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Carl Sagan

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The Final Frontier
The abyss stares back

The Cosmos is all that is, or ever was, or ever will be. Our feeblest contemplations of the Cosmos stir us — there is a tingling in the spine, a catch in the voice, a faint sensation as if a distant memory, of falling from a great height. We know we are approaching the grandest of mysteries.
—Carl Sagan, Cosmos[1]:1

Carl Sagan (1934–1996) was an American astronomer who did much to popularize science, especially astronomy, during his illustrious career. He co-wrote and presented Cosmos: A Personal Voyage, a television series that kicked ass. His legacy lies mainly in his advancement of humanism. He found a profound spirituality in experiencing the wonder and majesty of the universe. Sagan was also a prominent role model and mentor for Neil deGrasse Tyson.[2]

He is known for remarking how people were made of "star stuff." And, by the by, he was right: HHe → Li → Be → B → C → N → O → F, and on through various nuclear processes that synthesize the elements up to iron (Fe) — and it takes a supernova (or a particle accelerator!) to make a heavier nucleus.

Sagan was also very interested in extraterrestrial life, including UFO sightings (though he was a skeptic on the matter); he heavily promoted the search for extraterrestrial intelligence.

In 1974, he was enlisted by the American Association for the Advancement of Science (AAAS) to lead the attack at their conference, debunking the theories of Immanuel Velikovsky. His rather cavalier performance at this event was perhaps a salutary lesson in the fight against woo. Far from stamping out the growing cult of Velikovsky, he arguably further stoked it by allowing a few schoolboy errors to creep into his math and peppering his talk with cheeky jokes. The Velikovsky faithful seized this use of levity and lack of rigor as evidence that Thine Mainstream was not playing fair and was trying to suppress the truth.

A prominent non-believer, Carl Sagan is said by many fundamentalists to have converted to Christianity on his deathbed, the testimony of his widow notwithstanding. This is a cowardly attack because they know Dr. Sagan can't come back to make a refutation.[note 1] Some of them point to a quote from his famous novel Contact about "an intelligence that antedates the Universe" as evidence of this change in beliefs, but fellow science fiction author Robert J. Sawyer, also an agnostic, has pointed out Sagan was no more obligated to believe in the religious aspects of that novel than Star Wars creator George Lucas was to believe in The Force.

A recent development is a celebration of "Carl Sagan Day," which is celebrated on his birthday, November 9.[3] The first celebration of the event, in 2009, was attended by James Randi and Phil Plait as guest speakers.[4]

He was and still remains arguably one of the greatest science communicators ever.


Carl Sagan was a leader in the American space program from its earliest stages. He briefed the Apollo astronauts before the Moon missions and played an instrumental role in the planning and operation of the Viking, Voyager, Mariner, and Galileo space probes. He was also a prolific author and popularizer of science, creating the 13-part TV series Cosmos (the most widely watched PBS program in the world), appearing on late-night television numerous times, and writing Contact, Pale Blue Dot, Billions and Billions, and many other books. He married three times, the third time to Ann Druyan, his occasional co-author. He died in 1996 at the age of 62 after a prolonged battle with cancer, survived by Druyan and five children.[note 2]

Personal beliefs[edit]

Sagan called himself agnostic, although he is best defined today as a freethinker or a pantheist. He himself rejected the term "atheist", as he defined it as someone who knows there is no God. His definition is considered inaccurate by some today, but we're getting into Judean People's Front territory here.

Nuclear winter[edit]

Estimated global temperature changes after nuclear winter
Imagine, a room, awash in gasoline. And there are two implacable enemies in that room. One of them has 9,000 matches. The other has 7,000 matches. Each of them is concerned about who's ahead, who's stronger. Well, that's the kind of situation we are actually in. The amount of weapons that are available to the United States and the Soviet Union are so bloated, so grossly in excess of what's needed to dissuade the other that if it weren't so tragic, it would be laughable.

