Everything’s Gonna Be Alright

by Shane L. Larson

The inimitable Mary Fahl has a remarkable song that I listen to all the time, especially on days when it seems impossible that the world has not totally fallen apart. It is a sonorous and passionate piece called “Everything’s Gonna Be Alright.” It opens:

Blind Willie Johnson in a capsule singing ‘bout the soul of man
Encoded traces of the human race and what we understand
A human choir out in the distance trav’ling by a satellite
Symphonic strains of our existence burned into a single byte

Mary Fahl performing “Everything’s Gonna Be Alright.”

For the uninitiated, Mary’s song may seem strange or obtuse — lyrical renderings of language that may have philosophical meaning if contemplated long enough, or may inspire deep visceral emotions if interpreted in certain ways, or simply seem to be pleasant nonsense in the way only songs and poetry can be.

But in reality, Mary’s song is a tribute, heartfelt and full of wonder, for one of our species’ most audacious and hopeful acts: the creation of a message that will far outlive our civilization, promising whoever hears it that we are sometimes better than we often are. The message was created, physically engraved in precious metals, and cast out into the wild voids of the Cosmos, never to be seen again.

That message is known as the Voyager Golden Record. Two copies of the record were minted from disks of copper plated in gold, shrouded beneath protective covers of aluminum, and mounted on the side of each of the two Voyager spacecraft. 

The Voyager Golden Record; the panel on the left shows the cover (inscribed with information to decode the record), and the panel on the right shows the record itself. [Images: NASA/JPL]

Launched 16 days apart in the autumn of 1977, the Voyager spacecraft were ostensibly part of humanity’s first reconnaissance of the solar system, sent to explore the giant worlds of the outer solar system — Jupiter, Saturn, Uranus, and Neptune. They swung by each world, dutifully snapping pictures and radioing their precious scientific data back to the distant rock from which they hailed. As they passed by each world, gravity latched on to them, propelling them ever faster and farther, on to their next destination.

Voyager flight paths through the solar system [Image: NASA/JPL]

Voyager 1 passed Saturn in November of 1980, and the Ringed Planet flung it up and out of the plane of the solar system, toward the constellation of Ophiuchus. In August of 1989, after a twelve year journey, Voyager 2 passed by Neptune, letting the icy giant’s gravity swing it down and out of the solar system, propelling it in the direction of the constellation Sagittarius. After fleeting and tantalizing glimpses of our cosmic neighborhood, the Voyagers have started the long, slow sail to the stars. Today they are the most distant physical artifacts of the human race, both of them more than 20 billion kilometers away, the Sun and Earth mere flecks of distant light.

Powered by small nuclear generators, the Voyagers’ energy is nearly spent. They will dutifully continue to transmit faint bleeps of information back to Earth, but within a decade or so they will fall silent and grow cold, hurtling ever onward toward the stars. Time, space dust, and cosmic radiation will take their toll on these artifacts of Earth, but the Golden Records were designed to stall such inevitable decay for as long as possible. Made of metals that are unreactive and change slowly over time, and encased behind protective aluminum covers, they should resist the long slow death, surviving for a billion years or more..

But what possibly could we have put on the Golden Records to warrant such care and concern about their survival? Mary Fahl told us up front:

Encoded traces of the human race and what we understand

Within the limitations of a physical object that could survive a billion year journey into deep space, we captured what we could about our species, the planet on which we live, the lifeforms we share the Earth with, and the meager understanding of the Cosmos we have gained. Together with greetings in many languages of the planet, and a selection of music from around the world, we engraved the information on 12-inch disks of gold covered copper, and sent them to the stars. It was a gesture of hope and optimism that, in some imagined future, an intelligent species somewhere across the empty sea of space might stumble across Voyager and be able to know something about who we were, faint echoes of a lonely planet and species that once dreamed of sailing to the stars.

Blind Willie Johnson [Image: Wikimedia Commons]

The key elements of the Voyager record are the protective cover, an included stylus (phonograph needle) to play the record, 115 images, a collection of the “sounds of Earth,” spoken greetings in 55 languages, and 90 minutes of music in 27 tracks. Blind Willie Johnson is the second to last track, singing  Dark Was The Night, Cold Was The Ground, a blues Gospel song, with no words but Johnson murmuring and humming along with his soulful guitar picking.

By today’s standards, the amount of data on the record is miniscule — a handful of images that are 512 x 384 resolution, and only 90 minutes of music. But that’s all there is, a small snapshot of life on Earth at the end of the 20th Century. It is likely one of the only artifacts of humanity that will survive our species; for some distant intelligence that might someday find Voyager, it is the only thing they will ever know of us.

The assumption we are making is that whomever might find Voyager will make an attempt to decode the Record. It’s an all together human assumption — if you found a bottle washed up on the seashore, a message carefully preserved inside, would you open the bottle to read it? Of course you would! In our optimism, we trust the receivers of our message will do the same.

On the surface, it seems to be an audacious thought, that a message encoded on a facsimile of a phonograph record could be received and decoded by an extraterrestrial who knows absolutely nothing about us, our technology, our species, our cultures, or our languages. But the message was designed with precisely that concern in mind. Astronomers call the idea of receiving such a message “communication without preamble,” and believe understanding it is predicated on a single fact: that the receiving civilization is technologically skilled.

The Voyager record cover provides protection, but also has information about how numbers are expressed (the “barbell” in the lower right is a hydrogen atom, whose properties should be known), instructions for how to play the record (the image of the stylus on the circle in the upper left), instructions for how to get data off the record (the information on the upper right, showing the data and the first image), and a map of where Voyager came from (the starburst on the lower left). [Image: NASA/JPL]

One of the great truths of the Universe, and perhaps the greatest mystery, is that everything is governed by an immutable set of rules that we call The Laws of Nature. The idea, the logical chain of reasoning, is that if you are capable of travelling into space to discover Voyager, it means you have a deep understanding of those self-same laws, enough so that you can harness them to travel the void of space yourselves. So we encoded the Voyager message using the common foundations of astronomy, physics, and mathematics that apply in every corner of the Cosmos, and trust that an understanding of those foundations will provide enough of a clue to decode Voyager’s precious cargo of sounds, music, and images. 

If you think deeply about this, you might argue that an alien species that recovers Voyager may not have eyes to see as we do, so images may not carry the same meaning. They may not have ears to hear as we do, so music may not be perceivable in the same way. But consider: there are many phenomena in Nature that our senses cannot perceive, yet our intellect and technology make us perfectly capable of detecting and understanding. If an extraterrestrial species is technologically capable, we think they will similarly be able to apply their intellect to understand the story Voyager has to tell.

How do you decide what to include in a message you are sending to the stars? What do you put in a time-capsule to represent our planet and ourselves to an audience we will never know? What do you send to a world and a biology and a history and an intellect completely alien to our own? What do you want beings a million years from now to know about us?

We could be cynical, we could be optimistic, we could be realistic, we could be practical. What should we be?

It is often pointed out that we could have included images and messages about our great failings. The wars we fight, the violence we inflict on one another, our great failings in justice and equity for all the citizens and life of the planet. We could have included images of atomic mushroom clouds, of dead school-children, of wasted and decimated landscapes destroyed by our short-sighted obsessions. But we didn’t do that. We took a very neutral stance, perhaps a sanitized vision of our world. We included pictures of our planet from space, of a tropical island, of a mother and child, of a farmer in Guatelmala, and 111 others. A cynical person might suggest we were being overly deceptive, and not showing the truly ruthless and sad character of our species. Perhaps, but I think not.

