by Carl Sagan
The content of the message to this point should be clear to an advanced extraterrestrial civilization, which will, of course, have the entire Pioneer 10 spacecraft to examine as well. The message is probably less clear to the man on the street, if the street is on the planet Earth. (However, scientific communities on Earth have had little difficulty decoding the message.) The opposite is the case with the representations of human beings to the right. Extraterrestrial beings, which are the product of 4.5 billion years or more of independent biological evolution, may not at all resemble humans, nor may the perspective and linedrawing conventions be the same there as here. The human beings are the most mysterious part of the message.
4. A Message to Earth
The golden greeting card placed aboard the Pioneer 10 spacecraft was intended for the remote contingency that representatives of an advanced extraterrestrial civilization, some time in the distant future, might encounter this first artifact of mankind to leave the Solar System. But the message has had a more immediate impact. It has already been meticulously studied–not by extraterrestrials, but by terrestrials. Human beings all over the planet Earth have examined the message, applauded it, criticized it, interpreted it, and proposed alternative messages.
The graphics of the message have been reproduced widely in newspapers and television programs, small art and literary magazines, and national newsweeklies. We have received letters from scientists and housewives, historians and artists, feminists and homosexuals, military and foreign service officers, and one professor of bass fiddle. Our plaque has been reproduced for commercial sale by an engraving company, a distributor of scientific knickknacks, a manufacturer of tapestry, and an Italian mint specializing in silver ingots–all, incidentally, without authorization.
The great majority of comments have been favorable, some extraordinarily enthusiastic. The large street advertising billboards for the Tribune of Geneva, Switzerland, announced “Message de la NASA pour les extraterrestres!” One scientist writes to say that the description of the scientific basis of the plaque we published in the American journal Science was the first scientific paper he had ever read that moved him to tears of joy. A correspondent in Athens, Georgia, writes, “We’ll all be gone before this particular message in a bottle is picked up by some indescribable spacecomber; nevertheless, its very existence, the audacity of the dream, inevitably produces in me–and many others I know–the feelings of a Balboa, a Leeuwenhoek, a human being being human!”
At the California Institute of Technology, where the graffiti is arcane, some unknown artist drew the message life-size on a barrier at a building site, eliciting friendly greetings from the inhabitants, which we hope will serve as a model for extraterrestrial readers (see the illustration on the facing page).
But there were also critical comments. They were not directed at the pulsar map, which was the scientific heart of the message, but rather at the representation of the man and the woman. The original drawings of this couple were made by my wife and were based upon the classical models of Greek sculpture and the drawings of Leonardo da Vinci. We do not think this man and woman are ignoring each other. They are not shown holding hands lest the extraterrestrial recipients believe that the couple is one organism joined at the fingertips. (In the absence of indigenous horses, both the Aztecs and the Incas interpreted the mounted conquistador as one animal–a kind of two-headed centaur.) The man and woman are not shown in precisely the same position or carriage so that the suppleness of the limbs could be communicated–although we well understand that the conventions of perspective and line drawing popular on Earth may not be readily apparent to civilizations with other artistic conventions.
The man’s right hand is raised in what I once read in an anthropology book is a “universal” sign of good will–although any literal universality is of course unlikely. At least the greeting displays our opposable thumbs. Only one of the two people is shown with hand raised in greeting, lest the recipients deduce erroneously that one of our arms is bent permanently at the elbow.
Several women correspondents complain that the woman appears too passive. One writes that she also wishes to greet the universe, with both arms outstretched in womanly salutation. The principal feminine criticism is that the woman is drawn incomplete–that is, without any hint of external genitalia. The decision to omit a very short line in this diagram was made partly because conventional representation in Greek statuary omits it. But there was another reason: Our desire to see the message successfully launched on Pioneer 10. In retrospect, we may have judged NASA’s scientific-political hierarchy as more puritanical than it is. In the many discussions that I held with such officials, up to the Administrator of the National Aeronautics and Space Administration and the President’s Science Adviser, not one Victorian demurrer was ever voiced; and a great deal of helpful encouragement was given.
Yet it is clear that at least some individuals were offended even by the existing representation. The Chicago Sun Times, for example, published three versions of the plaque in different editions all on the same day: In the first the man was represented whole; in the second, suffering from an awkward and botched airbrush castration; and in the final version–intended no doubt to reassure the family man dashing home–with no sexual apparatus at all. This may have pleased one feminist correspondent who wrote to the New York Times that she was so enraged at the incomplete representation of the woman that she had an irresistible urge “to cut off the man’s … right arm!”
The Philadelphia Inquirer published on its front page an illustration of the plaque, but with the nipples of the woman and the genitalia of the man removed. The assistant managing editor was quoted as saying, “A family newspaper must uphold community standards.”