Sagan helped develop the TTAPS (short for the co-authors of the original paper, Turco, Toon, Ackerman, Pollack, and Sagan) climate model that predicted a resulting "nuclear winter" in the event of nuclear warfare.[5] Though later research revised the total cooling effect downward (and even later research bumped it back up a bit), the concept of nuclear winter has been considered a valid prediction by the scientific community.[6] The TTAPS model was used to argue against Ronald Reagan's Star Wars plan (i.e., the defense system would have to be perfect to prevent a nuclear strike and ensuing nuclear winter). Partially in response to this theory, Frederick Seitz established the George C. Marshall Institute to deny nuclear winter.

Thankfully, Reagan never got his wish.

Cannabis use[edit]

Sagan loved him some herb.
I think the ratio, R, of the time to sense the dose taken to the time required to take an excessive dose is an important quantity. R is very large for LSD (which I've never taken) and reasonably short for cannabis. Small values of R should be one measure of the safety of psychedelic drugs. When cannabis is legalized, I hope to see this ratio as one of the parameters printed on the pack. I hope that time isn't too distant; the illegality of cannabis is outrageous, an impediment to full utilization of a drug which helps produce the serenity and insight, sensitivity and fellowship so desperately needed in this increasingly mad and dangerous world.
—Mr. X[7]

Carl Sagan was a huge advocate of cannabis, also known as marijuana,[8] crediting it with inspiring many of his best works, in addition to improving food, sex, and music.

Apple Computer[edit]

In the 1990s, Apple was developing a line of three computers based on the new PowerPC processor. As was a common practice at the time, they used internal codenames to refer to these projects in-house, all following a common theme. The Power Macintosh 6100 was codenamed "Piltdown Man," the 7100 was named "Carl Sagan," and the 8100 was named "Cold fusion." These code names appeared from time to time in the trade press.

In 1994, when Carl Sagan discovered his name was used by Apple on the model that would become the 7100 — and that his name was associated with two of the most infamous blunders/hoaxes in the history of modern science — he sued, claiming defamation and wrongful use of his name for commercial purposes. The judge dismissed the suit, stating that Apple had honored him in selecting his name, and since these were not the actual product names, nor released to the general public, it was irrelevant, anyway.

In the meantime, Apple renamed the project BHA. Sagan sued Apple again (and lost), this time because BHA was claimed to stand for "butt-head astronomer".[9] Sagan appealed the decision and the matter was finally confidentially settled out of court.


  • "For small creatures such as we the vastness is bearable only through love."[10]:429
  • "How is it that hardly any major religion has looked at science and concluded, 'This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant!'" from Pale Blue Dot[11]:52
  • "The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff." from Cosmos[1]:144
  • "The surface of the Earth is the shore of the cosmic ocean. On this shore, we've learned most of what we know. Recently, we've waded a little way out, maybe ankle-deep, and the water seems inviting. Some part of our being knows this is where we came from. We long to return, and we can, because the cosmos is also within us. We're made of star stuff. We are a way for the cosmos to know itself." from episode one of Sagan's TV series Cosmos: A Personal Voyage.[12]
  • "If you wish to make an apple pie from scratch, you must first invent the universe." from Cosmos[1]:230
  • "It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring."[13]:12
  • "Personally, I would be delighted if there were a life after death—especially if it permitted me to continue to learn about this world and others, if it gave me a chance to discover how history turns out."[14]:302
  • "But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown."[15]
  • "Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works."[13]:336
  • "Imagination will often carry us to worlds that never were. But without it we go nowhere."[1]:2
  • "Extraordinary claims require extraordinary evidence."[14]:62
  • "The sky calls to us. If we do not destroy ourselves we will one day venture to the stars."[16]
  • "On this globe there are national boundaries marked, but on photographs of the Earth from space, there are no national boundaries to be seen, which is perhaps a useful lesson for politicians."[17]
  • "History is full of people who out of fear or ignorance or the lust for power have destroyed treasures of immeasurable value which truly belong to all of us. We must not let it happen again."[18]

Baloney Detection Kit[edit]

See the main article on this topic: The Fine Art of Baloney Detection

In the "Fine Art of Baloney Detection" chapter of The Demon-Haunted World, Sagan explains how to think like a scientist and spot pseudoscience. This is an abridgment of the full kit, not the partial versions that many people point to.