Just a few of the images included on the Voyager Golden Record. See a more complete list at NASA’s Golden Record Site. [Images: NASA/JPL]

No, flipping through the image library of the Voyager Golden Record one also gets the sense that this is not just who we are, but what we hope we are — a species that is living through the challenges of our own adolescence, a species that is for the moment surviving, and a species that aspires and believes that many thousands of years hence, our descendants will still be here, wiser and better off than we. We tried to choose a series of images that say we learned enough to build Voyager, and while we’re aware of the dangers we currently face, we are also aware that we are part of a much larger Cosmos.  Our meager collection of images and music is a realization of what we have learned, manifested in the optimistic act of constructing an impossibly limited message containing a few precious tidbits of life on Earth, from a species called “humans.”

And we tossed the message into the Cosmic Void, knowing not where the tides of space might take it.

There is absolutely no consequence if Voyager is never found, nor if the message is never decoded. There is a certain solace we gain from the mere notion that it might be found and might be decoded. Perhaps that solace is rooted in a deep fear — the fear that we are alone in the Cosmos, and everything that we are and think and do will someday perish, extinguished utterly from the Universe.

But I much rather like to think that the solace is rooted in optimism. We believe that it is worth shouting into the Void, shouting that we were here and this is who we were. We believe that, perhaps, there will be beings as intelligent and curious and emotional as we, and that they too might find joy in the discovery of Voyager. We imagine they might feel inexorably compelled to decode the carefully constructed message, and discover that they also are not alone in all the expanse of the Cosmos. We imagine that they too might be struggling through their own adolescence, hoping to not destroy themselves. We imagine that if they receive this small, meager message from Earth, the knowledge that they are not alone might help them somehow. We imagine that such a message might help us.

It is remarkable to think that the act of creating the Voyager Record is an act of optimism, and precisely what Mary Fahl’s lyrical exploration suggests to me. It suggests that despite all the challenges our species faces, despite all the clear failures that we foist upon ourselves, that some part of us still knows the remarkable things we can achieve, and we imagine the good that could result.

In days of gloom, in days of sadness, no matter what we do here on Earth, Voyager sails ever onward, its Golden Record cradled carefully on board, a message for a billion years from now. Perhaps, as Mary noted, “everything’s gonna be alright.”

A Majestic End for a Faithful Friend

by Shane L. Larson

We live in an age where digital technology can make anything seem real. Movies have become immersive experiences where any landscape, real or imagined is possible. Physics defying stunts are rendered on screens as tall as buildings and with sound louder than thunder. Creatures long extinct or completely imagined spring to life, and actors long since passed from the world magically return to the screen, appearing as they did in their youth. Anything seems possible, and the boundaries of reality are blurred, to say the least.

Anything can be given realism with modern technology, whether they be long dead creatures, imagined aircraft, or an architectural plan for a new building. [all images from Wikimedia Commons]

We are so used to this, that when confronted by real pictures of the real world, we often forget what we are looking at. Fantastic and awe-inspiring pictures slip past us and don’t always capture our attention. Photographers capture massive migrations of animals across the land and sea, forlorn sights of abandoned corners of our cities, and the vibrant colors of rainbows and autumn leaves. When we see those pictures, at just the right moment, we experience a visceral moment of joy and set our phone screens and computer desktops to the image, to remind us of that moment of wonder. But more often than not, we don’t remember that real pictures of the real world can evoke emotional responses in us. Some small part of our brain remembers, of course, else we wouldn’t takes selfies in front of restaurants where we enjoy fantastic dinners, or pictures of sunsets against the skyline of our backyards.

On many days, as the woes of the world sidle past me on my computer screen, I am reminded of something that I became aware of in my youth: the true masters of real pictures of the real world are the folks at NASA. They have long been part of the storytelling narrative, reminding us that we are part of a far larger Universe, showing us that with concerted effort and imagination and perseverance, we can overcome tremendous obstacles, solve incredibly difficult problems, and discover that the world around us is filled with unimagined and awe-inspiring grandeur. The Cosmos is alive and breathing around you, reminding you that you are part of something greater that the usual bibble-babble washing out of your device screen.

NASA’s digital artists are masters of putting us at the center of the action, even if it is impossibly far away. L to R: Curiosity skycraning onto Mars; Juno arriving at Jupiter; Cassini arriving at Saturn. [Images by NASA]

In the last few years, our friends at NASA have upped their game. Not only have they regaled us with real pictures of the real world, but they’ve picked up the story-telling torch, and as masterfully as any filmmaker in the world catapulted us into the drama of exploring the Cosmos. You may remember this when they told us about the Seven Minutes of Terror as we lowered the Curiosity rover onto Mars using a robotic, rocket-powered skycrane. Last year, they told us the tale of returning to the unknown regions around Jupiter with a hearty spacecraft called Juno, diving into the radiation belts where anything could happen. But recently, they turned their attention to a far-away world called Saturn, and a steadfast spacecraft we sent there called Cassini….

Saturn has been known to humans since antiquity, one of the bright moving lights in the sky known as the planētes asteres, the “wandering stars.” Like the other naked eye planets, Saturn moved slowly among the stars, tracing out a path along the band of constellations known as the Zodiac, cementing itself in the folklore and mythology of sky-gazers who watched it closely. In the 17th century, the era of Saturnian exploration began when the first telescopes were pointed skyward. The first fuzzy, warbling views of the world showed it was not like the stars at all. Telescopes improved rapidly, as did the views they showed of this far away planet, until at last we discovered the truth — Saturn was magnificently bejeweled by a brilliant, encircling ring. Since that time, Saturn has reigned supreme among all the planets for the awe it evokes at its splendor and beauty. More than any other planet, it looks like it is supposed to look. Today, millions of telescopes around the world are set-up in backyards and on sidewalks on clear nights, giving ordinary people like me and you views of one of the Cosmos’ great spectacles — you can have your own Saturn Moment.

View of Saturn you will have through a modern backyard telescope, taken with an iPhone [Image courtesy of Andrew Symes]

Like most things in space, Saturn is unfathomably far away. At a distance of 1.3 billion kilometers from Earth, it would take you about 1400 years to drive to Saturn’s orbit in your car, or about 150 years to fly there at the speed of a passenger jet. We are, by and large, restricted to staring at it from afar, gleaning what we can from the meager light gathered in our telescopes. The arrival of the Space Age put a new possibility on the table: travelling across the void. Suddenly, we had the chance to see Saturn up close.

While there are effervescent dreams to send humans, Saturn is still too distant to imagine easily crossing the void ourselves, so our attention has been focused on sending quasi-intelligent emissaries in our stead: robotic explorers whose sole purpose is to gather as much information and take as many pictures as possible, and transmit all of that information back to Earth.

Our robotic emissaries, Pioneer 11 (left) and Voyagers 1 and 2 (right). These are the only spacecraft to have ever visited the gas giant worlds of the Solar System. [Images by NASA]

In the 60 years since the start of the Space Age, only 4 spacecraft have ever visited Saturn. The first was a resolute robotic explorer called Pioneer 11.  In 1979, it flew by Saturn skimming through just 20,000 kilometers above the cloud tops, returning the first up close pictures of Saturn, but only a few. It was followed by Voyager 1 in 1980, and Voyager 2 in 1981. The Voyagers returned wide planetary views of Saturn that became iconic to an entire generation of humans, and showed us an ensemble of moons that are each unique and tantalizing, demanding their own careful program of exploration. All of these missions flew past Saturn, returning quick passing views before sailing onward. Today, Pioneer 11 and Voyagers 1 and 2 are on an unknown voyage, destined to drift in the great cosmic dark between the stars for a billion years.

