Tag Archives: Moon

#AdlerWall 04: Look Up and Sketch the Moon

by Shane L. Larson

You and I live in the future. Our world is one where information is transmitted instantly to everyone, blasting out of large flat screens and small hand-held devices owned by a billion humans around the globe. Information comes in small blurts of text, a few funny pictures, and now and then in a short video. Electronic memory, captured forever in the ephemeral electronic nothingness of the internets.

It is hard to remember that there was a time, not so long ago, where moving pictures were a marvel, a wondrous example of the technological age that was just beginning to expand its blanket across our civilization. That by-gone age that introduced the world to moving pictures is usually called the “Silent Film Era” and spanned more than 3 decades, from 1894 until the late 1920s when “the talkies” began to take over. In the midst of this age of wonder, an ingenious filmmaker made his trade in France, experimenting with all manner of ways of filming and editing to take his audiences on journeys of imagination and wonder. His name was Georges Méliès, and in 1902 he released one of the great classics of film: Le Voyage dans la Lune — “A Trip to the Moon.”

(L) Georges Méliès. (R images) Scenes from "La Voyage Dans la Lune" [Images: Wikimedia Commons]

(L) Georges Méliès. (R images) Scenes from “La Voyage Dans la Lune” [Images: Wikimedia Commons]

Inspired by the novels of Jules Verne and H.G. Wells, Méliès imagined making a voyage across the cosmic gulf to visit our celestial companion. This was in the days before rockets — Méliès imagined sending a space capsule to the Moon after launching it from an enormous cannon, a perhaps not unreasonable idea given Newton’s cannonball diagram in his De mundi systemate to describe orbits!

(L) In his "De Munde Systemate" Newton imagined going into space via an enormous cannon; this was before rockets were known. (R) In 1902, rocketry still had not been developed, and Méliès imagined sending his voyaguers to the Moon by launching them in an enormous cannon.

(L) In his “De Mundi Systemate” Newton imagined going into space via an enormous cannon. (R) In 1902, rocketry still had not been developed, and Méliès imagined sending his voyaguers to the Moon by launching them in an enormous cannon.

The Moon at that time was a great mystery to us, the target of much speculation and many wild imaginings. Méliès’ vision built on that — the Moon was an alien landscape, populated by alien cultures that his explorers did not understand nor appreciate. It was perhaps an obvious target for Méliès’ imaginings. More than any other place in the solar system, the Moon is a place that we can all imagine visiting, if for no other reason than we can see it with the unaided eye.

Today, more than a century after Méliès’ voyage of imagination, the Moon is a known place. Like many worlds in the solar system, we have photographed it up close and mapped its surface in exquisite detail. But it still holds a certain mystique that other celestial destinations do not. Mostly because we can see it with the unaided eye, but more because it is the only other place in the Cosmos, besides Earth, where human beings have walked. It is a great wonder to step outside and see the distant orb of the Moon riding high in the sky, and know that people just like you once walked there. It still makes me a little breathless, and encourages me to look for the Moon every time I walk out the door. It seems unlikely that I will ever get to walk the craggy lunar landscape myself, so I fall back on the next best thing: I try to see what I can see with my own eyes.

adlerWall_sketchMoonThe #AdlerWall exhorts us to “Look up and sketch the Moon.” Most of us have seen the Moon, probably unconsciously the way we notice trees, flowers and other ordinary, everyday things. Part of the Wall’s desire for you is simply to be cognizant of noticing what you are seeing (in the same spirit of our earlier exploration in looking closely at what is under rocks). But the other part of the imperative is the sketching.

Why should we do that? Personally, I’m probably the world’s worst sketcher, but I do it anyhow. Sketching, no matter how crude and rudimentary, helps you notice things. There are many different sketching exercises that you can do, and all of them will bring the Moon a bit closer to you.  Let’s explore some of those ideas together.

Right now, picture the Moon in your mind. What does it look like? Without getting up to look at it, without pulling up a picture of it, make a crude sketch of what you see in your mind’s eye on the back of an old cell phone bill.

What did you draw? Perhaps you drew patchy patterns of light and dark. The variations in brightness across the face of the Moon are caused by the geology that shaped it. The darker areas are called maria, or lunar seas. They are basaltic lowlands, the youngest surfaces on the Moon created by vast lava flows in an earlier, active phase of the Moon’s life. The brighter areas are called terrae, the lunar highlands. These jumbled and broken landscapes are the older parts of the lunar crust, covered with craters and criss-crossed by mountain ranges, escarpments, and vast rilles.

Did you draw any craters? How about mountains? The understanding that such features are found on the surface of the Moon is almost ubiquitous. But unless you have looked at the Moon through a telescope, you probably have never seen a crater for yourself.  You cannot see any craters or mountains on the Moon with your naked eye. Until the time of Galileo, it was widely believed the surface of the Moon was smooth.