An entire mythology has evolved about the absence of discernible female genitalia. It was a column by the respected science writer Tom O’Toole, of the Washington Post, that first reported that NASA officials had censored an original depiction of the woman. This tale was then circulated in nationally syndicated columns by Art Hoppe, Jack Stapleton, Jr., and others. Stapleton imagined the enraged citizens of another planet receiving the plaque, and in a paroxysm of moral outrage covering over with adhesive tape the pornographic representation of the feet of the man and the woman. One letter writer to the Washington Daily News proposed that if the woman was to be censored, then for consistency the noses of the humans should have been painted blue. A tut-tutting letter in Playboy magazine complained about this further intrusion of government censorship, already quite bad enough, into the lives of the citizenry. Editorials in sciencefiction magazines also took the government to task. The idea of government censorship of the Pioneer 10 plaque is now so well documented and firmly entrenched that no statement from the designers of the plaque to the contrary can play any role in influencing the prevailing opinion. But we can at least try.
What sexuality there is in the message also drew epistolary fire. The Los Angeles Times published a letter from an irate reader that went:
I must say I was shocked by the blatant display of both male and female sex organs on the front page of the Times. Surely this type of sexual exploitation is below the standards our community has come to expect from the Times. Isn’t it enough that we must tolerate the bombardment of pornography through the media of film and smut magazines? Isn’t it bad enough that our own space agency officials have found it necessary to spread this filth even beyond our own solar system?
This was followed several days later by another letter in the Times: I certainly agree with those people who are protesting our sending those dirty pictures of naked people out into space. I think the way it should have been done would have been to visually bleep out the reproductive organs of the drawings of the man and the woman. Next to them should have been a picture of a stork carrying a little bundle from heaven.
Then if we really want our celestial neighbors to know how far we have progressed intellectually, we should have included pictures of Santa Claus, the
Easter Bunny, and the Tooth Fairy.
The New York Daily News headlined the story in typical fashion: “Nudes and Map tell about Earth to Other Worlds.”
Some correspondents argue that the function of the sexual organs would not be obvious even had they been graphically displayed, and urged on us a sequence of cartoons from copulation to birth to puberty to copulation. There was not quite room for this on a 6-inch by 9-inch plaque. I can also imagine the letters that would then have been written to the Los Angeles Times.
An article in Catholic Review criticizes the plaque because it “includes everything but God,” and suggests that, rather than a pair of human beings, it would have been better to have borne a sketch of a pair of praying hands.
Another correspondent maintains that the perspective conventions are insuperably difficult, and urges us to send the complete cadavers of a man and a woman. They would be perfectly preserved in the cold of space, and could be examined by extraterrestrials in detail. We declined on grounds of excess weight.
The front page of the Berkeley, California, Barb, apparently intending to convey an impression that the man and woman on the message were too straight, reproduced them with the caption, “Hello. We’re from Orange County.”
This comment touches on an aspect of the representation of the man and woman that I personally feel much worse about, although it has received almost no other public notice. In the original sketches from which the engravings were made, we made a conscious attempt to have the man and woman panracial. The woman was given epicanthian folds and in other ways a partially Asian appearance. The man was given a broad nose, thick lips, and a short “Afro” haircut. Caucasian features were also present in both. We had hoped to represent at least three of the major races of mankind. The epicanthian folds, the lips, and the nose have survived into the final engraving. But because the woman’s hair is drawn only in outline, it appears to many viewers as blond, thereby destroying the possibility of a significant contribution from an Asian gene pool. Also, somewhere in the transcription from the original sketch drawing to the final engraving the Afro was transmuted into a very non-African Mediterranean-curly haircut. Nevertheless, the man and woman on the plaque are, to a significant degree, representative of the sexes and races of mankind.
Professor E. Gombrich, the Director of the Warburg Institute, a leading art school in London, criticizes the plaque in the journal Scientific American. He wonders how the plaque can possibly be expected to be visible to an extraterrestrial organism that may not have developed the sense of sight at visible wavelengths. The answer is derived simply from the laws of physics. Planetary atmospheres absorb light from the nearby sun or suns because of three molecular processes. The first is a change in the energy state of individual electrons attached to atoms. These transitions occur in the ultraviolet, X-ray, and gamma-ray parts of the spectrum and tend to make a planetary atmosphere opaque at these wavelengths. Second, there are vibrational transitions that occur when two atoms in a given molecule oscillate with respect to each other. Such transitions tend to make planetary atmospheres opaque in the near infrared part of the spectrum. Third, molecules undergo rotational transitions, due to the free rotation of the molecule. Such transitions tend to absorb in the far infrared. As a result, quite generally, the radiation from the nearby star, which penetrates through a planetary atmosphere, will be in the visible and in the radio parts of the spectrum–the parts that are not absorbed by the atmosphere.
In fact, these are the principal “windows” that astronomers use for surveying the universe from the Earth’s surface. But radio wavelengths are so long that no organisms of reasonable size can develop pictures of their surroundings with radio wavelength “eyes.” Therefore, we expect optical frequency sensors to be developed quite widely among organisms on planets of stars throughout the Galaxy.