Closeup views of Saturn by Pioneer (left) and Voyager (right). Their time with Saturn was short because they were doing flybys (try taking a picture of your friend on the sidewalk as you drive by at 50 miles per hour…). [Images by NASA]

The most recent of the quartet of august explorers is a two tonne spacecraft called Cassini. It spent seven years crossing the void to Saturn, and has spent the last 13 years circling Saturn, probing the ringworld and its remarkable moons. Twenty years ago, it was cocooned up inside its rocket, and hurled into space. No human has seen it since.

This image is one of the last pictures taken of Cassini in 1997, before launch; the whole spacecraft, together with a few of the people who gave it life. Not soon after, the rocket fairing was lowered into place and closed, cocooning Cassini inside. That was the last any human ever saw of it. [Image by NASA]

For more than a decade, we have been treated to remarkable images, ranging from the strange divided faces of Iaepetus, to the mangled surface of small, tumbling Hyperion. We saw stunning views of the blue-white ice of Enceladus, and ephemeral views of Saturn and its rings, backlit by the distant Sun.

The images returned by Cassini have been stunning, and are far too numerous to do justice to here. A few favorites include: Hyperiod (top left), Enceladus (top center), Iapetus (top right), and Saturn backlit by the Sun (lower). [Images by NASA]

But never among these has there been an image of Cassini itself. Unlike its siblings, the Mars rovers, Cassini cannot take a selfie. But our artists have continued to insert Cassini into imagined views of the Saturnian system, seen as if we were sailing along side it, snapping pictures for the family photo album. Cassini cruising over Titan; Cassini plummeting through the ice plumes of Enceladus; Cassini looking back toward a distant blue star that is Earth.

Artist imaginings of Cassini during its decades long exploration of Saturn. [Images by NASA]

Now, after a two decade journey, we are nearing the end. Cassini’s tasks are nearly over. Unlike Pioneer 11 and Voyager 1 and 2, Cassini is bound to Saturn forever; it will not embark on a lonely voyage to the stars, and in fact, it can’t: there simply isn’t enough fuel in its rockets. Instead, the humans who lovingly crafted it and meticulously planned its journey have planned a magnificent send-off. We call it The Grand Finale. The end of the journey is stunning, worthy of an adventurer as bold and brave as Cassini. But we won’t be able to see it, so once again we turn to our artists to illuminate the images in our minds eye.

Some images from Cassini’s Grand Finale. (L) Saturn’s polar regions, up close as Cassini loops over the top of the planet for another ring pass. (C) One of the highest resolution images of the rings ever taken. (R) The small moon Daphnis, carving out a corridor in the rings. [Images by NASA’s Cassini Imaging Team]

In a series of slowly descending orbits, Cassini will voyage closer to Saturn than any spacecraft before. Looping high over the planet, it will plunge down through the rings for the first time, then loop back around and do it again. Over and over again, it will pass through the rings and skim the top of Saturn’s atmosphere. In all, the Grand Finale consists of just more than 22 orbits. On each orbit it dutifully records what it finds, and relays that information back to us here on Earth. Already we have received stupendous views of the rings, of the cloudtops from closer than we’ve ever seen, and the nearby moons framed by a sky simultaneously more majestic and more alien than any we could imagine in a Hollywood studio.

But at the very end, when there is no where else to go, Cassini will finally succumb to the inexorable gravitational pull of Saturn, and be drawn down into the atmosphere. Travelling more than 75,000 miles per hour, it will burn up in a colossal fireball. One of a thousand meteors that might hit Saturn on any day, but this one from a nearby world. We won’t see Cassini. As it falls, it will be linked to Earth only by the tenuous thread of its radio link, faithfully relaying the last of its observations as it sinks forever into the ocean of Saturn’s atmosphere.  At some point, we don’t know when, Cassini will be gone. With no one to see it, Cassini will disintegrate into nothing. Out of our sight, the last of our dreams and aspirations for Cassini will come to an ultimate end.

Will will mourn. But always we will return to the vast photo album we have assembled over its 20 year life. Like a long time friend departing for the other side of the veil of death, we can’t help but be simultaneously overwhelmed by sadness together with admiration for everything that this little robot has accomplished, against all odds. Cassini has forever transformed our understanding of Saturn. Saturn is a real place, as much a part of the story of our solar system and our home as anything we have ever seen.

Once again our artists capture what we cannot see, rendered in NASA’s End of Mission video, using the tools of entertainment to tell us the story of our long departed emissary in it last moments over Saturn. More than any other art or video I’ve seen, they’ve succeeded in evoking how truly huge and majestic Saturn is, and how tiny Cassini is by comparison. All that we know, all that we’ve discovered, we owe to a tiny robot immeasurably dwarfed by the planet it has so faithfully explored.

You owe it to yourself to go watch this video; reflect on all that Cassini is and was, and know that we are capable of doing tremendous things.

Ad astra per aspera. Fare thee well, Cassini.

Feeling Small in a Big Cosmos 03: Proverbs

by Shane L. Larson

On 19 April 1610, Johannes Kepler wrote an open letter to Galileo Galilei, musing on possible future voyages that would allow explorers — human explorers — to see what Galileo’s telescope had shown.  He mused that some day inventors might “provide ship or sails adapted to the heavenly breezes, and there will be some who will not fear even that void.” Kepler called on Galileo to join him in preparing the way for those so0n to be travellers, and create a new science to light their way: astronomy.

Yuri Gagarin and the Vostok 1 launch on 12 April 1961.

It was almost exactly 351 years before Kepler’s speculations were realized — on 12 April 1961 the Soviet Union launched cosmonaut Yuri Gagarin into space. In a flight that lasted only 108 minutes, Gagarin orbited the Earth in a capsule bearing the callsign Kedr (“Cedar”), and initiated The Space Age.

Kepler’s poetic  words are a testament to our visceral desire to know the Cosmos. Gagarin was perhaps no less poetic when, in the middle of the launch, he belted out an exclamation of joy born from the same deep well of emotional longing — Gagarin’s hearty “Poyekhali!” (“Let’s go!”) ushered in a new era in the history of our species — the beginning of our quest to walk among the stars.

The Cosmos is vast, and nothing makes that point more abundantly clear than contemplating long journeys by humans into space. Trying to protect and sustain our fragile bodies for the duration of a long space voyage brings into sharp focus a single, glaring fact: we are designed for Earth, not for the void, not for alien landscapes, not for far-off icy moons. Despite all the tantalizing things we can see, it seems Nature never intended us to stray far from the small Blue Marble of Earth. We shouldn’t feel bad about that; it is also true for starfish, and seagulls, and housecats, and pine trees.

Every spaceprobe we have ever flung into space has returned remarkable pictures, and made new discoveries. Top to bottom: Mariner 4 was the first to flyby Mars, and returned the first pictures of the Red Planet’s surface. The Soviet Venera 9 was the first to send pictures back from the surface of Venus; it survived for only 53 minutes. The Sojourner rover was the first spacecraft to move around Mars, in 1997. In November 2014, the lander Philae was the first spacecraft to land on a comet.

