We are stardust

Billion year-old carbon

We are golden

Caught in the devil's bargain

And we've got to get ourselves

Back to the garden

—Joni Mitchell, "Woodstock"

The cosmos is also within us. We're made of starstuff. We are a way for the cosmos to know itself.—Carl Sagan

When I was in eighth grade, our teacher gave us a novel homework assignment: she told us to go home and watch television. Of course, it wasn't a sitcom or even the nightly news, it was Cosmos: A Personal Voyage, the 13-part series written and hosted by Carl Sagan which aired on PBS stations across America in 1980.

Somehow our teacher knew that this program would be special, a must-see. She was vindicated–to drive it home in Sagan-esque style–a billion-fold. The most widely watched series in American TV history until Ken Burns' groundbreaking 5-part The Civil War, Cosmos remains the most viewed PBS series worldwide, seen by over 500 million people in 60 countries.

With its images and ideas, its narration, and its beautifully haunting music courtesy noted Greek composer Vangelis (who'd win an Academy Award the following year for his similarly memorable Chariots of Fire score), Cosmos beguiled our young brains as it opened worlds–the cosmos!–of new understandings via astronomy, biology, chemistry, physics, the possibilities of extraterrestrial life, and, most importantly, our planet and ourselves.

The episodes employed new technologies and cinematic techniques to illustrate often rarefied concepts, but chiefly it was Sagan's explanatory skills, his gift for making tangible the infinitesimal and the seemingly infinite, from the sense-defying attributes of nanoparticles to mind-boggling magnitudes of space and time. He even explained a googol (and a googolplex) long before there was Google.

At one point in the truly grand finale of this series, Sagan concludes:

 It is the birthright of every child to encounter the cosmos anew, in every culture, at every age. When this happens to us we experience a deep sense of wonder; the most fortunate among us are guided by teachers who channel this exhilaration.

We're all fortunate: Sagan was that teacher. In the still-riveting episodes of his great television series, he happily remains so.

Many scientists have formidable intelligence harnessed to specialized expertise, but few can translate their field's increasingly complex technical details for the uninitiated, few have proved such successful liaisons to the masses. While "only" an astronomer, astrobiologist, astrophysicist, and cosmologist, Sagan could ably synthesize the highest attainments of so many arenas–anthropology; biology and evolutionary biology; chemistry; history and the history of science; mathematics; and philosophy.

Sagan's great powers were expansive knowledge, eloquence, and sincerity. He combined not only an immense fluency with science and its historical development, but a genial passion, an irresistible sense of wonder and attendant joy over discoveries of the past and possibilities in the future. He was calm, soothing, eminently sane. His enthusiasm proved infectious.

Cosmos aired 40 years ago. I just recently watched it again. Yet even before renewing that odyssey, I clearly remembered many segments, such as the magic he performed taking viewers through the Drake Equation, an estimate of the probable number of extraterrestrial civilizations in our galaxy capable of communicating with us.

That Sagan could mesmerize me with a long line of computations at a time when I was deeply intimidated by mathematics speaks volumes (it went a long way in boosting this future writer's confidence when he said so reassuringly that "this equation is only a sentence, the verb is 'equals'.")

Another segment which has stayed with me all these years is Sagan's rendering of the greatest achievement of Eratosthenes, who lived in Egypt in the 3rd century BCE. A Renaissance man 1600 years before the Renaissance, Eratosthenes was, among many things, chief librarian of the great library of Alexandria. One day he read that far to the south, in the outpost of Syene, a curious thing could be seen: precisely at noon on the longest day of the year, columns and other vertical structures did not cast a shadow and the sun shone directly down a well, illuminating its bottom.

Eratosthenes asked himself how a stick stuck upright in the ground south of Alexandria cast no shadow on the summer solstice, while in Alexandria, at that exact time, a stick cast a very definite shadow. The only answer is that the earth's surface is curved. But Eratosthenes didn't stop there. He hired a man to measure the distance between Alexandria and Syene (modern-day Aswan) by walking it, a span of 800 kilometers! Now he had enough data to do some geometry . . . and something truly earth-making: he realized that given the distance between Alexandria and Syene, if you extended those sticks into the ground until they intersected, the angle between them would be about seven degrees. And using that sample of "the pie," he deduced that the earth must be a sphere about 40,000 kilometers in circumference.

Sagan pauses here and delivers the punch line:

"That's the right answer. Eratosthenes' only tools were sticks, eyes, feet, and brains . . . plus a zest for experiment. With those tools he correctly deduced the circumference of the earth to high precision with an error of only a few percent. That's pretty good figuring for twenty-two hundred years ago."

Exhilaration channeled!

But however much I loved Cosmos as an adolescent, the understandings and appreciation–the perspective–now as a 53 year-old makes it as moving as anything I've ever watched or read.

I've assembled just a few of the astonishing facts with which Sagan peppers the narratorial courses:

Our galaxy, the Milky Way, has roughly 400 billion stars; there are 100 billion known galaxies.  (Now take that Drake equation and do the math!)

How many stars is that? There are more stars in the universe than grains of sand on all the beaches of the world.

It takes a ray of light 100,000 years to travel from one end of our galaxy to the other.

I've said it many times and I've written it as well: I find I have less and less interest in fiction; more and more, only reality interests me. Cosmos delivers 13 episodes of the grandest realities the universe can offer. But you could never describe Sagan as an absent-minded professor, head in the stars, lost in loftiest contemplation. Far from it. Repeatedly, Sagan speaks to the grave threats–all of our making–which imperil our planet and our offspring now. He offers perspective and the sagest counsel possible. Here is how he concludes Episode 8, Travels in Time and Space:

And our small planet, at this moment here we face a critical branch-point in history. What we do with our world right now will propagate down through the centuries and powerfully effect the destiny of our descendants. It is well within our power to destroy our civilization and perhaps our species as well. If we capitulate to superstition or greed or stupidity, we can plunge our world into a darkness deeper than the time between the collapse of classical civilization and the Italian Renaissance. But we are also capable of using our compassion and our intelligence, our technology and our wealth to make an abundant and meaningful life for every inhabitant of this planet, to enhance enormously our understanding of the universe, and to carry us to the stars.

As both an epilogue and a continuation of Cosmos, Sagan delivered a magisterial assessment, the ultimate dose of perspective, in his 1994 book Pale Blue Dot: A Vision of the Human Future in Space.

This excerpt, now known by many simply as "Pale Blue Dot," was inspired by an image taken, at Sagan's suggestion, by Voyager 1 on February 14, 1990. The spacecraft was departing our planetary neighborhood for the fringes of the solar system. Sagan had it turn around for one last look at its home planet.

You can hear him narrate it himself with his wonderful plosives and melifluous tones on several videos on YouTube. Here's what this great man had to say; it's one of the best things ever written:

Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering; thousands of confident religions, ideologies, and economic doctrines; every hunter and forager; every hero and coward; every creator and destroyer of civilization; every king and peasant; every young couple in love; every mother and father, hopeful child, inventor and explorer; every teacher of morals; every corrupt politician; every "superstar;" every "supreme leader;" every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.

 

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

 

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit? Yes. Settle? Not yet. Like it or not, for the moment, the Earth is where we make our stand.

 

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

On August 25, 2012, the Voyager 1 spacecraft crossed the heliopause, the furthest, faintest edge of the sun's bubble of gravitational and electromagnetic influence. Sagan would have been delighted. We may reach the stars yet.