Watch the video "Cosmos: Galaxy"
Watch the video "Cosmos: Galaxy"

If reading this article has made you want to listen to Sagan waxing poetic about the cosmos, then watch these videos. We think he tackles the big bang with aplomb.

Science Channel

Millions Upon Millions ... Watched Him

Sagan soon appeared more often on people's TV sets than in academic journals. After premiering in the 1980 PBS series "Cosmos: A Personal Voyage," he rose to the zenith of popular science communicators (think Stephen Hawking and Neil deGrasse Tyson). The studio became his new lab, as he gradually decreased his work in academia.

In "Cosmos," Sagan promoted viewers' interest in science by taking them along for an intergalactic journey through the universe. His entrancing voice reached millions of people worldwide across languages and cultures (not "billions upon billions," as he's teased for saying).

Not everyone praised Sagan as science's champion, though. Many scientists valued Sagan's efforts to popularize science, but some thought he was too big of a media star. When journalists and media outlets needed an expert opinion, they often went to Sagan because of his willingness to help. This sometimes overshadowed other researchers' public visibility and inflated Sagan's actual involvement [source: Poundstone].

Ann Druyan, Sagan's wife, says her husband wanted everyone to have access to the scientific knowledge usually locked away in the minds of experts. Sagan also credited the science-fiction genre as sparking people's love for scientific exploration and discovery. Sagan described science and science fiction interweaved in a "dance" of sorts, taking turns inspiring each other. In his audio message to Mars, he says sci-fi spurred young people to learn more about Mars -- a trend that might help humanity get there someday [source: The Planetary Society]. Sagan also shared success as a popular science writer.

But what made Sagan unique was his knack for straddling various disciplines. As scientific fields become more specialized, generalists like Sagan are now a rarity. Biographer William Poundstone described Sagan as a person who fired on multiple cylinders, meshing several realms of science into his public messages.