However, even if we imagine organisms whose eyes work in the infrared region (or, for that matter, in the gamma-ray region) and who are able to intercept Pioneer 10 in interstellar space, it is probably not asking too much of them to have contrivances that scan the plaque at frequencies to which their eyes are insensitive. Because the engraved lines on the plaque are darker than the surrounding goldanodized aluminum, the message should be entirely visible even in the infrared.
Gombritch also takes us to task for portraying an arrow as a sign of the spacecraft’s trajectory. He maintains that arrows would be understandable only to civilizations that have evolved, as ours has, from a hunting society. But here again it does not take a very intelligent extraterrestrial to understand the meaning of the arrow. There is a line that begins on the third planet of a solar system and ends, somewhere in interstellar space, at a schematic representation of the spacecraft–which the discoverers of the message have at “hand”: The plaque is attached to the spacecraft. From this I would hope they would be able to argue backward to our hunter-gatherer ancestors.
In the same way, the relative distances of the planets from the Sun, shown by binary notation at the bottom of the plaque, indicate that we use base-10 arithmetic. From the fact that we have 10 fingers and 10 toes–drawn with some care on the plaque–I hope any extraterrestrial recipients will be able to deduce that we use base-10 arithmetic and that some of us count on our fingers. From the stumpiness of our toes they may even be able to deduce that we evolved from arboreal ancestors.
There are other respects in which the message has proved to be a psychological projective test. One man writes of his concern that the message has doomed all of mankind. American movies of Second World War vintage, he argues, are very likely propagating via television transmission through interstellar space. From such programming, the extraterrestrials will easily be able to deduce (1) that the Nazis were very bad fellows, and (2) that they greeted each other with their right hand extended outward. From the fact that the man on the plaque is portrayed as making what our correspondent erroneously perceives as the same sort of greeting, he is concerned that the extraterrestrials will deduce that the wrong side won World War II and promptly mount a punitive expedition to Earth to set matters straight.
Such a letter more nearly describes the state of mind of the writer than of the likely extraterrestrial recipients of the message. The raised right hand in greeting is historically connected with militarism, but in a negative way: The raised and empty right hand symbolizes that no weapon is being carried.
For me, some of the most moving responses to the message are the works of art and poetry that it evoked. Mr. ‘Aim Morhardt is a painter of water colors of the desert and sierras who lives in Bishop, California, where, perhaps not coincidentally, the giant Goldstone tracking station, which commands Pioneer 10, is located. Mr. Morhardt’s poem follows:
Pioneer 10: The Golden Messenger.
The dragon prows that cruised the northern seas,
Questing adventure with the fighting clan;
The gallant mermaid bows blown down the breeze
On barquentine and slim-hulled merchantman;
All the discoverers of unknown lands
Gone in this winged age where naught remains
Of new strange treasure on some foreign strand,
So well-known earth, such charted routes and lanes.
Now the new figurehead of man appears,
Facing the vast immeasurable unknown,
Naked, star-sped, beyond the call of years,
Hand in hand, outward bound, and so alone.
Go, tiny messenger of our your race,
Touch, if you can, harbor in some far place.
Mr. Arvid F. Sponberg, of Belfast, Northern Ireland, writes: “The voyage ofioneer 10–and the voyages of those like her–will have an effect that poets, painters and musicians will not long ignore. The existence of the idea of Pioneer 10 is proof of this. The scientific mission of course is of incalculable value and interest, but the idea of the journey is of even greater imaginative value. Pioneer 10 brings closer the day when artists must confront man’s new voyage as experie
nce and not fantasy.”
Mr. Sponberg composed for us a poem in sonnet form:
New Odyssey
Away, afar, beyond, bereft of kin,
Wayward, wandering, far ranging vagabonds,
Yearning, stardrawn, the Pioneers sweep on,
Outward bound, adrift on the solar wind.
A man, a woman, orphans of warm earth
Or splendid voyageurs with golden sails,
Or gypsies roaming ancient stellar trails,
A caravan in quest of celestial berth.
If, deep within cold interstellar space,
Some fearful eye spies life on this raft,
Will it perceive the heart within our craft,
A pulsar pounding out the rhythms of peace?
A spirit’s starburst pierces new frontiers;
An Odyssey is our home; let us praise Pioneers!
There is, of course, the possibility that the message on Pioneer 10–invented by human beings but directed at creatures of a very different kind–may prove ultimately mysterious to them. We think not. We think we have written the message–except for the man and woman–in a universal language. The extraterrestrials cannot possibly understand English or Russian or Chinese or Esperanto, but they must share with us common mathematics and physics and astronomy. I believe that they will understand, with no very great effort, this message written in the galactic language: “Scientific.”
But we may be wrong. One exploration of a total misunderstanding–and by far the most amusing such description–was made by the British humor magazine Punch in an article headlined, “According to the [Paris] Herald Tribune only one in ten of NASA scientists was able to figure out its message. So what chance have the aliens got?” Punch presents an opinion sampling of four representative extraterrestrials. They should be read with close reference to the illustration of the actual message: