卡尔·萨根

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卡尔·萨根Carl Sagan
Image:Carl Sagan Scientist.jpg
出生	1934年11月9日 纽约市布鲁克林区
逝世	1996年 12月20日 华盛顿州西雅图

卡尔·爱德华·萨根（1934年11月9日—1996年12月20日Carl Edward Sagan），美国天文学家、科普作家、科幻作家。

他是研究外太空生命学的先驱，也是搜寻地外智慧生物项目(SETI)的创始人之一。他因为撰写了多部优秀的科普图书及电视系列片宇宙而享誉全球。他在自己的作品中经常提倡科学方法。

astrobiologist, and highly successful science popularizer. He pioneered 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 television series Cosmos, the most watched PBS program of all time ^[1]. A book to accompany the program was also published. He also wrote the novel Contact, upon which the 1997 film of the same name starring Jodie Foster was based. In his works, he frequently advocated 科学怀疑主义, 人文主义, and the 科学方法.

目录 1 教育背景和科学研究 2 科学成就 3 Scientific advocacy 4 Social concerns 5 科学普及 6 人格 7 萨根与飞碟 8 对后世的影响 9 获奖列表 10 有关书籍和媒体 11 参考资料 12 参考书籍 13 外在链接

[编辑] 教育背景和科学研究

卡尔·萨根出生在纽约市布鲁克林区^[2]. His parents were 犹太人; his father, Sam Sagan, was a garment worker and his mother, Rachel Molly Gruber, was a housewife. Sagan attended the 芝加哥大学, 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 H. J. Muller.

In the early 1960s, no one knew for certain the basic conditions of the surface of the planet 金星 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 a visiting scientist to NASA's Jet Propulsion Laboratory, he contributed to the first Mariner missions to Venus, working on the design and management of the project. Mariner2 confirmed his views on the conditions of Venus in 1962.

Sagan taught at 哈佛大学 until 1968, when he moved to 康乃尔大学. He became a full professor at Cornell in 1971 and directed a lab there. He contributed to most of the unmanned space missions that explored the 太阳系. He conceived the idea of adding an unalterable and universal message on spacecraft, destined to leave the 太阳系, that could be understood by any extraterrestrial intelligence that might find it. The first message that was actually sent into space was a gold-anodized plaque, attached to the space probe Pioneer 10. He continued to refine his designs and the most elaborate such message he helped to develop was the Voyager Golden Record that was sent out with the Voyager space probes.

Sagan taught at 康乃尔大学 a course on critical thinking until the year of his death in 1996. 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.

[编辑] 科学成就

Sagan was among the first to hypothesize that 土星's moon 土卫六^[3] and 木星的卫星木卫二 may possess oceans (a subsurface ocean, in the case of Europa) or lakes, thus making the hypothesized water ocean on Europa potentially habitable for 生命. Europa's subsurface ocean was later indirectly confirmed by the spacecraft Galileo.

He furthered insights regarding the atmosphere of Jupiter, seasonal changes on 火星, and Saturn's moon Titan. Sagan established that the atmosphere of Venus is extremely hot and dense. He also perceived global warming as a growing, man-made danger and likened it to the natural development of Venus into a hot life-hostile planet through 温室气体. He suggested that the seasonal changes on 火星 were due to windblown dust, not to vegetation changes, as others had proposed.

[编辑] Scientific advocacy

萨根主张积极寻找地外生命. He urged the scientific community to listen with large 射电望远镜 for signals from intelligent extraterrestrial lifeforms. He advocated sending probes to other planets. Sagan was Editor in Chief of Icarus (a professional journal concerning planetary research) for 12 years. He cofounded the Planetary Society and was a member of the SETI Institute Board of Trustees.

He was well known as a co-author of the scientific paper that predicted nuclear winter^[4] would follow nuclear war. Sagan famously predicted that smoky oil fires in Kuwait (set by Saddam Hussein's army) would cause an ecological disaster of black clouds. Retired atmospheric physicist 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, 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.

萨根 is also known for being involved as a researcher in Project A119, a secret 美国空军 operation whose purpose was to drop a bomb on Earth's 月亮.

[编辑] 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.