Key questions[edit]

  • How reliable is the source of the claim?
  • Does this source often make similar claims?
  • Have the claims been verified by another source?
  • How does the claim fit with what we know about how the world works?
  • Has anyone gone out of the way to disprove the claim, or has only supportive evidence been sought?
  • Does the preponderance of evidence point to the claimant's conclusion or to a different one?
  • Is the claimant employing the accepted rules of reason and tools of research, or have these been abandoned in favor of others that lead to the desired conclusion?
  • Is the claimant providing an explanation for the observed phenomena or merely denying the existing explanation?
  • If the claimant proffers a new explanation, does it account for as many phenomena as the old explanation did?
  • Do the claimant's personal beliefs and biases drive the conclusions, or vice versa?

Warning signs[edit]

  • Ad hominem
  • Argument from authority
  • Argument from adverse consequences
  • Appeal to ignorance - the claim that whatever has not been proved false must be true, and vice versa
  • Special pleading
  • Begging the question, also called assuming the answer
  • Observational selection, also called the enumeration of favourable circumstances, or as the philosopher Francis Bacon described it, "counting the hits and forgetting the misses"
  • Statistics of small numbers
  • Misunderstanding of the nature of statistics
  • Inconsistency
  • Non sequitur - Latin for 'it doesn't follow'
  • Post hoc, ergo propter hoc - Latin for 'it happened after, so it was caused by'
  • Meaningless question
  • Excluded middle, or false dichotomy
  • Short-term v. long-term
  • Slippery slope, related to excluded middle
  • Confusion of correlation and causation
  • Straw man
  • Suppressed evidence, or half-truths
  • Weasel words


  • Planets (LIFE Science Library). Sagan, Carl, Jonathon Norton Leonard and editors of Life, Time, Inc., 1966. ISBN 0-809-40424-9
  • Intelligent Life in the Universe. I.S. Shklovskii co-author, Random House, 1966. ISBN 1-892-80302-X
  • UFO's: A Scientific Debate. Thornton Page co-author, Cornell University Press, 1972. ISBN 0-801-40740-0
  • Communication with Extraterrestrial Intelligence. MIT Press, 1973. ISBN 0-262-19106-7
  • Mars and the Mind of Man. Sagan, Carl, et al., Harper & Row, 1973. ISBN 0-060-10443-0
  • Cosmic Connection: An Extraterrestrial Perspective. Jerome Agel co-author, Anchor Press, 1973. ISBN 0-521-78303-8
  • Other Worlds. Bantam Books, 1975. ISBN 0-553-06439-8
  • Murmurs of Earth: The Voyager Interstellar Record. Sagan, Carl, et al., Random House, 1978. ISBN 0-394-41047-5
  • The Dragons of Eden: Speculations on the Evolution of Human Intelligence. Ballantine Books, 1978. ISBN 0-345-34629-7
  • Broca's Brain: Reflections on the Romance of Science. Ballantine Books, 1979. ISBN 0-345-33689-5
  • Cosmos. Random House, 1980. Random House New Edition, 2002. ISBN 0-375-50832-5
  • The Cold and the Dark: The World After Nuclear War. Sagan, Carl et al., Sidgwick & Jackson, 1985. ISBN 0-393-30241-5
  • Comet. Ann Druyan co-author, Ballantine Books, 1985. ISBN 0-345-41222-2
  • Contact. Simon and Schuster, 1985; Reissued August 1997 by Doubleday Books. ISBN 1-568-65424-3
  • The Varieties of Scientific Experience: A Personal View of the Search for God. Ann Druyan editor, 1985 Gifford Lectures, Penguin Press, 2006. ISBN 1-594-20107-2
  • A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race. Richard Turco co-author, Random House, 1990. ISBN 0-394-58307-8
  • Shadows of Forgotten Ancestors: A Search for Who We Are. Ann Druyan Coauthor, Ballantine Books, 1993. ISBN 0-345-38472-5
  • Pale Blue Dot: A Vision of the Human Future in Space. Random House, 1994. ISBN 0-679-43841-6
  • The Demon-Haunted World: Science as a Candle in the Dark. Ballantine Books, 1996. ISBN 0-345-40946-9 (Note: the book was first published and copyrighted in 1995 with an errata slip inserted)
  • Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium. Ann Druyan coauthor, Ballantine Books, 1997. ISBN 0-345-37918-7
  • The Varieties of Scientific Experience: A Personal View of the Search for God. Carl Sagan (writer) & Ann Druyan (editor), Penguin Press HC, 2006. ISBN 1-594-20107-2