My two sketches of the Moon. (L) The Moon from memory [not very good!] (R) A direct sketch at full moon. [Images: S. Larson]

My two sketches of the Moon. (L) The Moon from memory [not very good!] (R) A direct sketch at full moon. [Images: S. Larson]

Now go out and make a sketch of the Moon, whatever phase it might be in. The patterns of light and dark are the same ones that have been seen by 40,000 generations of humans before us. The surface of the Moon is millions of years old, changing on slow geologic timescales — human lives, and indeed all of human history, are the merest flashes of an instant in the long history of the planets in the solar system. The face of the Moon you see today is the only one ever seen by humans.

Whenever we look at the sky we project all manner of human interests and problems on the sky, a manifestation of our deep and abiding desire to be part of the Cosmos. The Moon is no different than the rest of the sky in this regard. As our most prominent neighbor, it has oft been the target of imaginative musings. There is a long tradition of recognizing and naming patterns in the patchwork of light and dark — moonshadows.

The most famous of the moonshadows is the Man in the Moon, but if you look closely you can also see the Bunny in the Moon, and the Woman with the Pearl Necklace. Can you make up your own moonshadows that you can easily recognize and teach others to see?

Some of the classic moonshadows you can see in the full moon. Clockwise from upper left: the Full Moon, the Man in the Moon, the Bunny in the Moon, the Woman in the Pearl Necklace.

Some of the classic moonshadows you can see in the full moon. Clockwise from upper left: the Full Moon, the Man in the Moon, the Bunny in the Moon, the Woman in the Pearl Necklace.

The fact that you know the Moon is covered in craters and mountains and canyons is a testament to our civilization’s ability to share knowledge. But in reality, you can discover for yourself exactly what Galileo discovered, even if you don’t own an astronomical telescope. Common birding binoculars or small spotting scopes are all much better than Galileo’s first telescope, and will show you the wonders of the Moon.

You can turn your small scope or binoculars on the Moon at any time, but it is easiest to see surface features when there are strong shadows. This happens at any time during the month except near Full Moon (though you should certainly look at the Moon when it is full!). The boundary between the light and dark on the lunar surface is called the terminator — it is the dividing line between day and night on the surface of the Moon. The shadows of craters and mountains are strongest on the terminator, and if you focus your attention there, you can see some fantastic topography. If you’re inclined to carefully record the shadows you see, some simple mathematical investigations with geometry can be used to figure out how tall and wide the mountains and craters are.

Some of my sketches of the Moon. (L) The lunar terminator, made through a small birding scope. The numbers and letters are to an identification key, figured out after the observations with the aid of a detailed Moon map. (R) A telescopic sketch of the crater Archimedes. [Images: S. Larson]

Some of my sketches of the Moon. (L) The lunar terminator, made through a small birding scope. The numbers and letters are to an identification key, figured out after the observations with the aid of a detailed Moon map. (R) A telescopic sketch of the crater Archimedes. [Images: S. Larson]

If you look at Galileo’s classic sketches of the Moon, you may notice that he sketches the entire Moon. In your own viewings, especially during the crescent phases, you can often see the faint outline of the dark part of the Moon; through a telescope, you will see fleeting, ghostlike impressions of craters, lunar seas, and mountains in the ephemeral shadows. What is going on here?

This phenomenon is called “Earthshine” — sunlight hits the Earth, bounces off the Earth, and hits the dark side of the Moon, making it appear in ghostly shadows. This is the same effect that lets you see things in the shade of a tree at the park — light from the sunny parts of the park bounces off of everything and illuminates the parts of the park in shadow. The first person to explain the origin of this shadowy illumination of the Moon by Earth was Leonardo da Vinici, in his famous notebook, the Codex Leicester.

Galileo's sketches of the Moon always showed the unilluminated half of the Moon as well. You can and will notice this, with your naked eye and through a telescope, due to "Earthshine." [Image: Wikimedia Commons]

Galileo’s sketches of the Moon always showed the unilluminated half of the Moon as well. You can and will notice this, with your naked eye and through a telescope, due to “Earthshine.” [Image: Wikimedia Commons]

Even if you don’t want to sketch the craters and the mountains, even if you don’t want to peer at the Moon through a telescope or binoculars, you may still see the Moon in striking moments of beauty, framed by life here on Earth. A common experience many of us have had is witnessing a Moonrise or a Moonset against the landscape or against the skyline of the city. In many instances you get the overwhelming perception that the Moon is enormous, looking over the Earth like a gigantic cauldron of boiling light, waiting to pour itself out across the landscape.

