SEATTLE - Carl Sagan, who rhapsodized about a universe populated by "billions and billions" of stars, was a rare star himself: a celebrity astronomer who helped make the vast unknown a little less mysterious.
Sagan died of pneumonia Friday at age 62 at the Fred Hutchinson Cancer Research Center. He had suffered from the bone marrow disease myelodisplasia for two years and had a bone-marrow transplant in 1995.
He leaves behind a generation of Americans inspired by his enthusiastic lectures, books and documentaries about space and life.
"Sagan understood the need to bring science into American living rooms, to show its relevance to our everyday lives and to share the excitement of discovery," said Neal Lane, director of the National Science Foundation.
Sagan, who lived in Ithaca, N.Y., won the Pulitzer Prize for general nonfiction in 1978 for "The Dragons of Eden: Speculations on the Evolution of Human Intelligence."
In 1980, his acclaimed 13-part Public Broadcasting Service series "Cosmos" became the most-watched limited series in the history of American public television, a record since surpassed by "The Civil War."
Co-written with his wife, Ann Druyan, the series retraced the 15 billion years of cosmic evolution that have transformed matter into life. It won three Emmys and a Peabody Award, and a companion book was a New York Times best seller for more than a year, including 15 weeks at No. 1.
The series has been seen by more than 500 million people in 60 countries, and it made Sagan a celebrity, caricatured in cartoons and parodied by comics who seized on his references to "billions and billions" of stars.
Said NASA Administrator Dan Goldin: "As much as any scientific figure of our time, Carl described for an entire generation - the generation of the Space Age - the true wonders of the universe around us."
A Cornell University professor with more than a score of honorary degrees and a decorated NASA adviser, Sagan had the rare gift of being able to communicate his enchantment with science to the masses.
Once asked to explain the public's interest, he said: "They're not numskulls. Thinking scientifically is as natural as breathing."
Sagan's research focused mostly on the chemistry of the planets. But he also contributed to the search for habitable worlds and intelligent life beyond the solar system, as well as theories about life's origins.
Some purists complained that Sagan sometimes oversimplified and made interpretive errors, but he had the full confidence of his department chairman at Cornell University.
"Carl was the best teacher of science in the world," Professor Yervant Terzian said. "It is difficult to think of a more positive, compassionate, and intelligent person."
Sagan never shied away from the label of science popularizer, declaring in 1994 that "I wear the badge proudly." And while he had a flair for making scientific ideas comprehensible and exciting, Sagan built up an impressive research record and insisted that research was his top priority.
"From when I was a little kid, the only thing I really wanted to be was a scientist, to actually do the science, to interrogate nature, to find out how things work," he said. "That's where the fun is. If you're in love, you want to tell the world!"
Born in New York on Nov. 9, 1934, Sagan said he fully expected to follow his Russian-born father into the garment industry but began to chart a career in astronomy while at high school in Rahway, N.J.
While his parents knew little about science, they nurtured his sense of wonder and instilled a healthy skepticism.
He earned a physics degree from the University of Chicago in 1954 and a doctorate in astronomy and astrophysics in 1960. He was appointed lecturer and assistant professor of astronomy at Harvard in 1962.
In 1971, he became a full professor at Cornell, where his lectures drew standing-room-only crowds. His research dipped into the greenhouse effect on Venus and the environmental consequences of nuclear war, among other things.
Sagan helped design robotic missions for NASA, and played leading roles in the Mariner, Viking, Voyager and Galileo and Galileo expeditions.
He also journeyed into the political arena, pushing for more government funding of space missions and stricter measures to counter the environmental threats of ozone depletion and global warming.
As for UFOs, lost continents and the like, Sagan said the world could ill afford such pseudoscientific twaddle.
"We sometimes pretend something is true not because there's evidence for it but because we want it to be true," he said. "We confuse reality with our hopes and fears."
Sagan was a firm believer in the existence of extraterrestrial intelligence, noting that organic molecules, the kind that life on Earth is dependent on, appear to be almost everywhere in the solar system.
Finding out whether mankind is alone or not alone, he believed, is one of the world's most important puzzles. He published "The Cosmic Connection: An Extraterrestrial Perspective" in 1973, the same year, he made the first of 25 appearances on NBC's "Tonight Show with Johnny Carson."
His 30th book, titled "Demon Haunted World," was published last year, and a movie of his 1985 best-selling novel, "Contact," is due out in 1997.
Sagan is survived by his wife; his sister, Cari Sagan Greene; five children; and a grandson.
AP writer Ben Dobbin contributed to this report from Rochester, N.Y.