See also[edit]

External links[edit]


  1. Then again, they are fundamentalist Christians. Perhaps some of them think he could pull a Lazarus.
  2. Thank God for that.


  1. 1.0 1.1 1.2 1.3 Cosmos by Carl Sagan (1980) Ballantine Books, 2013 Ballantine Books Trade Paperback Edition. ISBN 978-0-345-53943-4
  2. [1]
  3. Center for Inquiry, Celebrate Carl Sagan Day November 9th!
  4. Florida Citizens for Science, Carl Sagan Day.
  5. R. P. Turco, O. B. Toon, T. P. Ackerman, J. B. Pollack and Carl Sagan. Nuclear Winter: Global Consequences of Multiple Nuclear Explosions. Science 1983: Vol. 222 no. 4630 pp. 1283-1292. (Full text of a later article called Climate and Smoke.)
  6. See Wikipedia's nuclear winter articleWikipedia for a fuller treatment.
  7. Essay by Carl as the pen name Mr. X, written in 1969 for Marihuana Reconsidered (1971) by Dr. Lester Grinspoon
  8. Biographer: Astronomer Carl Sagan Smoked Marijuana, AP
  9. Sagan sues Apple over name
  10. Contact: A Novel by Carl Sagan (1985) Simon and Schuster, First Edition. ISBN 0-671-43400-4. Chapter 124
  11. Pale Blue Dot by Carl Sagan (1994) Random House: New York, First Edition. ISBN 0-679-43841-6
  12. Sagan, C. (Writer), Druyan, A. (Writer), & Malone, A. (Director). (1980, September 28). The Shores of the Cosmic Ocean (1) [TV series episode]. In A. Malone, D. Kennard, G. Haines-Stiles, and G. Andorfer (Executive Producers), Cosmos: A Personal Voyage. Public Broadcasting Service.
  13. 13.0 13.1 The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan (1995) Random House: New York, First Edition. ISBN 0-394-53512-X
  14. 14.0 14.1 Broca's Brain: Reflections on the Romance of Science by Carl Sagan (1979) Random House: New York, First Edition. ISBN 0-394-50169-1.
  15. Sagan, C. (Writer), Druyan, A. (Writer), & Malone, A. (Director). (1980, December 14). Encyclopaedia Galactica (12) [TV series episode]. In A. Malone, D. Kennard, G. Haines-Stiles, and G. Andorfer (Executive Producers), Cosmos: A Personal Voyage. Public Broadcasting Service.
  16. Sagan, C. (Writer), Druyan, A. (Writer), & Malone, A. (Director). (1980, November 9). The Backbone of Night (7) [TV series episode]. In A. Malone, D. Kennard, G. Haines-Stiles, and G. Andorfer (Executive Producers), Cosmos: A Personal Voyage. Public Broadcasting Service.
  17. Christmas Lecture, 1977
  18. Sagan, C. (Writer), Druyan, A. (Writer), & Malone, A. (Director). (1980, December 21). Who Speaks for Earth? (13) [TV series episode]. In A. Malone, D. Kennard, G. Haines-Stiles, and G. Andorfer (Executive Producers), Cosmos: A Personal Voyage. Public Broadcasting Service.