The Moon Illusion at work over the Adler Planetarium. What my eye saw (sketch on the Left) and what my camera captured (picture on the Right) are significantly different! [Images: S. Larson]

The Moon Illusion at work over the Adler Planetarium. What my eye saw (sketch on the Left) and what my camera captured (picture on the Right) are significantly different! [Images: S. Larson]

This apparent enlarging of the Moon is an optical illusion known as the “Moon illusion.” While you can generically break the illusion by disrupting your normal viewing of the scene (try standing on your head, or looking at it upside down), the existence of the illusion does not diminish the awe-inspiring effect it has on your mind’s eye. Somewhat surprisingly, simply taking a picture often destroys the illusion — unless cropped very closely around the Moon, pictures flatten the perspective and bring peripheral parts of the scene into play, destroying whatever visual queues your brain was using to make the Moon look big. It’s weird.

The Moon is always up there, waiting for you to notice it, providing intriguing and beautiful opportunities to snap a picture or make a quick sketch. Look up! [Image: S. Larson]

The Moon is always there, waiting for you to notice it, providing intriguing and beautiful opportunities to snap a picture or make a quick sketch. Look up! [Image: S. Larson]

The Moon, like the Sun and stars, is one of the dependable denizens of the sky. Sometimes it is up during the day, sometimes it is up at night. It is constantly changing its shape, and adds majesty and brilliance as a backdrop to images of life on Earth. So the next time you’re out take a look around for the Moon; if you have a moment, snap a picture or make a quick sketch, so you can remember it.  See you out in the world — I’m the guy looking dumbstruck on the street corner, craning his head to see the Moon rising behind the city skyline! 🙂

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This post is part of an ongoing series about the #AdlerWall. I encourage you to follow along with the activities, and post your adventures, questions and discoveries on social media using the hashtag #AdlerWall.  Links to the entire series are here at the first post of the #AdlerWall Series.

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Feeling Small in a Big Cosmos 02: Discovery

by Shane L. Larson

Suppose we wanted to imagine some very big numbers, to somehow develop an appreciation for how BIG the Cosmos truly is. Sitting on a the beach somewhere, one might idly wonder “how many grains of sand are there on all the beaches and in all the deserts of Earth?”  Counting is certainly out of the question, so how might you figure that out?

Bear Lake, Utah.

How many grains of sand, on all the beaches and in all the deserts of Earth?

You would do it the same way we “counted” the galaxies in the sky using the Hubble Extreme Deep Field. You count all the grains in some small amount, perhaps a handful of sand picked up off the shores of Lake Michigan. Then you figure out how long and wide all the beaches and deserts are, and how deep the shifting sands run, and figure out how many handfuls of sand would cover them all. Multiplying my the number of grains in my hand, you would find there are some 10 billion billion (1019) grains of sand on the planet Earth.  That’s a BIG number; a number that is beyond ordinary human understanding, beyond our everyday experience.

The night sky over the Pando Forest in central Utah. Pando is an 80,000 year old aspen grove -- it has seen almost 30 million nights like this one, but very little has changed. The constellations change over thousands of years, but the sky is still full of stars, and the Milky Way still arches over the sky, giving the impression that the Universe is unchanging. [Image: Shane L. Larson]

The night sky over the Pando Forest in central Utah. Pando is an 80,000 year old aspen grove — it has seen almost 30 million nights like this one, a sky full of stars [Image: Shane L. Larson]

But imagine for a moment comparing it to the total number of stars in all the Cosmos. The Hubble Deep Fields have convinced us there must be something like 100 billion galaxies in the Cosmos. A galaxy like the Milky Way has more than 100 billion stars in it, so multiplying those two numbers together, there are some 10,000 billion billion (1022) stars in all the Cosmos, more than all the grains of sand on Earth. An even bigger number, well beyond our everyday experience.

When there is so much we don’t understand here on our own small planet, it is easy to be overwhelmed by the immense size, the immense possibilities of what we don’t understand in a Universe far larger than our brains can easily imagine. We could very easily crawl into our shells, hide from the immensity, and turn our vision inward, with nary another glance outward into the deep vastness that doesn’t even notice we are here.

But we don’t do that. We have, for countless generations, stared into the immensity in an ongoing  (and surprisingly successful) camapign to understand and explain all we can about the Universe. But when everything is so impossibly far away, when the Cosmos is full of so many different and unknown things, how is it that we can know anything?  The answer to that question is that we ask questions.

questionMarkConsider a popular game that most of us have played since we were kids (I have a 9 year old — I get to play this A LOT).  Here is a box (with a question mark on it). You want to figure out what is under this box by asking 20 “Yes-No” questions. Go!

