Remembering Carl Sagan on His Birthday: Innovator, Visionary, and Humanitarian

Today marks the birthday of Carl Sagan, American astronomer, astrophysicist, cosmologist, agnostic, marijuana advocate, nuclear cautionary, author, science popularizer, and science communicator.

Brooklyn-born Sagan's achievements were many and started to develop at a young age, with his first inspiration coming from attending the 1939 New York World's Fair with his parents. That experience would go on to spawn a career of exceptional thought output and innovation that are immeasurable—though if he were alive today, he may have found a way to measure them. His contributions were cut short, by his death at 62 years of age from pneumonia.

Sagan assembled the first physical message that was sent into space attached to the antenna of the space probe Pioneer 10 which launched in 1972. The gold plaque featured nude figures of a human male and female with several symbols that detailed information about the origin of the spacecraft. Sagan later went on to create a more elaborate message with the Voyager Golden Record, sounds and images selected to portray the diversity of life and culture on Earth, sent out with the Voyager space probes in 1977.

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He established groundbreaking insights regarding the atmospheres of Venus and Jupiter and seasonal changes on Mars. He also spoke widely about the phenomena of global warming as a growing, man-made danger. He equated it to the natural expansion of Venus into a hot, life-hostile planet through a kind of runaway greenhouse effect.

Sagan's work around searching for extraterrestrial life spawned the popular PBS series Cosmos: A Personal Voyage, that he penned as well as the book Contact, which was made into a film after Sagan's death starring Jodi Foster. Sagan was also considered somewhat of a radical in his field, protesting the Vietnam war and later the nuclear arms race, in particular Ronald Reagan's Star Wars program.

When others suggested creating large nuclear bombs that could be used to alter the orbit of a Near Earth Object (NEO) that was predicted to hit the Earth, Sagan proposed what he called the Deflection Dilemma: "If we create the ability to deflect an asteroid away from the Earth, then we also create the ability to deflect an asteroid towards the Earth—providing an evil power with a true doomsday bomb."

But one of Sagan's most touching contributions to the world was the Pale Blue Dot. Captured in 1990 by the Voyager 1, it is a photograph of our planet taken on Sagan's request from a distance of around 4 billion miles from Earth. In it, the Earth appears as a dot (about 0.12 pixels in size) against a backdrop of a vast universe. Sagan wrote extensively about this humbling perspective and the video below is his narration, which put everything in perspective. It's his reminder that all of us Earthlings are really just a spec, a tiny, tiny dot in this ongoing universe—so why not be good to one another?

[youtube]http://www.youtube.com/watch?v=p86BPM1GV8M

Photos via Wikimedia Commons