires]] "might get so high as to disrupt agriculture in much of South Asia ..." and that this possibility should "affect the war plans";<ref>{{Cite web |url=http://articles.baltimoresun.com/1991-01-23/news/1991023131_1_kuwait-saddam-hussein-sagan |title=Baltimore Sun – We are currently unavailable in your region |date=January 23, 1991 |access-date=October 3, 2014 |archive-date=October 6, 2014 |archive-url=https://web.archive.org/web/20141006144456/http://articles.baltimoresun.com/1991-01-23/news/1991023131_1_kuwait-saddam-hussein-sagan |url-status=
In his later years, Sagan advocated the creation of an organized search for asteroids/[[near-Earth object]]s (NEOs) that might impact the Earth but to forestall or postpone developing the technological methods that would be needed to defend against them.<ref>[[#Head|Head 2006]], p. 86–87.</ref> He argued that all of the numerous methods proposed to [[asteroid impact avoidance|alter the orbit of an asteroid]], including the employment of [[nuclear weapon design|nuclear detonations]], created a [[Asteroid impact avoidance#Deflection technology concerns|deflection dilemma]]: if the ability to deflect an asteroid away from the Earth exists, then one would also have the ability to divert a non-threatening object towards Earth, creating an immensely destructive weapon.<ref name="auto">{{Cite journal |last1=Sagan |first1=Carl |last2=Ostro |first2=Steven J. |author-link2=Steven J. Ostro |date=Summer 1994 |title=Long-Range Consequences Of Interplanetary Collisions |journal=[[Issues in Science and Technology]] |volume=10 |issue=4 |pages=67–72 |issn=0748-5492 |bibcode=1994IST....10...67S |access-date=August 31, 2013 |url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/33108/1/94-1042.pdf |url-status=dead |archive-url=https://web.archive.org/web/20131203014812/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/33108/1/94-1042.pdf |archive-date=December 3, 2013}}</ref><ref name="e-reading.club">{{cite web |url=http://www.e-reading.club/chapter.php/72440/26/Sagan_-_Pale_Blue_Dot__A_Vision_of_the_Human_Future_in_Space.html |title=Chapter 18. The Marsh of Camarina – Pale Blue Dot: A Vision of the Human Future in Space |work=e-reading.club |access-date=September 1, 2015 |archive-date=September 24, 2015 |archive-url=https://web.archive.org/web/20150924003823/http://www.e-reading.club/chapter.php/72440/26/Sagan_-_Pale_Blue_Dot__A_Vision_of_the_Human_Future_in_Space.html |url-status=live}}</ref> In a 1994 paper he co-authored, he ridiculed a three-day-long "[[Asteroid impact avoidance#Nuclear explosive device|Near-Earth Object Interception Workshop]]" held by [[Los Alamos National Laboratory]] (LANL) in 1993 that did not, "even in passing" state that such interception and deflection technologies could have these "ancillary dangers."<ref name="auto"/>
Line 212:
=== Social concerns ===
Sagan believed that the [[Drake equation]], on substitution of reasonable estimates, suggested that a large number of extraterrestrial civilizations would form, but that the lack of evidence of such civilizations highlighted by the [[Fermi paradox]] suggests [[Technology|technological]] civilizations tend to self-destruct. This stimulated his interest in identifying and publicizing ways that humanity could destroy itself, with the hope of avoiding such a [[Risks to civilization, humans, and planet Earth|cataclysm]] and eventually becoming a [[spacefaring]] species. Sagan's deep concern regarding the potential destruction of [[Risks to civilization, humans, and planet Earth|human civilization]] in a [[nuclear holocaust]] was conveyed in a memorable cinematic sequence in the final episode of ''Cosmos'', called "Who Speaks for Earth?" Sagan had already resigned{{date?}} from the [[United States Air Force Scientific Advisory Board|Air Force Scientific Advisory Board]]'s UFO-investigating [[Condon Committee]] and voluntarily surrendered his [[
[[File:US and USSR nuclear stockpiles.svg|thumb|The United States and [[Soviet Union]]/Russia nuclear stockpiles, in [[Historical nuclear weapons stockpiles and nuclear tests by country|total number of nuclear bombs/warheads in existence]] throughout the [[Cold War]] and post-Cold War era]]
