From childhood he shows a clear inclination towards science, and especially astronomy, because of his early fondness for science fiction stories, having very clear from very early on to the that would be dedicated.
After graduating from high school in N.Y., he moved to Chicago, where he enrolled.
Very soon it stands out among his peers.
In 1955 he graduated in Physics from the University of Chicago, and little else Later, while preparing for his doctorate, he began his collaboration as an advisor of NASA, an activity that he would carry out for 30 years, participating in the Mariner, Pioneer, Voyager and Galileo.
In 1960 he obtained his doctorate in astronomy and astrophysics.
In 1961 he published the results of his first major research as a scientist ("Atmospheres of Mars and Venus"), in which he suggests that the greenhouse effect on Venus is the cause of its high temperatures, and that this phenomenon could be repeated on Earth.
In 1962 he accepted a teaching position at Harvard University, which he would occupy until his next move (in 1968).
In 1964 he collaborates with the Mariner IV project, in charge of exploring, orbit, the planet Mars, obtaining the first photographs of its surface by means of a television camera.
In 1966, "Intelligent life in the universe" was published "Intelligent Life in the Universe," a book he co-authored with Yosef Shklovsky, a Russian scientist (whom he never met in person), setting an example of collaboration with "the other side" in the midst of cold war.
"Intelligent life in the universe" studies the chances of finding intelligent life outside of Earth.
In 1968 he moved to New York, where he was appointed director of the Cornell University Space Science Laboratory, Position which, together with his lectures at that university, occupies the remainder of his life.
In the same year he was also appointed editor-in-chief of the magazine "Icarus" (the leading journal specializing in studies on the solar) and participates in the astronaut readiness program.
In 1971, NASA accepted Sagan's proposal to include in the spacecraft Pioneer 10 (designed to provide data on the solar system) a plaque designed by him in collaboration with Frank Drake (and drawn by his then-wife, Linda Salzman Sagan) with the to send a message such as:
"Hello, we're here."
to a possible extraterrestrial civilization to find it.
It was the first message that has been sent to a possible extraterrestrial civilization and it is also the first man-made spacecraft to go beyond of the solar system, from which it is currently moving farther and farther away.
In 1972 "UFO's: A scientific debate" is published, written by Carl Sagan and Thornton Page, which deals with the subject of UFOs from a from a scientific point of view, thus ruling out that its origin is due to extraterrestrial civilizations visiting Earth.
In 1973 "The cosmic connection" is published.
A book about the solar system, its exploration, and speculation about possible extraterrestrial life.
In 1975 he was appointed director of the radio physics and research center Cornel University and Director of the Science Division of the American Astronomical Society.
In 1976 he collaborates with the Viking space probe program, which lands on Mars, carrying out on-site soil analyses and taking spectacular photographs all around it.
The scientific aims of this missions were varied, but the most spectacular in the public eye was discovering life on Mars.
Unfortunately, the analyses carried out did not were conclusive in no sense due to a number of difficulties, so the issue is still open today.
In 1977 his book "The Dragons of Eden" was published, an essay on the evolution of the human brain and intelligence.
It was the most important book in the world, away from his specialty that he wrote, and with it he won the Pulitzer Prize.
That same year, he chaired NASA's study group on Artificial intelligence and robotics.
In addition, NASA invites you to create a commission to select the contents of the disc that each one would carry of the Voyager I and II spacecraft (destined to depart from the solar system), oriented to some possible extraterrestrial civilization that found it.
The Voyager disk would feature greetings in 60 human:
languages
sounds
photographs
etc. of our world, and even Ann Druyan'sThought Waves, with whom he fell in love with during that investigation and who would be Sagan's wife during the 20 years until his death.
In 1979 he was appointed president of the planetary society.
Then he publishes "Broca's Brain: Reflections on the Romance of Science", where he reflects on the advances of science and astronomy.
In 1980, in addition to being appointed president of the Planetology of the American Geophysical Union, creates and presents the series Cosmos, whose 13 episodes also become part of the book of the same name.
Cosmos was arguably Carl's most popular work of Sagan.
The television series Cosmos was seen in 60 countries - approximately 3% of the population of planet Earth, and its edition on paper it spent 70 weeks as a bestseller in "The New York Times". becoming the best-selling science book of the 20th century.
In 1982 asteroid 2709 is named "Sagan asteroid", in its honor.
In 1985 he published his only science fiction novel:
"Contact: a novel" ("Contact"), which would become a bestseller.
It's about what it would be like humanity's first contact with a technologically advanced civilization extraterrestrial advanced extraterrestrial, based on the S.E.T.I. (Search for Extraterrestrial Intelligence) program, of which he was a collaborator and popularizer in reality.
In 1986 he commemorates the return of Halley's Comet with his book "Comet" ("The Comet"), which he wrote in collaboration with Ann Druyan, his wife.
In 1992, "Shadows of Forgotten Ancestors: A Search for Who"was published.
"We Are" written by Carl Sagan and Ann Druyan, where they deal with the theme of origin and evolution of life on Earth.
In "Pale Blue Dot: A Vision of the Human Future in Space" (1994) he talks about space exploration again, but with a perspective of future.
In 1994 he was diagnosed with a strange disease unknown until then: myelodysplasia, which if it had not been treated immediately, would have ended his life in a few months.
Fortunately, after a transplant bone marrow (donated by his sister Caris) and radiation therapy sessions his life got back to normal.
Complete several investigations, finishes what would be the last book he published in his lifetime ("The demon-haunted world: Science as a candle in the dark")
and began co-producing with Ann Druyan, his wife, the film "Contact: The movie" (for which they both wrote a screenplay based on his novel "Contact: A novel".)
Only a few Months after his improvement, the disease reappears.
and his posthumous work was published "Thousands of Millions," a series of essays on a variety of topics, both scientific and of a general nature, which he wrote in the last stage of his life, beset by illness.
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 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 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.
"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 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 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."
"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.
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View full-sizeDownload 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.
However, in another episode he said the stars would "beckon" to humanity, and described the Bussard ramjet as one way that humans might achieve interstellar travel.
It has been pointed out that Sagan wasn't being logically consistent.
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).
in the history of our species lived there-on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena.
Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.
Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light.
Our planet is a lonely speck in the great enveloping cosmic dark.
In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life.
There is nowhere else, at least in the near future, to which our species could migrate.
Visit, yes.
Settle, not yet.
Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience.
There is perhaps a no better demonstration of the folly of human conceits than this distant image of our tiny world.
To me, it underscores our responsibility to deal kindlier with one another and to preserve and cherish the pale blue dot, the only home we've ever known.