But humans are a particularly stubborn and imaginative species. We could easily abandon the dream of travelling beyond Earth, but instead we designed and built machines to make the voyage for us. Our knowledge of the Cosmos today is largely populated by images collected by semi-intelligent robots built to be our eyes and ears. They have travelled where we cannot, and faithfully returned images which are arguably the most artistic, the most beautiful, the most stunning, the most confusing, the most awe-inspiring, and the most thought-provoking things humans have ever seen.

For every space probe we have thrown into space, for every world they have visited, for every picture they have snapped, there is a tale to tell. All of them unique, all of them stirring. Let’s revisit the tale of one spacecraft that has been outbound now for almost 38 years; a spacecraft called Voyager 1.

Launched on a bright September morning in 1977, Voyager set sail for the outer solar system. Its mission was to visit Jupiter and Saturn and tell us what it discovered, and then to begin a long slow march into space, searching for the edge of the solar system. Voyager returned tens of thousands of pictures during its mission, but I find two particularly compelling.

In February of 1979, as Voyager was speeding toward its encounter with Jupiter, it snapped this photo: the most exquisite and detailed image of the iconic Great Red Spot ever taken. Voyager showed us the magnificent swirl and drift of the clouds on Jupiter, bands of colorful and dynamic gas driven by 600 kilometer per hour winds around the boundaries of a 400 year old hurricane twice the size of the Earth. This is a storm that,  before we turned our eyes to the skies, our species had never encountered nor imagined. But Voyager painted it for us, indelibly etching it into our memory, with a casual snap of a camera.

Voyager I view of the Great Red Spot as it approached Jupiter in 1979 [Image: NASA].

I like this picture because, to the unknowing eye, one might assume that it is a painting, made by an Earthbound artist, trying to capture or evoke some deep feeling or emotion about the human condition. But this was not painted by human hands. This is Nature painting, using a planet as its canvas.

After sailing past Jupiter, Voyager sped on to Saturn, where it took even more pictures and uncovered more mysteries, painting new pictures of a gentle giant bejeweled by a ring of ice. The encounter with Saturn ultimately propelled it on a course to carry it out of our solar system and into interstellar space. On Valentine’s Day in 1990, right after Voyager crossed the orbit of Neptune, we commanded it to turn its cameras inward and take one last series of pictures before they were turned off. In a sequence of 60 pictures, Voyager snapped a family portrait — a stitched panorama that contains every planet of the Solar System, the family of the Sun. This is the frame that contains the Earth. Like the Blue Marble, it is one of the most iconic images of Earth ever taken, dubbed The Pale Blue Dot.

The Pale Blue Dot — the frame from the Voyager family portrait that includes the Earth [Image: NASA].

More than any other picture, this captures how small and tiny the Earth is. Voyager wasn’t even out of the solar system when it took this picture. In a Cosmic sense it was still close to home, and already the Earth was nothing bigger than a small fleck of light that if we weren’t looking for it, we may not have noticed.  Everything you’ve ever known is inside that dot.

This is the Earth. It’s tiny. And what I find most remarkable when I look at this image: there is nothing in this picture to indicate there is anything special about this planet. Nothing to indicate there is life there, nothing to indicate that we are there, nothing to indicate that this is where Voyager hails from. This one picture captures indelibly in a single frame the fact that we are small, in a Cosmic sense. Some days, we might feel despondent and overwhelmed by the immensity of it all.

The Voyager Golden Record.

But Voyager also carries a sign of our optimism about belonging to a much larger Cosmos. Bolted onto its side, is a Golden Record. It is a phonograph record, a message to anyone who might stumble on Voyager in the distant future, long after its electronics have died and it becomes little more than a fleck of space junk drifting aimlessly through the galaxy. Should someone find Voyager and its Golden Record,  they would find information about the record, and instructions for playing it. Included in those instructions is a map of the galaxy, pointing back to Voyager’s point of origin. On the reverse, etched in golden grooves that will survive a million year journey into the void, is a collection of data about us, and about our world. It includes greetings recorded in 55 languages of Earth. It includes 115 images from the planet Earth from the time when Voyager set sail into the Cosmos. It includes 90 minutes of music from our civilization. And engraved on the inner edge is a single sentence, in English, that reads “To the makers of music, all worlds, all times.”

This is not the kind of thing  you make and throw out into the vast sea of the Cosmos if you are hiding from the immensity of the Universe. Voyager will outlast every person alive on Earth today. It will outlast every one of us, every person who selected music or pictures to be included on this Golden Record. It will outlast our entire civilization. But some part of us can imagine — hopes — that Voyager will survive and be found, and tell the tale of who we are. Perhaps those listeners will be unimaginable alien intelligences; perhaps they will be our descendants who have utterly forgotten us and our civilization.

Voyager and all the other robotic spacecraft we have built are magnificent creations. We can look at them and be amazed that they have gone so far and seen so much. The very existence of pictures like those I have shown you, and literally millions of others like them, should convince you that we can do anything. We can solve any problem we face, we can uncover any mystery the Cosmos puts before us.

Which leads to one last, important thought. Let’s go back to where we started, thinking about the 10 billion billion grains of sand on Earth, and the 10,000 billion billion stars in the Cosmos.

Consider: in just ten drops of water, splashed on your window in a summer rainstorm, there are as many molecules of water as there are stars in the entire Universe. You have heard that every one of us is made of 50%-60% water. Which means there are 100,000 times more molecules of water in your body than there are stars in the entire Universe.

And every molecule of water has two atoms of hydrogen, which is what the stars are made of. And the other atom in every molecule of water is oxygen, which was made by stars, burning hydrogen. At the end of their lives, those stars exploded and threw all that they were back out into the Cosmos to eventually become all that you and I are.

In a very real way, you are atoms the Universe has assembled to look at itself. You are atoms that have been organized to look out into the Cosmos and ask the question, “What’s the deal with all those other atoms?”

You are the Cosmos made manifest.

You are a way the Cosmos has organized itself to ask those questions that humans have always asked. Where did we come from? Where are we going? Why are we here? And what is our role to play in the enormous universe all around us?

We’re not different than all those other galaxies, than all those other stars, than all those other grains of sand. We’re all made of the same star stuff.

There is a meme that floats around the internet that is a purported Serbian proverb (1). “Be humble, you are made of the Earth. Be noble, you are made of the stars.”

It’s okay to feel small. We are small, so we should be humble. We don’t know all there is to know about the Universe.  But be noble, because you are made of the stars. You and I are members of the only species we know that is capable of asking the questions we ask, of figuring things out and asking new questions. It’s very empowering and an important part of who we are. It’s something I think we tend to forget; we get caught up in our problems and in our concerns every single day. But just like artists, scientists, and clergy, we are all true seekers. We’re just trying to understand what our place in the Cosmos really is.

— (1) I have been unable to indeed verify that this is a proverb from Serbian culture! I would love it if someone actually knew where this came from!

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This post is the last in a series of three that capture the discussion in a talk I had the great pleasure of giving for Illinois Humanities as part of their Elective Studies series, a program that seeks to mix artists with people far outside their normal community, to stimulate discussion and new ideas for everyone.  The first post can be found here:  http://wp.me/p19G0g-xB

Illinois Humanities taped this talk and you can watch it online;  many thanks to David Thomas for doing the videography!

A Pale Blue Glow

by Shane L. Larson

One of the great things about being a scientist is I’m exposed to amazing and awesome things. Every. Single. Day. Sometimes I am astonished by Nature itself, and other days I am amazed by our ingenuity and abilities as we come of age in the Cosmos. Today was one of those days.