In March 1983, Reagan announced the [[Strategic Defense Initiative]]—a multibillion-dollar project to develop a comprehensive [[missile defense|defense]] against attack by [[Nuclear weapons delivery#Ballistic missile|nuclear missiles]], which was quickly dubbed the "Star Wars" program. Sagan spoke out against the project, arguing that it was technically impossible to develop a system with the level of perfection required, and far more expensive to build such a system than it would be for an enemy to defeat it through [[Decoy#Military decoy|decoys]] and other means—and that its construction would seriously destabilize the "nuclear balance" between the United States and the [[Soviet Union]], making further progress toward [[nuclear disarmament]] impossible.<ref>{{cite web |url=https://www.youtube.com/watch?v=fVUk30GFsL4 |archive-url=https://web.archive.org/web/20150711151236/https://www.youtube.com/watch?v=fVUk30GFsL4 |archive-date=July 11, 2015 |url-status=dead |title=YouTube |via=YouTube}}</ref>
Line 248:
Sagan also commented on Christianity and the [[Jefferson Bible]], stating "My long-time view about Christianity is that it represents an amalgam of two seemingly immiscible parts, the religion of Jesus and the religion of [[Paul the Apostle|Paul]]. [[Thomas Jefferson]] attempted to excise the Pauline parts of the New Testament. There wasn't much left when he was done, but it was an inspiring document."<ref>{{cite book |last=Schei |first=Kenneth A. |title=An Atheist for Jesus |year=1996 |publisher=Synthesis |isbn=978-0-926491-01-4}}</ref>
Sagan thought that spirituality should be scientifically informed and that traditional religions should be abandoned and replaced with belief systems that revolve around the scientific method,<ref>{{Cite
outside the realm of science. On occasion, I will feel free to use the word. Science is not only compatible with spirituality; it is a profound source of spirituality. When we recognize our place in an immensity of light-years and in the passage of ages, when we grasp the intricacy, beauty, and subtlety of life, then that soaring feeling, that sense of elation and humility combined, is surely spiritual.<ref>Sagan, Carl; Druyan, Ann (1997). [[The Demon-Haunted World: Science as a Candle in the Dark]]. Ballantine Books {{ISBN|0345409469}}</ref>}}
Line 376:
== Books ==
{{refbegin|30em|indent=}}
* {{cite book |last1=Sagan |first1=Carl |title=Organic Matter and The Moon |series=Panel on Extra-Terrestrial Life for the Armed Forces – NRC Committee on Bio-Astronautics, Publication 757 |year=1961 |publisher=National Academy of Sciences—National Research Council |location=Washington, D.C. |lccn=61-60064 |ref=Sagan |title-link=Organic Matter and The Moon|bibcode=1961orm..book.....S }}
* {{cite book |last1=Sagan |first1=Carl |last2=Leonard |first2=Jonathan Norton |others=Editors of ''[[Life (magazine)|Life]]'' |title=Planets |url=https://archive.org/details/planetssaga00saga |url-access=registration |series=[[Life Science Library]] |year=1966 |publisher=[[Time Inc.]] |location=New York |oclc=346361 |lccn=66022436 |ref=Sagan & Leonard}}
* {{cite book |last1=Sagan |first1=Carl |last2=Shklovskii |first2=I.S. |author-link2=Iosif Shklovsky |others=Authorized translation by Paula Fern |title=Intelligent Life in the Universe |orig-year=Originally published 1962 as ''Вселенная, жизнь, разум''; Moscow: [[Nauka (publisher)|USSR Academy of Sciences Publisher]] |year=1966 |publisher=Holden-Day, Inc. |location=San Francisco |oclc=317314 |lccn=64018404 |author-mask=2 |ref=Shklovskii & Sagan |title-link=Ancient astronauts#Shklovskii and Sagan}}
Line 431:
* [https://www.youtube.com/watch?v=PQ4qBBWv3b4 Sagan interviewed by Ted Turner], CNN, 1989, video: 44 minutes.
* [https://www.bbc.co.uk/iplayer/episode/b00scvqk/Great_Lives_Series_21_Carl_Sagan/ Carl Sagan]—''Great Lives'', [[BBC Radio]], December 15, 2017
* [https://web.archive.org/web/20221018010748/https://books.google.
* {{IMDb name|755981|Carl Sagan}}
* [https://web.archive.org/web/20160201115954/http://www.csicop.org/si/show/carl_sagans_life_and_legacy_as_scientist_teacher_and_skeptic "Carl Sagan's Life and Legacy as Scientist, Teacher, and Skeptic"], by David Morrison, [[Committee for Skeptical Inquiry]]
| |||
