The Life of Carl Sagan, Astronomer of the People

carl sagan with viking lander
Dr. Carl Sagan with a mockup of a Viking lander in California.  NASA/.JPL

Astronomer and author Carl Sagan (November 9, 1934 — December 20, 1996) burst into public consciousness as the star and producer of the TV series Cosmos. He was a prolific researcher in astronomy as well as a science popularizer who sought to educate the public about the universe and the value of the scientific method. 

Early Years

Born in Brooklyn, New York, Sagan grew up with a strong interest in the planets, stars, and science fiction.

His father, Samuel Sagan, immigrated from what is now Ukraine and worked as a garment worker. His mother, Rachel Molly Gruber, encouraged his great interest in science. Sagan often cited his parents' influence on his career, saying that his father influenced his imagination and his mother urged him to go to the library to find books about stars.

Professional Life

After graduating from high school in 1951, the young Sagan headed the University of Chicago for a degree in physics. At the University of Chicago, he took part in chemistry research about the building blocks of life. He went on to earn a Ph.D. in astronomy and astrophysics in 1960. Sagan left Illinois and began working at University of California - Berkeley, where he worked with a team to build an instrument for a NASA mission to Mars called Mariner 2.

In the 1960s, Sagan moved to Harvard University, where he worked at the Smithsonian Astrophysical Observatory.

There, he focused his research more closely on planetary science, with a particular interest in Venus and Jupiter. Sagan later moved again to Cornell University, where he served as director of the Laboratory for Planetary Studies.

Sagan's work with NASA continued. He was a principal advisor for the Viking missions and worked on the landing site selection.

He also was instrumental in a project to put messages from humanity aboard the Pioneer and Voyager probes to the outer solar system. In 1976, he became the David Duncan Professor of Astronomy and Space Sciences, a chair he held until his death.

Research Interests and Activism

Throughout his career, Carl Sagan remained deeply interested in the possibility of life on other worlds.  Throughout his work with NASA and the U.S. space program, he tirelessly promoted the ideas behind the search for extraterrestrial intelligence, colloquially known as SETI. Sagan worked on several collaborative experiments, which ultimately demonstrated that, when exposed to ultraviolet light, mixtures of amino acids and nucleic acids could be produced in conditions much like those of early Earth.

Carl Sagan conducted early research on climate change. One of his studies showed that the high temperatures on the surface of Venus could be attributed to a runaway greenhouse effect. Throughout his career, Sagan continued his scientific research, ultimately publishing more than 600 papers. Throughout his work, he advocated for scientific skepticism and healthy reasoning, promoting skepticism as an alternative to belief systems of politics and religion.

Sagan was also an anti-war activist. He studied the potential impact of nuclear war and advocated for nuclear disarmament.

Science as a Way of Thinking

As an avid skeptic and agnostic, Sagan promoted the scientific method as a tool for better understanding the world. In his book Demon-Haunted World, he laid out strategies for critical thinking, deconstructing arguments, and testing claims. Sagan published a number of other science books aimed at a lay audience, including The Dragons of Eden: Speculations on the Evolution of Human Intelligence, and Broca's Brain: Reflections on the Romance of Science.   

In 1980, Carl Sagan's: Cosmos: A Personal Voyage premiered on television. The premiere turned Sagan into a well-known science popularizer. The show was aimed at a general audience, with each episode focusing on a different aspect of scientific discovery or exploration.

 Cosmos received two Emmy Awards. 

Later Years and Legacy

In the 1990s, Carl Sagan was diagnosed with a blood condition called myelodysplasia. He received three bone marrow transplants and ongoing treatment, continuing to work on his research and writing even as the condition worsened. At age 62, Sagan died of pneumonia associated with his condition.

Sagan left a long-lasting legacy in the fields of astronomy and science education. Several awards for science communication are named after Carl Sagan, included two given by the Planetary Society. The Mars Pathfinder location on Mars is named the Carl Sagan Memorial Station. 

Carl Sagan Fast Facts

  • Full Name: Carl Edward Sagan
  • Known For: Astronomer, author, and science popularizer 
  • Born: November 9, 1934 in Brooklyn, New York, USA
  • Died: December 20, 1996 in Seattle, Washington, USA
  • Education: University of Chicago (B.A., B.S., M.S., Ph.D.)
  • Selected WorksCosmos: A Personal JourneyDemon-Haunted WorldThe Dragons of EdenBroca's Brain
  • Key Accomplishments: NASA Medal of Honor (1977), Emmy Award for Outstanding Personal Achievement (1981), authored 600+ scientific papers and dozens of popular science articles and books.
  • Spouse Name: Lynn Margulis (1957-1965), Linda Salzman (1968-1981), Ann Druyan (1981-1996)
  • Children's Names: Jeremy, Dorion, Nick, Alexandra, Samuel 
  • Famous Quote: "Extraordinary claims require extraordinary evidence."

Sources and Further Reading

  • Kragh, Helge. “Carl Sagan.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 27 Oct. 2017, 
  • Head, Tom. Conversations with Carl Sagan (Literary Conversations), University Press of MIssissippi, 2006. 
  • Terzian, Yervant, and Elizabeth Bilson. Carl Sagan's Universe. Cambridge University Press, 2009.