  • Is it alive? No.
  • Is it something made by humans? Yes.
  • Is it small enough to hold in my hand? Yes.
  • Is it edible? No.
  • Does it have batteries? No.

So there we have asked just 5 questions. The answers are nothing more than a simple yes or no. But the tremendous power of asking questions is clear. Despite the vastness of the Cosmos, despite its immense size and the mind-boggling large number of things it contains, you have eliminated almost ALL of it from consideration with only 5 simple questions. You know it is not something huge (galaxy, star, planet, white dwarf, asteroid, comet, …). You know it is not alive, so every organism on Earth — plant, animal, bacteria, fungus, protozoan — is eliminated.  Your attention is now focused on only things that humans make, and only those things that aren’t powered by batteries.

me_ndgt_legoAnd you have 15 questions left! With 20 carefully constructed questions, you will be able to figure out almost anything I wanted to hide under that question mark, with a high degree of success! If we went on and I let you ask the rest of your 15 questions, I am confident you would eventually arrive at the fact that hiding in my question mark box is a little Lego version of me and Neil deGrasse Tyson.

We could have done this with anything in the Cosmos. I could have had anything under that box — an elephant, a quasar, a piece of Pluto, the left foreleg of a carpenter ant, a circle of paper from a hole punch, a cough drop wrapper, an oyster shell, that little plastic do-hickey that holds your gas cap on your car, a Calving & Hobbes sketch, a molybdenum atom, Marie Curie’s lab notebook, a lost pawn from a Sorry game, and so on. ANYTHING!

But you can figure out what it is with only a few questions so reliably we’ve made it into a game children can play and enjoy! It’s usually called “20 questions,” but it also goes by the name science. Except when we play science, we don’t limit ourselves to just 20 questions — we ask as many as we want! You can learn a LOT with carefully constructed questions. And we have learned a lot. We have collected and gathered and recorded our knowledge of the Cosmos so effectively that much of it has passed into the communal memory of our species, integrating itself into the fabric of who and what we are so effectively that we often don’t give it a second thought. We’ve forgotten how hard it was to earn that knowledge, the struggle our forbears went through to wrest some secrets from Nature and then understand what they meant.

A 1/2 globe of the Moon, roughly 5 feet in diameter, made before spacecraft had ever flown to the far side. You can see this in the Rainbow Lobby of the Adler Planetarium in Chicago.

A 1/2 globe of the Moon, roughly 5 feet in diameter, made before spacecraft had ever flown to the far side. You can see this in the Rainbow Lobby of the Adler Planetarium in Chicago.

To understand this, consider the Moon. What do you know about the Moon? It orbits around the Earth. It is spherical, and is illuminated by the Sun. The near side always faces the Earth. It is covered with lowlands (called maria, lunar “seas”), highlands (called terrae, the brighter areas), mountains, craters, and canyons. All of this is common knowledge, which if you didn’t know it you could have found out using the electronic web that girdles our world. I’m pretty sure almost everyone reading this has not been to the Moon. In all the history of our species, only 24 humans have ever crossed the gulf between the Earth and the Moon; only 12 humans have ever walked on the Moon and seen what we know with their own eyes. The pictures of the Moon, taken by the Apollo astronauts and robotic emissaries have virtually erased from our memory what it was like to not know what the Moon was like.

Consider the globe of the Moon shown here. It is about 5 feet in diameter, and lives up to our expectations of a rugged, desolate landscape covered in mountains and craters. How far away from this globe would I have to stand, for it to look roughly the same as the Moon in the sky?  About 140 feet. The full moon in the sky, is about the size of a US dime, held at arm’s length.

When you see the Moon in the sky, it is quite small, roughly the size of a dime held at arm's length. The detail your eye can see is minimal -- mostly just dark and light shading, with no topography! [Image: Shane L. Larson]

When you see the Moon in the sky, it is quite small, roughly the size of a dime held at arm’s length. The detail your eye can see is minimal — mostly just dark and light shading, with no topography! [Image: Shane L. Larson]

When the Moon is that small, you can’t tell it has any topography at all. It is clearly shaded in some irregular pattern (which allows you to make the famous Moon shadows), but there are no craters or mountains to be seen. Go out and look, but don’t look with your brain plugged in to what you know; just look at what you can see. This is how the Moon has always look to the naked eye; it wasn’t until the  application of the telescope to astronomy that we knew anything different.

Galileo's early views of the Moon through his telescope revealed previously unknown topography.

Galileo’s early views of the Moon through his telescope revealed previously unknown topography.