The first picture of the Moon and Earth together in space, taken by Voyager 1.

This story has its origins long ago. On 5 September 1977 we hucked a 722 kg spacecraft into the sky, named Voyager 1. That was the last time any of us ever saw Voyager 1 with our own eyes. But Voyager has been on a 37-year journey to act as our eyes in the Solar System. On 18 September 1977, barely 13 days after launch, when it was 7.25 million miles from Earth, Voyager sent home the first picture ever of the Earth and Moon together in space. It went on to Jupiter, where it took pictures of clouds and storms that look for all the world like the finest paintings on Earth, and discovered the first active volcanoes beyond the Earth on the enigmatic moon Io. At Saturn, it returned the first high-resolution images of an exquisite ring system, and showed us a shattered Death Star like Moon known as Mimas, dominated by an enormous crater named Herschel. But for all the wondrous pictures, we never saw Voyager. Like your Mom taking pictures of your childhood, we have never once seen the photographer chronicling our growth.

Just a sample of the kinds of discoveries made by Voyager 1. (TopL) Exquisite cloud structure on Jupiter. (TopR) Active volcanism on Jupiter’s moon, Io. (BottomL) Tremendous structure in Saturn’s rings. (BottomR) Saturn’s moon, Mimas.

But today, I saw something that made me smile. Since it began its long outbound journey, we’ve been talking with Voyager 1 on a radio. In all, it only transmits about 20 watts of power, something typical of a larger compact-fluorescent-lightbulb. The total power received on Earth from Voyager is about a ten-billionth of a millionth of a watt. In one second, we receive less than a trillionth the energy a single snowflake delivers to your shoulder as you’re walking to work.

VLBI image of Voyager 1, diligently beaming its signal back to Earth.

But take a look at the picture above, released by NASA last fall. See that pale blue dot right there? That is Voyager 1, seen through the eyes of the Very Long Baseline Interferometer, an array of linked radio telescopes that stretches from one side of the Earth to the other. It sees the sky in radio light. Normally it looks at quasars and distant nebulae, but this image is of Voyager 1, shining its radio back at Earth. This is the first radio signal of human origin ever to be received from outside the solar system. It is also the first picture of Voyager 1 taken since its launch. It’s a bit like seeing your friend in the dark, waving their cellphone at you from a distant mountaintop.  But it’s there, and we can see it — the pale radio beacon of Voyager 1, drifting alone in the immense dark between the stars.

Long after it runs out of power, Voyager 1 will continue to drift alone through the galaxy.

What will happen to Voyager 1? It will continue to talk to us for a little while longer. It is powered by a small nuclear power plant, gleaning energy from the decay of plutonium. But that energy supply is dwindling, and sometime around the mid 2020’s, just more than a decade from now, Voyager 1 will fall silent. The pale blue glow will disappear forever; there will be no more pictures of our loyal emissary. Voyager 1 will continue onward however, bound for the depths of the galaxy, a dead hulk built by a race of curious lifeforms that call themselves “humans.”

But now this has me thinking. All of our knowledge of the outer solar system has been gleaned with telescopes, and with robotic emissaries.  None of the sights you have seen in pictures has ever been witnessed directly by human eyes. Not the dual-tone colors of Saturn’s enigmatic moon Iapetus; not the spider-web of canyons in Mercury’s Caloris Basin; not the misty depths of the Valles Marineris on Mars. Instead, Casinni has been twirling through the Saturn system for almost a decade, and has returned the highest resolution images of Iapetus we’ve ever seen.  Mercury MESSENGER, only the second spacecraft ever to visit Mercury, finally arrived in 2011 and sent high resolution images of the Spider Crater back to Earth. And Mars? Well, Mars has its own fleet of orbiting satellites and ranging rovers to investigate its mysteries.

(L) Saturn’s moon Iapetus has a light and a dark side. (C) The Spider Crater on the floor of Mercury’s Caloris Basin. (R) Fog in the Valles Marineris on Mars.

What happens to all our tiny robots, sent out into the Cosmos all on their own? We’ve been tossing them into space almost non-stop since the start of the Space Age — what happens to all of them?

Only 5 will ever travel beyond the solar system. Pioneers 10 and 11 are both bound for interstellar space, now quiet and dead after their power supplies failed in 2003 and 1995. Voyager 1 and 2, having completed their Grand Tour of the outer solar system, are also outbound; we expect to lose contact with them within the next 10 to 20 years. And lastly, there is New Horizons, bound for Pluto and the Kuiper Belt beyond. It is by far the youngest of this august group of explorers. It was designed to have power for 20-25 years, but it has already spent the last eight-and-a-half years just getting to Pluto — it should last another 15 years or so.

Spacecraft that are going to escape from the solar system. (L) Pioneer (C) Voyager (R) New Horizons

(T) When Spirit got stuck on Mars, NASA engineers recreated the situation on Earth, trying to figure out how to free the rover. (C) Artist’s imaging of what Galileo looked like as it burned up in the Jovian atmosphere. (B) The LCROSS mission before impact.

Many of our robots, like the Voyagers and Pioneers, will just die. This famously happened to the Spirit rover on Mars. It trundled around the Martian surface for 2269 days (perhaps, some say, trying to earn a trip back home) before we lost contact with it. Spirit had become stuck in a Martian sand dune and was unable to free itself. Stuck on flat ground, unable to tilt itself toward the Sun to keep warm in the cold Martian winter, we last spoke with Spirit on 22 March 2010.

The Galileo mission, which spent more than seven-and-a-half years exploring the Jovian system, was crashed into Jupiter, to prevent it from tumbling out of control when its power failed, possibly contaminating a moon like Europa, where we can imagine extraterrestrial life may exist. On 21 September 2003, it was plowed into Jupiter. We couldn’t see it take the final plunge, but we listened to it faithfully radioing us everything it could for the last few hours before its end.

Sometimes, we crash our spacecraft on purpose, for science! One of the most spectacular examples of the was LCROSS, the Lunar Crater Observation and Sensing Satellite. The goal of this mission was to look for water ice in the perpetually shadowed craters on the surface of the Moon; water on the Moon would have important implications for the sustainability of lunar colonies. LCROSS had two pieces — it’s Centaur rocket stage, and the Shepherding Spacecraft that carried the science instruments. On 9 Oct 2009, the Centaur rocket impacted the Moon at a speed of about 9000 kilometers per hour; the Shepherding Spacecraft flew through the cloud of debris and radioed the composition back to Earth. This exquisitely timed dance was a planned suicidal flight for the Shepherding Spacecraft; its unavoidable fate was to impact on the Moon about 6 minutes after the Centaur stage. The result? There is water, frozen in the lunar soil.

But the saddest fate to me, is that of Mercury MESSENGER. MESSENGER was the first spacecraft to visit Mercury since Mariner 10 flew by three times in 1974. Despite three passes, Mariner 10 only mapped out about 45% of the surface; until MESSENGER’s arrival in 2011, we had no idea what more than half of Mercury looked like.  It took MESSENGER 7 years to get to Mercury. It has been there for about three-and-a-half years at this point, and we are looking ahead to the end. Over time, the closest point of MESSENGER’s orbit has been getting lower and lower, affording us the opportunity to understand Mercury’s gravitational field and to map and  probe the surface of Mercury with exquisite resolution. But lowering the orbit, to get a closer view of the planet, is a one way ticket, eventually leading to MESSENGER’s impact on the surface of Mercury.

