Carl Edward Sagan (/ˈseɪɡən/; November 9, 1934 -- December 20, 1996) was an American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences. He spent most of his career as a professor of astronomy at Cornell University where he directed the Laboratory for Planetary Studies. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He advocated scientific skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI). Sagan is known for his popular science books and for the award-winning 1980 television series Cosmos: A Personal Voyage, which he narrated and co-wrote. The book Cosmos was published to accompany the series. Sagan wrote the novel Contact, the basis for a 1997 film of the same name. He attended the University of Chicago, where he participated in the Ryerson Astronomical Society,[10] received a bachelor of arts in self-proclaimed "nothing" with general and special honors in 1954, a bachelor of science in physics in 1955, and a master of science in physics in 1956 before earning a PhD in astronomy and astrophysics in 1960.[11][12][13] During his time as an honors program undergraduate, Sagan worked in the laboratory of the geneticist H. J. Muller and wrote a thesis on the origins of life with physical chemist H. C. Urey. He used the summer months of his graduate studies to work with planetary scientist Gerard Kuiper (thesis advisor), physicist George Gamow, and chemist Melvin Calvin. From 1960 to 1962 Sagan was a Miller Fellow at the University of California, Berkeley.[14] From 1962 to 1968, he worked at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. At the same time, he worked with geneticist Joshua Lederberg. Sagan lectured and did research at Harvard University until 1968, when he moved to Cornell University in Ithaca, New York, after being denied tenure at Harvard. He became a full professor at Cornell in 1971, and he directed the Laboratory for Planetary Studies there. From 1972 to 1981, Sagan was the Associate Director of the Center for Radiophysics and Space Research (CRSR) at Cornell. Sagan was associated with the U.S. space program from its inception. From the 1950s onward, he worked as an advisor to NASA, where one of his duties included briefing the Apollo astronauts before their flights to the Moon. Sagan contributed to many of the robotic spacecraft missions that explored the Solar System, arranging experiments on many of the expeditions. He conceived the idea of adding an unalterable and universal message on spacecraft destined to leave the Solar System that could potentially be understood by any extraterrestrial intelligence that might find it. Sagan assembled the first physical message that was sent into space: a gold-anodized plaque, attached to the space probe Pioneer 10, launched in 1972. Pioneer 11, also carrying another copy of the plaque, was launched the following year. He continued to refine his designs; the most elaborate message he helped to develop and assemble was the Voyager Golden Record that was sent out with the Voyager space probes in 1977. Sagan often challenged the decisions to fund the Space Shuttle and the International Space Station at the expense of further robotic missions.[15] Sagan taught a course on critical thinking at Cornell University until he died in 1996 from pneumonia, a few months after finding that he was in remission of myelodysplastic syndrome. Former student David Morrison describes Sagan as "an 'idea person' and a master of intuitive physical arguments and back-of-the-envelope calculations."[16] Sagan's contributions were central to the discovery of the high surface temperatures of the planet Venus. In the early 1960s no one knew for certain the basic conditions of that planet's surface, and Sagan listed the possibilities in a report later depicted for popularization in a Time--Life book, Planets. His own view was that Venus was dry and very hot as opposed to the balmy paradise others had imagined. He had investigated radio emissions from Venus and concluded that there was a surface temperature of 500 °C (900 °F). As a visiting scientist to NASA's Jet Propulsion Laboratory, he contributed to the first Mariner missions to Venus, working on the design and management of the project. Mariner 2 confirmed his conclusions on the surface conditions of Venus in 1962. http://en.wikipedia.org/wiki/Carl_sagan

• published: 25 Jul 2014
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