Carl Sagan

American astronomer Dr. Carl Sagan's impact on the public's perception of science reaches heights unmatched even by his mountain of achievements and awards. His charming delivery and abundant charisma propelled him into the ranks of pop culture phenomena and brought the wonders of science into a realm where the rest of us could marvel at them.

When the National Academy of Sciences awarded Sagan the Public Welfare Medal, their highest award, they cited his "distinguished contributions in the application of science to the public welfare ... Carl Sagan has been enormously successful in communicating the wonder and importance of science. His ability to capture the imagination of millions and to explain difficult concepts in understandable terms is a magnificent achievement."

Sagan was a leader in the U.S. space program since its inception and worked as an adviser to NASA since the 1950s. His many duties during his tenure at the space agency included briefing the Apollo astronauts before their flights to the moon and placing experiments on the Mariner, Viking, Voyager and Galileo robotic space expeditions.

He helped solve the mystery of high temperatures on Venus (answer: massive greenhouse effect), seasonal changes on Mars (answer: windblown dust) and the reddish haze on Saturn's moon, Titan (answer: complex organic molecules). Asteroid 2709 Sagan is named after him.

Sagan pioneered the science of exobiology (the study of extraterrestrial life) and promoted the Search for ExtraTerrestrial Intelligence, or SETI. He was awarded the Masursky Award of the American Astronomical Society "for his extraordinary contributions to the development of planetary science ... As a scientist trained in both astronomy and biology, Dr. Sagan has made seminal contributions to the study of planetary atmospheres, planetary surfaces, the history of the Earth and exobiology. Many of the most productive planetary scientists working today are his present and former students and associates."

Sagan was the author of many best sellers, including the Pulitzer Prize-winning Dragons of Eden: Speculations of the Evolution of Human Intelligence and Cosmos, which became the best-selling science book ever published in English. The accompanying Emmy and Peabody award-winning television series has been seen by 500 million people in 60 countries. His novel, Contact, was made into a major motion picture starring Jodie Foster.

In their posthumous award, the National Science Foundation declared that Sagan's "research transformed planetary science ... his gifts to mankind were infinite."