Mercury MESSENGER

The end will come sometime after March of 2015, on the far side of Mercury from our view.  MESSENGER will die alone, cut-off from us by distance and astronomical happenstance. In the words of MESSENGER PI, Sean Solomon, “This will happen in darkness, out of view of the Earth. A lonely spacecraft will meet its fate.”

This emotional attachment and personification of machines seems disingenuine to some people; spacecraft aren’t people, they are collections of wires and circuits and nuts and bolts — they don’t have souls to become attached to.  I dunno. I think they do have souls. They are the embodiment of every one who ever imagined them, worked on them, or stared at the data and pictures they returned. These little robots, in a way, are us. They are our dreams. Dreams of adventure, of knowledge, of a better tomorrow, of understanding who and what we are in a Cosmos that is vast and daunting.

And so today I smiled at the pale blue picture of our long departed friend, Voyager 1. And on the day it falls silent, I’ll shed a tear and drink a drink to its remarkable voyage, a voyage it made for you and me.

Cosmos 11: The Persistence of Memory

by Shane L. Larson

One of my all time favorite books is the 1952 novel “City” by Clifford D. Simak. It is a yarn spun of a distant future where humans have utterly vanished from the planet, and the Earth is inhabited by an intelligent society descended from our domesticated canine friends.  The dogs regale their young pups with tales of the websters (humans) who once inhabited the world.  After the telling of the tales, the pups are always full of questions: “What is Man? What is a city? What is a war?”  As their elders calmly tell them, “There is no positive answer to any of these questions.”

It is a curious thought, to look at our civilization, and ask what some future generation might ask of us if they had nothing but our cities to look at.  It is a question we often ask ourselves when encountering the constructions of civilizations that have utterly vanished from the annals of history.  Staring at the crumbling remains of ancient buildings, massive temples and pyramids, and monolithic stones, we ask ourselves questions: “Why are these here? What was this for? Who were these people?”

Imagining a distant future without us has become a cottage industry, with striking images by excellent, modern artists, imagined against the backdrop of our greatest cities, such as Chicago (L) or New York (R).

As scientists, when we look at the crumbling remains of lost civilizations, we try to let our minds imagine how it happened.  When I stare into the ruins of a society long since vanished from the Earth, such as the Anasazi of the American Southwest, the Tiwanaku of western Bolivia, or even the ancient Romans, I often wonder what happened near the end?  Did they know their civilization was crumbling, that it would soon be subsumed by the slow and steady march of time?  What did the people think and do as their society was collapsing around them?

(L) The Cliff Palace at Mesa Verde, one example of an abandoned Anasazi city [National Park Service image] (R) The Kalasasaya and lower temples at Tiwanaku. At equinoxes, the sun shines into the Ponce Monolith, aligned in the main door. [Image from Wikimedia Commons]

One of the difficulties we have when considering the fate of these long lost ancestors of ours, is there are few, if any, records of their civilization that survive to the current common era. No great papers of statesmanship, no news clippings; no children’s textbooks, no essays from great scholars; no grocery lists, no lusty romance novels.  A few works survive, to be sure, but nothing in great numbers; nothing to give our anthropologists and historians the raw material to understand what was going on in the minds of the people in those far away civilizations.  Virtually everything they were, everything they thought, is now lost. They speak to us only through shattered and incomplete artifacts, remnants of everyday life buried under centuries of accumulated soil and detritus, and through what few remaining architectural constructions still stand in the shadow of our civilization.

A typical household bookshelf (this is one of mine) contains a wide variety of books — the collected knowledge, wisdom, and imagining of our civilization, gathered and preserved on paper and capable of surviving into the far future.

But today, unlike 2000 years ago, books and paper and writing abound. In addition to those who diligently secure the knowledge of the human species in scholarly works, there are tremendous amounts of other information being captured by a species that has become enamoured with the written word.  Bookstores abound, and books are produced and sold in massive numbers. Journalling and daily writing are a common and well regarded activity.  People collect, hoard, and use notebooks and fountain pens. Families, libraries, and city councils make and bury time-capsules full of books, newspapers, messages, and artifacts for future generations. I would love to slip into hibernation, and emerge several centuries in the future, to see what survives, and what our descendants think of us after sifting through the surviving scraps. 

A family time capsule my wife and I made in 2000. We picked the 2017 opening date, guessing that any potential children we might have would be in elementary school, and interested in artifacts of the past. Our daughter will be 10 years old when we open this time capsule. The suspense is killing her!  🙂

Imagining how to store information, so our memory persists and is understandable in the future brings three immediate questions to mind: What would we want the future to know about us? What will the future think about us? And how do we get a message (that can be understood) from us to them?

It is a fascinating mental puzzle to me, to try and imagine how best to speak to someone far removed from you in time, if not also in space and culture. Consider this blog.  The post you are reading lives now, in this moment.  Will WordPress and web-browsers and Unicode-8 exist 400 years from now? Probably not. All this will be lost, faded back into the ethereal fabric of the Cosmos.  For the moment, these words are organized into well-ordered bits of data, stored and represented as a few fleeting photons of light that leap from the surface of your tablet to the retina of your eye, where they are transformed into electrical impulses deep in the furrows and cores of your brain. But eventually it will be gone; the memory circuits will be loose silicon atoms in a landfill, perhaps. When I’m 107, I may remember writing this, but when I return to star-stuff, those memories will become unorganized electrical and thermal energy once again, lost forever. Maybe, on a forgotten and dusty shelf, someone will find my hardback copy of Carl Sagan’s Cosmos, the pages somewhat yellowed with age,and obviously well-thumbed, but still readable. They will scan the words, and wonder what it was like to live today, in the age where we were first exploring the Cosmos beyond Earth. But this blog, this personal exploration of Carl Sagan’s Cosmos, will be lost forever.

Do you think the loss of information in today’s age is unlikely?  Try finding something on Geocities — it is estimated that 38 million webpages vanished when it shut down in 2009. Where are the 97 lost episodes of Dr. Who? Information can and does disappear, even in our digital age.  How often do you back up your hard drive? Do you have a copy of every email you’ve sent and received (Stephen Wolfram has his)?  Can you still read the report on life in Rhodesia (now Zimbabwe) you wrote in high school using WordStar? 

The lack of WordStar, the computer it can run on, and a floppy disk drive that can read a 5-1/4” floppy disk means all that you wrote in that report is virtually gone, lost forever.  Technology creates the ability to collect, store, and distribute information; but when the technology becomes obsolete the information becomes endangered.  I’m pretty sure in our family time capsule, there is a VHS tape.  I haven’t owned a VHS player since around 2006, a scant 6 years after I closed up the time capsule!  How am I going to play that tape back???

But the truth is, no matter how carefully we preserve our technology, and strive to make it readable by some distant future generation, it will all be lost eventually.  Because someday, all stars die.  When they do, they destroy the planets around them, and all record of the life and civilizations that may have existed there.  Someday, around 5 billion years in our future, the last day of the Earth will dawn.  The Sun, having exhausted its supply of hydrogen deep in its core, will be on its way to the grave. It will have swollen to enormous size, swelling until it swallows the entire inner solar system during its “red giant phase.”  When that happens, the Earth will be no more.  It has happened to billions of stars before the Sun, and it will happen to us.  When those stars that came before the Sun died, did the galaxy lose some impossibly ancient civilizations?  Does there perhaps exist some persistent memory of them, drifting among the stars?  And if there is, can we possibly hope to understand how those memories are encoded?

I often daydream about a distant future, thousands if not hundreds of thousands of years in the future, where our distant descendants sail the stars. Still not far from us in evolutionary terms, our imagined future descendants will be far separated from us in time, farther than we are from our ancestors who walked the Nile Delta or the Indus River Valley a few thousand years ago. It is improbable, but not impossible, that they may stumble across a ancient hulk drifting among the stars — a device of intelligent design, cast out among the stars by some ancient, long lost civilization.

Taking it amidships, they will quarantine it.  Like us, our descendants will be good at figuring things out — science and engineering are tools that will have allowed them to overcome many challenges, and led them to the stars.  The intriguing device will be scanned, examined, and prodded from afar. Once they are convinced it is safe, they’ll approach it up close, touch its surface, and see how it is constructed. It is only then they will discover a great wonder — bolted to the side, obviously meant for intelligent eyes, is a message. It is not written in any language that they will recognize, but it is clear it is meant to be decoded — a message from the builders.

What will a message found drifting on a lost hulk in space look like? If we stumble on a message, will we be able to decode it?

Science and engineering teams will be brought in, together with linguists, technologists, and mathematicians. They will uncover a code, a simple cipher built around fundamental numbers related to hydrogen, the most common substance in the Cosmos. Following the simple, encoded instructions, they will find sounds and images, and a great mystery. The languages are foreign to their ears, the messages meaningless; but there is music — stunning music; and images, probably of the builders and their far-away world, cloudy and water shrouded.  But the builders are us.  The device is one that you and I are intimately familiar with. We call it Voyager 1, and the message is known as the Voyager Interstellar Record.  But to our distant star-faring progeny, it will be a long forgotten artifact, unknown in the fragmented historical records they have from their past.

It is not impossible that our descendants will have forgotten us, and possibly forgotten the world they even came from.  Consider our own distant past. Some of the oldest known artifacts from our ancestors are pieces of jewelry, made from mollusk shells between 90,000 and 100,000 years ago. We know nothing about the people who made those artifacts, only that they were deliberately made; all other knowledge of them is gone, lost forever.

Someday the knowledge of us could similarly be lost forever, but some small and incomplete memory of us will persist.  Buffetted by the quiet tradewinds of the galaxy, the two Pioneer and two Voyager spacecraft will spend the next billion years sailing the interstellar voids, far outliving their creators, bearing only the merest scrap of memory about who and what we are.

As of this moment, the Pioneer and Voyager spacecraft are the only artifacts of our civilization, the only memory of us, that will definitely persist beyond the death of the Sun.

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This post is part of an ongoing series, celebrating the forthcoming science series, Cosmos: A Spacetime Odyssey by revisiting the themes of Carl Sagan’s classic series, Cosmos: A Personal Voyage.  The introductory post of the series, with links to all other posts may be found here:  http://wp.me/p19G0g-dE

Cosmos 6: Travellers’ Tales

by Shane L. Larson

Sitting at the gate at Chicago’s O’Hare International Airport, staring at the thousands of other people around me, I am struck by how remarkably connected the modern world is.  I’m not thinking about smartphones and instant personal communication; rather I’m staring out the window at a Boeing 777 and thinking that I can go travelling virtually anywhere on the Earth, in just a day or so, by walking down the jetway.  And we all do it in a blink of an eye.  Sometimes we go for work, to exotic places like Dallas or Albuquerque.  Sometimes we go to visit family, like grandma in Mobile, or Aunt Becky and Uncle Bob in Bemidji.  But sometimes, we jet off across the world, just to go exploring.  We go to see the grand Buddha of Leshan, or the primeval rain forests of the Amazon, or the volcanoes near Reykjavik, or Gaudi’s Sagrada Familia in Barcelona.

(L) The Grand Buddha of Leshan. (R) Sagrada Familia. [Photos by S. Larson]

While on our adventure, we take selfies, we send text messages that say “Guess where I am?”, and we wonder at the marvels of the world. When we return home, we may bring a few trinkets — a silk shirt, a wall hanging, a journal embossed with foreign words and images.  But the things we return to time and again, years after our voyage, either in idle strolls down memory lane or to show family and friends, are our pictures.  Pictures are the single most common and important thing brought back from adventure voyages, as they alone have the magic to transport us  back to those far away lands, with our friends alongside us.

Text messages and selfies, some of the most common travellers’ tales of the modern age.

There was a time when our world was not so easily accessible, when the far corners of the Earth had not yet been discovered, and adventurers didn’t know what they would find on a long voyage of discovery. In the 1700’s, Captain James Cook made three epic voyages around the world, aboard ships whose names have become synonymous with exploration and discovery: HMS Endeavour (a name latter passed onto a United States space shuttle orbiter), and HMS Resolution. Cook’s papers and journals of those voyages were collected and studied for many years after his death, but one of the greatest treasures returned from the voyages were images of far away lands. In those days of exploration, every ship was crewed not just by sailors, but by professionals.  Some were scientists tasked with observing and recording discoveries along the voyage, and others were artists tasked with capturing images of the voyage to record and relay the adventure to those left behind. Without those artists eyes, we would never know what Cook saw on those first, epic voyages.

Images by artist William Hodges, who accompanied James Cook on his second voyage. (L) The HMS Resolution near Antarctica, and (R) HMS Resolution in Matavai Bay, Tahiti.

Today, the world is completely mapped, cultures (for the most part) have been found and documented, and there are precious few places humans have not yet tread.  Voyages of new discovery come more rarely, and people like you and me have adventures that begin with airplane rides and are documented through the lenses of smartphones.  While you and I have set our sights on worldly adventures like visiting Mammoth Cave in Kentucky, or picnicking in the shadow of Moai on Easter Island, our species’ thirst for adventure has grown beyond the Earth.  We have embarked on a new adventure to seek out new horizons and unknown landscapes far out into the Cosmos. The primary commodity of these new adventures are pictures — thousands and thousands of stunning pictures of cosmic vistas that move our spirits in ways we could have never imagined.

I often dream of being able to visit the Moai of Easter Island. [Illustration by S. Larson]

The sky has always compelled us to look up.  Even were we not fascinated with the strange and unearthly things we have found in the sky, the sky presents events that compel us to look up.  Consider the case of eclipses.  The Sun is the most brilliant source of light in the solar system, and every object it shines on casts a shadow, including the Earth. The Moon, on its rounds about the Earth, sometimes fleets through the shadow of the Earth.  As it passes into the shadow, it begins to disappear, an ever growing curve of shadow slowly eating the bright disk of the Moon. When it reaches the center of the shadow, the Moon takes on a deep reddish hue, cast in scarlet tones by the sunlight streaming around the Earth and through its atmosphere — an Earth sunset on our closest neighbor in the Cosmos.  This event is called a lunar eclipse.

(L) The geometry of a lunar eclipse. (R) iPhone image of the total lunar eclipse on 10 Dec 2011. [images by S. Larson]

The Moon also casts a shadow, and sometimes that shadow falls on the surface of the Earth, casting a fleeting moment of darkness wherever it falls.  Seen from the Earth, the Moon creeps across the Sun, an ever growing curve as the Moon blocks the brilliant solar disk.  At the center of the eclipse, the Moon covers the Sun and those standing in the center of the shadow are treated to a rare sight — the blazing corona of the Sun.  This event is called a solar eclipse.  Eclipses in our ancient past were unexpected and likely inspired fear and superstition.  Today, we can predict when they occur and where to stand to see them. People from all over the world step onto airplanes, and fly to stand in the shadow of the Moon.  They take their cameras with them, and capture images of the event to share with friends and family when they return from their travels.