In 1609, Galileo Galilei was the first person to plumb the depths of the sky with a telescope, and what he saw shook the foundations of what we thought we knew about the Cosmos. In 1610, he published one of the seminal works in astronomy: Sidereus Nuncius, “The Starry Messenger,” wherein he described all that he had seen during his first excursions in 1609.  He wrote of the Moon

“... the Moon certainly does not possess a smooth and
polished surface, but one rough and uneven, and, just
like the face of the Earth itself, is everywhere full
of vast protuberances, deep chasms, and sinuosities.”

Two things stand out to me about this passage. The first is how he initially describes the Moon: a smooth and polished surface. This is how people thought of the Moon — it is, in a very real sense, what the Moon looks like, and what you would think if you had never been taught that there were craters and mountains on its surface. The second is when he describes what he saw on the Moon: just like the face of the Earth itself. The telescope allowed us to see that the Moon had features and topography that were at once recognizable and intimately familiar, appearing just like the topography we see here on Earth. In a singular moment of discovery, the telescope deprovincialized our view of the Earth. The Moon is, in a very real sense, the first world other than the Earth that we ever discovered, and this is how it happened.

Galileo's planet sketches, while not showing the detail of his lunar observations, were no less revolutionary.

Galileo’s planet sketches, while not showing the detail of his lunar observations, were no less revolutionary.

There were many other startling revelations Galileo had looking through the telescope. In addition, he was the first person to look at the planets through a telescope. And what he found was that the planets were not stars at all, but also were other worlds. Every planet showed size, and round shape. The planet Saturn had odd protrusions; Galileo wrote “Saturn has ears.”  Turning his telescope to Venus, Galileo found that it went through phases, just like the Moon, a fact that was easily explained by the still new Copernican idea that the Sun was at the center of the solar system.  But Jupiter revealed one of the greatest secrets of all — it held in its grasp its own entourage of moons, that orbited the great world much as our own Moon orbits the Earth. Today, they are known as Io, Europa, Ganymede, and Callisto — the Galilean moons.

When I think about these momentous discoveries, my mind always wanders to the following, often overlooked fact: even though Copernicus’ De revolutionibus orbium coelestium had been published more than 60 years before Galileo’s observations, and placed the Earth in orbit around the Sun, Galileo’s observations were the first to reveal the planets were indeed other worlds. To put an even finer point on it, Galileo’s observations were the first to definitively show that the Earth was a planet, possibly not unlike the other planets that orbit the Sun. Galileo’s telescope allowed us to discover the planet Earth.

Galileo's telescopic observations of the Pleiades revealed stars that could not be seen with the naked eye. There was an unseen -- an unknown -- part of the Cosmos to discover.

Galileo’s observations of the Pleiades revealed stars that could not be seen with the naked eye. There was an unseen — an unknown — part of the Cosmos to discover.

Galileo also peered at stars. He found that when he looked at the Pleiades, the Seven Sisters, the telescope revealed stars that could not be seen with the unaided eye. When he peered at the diaphanous glow of the Milky Way, arching horizon to horizon in the dark skies of 17th Century Italy, he found it was comprised of uncountable numbers of individual stars, so far away and so dim that without the telescope their combined light looked no more than an evanescent fog in the dark.  The scale of the Universe was suddenly much larger. The structure of the Universe was suddenly more complex. Larger and more complex than humans had ever imagined. The revelation of the Cosmos had begun.

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This post is the second 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

The idea of describing science in the context of 20 Questions is one I was introduced to at a very young age, by Carl Sagan in “Cosmos: A Personal Voyage” (in Episode 11: Persistence of Memory).

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.

(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].

(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.

waveRockHydenScience 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.]

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.]

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.]

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.]

(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

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.

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.

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 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

The Far Side of the Sky

by Shane L. Larson

I grew up in the Rocky Mountains and the American West, from Colorado to Oregon to Montana. Since the earliest days of my youth, I’ve been an explorer of sorts. When I was growing up, my parents had carefully delineated boundaries for our adventures that kept us close to home. I don’t think they needed to worry much, because fronting the northern edge of our domain, there was a creekland paradise of bushes, fallen logs, and crumbling cliffsides that sloped down to shoals, rushing rapids, and gentle fords where we could wander back and forth across the water course. This was the frontier — full of adventure, mystery, and discovery.

A map from memory of the creek adventureland near the house where I grew up.

A map from memory of the creek adventureland near the house where I grew up.

Nowadays, my explorations are less filled with the wanderings of boyhood, and more focused on the world around me. I’ve walked through the deep pine forests of the Rockies, reveled in the roaring spray of mountain waterfalls, peered over the precipice of vast canyons carved from the stone of the Earth, and stood in darkened mountain meadows soaking up starlight billions of years old. All of these experiences sit well with me, but this last one truly moves me.