Sagan became more politically active after marrying novelist Ann Druyan, performing acts of civil disobedience at nuclear weapons sites during the Nuclear freeze era. He spoke out against 罗纳德·里根总统的星球大战计划, 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 冷战核武器 disarmament progress.

萨根还使用大麻。虽然他从来没有公开承认，但在一本1971年的书Marihuana Reconsidered中，用“X先生”的匿名写了一篇有关文章^[5]，提到大麻激发了他很多工作的灵感。萨根去世后，该书的编辑者把此事告诉了萨根的传记作家，1999年出版的传记^[6]由此激起了媒体注意^[7]。

[编辑] 科学普及

Sagan's capability to convey his ideas allowed many people to better understand the cosmos. He delivered the 1977/1978 Christmas Lectures for Young People at the Royal Institution. He narrated and, with Ann Druyan, co-wrote and co-produced the highly popular thirteen part PBS television series: Cosmos: A Personal Voyage (modeled on Jacob Bronowski's The Ascent of Man).

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 and a Peabody Award; according to the NASA Office of Space Science, it has been since broadcast in 60 countries and seen by more than 600 million people.

Sagan also wrote books to popularize science, such as Cosmos, which reflected and expanded upon some of the themes of A Personal Voyage, 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, but never lived to see the book's 1997 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, but his distinctive delivery and frequent use of billions made this a favorite phrase of Johnny Carson and others, doing the many affectionate impressions of him. Sagan took this in good humor, and his final book was entitled Billions and Billions - see below.) A humorous unit of measurement, the 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: 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 卐字 symbol in his book, Comet. Sagan hypothesized that a 彗星 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 中国 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 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, rather than his own personal views. Some believe this unease to have been motivated in part by professional jealousy, that scientific views contrary to those that Sagan took (such as on the severity of nuclear winter) were not being sufficiently presented to the public.

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." His comments on the Kuwait oil well fires during the first Gulf War were shown later to be incorrect; Sagan himself acknowledged his error in print.

Late in his life, Sagan's books developed his skeptical, naturalistic view of the world. In The Demon-Haunted World: Science as a Candle in the Dark, he presented tools for testing arguments and detecting fallacious or fraudulent ones, essentially advocating wide use of the scientific method. The compilation, Billions and Billions: Thoughts on Life and Death at the End of the Millennium, published after Sagan's death, contains essays written by Sagan, such as his views on 堕胎, and Ann Druyan's account of his death as a non-believer.

[编辑] 人格

In 1966, Sagan was asked to contribute an interview about the possibility of extraterrestrials to a proposed introduction to the film 2001太空漫游. According to an uncited anecdote in The Independent, Sagan "responded by saying that he wanted editorial control and a percentage of the film's takings, which was rejected."^[8]

In 1994, 苹果电脑 began developing the Power Macintosh 7100. They chose the internal code name "Carl Sagan," in honor of the astronomer.^[9] 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" (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).

Sagan is regarded by most as an atheist, agnostic, or 泛神论 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 祈祷 to the law of 重力."^[10] Sagan was also a skeptic; as he states in Cosmos, "Extraordinary claims require extraordinary evidence."

萨根一共结婚三次：第一次是1957年与著名生物学家Lynn Margulis（生Dorion Sagan和Jeremy Sagan)，1968年与艺术家Linda Salzman （生Nick Sagan]]），1981年与作家Ann Druyan （生Sasha和Sam）。

艾萨克·阿西莫夫說生平只遇過兩個人比他更為聰明，薩根是其中之一，另一個則是電腦科學家马文·闵斯基。

[编辑] 萨根与飞碟

Sagan had some interest in UFO reports from at least 1964, when he had several conversations on the subject with Jacques Vallee. (Westrum, p37) 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 logical and empirical fallacies regarding UFOs and the abduction experience. Sagan rejected an 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, p 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), lead 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 AAAS's symposium in 1969. A wide range of educated opinions on the subject were offered by participants, including not only proponents as 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, pp. 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, p. 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, 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 revealed his views on interstellar travel in his 1980 Cosmos series. Although he scoffed at the idea that UFOs are visiting Earth, maintaining that the distance between stars was too great to make interstellar travel feasible for aliens,in another episode he said the stars would "beckon" to humanity, describing the Bussard ramjet as one way humans might achieve interstellar travel. Sagan pointed out that there is no evidence that aliens have actually visited the Earth, either in the past or present (Sagan, 1995:81-96, 99-104).

[编辑] 对后世的影响

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

The landing site of the unmanned 火星探路者 spacecraft was renamed the Carl Sagan Memorial Station on July 5 1997. Asteroid 2709 Sagan is also named in his honor.

1997年的电影《接触》(参见上面), based on Sagan's novel of the same name and finished after his death, ends with the dedication "For Carl."

In 2004, the electronic music group Sagan released the CD/DVD "Unseen Forces." The music was accompanied by a DVD which featured humorous music video format homages of many of the historical sketches from Cosmos.

In an episode of Star Trek: Enterprise entitled "Terra Prime", a quick shot is shown of the relic rover 火星探路者, 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."

[编辑] 获奖列表

• Apollo Achievement Award - NASA
• Chicken Little Award 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 Public Service Medal
• 艾美奖 - Outstanding individual achievement - 1981 - PBS series Cosmos
• 艾美奖 - Outstanding Informational Series - 1981 - PBS series Cosmos
• NASA Exceptional Achievement Medal
• Helen Caldicott Leadership Award
• Homer Award - 1997 - Contact
• 雨果奖 - 1981 - Cosmos
• American Humanist Association: Humanist of the Year - 1981
• In Praise of Reason Award - 1987 - Committee for the Scientific Investigation of Claims of the Paranormal
• Isaac Asimov Award - 1994 - Committee for the Scientific Investigation of Claims of the Paranormal
• John F. Kennedy Astronautics Award - American Astronautical Society
• John W. Campbell Memorial Award - 1974 - The Cosmic Connection
• Klumpke-Roberts Award of the Astronomical Society of the Pacific - 1974
• Konstantin Tsiolkovsky Medal - awarded by the Soviet Cosmonauts Federation
• Locus Award 1986 - Contact (novel)
• Lowell Thomas Award - Explorers Club - 75th Anniversary
• Masursky Award - [[American Astronomical Society
• Peabody Award - 1980 - PBS series Cosmos
• Public Welfare Medal - 1994 - National Academy of Sciences
• 普利策非小说类作品奖 - 1978 - The Dragons of Eden
• The San Francisco Chronicle Award - 1998 - Contact (film)
• Carl Sagan Memorial Award - Named in his honor
• Named 99th "Greatest American" on the June 5 2005 "Greatest American" show on the Discovery Channel.

[编辑] 有关书籍和媒体

• 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 (1998)
• Sagan, Carl and Jonathon Norton Leonard and editors of Life, Planets. Time, Inc., 1966
• Sagan, Carl and I.S. Shklovskii, Intelligent Life in the Universe. Random House, 1966
• Sagan, Carl, Communication with Extraterrestrial Intelligence. MIT Press, 1973
• Sagan, Carl, et. al. Mars and the Mind of Man. Harper & Row, 1973
• Sagan, Carl, Other Worlds. Bantam Books, 1975
• Sagan, Carl, et. al. Murmurs of Earth: The Voyager Interstellar Record. Random House, 1977
• Sagan, Carl et. al. The Nuclear Winter: The World After Nuclear War. Sidgwick & Jackson, 1985
• Sagan, Carl, Contact (novel). Simon and Schuster, 1985; Reissued August 1997 by Doubleday Books, ISBN 1568654243, 352 pgs
• Sagan, Carl and Richard Turco, A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race. Random House, 1990
• Sagan, Carl, The Dragons of Eden|The Dragons of Eden: Speculations on the Evolution of Human Intelligence. Ballantine Books, December 1989, ISBN 0345346297, 288 pgs
• Sagan, Carl, Broca's Brain: Reflections on the Romance of Science. Ballantine Books, October 1993, ISBN 0345336895, 416 pgs
• Sagan, Carl and Ann Druyan, Shadows of Forgotten Ancestors: A Search for Who We Are. Ballantine Books, October 1993, ISBN 0345384725, 528 pgs
• Sagan, Carl, Pale Blue Dot: A Vision of the Human Future in Space. Random House, November 1994, ISBN 0679438416, 429 pgs
• Sagan, Carl and Ann Druyan, Comet. Ballantine Books, February 1997, ISBN 0345412222, 496 pgs
• Sagan, Carl and Ann Druyan, Billions & Billions: Thoughts on Life and Death at the End of the Millennium. Ballantine Books, June 1998, ISBN 0345379187, 320 pgs
• Sagan, Carl, The Demon-Haunted World: Science as a Candle in the Dark. Ballantine Books, March 1997, ISBN 0345409469, 480 pgs
• Sagan, Carl and Jerome Agel, Cosmic Connection: An Extraterrestrial Perspective. Cambridge University Press, January 15, 2000, ISBN 0521783038, 301 pgs
• Sagan, Carl, Cosmos: A Personal Voyage. Random House, May 7, 2002, ISBN 0375508325, 384 pgs
• Westrum, Ron, "Limited Access: Six Natural Scientists and the UFO Phenomenon" (pages 30-55 in Jacobs)
• Zemeckis, Robert, Contact (film). Warner Studios, 1997, IMDB
• Davidson, Keay, Carl Sagan: A Life. John Wiley & Sons, August 31, 2000, ISBN 0471395366, 560 pgs
• Head, Tom (editor), Conversations with Carl Sagan. University Press of Mississippi, 2005, ISBN 1578067367, 170 pgs