(L) The geometry of a solar eclipse. (C) Image of total solar eclipse taken by Arthur Eddington in 1919. (R) Hydrogen alpha image of the annular solar eclipse on 20 May 2012 in Cedar City, Utah. [by S. Larson]

Another, rare kind of eclipse is called a Transit of Venus, when Venus passes between us and the Sun, appearing as a small black dot traversing the solar disk. Beautiful and inspiring to see, observing a transit of Venus was one of the first ways that people figured out to measure the distance from the Earth to the Sun. Transits can be seen in pairs roughly every 121 or 105 years (a 243 year pattern), when the orbits of Earth and Venus are aligned just right. The most recent pair of transits was in 2004 and 2012. Two scientists, Charles Green and Daniel Solander, accompanied James Cook on his first voyage, tasked with observing a transit of Venus, which they did from Tahiti on 3 June 1769.

Transit of Venus seen from Wasilla, Alaska on 5 June 2012 [iPhone photo, through a solar telescope, by S. Larson]

While one could spend a lifetime standing on the surface of the Earth looking up into the Cosmos, some part of us knows that we could learn so much more if we just go up there.  And so we have.  For the most part, our emissaries beyond the Earth have been robots — machines of human design, supremely instrumented and exquisitely engineered to make interplanetary voyages that we cannot. Our robots have sailed the interplanetary sea and visited every major world in the solar system, providing tantalizing and brief glimpses of alien shores through pictures radioed back to their creators on faint radio links.  Travellers’ tales, recorded through the electronic eyes of semi-intelligent robots, are the principal commodity of the age of space exploration. Tales that paint a tapestry of wonders brilliant and evocative, tempting us with the promise of what we might discover if we were to dig deeper, push farther, and continue the exploration.

Of all the many worlds in the solar system of which we are aware, there are only five on which we have landed and returned images from the surface: the Moon, Venus, Mars, Saturn’s moon Titan, and the asteroid Eros. These are the only worlds beyond the Earth whose surfaces we have tread upon, and only on the Moon and Mars have we ventured away from the landing site (using rovers). At all of the sites, we have tantalizing pictures of alien shores that sing a siren song of adventure when we look out across them. 

(A) Surface of Eros by NEAR-Shoemaker. (B) Surface of Titan by Huygens. (C) Surface of Venus by Venera 14. (D) Apollo 15, station 9 on Hadley Rille. (E) Surface of Mars, near Bonneville Crater by the Spirit Rover.

But most of our probes are not landers — they are semi-intelligent cans of electronics, wires, metal and composites that we have hucked out into the Cosmic sea, leaving them destined to drift forever in the sky.  Most of the images they return are all taken from orbit or on a one chance “flyby.”  The stories they tell are a bit like describing a state by looking out the window of a plane as it passes overhead, but the tales are riveting mysteries of the past, present and future of the worlds in our solar system. 

On Mercury, we’ve found a vast impact basin, just discovered in 2008 by the MESSENGER spacecraft. The basin is more than 700 kilometers across; if it were on Earth it would stretch from San Francisco to Seattle.  A vast circular hollow excavated in the early days of the solar system, the central plains are a vast expanse of ancient lavas criss-crossed with ridges and troughs that have been frozen into the landscape since their formation — there is no weather on Mercury to weather and fade the scars of ancient geologic trauma.  We’ve named it Rembrandt after the famous Dutch painter — a fitting name for such a picturesque place.

(L) Rembrandt, on Mercury. (R) Saturn by Cassini.

At Saturn, Cassini has radioed back exquisite images of the subtle tawny clouds of Saturn, always framed by the brilliant arc of the great rings.  But on its way to Saturn, Cassini did a little sight-seeing, and as it sailed past Jupiter toward Saturn, recorded a mesmerizing movie of that planet’s banded clouds. The clouds swirl and rotate as they are pressed before winds blowing as fast as 500 kilometers per hour, nearly twice as fast as the strongest winds ever seen on Earth.  

Jupiter’s cloud bands, as seen by Cassini (click to animate).

Among all the space probes we have set adrift, five hold a special place of honor.  They are Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, and New Horizons.  These are the only probes we’ve built that are destined for interstellar space after their reconnaissance of the solar system.  Thousands of years from now, their creators long forgotten and returned to dust, these spacecraft will sail on into the interstellar void of the galaxy.

Now fallen silent, their energy reserves exhausted, the Pioneers no longer send tales home to Earth. But each carries a story with it, in the form of a small plaque telling the tale of the probes’ origins, should any intelligent being find it in the distant future.  A bottle cast into the Cosmic Ocean, I often wonder about those who might one day stumble on Pioneer 10 and 11.  Will they be alien intelligences?  Or perhaps will they be some impossibly distant descendant of humans, stumbling on a forgotten remnant of their past? Will they understand the message, and understand what Pioneer was doing in a long forgotten epoch of time?

(L) The Pioneer plaque, amidships on Pioneer 10. (R) The two sides of the Voyager record. You can explore the Voyager record online (at the JPL Voyager site, or at a complete online archive), or in the (now out of print) book Murmurs of Earth.

Both Voyager spacecraft also carry a message in the form of a Golden Record. The record contains instructions for use, a map pointing back toward Voyager’s origin, and its own set of travellers’ tales: a set of 55 greetings in different languages of Earth, 116 images of life on Earth, and 90 minutes of music from around the world ranging from masterpieces by Mozart, to Chuck Berry’s Johnny B. Goode, to a traditional Peruvian wedding song.  The record bears one final message, inscribed on its inner edge, a handwritten message: “To the makers of music — all worlds, all times” (etched by Timothy Ferris, the producer, when the record was completed).

The ADS All Sky Survey, a rotatable interactive map showing where we’ve taken pictures of the sky.

The principal commodity of science, and astronomy in particular, is knowledge. The tangible evidence of that knowledge is pictures.  Images capture both scientific knowledge and cultural aesthetic; they can be appreciated by everyone for the wonder they evoke and the questions they provoke.  At a recent gathering of the American Astronomical Society, some of my colleagues showed a new kind of astronomical map.  It is a map of the entire sky, but instead of showing us the secrets veiled away in the deep Cosmos, the map shows us how often we have looked at or studied — taken a picture of — a particular place in the sky. To the trained eye, you can see the Andromeda Galaxy, the Large and Small Magellanic Clouds, the plane of the Milky Way, the plane of the Solar System, and the area covered by the Sloan Digital Sky Survey.  But what amazes me most about this picture is how LITTLE of the sky we have seen — most of the map is  black, meaning no picture has been taken there.  That is a staggering shame, since as the Hubble Deep Field as shown (and its successors, the Ultra Deep Field, and the Extreme Deep Field), even the most remote, dark and (we thought) empty places in the sky are filled with uncountable mysteries.  The sky is a BIG place, and we are far from having seen it all.

And so we continue to stare, we continue to take pictures, and we continue to spin travellers’ tales about what we’ve seen, what we know, and what we still would like to discover.

The Hubble Ultra Deep Field (UDF), showing what is unseen but can be found if you stare at an empty part of the sky for long enough.

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This post is part of an ongoing series, celebrating the forthcoming science series, Cosmos: A Spacetime Odyssey by revisiting the themes of Carl Sagan’s classic series, Cosmos: A Personal Voyage.  The introductory post of the series, with links to all other posts may be found here:  http://wp.me/p19G0g-dE