All my life, I have always carried one over-riding dream with me — I want to see the far side of the sky. I would love to climb into a ship, “accustomed to the breezes of heaven” (as Kepler once wrote), and set sail across the great dark between the planets and off into the vast deepness of the galaxy. To travel beyond the confines of the Earth is the ultimate dream.

I’ve often wondered where this dream came from. How did I become so enamoured with exploring the vastness of the Cosmos? I asked my Mom about this once, and she responded, “You’ve kind of always known about this stuff, ever since you were a little feller.” But I know it is all her fault, because if I ask a slightly different question, like “When did I start watching Star Trek?” she replies, “Oh, I started you on that when you were about three.” 🙂

But in all seriousness, I think my parents are largely responsible for me being an explorer. They were my first science teachers. My dad is a plant ecologist. He was born and raised in the ranch country of Colorado, he was a fist generation college student, and received his PhD from the Colorado State University. My mom is a forester. She was one of the first women in the country to enter forestry school at Stephen F. Austin University in Texas. One of the earliest stories I remember my parents telling is a story about science. After my mom and dad were married, they went on their honeymoon to Canada, driving my dad’s pickup truck (a brown Ford F150 that we had through my high school days; we called her “Bertha”) and camping along the way. The way my mom tells the story is they were driving down a lonely stretch of highway in northern Montana, and she was sitting there thinking to herself “Damn he drives slow; what’s he think he’s doing? It’s the long skinny one on the right, Larry!” She was getting ready to say something, when my dad turns to her and says, “See that duck over there? He’s flying at 45 miles per hour!”

A male Mallard Duck.

A male Mallard Duck.

That is an awesome story! It is very typical of what I expect from both of my parents growing up. They were always cognizant of the world around them, and masters of not just figuring things out, but of noting and measuring the world around them for the sheer joy of it. There was no grand reason why my dad had to know that mallard duck was flying at 45 miles per hour, other than his own pure, curiosity about the matter. They always encouraged this kind of curiosity among me and my brothers when we were growing up.

Somewhere around the 4th grade, I distinctly remember sitting outside at our picnic table, staring at the Moon with my mom’s Bushnell spotting scope she used for bird watching. It was, as far as I can remember, the first time I had ever looked through a telescope of any sort. I don’t know how or why I came to be out on that patio with that spotting scope; perhaps my mom suggested it, or maybe I got the idea from a picture of Galileo in my favorite book, National Geographic’s “Our Universe” by Roy Gallant.

[L] "Our Universe" by Roy Gallant (still one of my favorite books!)  [R] Galileo observing the Moon, from Gallant's book.

[L] “Our Universe” by Roy Gallant (still one of my favorite books!) [R] Galileo observing the Moon, from Gallant’s book.

Somehow, I ended up on the patio with my mom’s spotting scope, staring at the Moon. I was transfixed. I had seen pictures of the Moon, but I had never seen it up close, and personal. I wasn’t looking at some picture some astronaut had taken. I was seeing the Moon with my own eyes; light from every crater and mountaintop that night was funneled into my eye and burned into my brain.

My Mom's spotting scope.  This is the first telescope I ever looked at the sky with.

My Mom’s spotting scope. This is the first telescope I ever looked at the sky with.

What is so alluring about the sky? Galileo was not the first person to be fascinated with the sky, but he was the first person to see it up close. His first telescopes were poor ancestors of my mom’s spotting scope, but they let him see further than any human had ever seen. He too turned his telescope to the Moon, and on a summer’s night in 1609 beheld what I would see almost 400 years later. Not a smooth vista of alternating bright and dark shades, what you can see with your naked eye, but rather a wonderland of illuminated plains and soaring mountains dotted with a mind-boggling array of craters of various sizes, overlapping everything else. What he saw astonished him; the telescope challenged the conventional wisdom of the day, and presented Galileo with new mysteries and new ideas that had never occurred to him (or anyone else in the human race!). He found that Venus went through phases, just like the Moon. He discovered four brilliant points of light orbiting Jupiter — the Jovian Moons, Io, Europa, Ganymede and Callisto; they were the first worlds to be discovered in the collective memory of our species. He discovered that Saturn had a ring, though his telescopic view was poor enough he did not understand it as such; “Saturn has ears,” he wrote. When he turned his telescope to the darkened sky, he found that it revealed stars that could not be seen with the naked eye, and that the Milky Way was not a diffuse band of light, but was comprised of an uncounted multitude of stars, each casting a little bit of light toward the Earth.  Galileo published his astonishing discoveries in the spring of 1610, in a book called Sidereus Nuncius (“The Starry Messenger”; you can view a digital copy of the book here).

Those views were the beginning of a journey, for Galileo and for millions of others who came after him, gazing skyward through telescopes and dreaming about what lay beyond the cerulean boundary of the sky. Astronomy with your eyeballs is awe-inspiring, astonishing, mind-boggling, and soul nourishing all at once. But for some of us, myself included, there is still a dimly lit corner of my heart that longs to go to the places I can see — to touch the sands of Mars, bound down mountainsides on the Moon, and gaze skyward to see our home the Earth suspended against the velvet of night. I would dearly love to touch the Cosmos, up close and personal. As it turns out, I can, at least in small part.

In the Sky Pavilion of the Adler Planetarium, they have a vast display about our homeworlds — giant planets hanging overhead, large displays with all the wondrous facts our telescopes and robotic emissaries have revealed, a full size model of the Curiosity rover (about the size of a Mini Cooper!). It’s an awesome place to lose yourself.

The Solar System Gallery, in the Sky Pavilion of the Adler Planetarium.

The Solar System Gallery, in the Sky Pavilion of the Adler Planetarium.

Off to one side, they have a large, metallic meteorite — a 1000 pound chunk of nickel and iron, a fragment of the 150 foot wide meteorite that impacted in Arizona 50,000 years ago and created the Barringer Meteor Crater. Now I’ve seen plenty of meteors in my museum wanderings, but I still like to touch them, to feel them under the palm of my hands and knowing that this thing came from outer space! But the other day, while I was caressing the fragment from the Barringer meteor, I noticed a trio of other displays that hadn’t captured my attention before.

A fragment of the nickel-iron meteorite that struck in Arizona, creating the Barringer Meteor Crater.

A fragment of the nickel-iron meteorite that struck in Arizona, creating the Barringer Meteor Crater.

The first held two fragments of asteroids. Fragments I could touch. One came from Vesta, the third largest asteroid in the asteroid belt. The other came from Ceres, the first minor body discovered in the solar system between the orbit of Mars and Jupiter. Once considered an “asteroid”, astronomers now call Ceres a “dwarf planet”, in the same league as our much maligned favorite child of the Sun, Pluto. There has been much talk recently of a human mission to an asteroid, and many have dreamed of mining the asteroids for the untapped riches they may hold (see John Lewis’ excellent book, “Mining the Sky”). It seems unlikely that I will be selected for one of those missions, if they ever occur. But there I stood, in downtown Chicago, touching an asteroid none the less.

Four pieces of rock from the far side of the sky, which you can touch at the Adler Planetarium. [Upper L] A piece of Vesta. [Upper R] A piece of Ceres.  [Lower L] A piece of the Moon. [Lower R] A piece of Mars.

Four pieces of rock from the far side of the sky, which you can touch at the Adler Planetarium. [Upper L] A piece of Vesta. [Upper R] A piece of Ceres. [Lower L] A piece of the Moon. [Lower R] A piece of Mars.

A bit farther on, there is a fragment from the Moon. A fragment I could touch. Humans have not been to the Moon for 41 years; only 382 kg of lunar material was brought back from the Moon. But there I stood, in downtown Chicago, touching a rock from the surface of the Moon.

A little farther on from that, there is a fragment from Mars. A fragment I could touch. Humans have never visited Mars, though as you are reading this, our emissaries Opportunity and Curiosity are roving the surface of Mars, sampling the air and testing the rocks, rolling ever onward toward their distant horizons. Our robots have carried sophisticated laboratories with them, and have taught us much about the rusty rocks and soil of Mars by doing experiments in situ, on Mars. But there I stood, in downtown Chicago, touching a rock from the surface of Mars.

Four fragments of rock from the far side of the sky, from the four closest worlds to Earth that I could imagine humans visiting in my lifetime. Four close worlds that I could reasonably (though perhaps improbably) be able to visit before I drink my last Slurpee at the ripe old age of 107. Touching rocks from the far side of the sky really speaks to the explorer buried deep inside me.

One of my friends from graduate school once used as his signature file the words of an ancient Hawaiian chant:

E `a`a `ia makou e ho`okele hou. `A`ohe halawai ma`o oa aku.
(We are challenged to sail once again. No horizon is too distant.)

The vast blue frontier of the Pacific Ocean.

The vast blue frontier of the Pacific Ocean.

Hearing the chant roll through the back corners of my mind, I imagine the unbridled joy of the ancient Polynesians, setting out into the trackless blue waters of the Pacific, not knowing where they may make landfall, but only knowing that if they pressed on far enough, they would.

Were there new lands to discover and settle? Perhaps. Would there be fertile landscapes to provide sustenance and security to a family or a village? Perhaps. Would there be other denizens of the Earth, willing to trade the products of their livelihood for the products of yours in a mutually beneficial economy? Perhaps. But I don’t like to think that’s why they sailed the seas.