[编辑] 参考资料

1. ↑ according to nasa.gov, [1], [2] and [3]
2. ↑ For biographical information see Carl Sagan: A Life in the Cosmos by William Poundstone. Henry Holt & Company (October 1 1999) ISBN 0-805-05766-8
3. ↑ Much of Sagan's research in the field of planetary science is outlined by William Poundstone (see reference #1, 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 The Encyclopedia of Astrobiology, Astronomy, and Spaceflight.
4. ↑ Turco RP, Toon OB, Ackerman TP, Pollack JB, Sagan C. Climate and smoke: an appraisal of nuclear winter, Science, volume 247, pages 166-176 (1990). PubMed abstract | 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.
5. ↑ Marihuana Reconsidered by Lester, M.D. Grinspoon. Publisher: Quick American Archives (2nd edition; April 1 1994) ISBN 0932551130. 萨根的文章 在这里 可以看到。
6. ↑ Carl Sagan: A Life by Keay Davidson. John Wiley & Sons (August 30 1999) ISBN 0471252867
7. ↑ BBC news story
8. ↑ 2001: The secrets of Kubrick's classic" by Anthony Barnes (23 October 2005).
9. ↑ An account of this lawsuit is given in Carl Sagan: A Life in the Cosmos, pages 363-364 and 374-375.
10. ↑ A similar quote can be found in Chapter 23 of Sagan's book 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 巴魯赫·斯賓諾莎 and 阿尔伯特·爱因斯坦 - 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."

[编辑] 参考书籍

• Sagan, Carl, (1995). The Demon-Haunted World:Science as a Candle in the Dark, Random House, ISBN 0-394-53512-X

[编辑] 外在链接

• In Memory of Carl Sagan. Tributes by Tom McDonough, James Randi and Michael Shermer, and a selection of quotes from Sagan's works, published in Skeptic, Vol. 4, no. 4, 1996, pp. 10-17.
• CarlSagan.Com. Homepage of Cosmos Studios, which sells the Cosmos series on DVD.
• Carl Sagan, Cornell astronomer, dies today (20 December) in Seattle. Cornell University press release on Sagan's death.
• Astronomy Picture of the Day: Carl Sagan. December 26 1996.
• Mr. X - Sagan's essay in the 1971 book Marihuana Reconsidered
• Larry Klaes' in-depth analysis of the film and novel Contact
• "Big Bang Bust" TIME magazine, December 14 1981
• "The Quest for Extraterrestrial Intelligence" Cosmic Search Magazine Vol. 1 No. 2, March 1979
• Carl Sagan's Religion of Science An analysis of Sagan's view of religion as expressed in his writings
• Carl Sagan Planet Walk
• Sagan The electronic music group
• 25th Anniversary Rebroadcast of Cosmos on The Science Channel
• Carl Sagan Takes Questions
• COSMOS tribute clip on youtube