Cosmos 4: Heaven and Hell

by Shane L. Larson

I am writing this on the 45th anniversary of one of the most iconic photographs of the Space Age. As Bill Anders, Frank Borman and Jim Lovell rounded the far side of the Moon, after traveling farther than any humans in history, they beheld a sight that had never been seen before — the distant blue sphere of the Earth rising over the horizon of the Moon. This single image captured an idea which up to that time was a mere abstraction — that the Earth is a single world, without borders and boundaries, interconnected and bound together in ways that are simultaneously obvious and subtle.

(L) The original Earthrise image, shot by Bill Anders on Apollo 8’s 4th lunar orbit in 1968. (R) Recreated Earthrise image by NASA’s Lunar Reconnaissance Orbiter.

This is the nature of great voyages of exploration and discovery — finding the unexpected, and realizing it was the most important thing that happened. The Earthrise image, like image of Buzz Aldrin’s bootprint on the Moon, or the Genesis rock found by Apollo 15 Commander Dave Scott on the delta of Hadley Rille — those are transformative moments from the Age of Space Exploration that changed how we think about who we are. 

(L) The Apollo 15 Genesis Rock, in situ as found on the Moon at Hadley Rille, and in the Lunar Sample Laboratory at Johnson Space Center. (R) Aldrin’s bootprint experiment on the surface of the Moon [Apollo image AS11_40_5880], and the iconic image that symbolizes humanity’s first voyage beyond the Earth [Apollo image AS11_40_5878].

To be connected to the Cosmos, to know why we are here and understand the part we play in the design of the grand machine of Nature — these are the deepest passions of the human psyche, passions that fuel art, exploration, and science, endeavours one and all whose sole purpose is to figure out what it all means.

Human beings are good at figuring things out. Sometimes we do it for recreation — we play tangrams, we play matchstick riddles, we solve Soduku puzzles.  Sometimes we do it because we have to, because our very survival depends on it — we figure how to shore up the banks of a river before it floods a town, we figure how to rescue a family who’s car has skidded off an icy road into a ravine, or we figure how to increase grain yields to feed a million starving people.  Sometimes we do it to improve our lives — we know how to make the human body invincible against the polio virus, we know how to forecast the arrival of a hurricane along our seaboards, and we know how to make the sum total of all the knowledge of the human race available to anyone on a device that fits in your pocket.

Science is a way of thinking about the world specifically geared toward figuring out how things are related. That everything on Earth is deeply interconnected is one of the great realizations of the last two hundred years. Consider the Wave Rock in the Hyden Wildlife Park of Western Australia: 14 meters high, and 110 meters long, Wave Rock has the shape of an enormous cresting wave on the ocean, but the nearest seashore is 300 km away. That Wave Rock is a natural formation is clear. But how did it get there? How did it form?  This formation is an example of weathering and erosion.  Constant and continued exposure to weather, wind and rain have eroded the rockface away, leaving the flared shape of a cresting wave.  It happened slowly, over millions of years, far too slowly for humans to observe, but we figured it out.

Examples of weathering processes on Earth. (L) The Grand Canyon of the Yellowstone. (C) Rub’ al Khali, the “Empty Quarter” on the Arabian Penninsula. (R) The Elephant’s Foot Glacier, in Greenland. [Images from Wikimedia Commons.]

The idea that the weather and climate of the Earth are responsible for some of its physical features is not at all immediately obvious, but part of figuring things out about the Cosmos is connecting the dots.  Rivers run in channels, clearly carved into the skin of the Earth. Wind moves vast dunes of sand as it blasts across the empty quarters of the Earth’s deserts.  Ice, in the areas where it persists, also shapes and molds the land in stunning and pictueresque ways.  At the heart of all of this, is water. The most common substance we encounter everyday, our planet is a veritable water paradise.  We encounter it all of its forms, and all are spectacular eye candy — ice, liquid, and vapor. When we see the Earth from the near reaches of outer space, seen as the Apollo astronauts saw Earth from the Moon, what is immediately noticeable is the water — the blue oceans, the white clouds. Water is the stuff of life, the single most important substance that, to our biology, makes the Earth a paradise without peer.

Water in all three forms found on Earth: liquid, ice, and vapor (clouds). [Image from Wikimedia Commons.]

A hot Jupiter near its parent star. [Image from NASA.]

It is not surprising then that, as we begin to search the Cosmos for other worlds and planets, our prejudice is always skewed toward worlds that remind us of home, worlds that harbor water in some shape or form.  In the last two decades, we have tallied up an impressive catalogue of planets, 1056 as of the time of this writing.  But this number is only the smallest fraction of all the worlds that must exist; these are only those that we have found so far. In their number, we have yet to find any that have the biological friendliness of Earth.  There are many which can only be described as hellish.  Consider the “Hot Jupiters,”  which are sometimes called “roasters.”  These planets orbit closer to their star than any planet we have ever seen. The first hot Jupiter discovered was the first planet found beyond our solar system, called 51 Pegasi b (sometimes known as Bellerophon).  This planet orbits its parent star once every 4.2 days!  By contrast, Mercury, the closest planet to the Sun, orbits once every 88 days!  51 Pegasi is located 50 lightyears from Earth, so we may never know what it is like on that far away world, but we can be quite certain it is nothing like the Earth; I’m willing to bet it is not a water paradise.

(L) Saturn’s moon Titan, seen up close by the Cassini spacecraft in ultraviolet light. (R) Titan’s liquid hydrocarbon lakes, displayed in false color (colored by computer). [Images from Wikimedia Commons.]

Closer to home, we have discovered many worlds that may harbor some water in some form, but none have exactly the perfect balance of energy, water, and air to produce the veritable garden that is the hallmark of Earth.  The only other world in the solar system known to have liquid of any sort on its surface is Saturn’s moon, Titan.  We have sent our spacecraft to reconnoiter Titan, and have even landed on its surface. Our maps are colored in a way that is pleasing to the eye, seductive in its suggestions of land and sea.  But the seas of Titan are unlike any that humans have sailed. They are not water at all; they are liquid methane, roiling under the “oppressive heat” of the distant Sun at Titan’s surface temperature of -180 ºC.  Closer, but still beyond easy reach, is Jupiter’s icy moon Europa. Only slightly smaller than Earth’s Moon, Europa is covered in a thick layer of water ice, laced with vast  enigmatic colored striations known as linae (scientists believe these are fractures where Europa’s icy crust has broken and shifted back and forth). Europa is too far from the Sun for enough radiant energy to keep water liquid on the surface, though there is strong evidence that below the ice may lie a sub-surface ocean.  What might we find, if we could dive below the ice shield, and skim the seas of another world?

What might lie beneath the icy surface of Europa? Future missions may tell us. [Illustration by S. Larson]

Venus, as seen by Mariner 10 in February 1974. [Image by NASA.]

Perhaps the most interesting nearby world is Venus. Nearly the twin of Earth in terms of size and gravity, Venus lies slightly closer to the Sun, on the edge of what astronomers call the “habitable zone” — the distance from a star where the laws of physics make the existence of liquid water “easy.”  Like the Earth, Venus lies just far enough from the Sun that water could remain liquid and not freeze. But unlike the Earth, the atmosphere of Venus is dominated by carbon dioxide, a gas that traps energy on the surface of the planet.  As a result, the temperature has sky-rocketed to 462ºC (863º F) — hot enough to melt lead. Like an oven, the blanket of heat fills every far flung corner of the planet — there are no tropical, temperate or polar zones on Venus. The entire planet is consumed by the pressing heat; the planet is a hellish world without peer.

The knowledge that Venus is a hothouse without equal has passed into the collective knowledge of our civilization, a bit of information that most people know and can use to win a Saturday night game of Trivial Pursuit.  But we have not always known this fact; it was something we figured out.  That Venus was shrouded in an apparently eternal cloud layer was a fact known since the invention of the telescope. Having little experience with clouds other than those on Earth, it was oft assumed that the clouds were water-based, and that Venus was a watery, swampy morass — perhaps not a heavenly paradise, but certainly no less-liveable than the jungles of the Congo or the back-bayous of southern North America.

Approximately true color image from the surface of Venus, taken by the Soviet Venera 14 lander in 1981.

But science is a self-correcting process. When new information is discovered, we revisit old thoughts, old models, old assumptions and view them anew, asking ourselves “how have we fooled ourselves this time?”  We generate new ideas that explain all of the old information and the new information together.  Such is the case with Venus. In the 1950’s, the advent of electronic technology allowed us, for the first time, to detect microwaves being emitted from our nearby sister world.  This was a startling revelation — how could it be that a planet was emitting copious amounts of microwaves?  The puzzle was resolved by a young Carl Sagan in 1960, who in his Ph.D. thesis demonstrated the basic runaway-greenhouse effect model that successfully explains the character of Venus.  The clue to the existence of the greenhouse effect was the microwaves — hot gasses produce copious amounts of microwaves. This was confirmed directly by the Soviet Venera 9 spacecraft, which soft-landed on Venus on 20 October 1975. It was the first human spacecraft to return pictures from the surface of another planet; it survived for 53 minutes.  Today, Venera 9 is slowly eroding away under the oppressive heat, pressure, and acidic rain, a decaying testament to the human penchant for figuring things out.

The Venera landers lived very short lives on the hellish landscape of Venus. Long ago fallen silent, they are now slowly eroding away. [Illustration by S. Larson]

The desire to find a world like Earth is a reflection of our understanding of how fragile and, so far as we know, unique the Earth is. The paucity of Earth-like worlds might be reason for discouragement, but we are still figuring out how to find other planets, and we aren’t giving up yet. But one thing is true — there are no worlds like Earth anywhere close to us; there are no places we can go and exist as easily as we do in the garden of Earth.  The idea that we as a civilization can and are changing our planet in dramatic (and possibly irreversible) ways is something we are just figuring out. The existence of worlds like Venus should serve as gigantic flashing billboards to our civilization screaming “Do not Enter! Wrong way!”  Part of exploration is discovering not just who we are, but what the future may hold.

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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

Improbable, Awesome Pictures

by Shane L. Larson

A friend of mine, who shall remain nameless, was grousing about last month’s enormously successful “Wave at Saturn” campaign.  “WTF? It’s not like Cassini will see any of us in the picture!  People can’t even see Saturn when they’re out waving because the Sun is up!  Why are you going out to wave? You know better!”  Perhaps in a less grumpy-old-man but more conversation-and-education fashion, Sky & Telescope even did a simple analysis to find out if any light from your waving hand actually would have made it onto Cassini’s imaging system (Will Cassini See You?).  I follow this little mathematical exercise perfectly well, and I had made a similar estimate myself.  But I still went outside and waved at Saturn!

I don’t think my friend (or other Grumpy Old Scientists, “GOSes”) understood the point at all, so we had to have a long conversation.  Let’s do the easy one first.  Why did I go out and wave?  Because when I’m a stooped old man who has to have a nurse feed him his Slurpee’s, I didn’t want to look back on my life and regret not going out to wave at Saturn with the rest of humanity. I went out and waved!

Now when I’m 107, I’ll say to my nurse “Did I ever tell you when I was young like you I went out and waved at Saturn?”  He’ll smile at me, pat my arm, and say, “Here Mr. Larson, have another sip of your blue Slurpee.”  I made sure I went and got my certificate from NASA too!  I hope they hang it over my bed in the old folks home. 🙂

My Wave at Saturn certificate. I waved at Saturn!

To address the question of what’s the point, I like to ask a slightly different question: why did people bother to go out and wave at all?  All over the country, people took their kids outside after dinner, or took 15 minutes out of their workday and went out and stood on the sidewalk to wave at a planet 898 million miles away. Why?

Because it is an AWESOME idea.  It sparks a little bit of wonder in the back of your brain to contemplate that the light from every rock, cloud, puddle, car windshield, tree, rooftop, discarded box of macaroni, and waving human hand would travel almost 80 minutes before it arrived at Saturn to be captured by the camera on a robot from another world.  The simple fact that this could even be true should inspire a little bit of pride in every one of us, and make us stand up a little taller.  Only a little more than a century ago, we didn’t even know how to make an airplane fly under its own power.  But today, barely three generations later, our species quite reliably demonstrates the ability to fly beyond the confines of our small world, to send ships sailing the vastness of interplanetary space and send back to us tales of its adventures.

Titan’s surface.

Cryovolcanic Enceladus.

That is AWESOME.  Cassini is only the latest is a long series of emissaries that have been exploring the homeworlds of our solar system, and it has sent us enormous numbers of improbable pictures, not the least of which include pictures from the surface of Titan; images of a blue and white wonderland of the enigmatic moon Enceladus, studded with cryovolcanoes; and of course Saturn itself, bejeweled with its mesmerizing ring system.

Saturn from Cassini.

Saturn hurricane.

For thousands of human generations, Saturn was little more than a point of light in the sky. Galileo’s telescope was so crappy he couldn’t even tell Saturn had a ring; “Saturn has ears,” he wrote.  But today, we can build a self-sufficient robot capable of flying high above Saturn, where it can take pictures of a hurricane large enough to cover half of North America, locked onto the north pole of Saturn inside a mysterious six sided cloud formation called “The Hexagon” (you can’t make this stuff up!).

That is AWESOME.  I think all of us know it is awesome too; that’s why a million people went outside and waved at Saturn.  They were waving at Cassini, our little robot friend who tirelessly circles a world that most of us will never see with our own eyes, uncovering its mysteries and teaching us not just about Saturn, but about ourselves.  Deep down, people understand this, and they want to feel connected to it.  That’s why they all tore themselves away from their Excel spreadsheets, paused in their marketing meetings, left three of the tires off and the oil unchanged in the AMC Pacer, and went outside to join their fellow humans in waving.

The crowd at NASA’s Jet Propulsion Laboratory, waving at Saturn (photo by NASA).

People were so engaged with the activity, they took pictures of themselves waving and posted them to twitter, facebook and instagram.  I get the feeling that they didn’t really care whether Cassini got some light from their furiously waving appendages, but their iPhones did, and they basked in the coolness factor as a result.  Yep, for whatever reason, this geeky, crazy idea to participate in something related to science had some serious street cred.  It was an adventure, and they all participated!

I think every one of us who engages in the profession of science should pay attention to that fact, especially all the GOSes (many of whom aren’t all that old, they’ve just become old in their thought patterns — they probably don’t read blogs, so you should spend some time talking them through this!).  People freely engaged in something related to science. People in vast numbers freely engaged in something related to science. They had fun, they probably learned a little bit (like Saturn is up in the sky, even during the daytime), and walked away with a positive and optimistic view of something that isn’t related to reality TV or Hollywood celebrities.

As scientists, we like to bemoan the state of science literacy in the world today, a malaise that is driven by the very vocal anti-science rhetoric that has become inextricably entwined with politics.  There are climate-change deniers and anti-vaxxers to be sure, but when I see a million people standing out on a sunny Earth afternoon waving at a camera improbably far away, I have a little hope.

And to top it all off, we’re still getting payback from the event!  NASA released Casssini’s snapshot of us all to great fanfare.  Here it is.

The Earth, seen from Saturn.

See that little dot, lost in the blackness below the majestic arc of Saturn’s ring?  That’s us; that’s home.  You’re in that picture, waving. Your mother is in that picture, waving. I’m in that picture, waving.  Every human being, waving or not, is in that picture.  At the moment this picture was snapped, we were all paying attention.  An improbable moment, captured for all time by a little robot with an improbable mission: seek out new things, learn all you can, and return that information to your creators.

That is AWESOME.

Take some time tonight, and before you fold up your laptop, take a moment to sift through some of the pictures from Cassini.  Take a look at the pictures you snapped during Wave at Saturn, and the ones that Cassini sent back, and remember how engaged the world was with this activity.  Improbable pictures, improbable engagement, but a stunning success.

Well played, NASA.  Well played.  Now let’s do it again.

The Size of the Cosmos

by Shane L. Larson

As many of you know, I ascribe much of my aspirations in life as a scientist to being exposed to Cosmos at a very early age.  Within the first five minutes of the first episode, Carl said a very big thought: “The size and scale of the Cosmos are beyond ordinary human comprehension.”

As I have grown into my career in science, I have lost sight of this simple fact. I’ve learned to write big numbers. I’ve learned to convert between meters and kilometers and lightyears when needed. I’ve even learned to use “crazy relativist units” and measure distance, time, energy and mass all in meters (something that confounds my students, my parents, and many of my astronomer friends!). I’ve done this enough now that when I calculate numbers, I know if they sound right.  Two million lightyears to a galaxy in the Local Group? Sure that sounds fine.  750 Megaparsecs to a quasar? Sure, I’m down with that.  1.3 billion kilometers to Saturn?  Word.

Developing a sense for big (and small!) numbers and whether they “sound right” is an essential skill for scientists, and we spend inordinate amounts of time training ourselves and our students to be facile with them.  But that completely bypasses Carl’s point — these numbers are HUGE.  They encode how utterly small we are on the grand scale of the Cosmos!

One of my hobbies is walking Solar System Walks when I encounter them (here is a long list at Wikipedia; another list at Air & Space).  These scale models lay out the Solar System, marking the location of planets at the appropriate spatial scale to give you a sense of how large the Solar System is (forget the Universe itself).  My favorite is one in Anchorage, Alaska, known as the “Lightspeed Planet Walk”  — if you walk at normal speed, the time it takes you to reach each planet is the same time it would take light to make the journey you made.  That is awesome.  Start at Earth, and shine a laser pointer at Neptune the moment you start walking; you’ll reach Neptune at the same time your feeble green laser beam reaches the real planet Neptune!

The center of the Lightspeed Planet Walk in Anchorage, Alaska, with a scale model of the Sun.

Despite the large physical scale of these walking models, I still often feel like they don’t capture the immensity in a way that really shocks my brain. I’ve thought about this fact a lot, and suspect it is because when I’m walking the model, it feels quite ordinary.  As I’m meandering from Mars to Jupiter, I’m not really thinking about how far I’m walking. I’m distracted by my daughter prattling about why Pluto should still be a planet, and watching ducks eat algae, and avoiding speeding mountain bikers.

But a couple of weeks ago, one of my astronomy friends showed me something that blew my socks off.  It’s a very simple demonstration you can do right at home that captures how messed up my mental picture (and I’ll bet yours!) of the solar system is!  I think my mental pictures are messed up because we often show the family of the Sun all together, to better show the relative size of the planets, like the image below.

A typical representation of the Solar System, often used in books, online references, and mass media.

What this image fails to show, is the spacing between the worlds.  We’ve known the relative spacing of the planets for some time, the distances having been worked out using basic geometry together with clever observations (many of which can easily be done in your own backyard), and through application of the laws of physics (notably Kepler’s Laws of Motion, and Newton’s Universal Law of Gravitation).

Folding pattern to make a reasonably spaced representation of the planetary orbits in the Solar System on a long strip of paper.

Let me teach you the trick my friend showed me.  Get a long strip of paper (adding machine paper, or other strip paper works well), about 1 meter long.  On one end, write the word SUN and on the other end write PLUTO.  Now fold the strip in half, and unfold it again.  What object in the solar system lies halfway between the Sun and Pluto?  It is the planet Uranus; write this on the fold.  Now fold the end marked Pluto down to Uranus.  Label this as the location of the orbit of Neptune.  What does this show us?  There isn’t  much in the way of planets in the outer half of the solar system!

Now fold the end marked Sun down to Uranus.  On  this new fold write Saturn.  Fold the Sun down to  Saturn and label the new fold Jupiter.  Fold the  Sun to Jupiter and label the new fold  Asteroids.  At this point, about 93% of your strip is  between the asteroids and Pluto.  This is the part of the solar  system that is euphemistically called “The Outer Solar  System.”  Fully half of the known planets in the solar  system are still to be squeezed between the Asteroids and  the Sun!  Let’s do that next.

Fold the Sun to Asteroids, and label this fold  Mars.  The last part is two folds before labeling: fold the Sun to Mars, then fold the end over to Mars again.  The result is three folds.  Starting at the  Sun, label them Mercury, Venus and Earth.  The entire procedure creates a map with amazingly accurate spacing between the worlds (yes! I calculated the errors; I was curious!).

The results of all your folding endeavours!

Now stare at your model for a moment.  The solar system is a lot of empty space!  The places that are easiest to get to are close to Earth, but are still very far away.  The distance to the Moon is about the width of a pencil line, and it took Apollo astronauts 4 days to cross that gulf.  Mars is six to eight months away by rocket.  Look how close it is to Earth!  It took the Cassini spacecraft almost seven years to get to Saturn.   When the New Horizons spacecraft flies by Pluto in 2015, it  will be have been outbound for almost nine-and-a-half years!  The  solar system is a big place. And the Cosmos is far vaster.

I think what amazes me the most about this model is that places I normally think of as very far away are much closer to Earth than my brain normally thinks of them.  Consider Jupiter; it is in the Outer Solar System.  But on the map, it is only 1/8th the distance between the Sun and Pluto!  Wow.

“The size and scale of the Cosmos are beyond ordinary human comprehension.”  Perhaps; certainly outside the realm of our everyday experiences. But our ingenuity gives us ways to push our brains to try to understand, and clever demonstrations like this one give you ways to ponder and think.  So get out your scissors, and start folding.

(L) The full length of the Solar System model. (R) My own version of this model, shown next to a typical Earthling.