The far side of the sky, like the wide blue ocean, promises something much more than distant, undiscovered lands — something valuable beyond measure. Grandeur. There is something to be said for the discovery and exploration of beautiful places. It’s good for the spirit.

Time to go exploring again. 🙂

NOTE: I confess to quoting the line about grandeur from the HBO miniseries, “From the Earth to the Moon”, Episode 10: “Galileo Was Right.” It is my most favorite episode of that entire series. Go watch it now.

An Evanescent Memory of Exploration

by Shane L. Larson

On February 27, 2011, Frank Woodruff Buckles passed away at the age of 110.  Frank was the last surviving American veteran of World War I. The United States was in the war for 19 months.  In that time 116,000 Americans were killed, and more than 204,000 wounded.  In totality, more than 16.5 million people were killed during the four years of the war.  At the time, it was called “The Great War” because until World War II, no one could imagine a more terrible conflict or a more terrible cost in human lives.  With Frank’s passing, the United States’ involvement in the devastating conflict passes from direct experience into memory.  No longer will the Great War be relayed through the eyes of one who saw it; instead, it will be relegated to the history books, and spoken of from the dry voice of history like the War of 1812 and the Spanish American War.

In 1901, the year of Frank’s birth, a young 19 year old named Robert Goddard had started indulging his passion for aerodynamics, a passion that would ultimately lead him into the field of rocketry.  In 1914, the first year of The Great War, Goddard was awarded two of the first patents in rocketry, cementing ideas that would lead to the space age and the human exploration of space.  As a young man, Goddard had been enchanted with the idea that humans might make a journey to space and visit other worlds using rockets. Goddard passed away in 1945 (3 weeks before the end of World War II), before the first rockets ever plied the vacuum of space. But ultimately his dream was realized, and between December of 1968 and December of 1972, nine voyages were made from the Earth to the Moon.  In all, 24 American astronauts made the journey across the gulf of space, and 12 walked on the surface of the Moon as part of Project Apollo.

Today, Project Apollo is 40 years gone, and of those 24 astronauts, 6 have died.  Of all the rest, none is younger than 74.  The only humans ever to leave the Earth and walk the shores of another world are slowly passing away, and soon, the memory of of the voyage to the Moon will also pass into history.  Project Apollo was arguably the greatest technological achievement in human history, an exploratory endeavour to carry humans beyond the confines of Earth that was many decades ahead of its time.  But here we stand today, 40 years hence, with no permanent human presence beyond our small blue marble, and no ambitions to go.  In June of this year, the space shuttle Atlantis will make her final flight, and America’s manned spaceflight technology program will come to an end.

As a society, we have let the wonder of those few evanescent moments of exploration slip away from us.  We have forgotten the grandeur of the Moon’s desolation, and let go of the memory that the exploration of beautiful places is good for the spirit.  Instead, we worry about the costs of projects like Apollo, and have whittled away our investment in exploration into almost nothing.  This deinvestment in exploration has been done with much political posturing and grandiose swaggering in the name of fiscal responsibility, but with a complete and callous disregard for what these programs cost and return to our country.

Project Apollo is often historically depicted as a political action, a demonstration of technological supremacy driven by the Cold War with the Soviet Union that had risen out of the ashes of World War II.  All told, the program employed 400,000 people and the United States invested $25.4 billion in the endeavour, approximately $65 for every man, woman and child currently living in the United States today.  For each of us, the cost of Project Apollo was only 16 cups of Starbuck’s coffee, less than a third the cost of an iPod, less than a monthly satellite TV bill, and only about 1/10th the average yearly cell phone bill of a typical US citizen.  These are easy cost comparisons to make, and probably a bit misleading because let’s face it: most three year olds don’t have cell phone plans, though quite a few watch quite a bit of satellite TV.  The truly misleading part of these cost comparisons is that they only represent the money saved out of pocket, and do not consider the economic returns of the program — when the fiscal axe is dropped on programs like Apollo, the economic returns are usually totally ignored.

Consider the Apollo Lunar Module.  Before Apollo, nothing as complicated as the Lunar Module had ever been constructed, nor had any machine ever been built with such stringent design requirements.  NASA and their industry partners spawned a new technology known as CNC (“computer numerical control”) machining to make the parts for the moonships.  Today, CNC machines are standard pieces in every precision machine shop in America.  Conservative estimates suggest that there are about 75,000 machining firms in the United States, employing more than 200,000 machinists and generating gross revenues in excess of $37 billion per year.  In less than one year, the American economy uses Apollo derived technology to generate enough money to pay for the entire decade long investment in Apollo.

In order to keep the spacecraft warm on the voyage from the Earth to the Moon, NASA had to develop a metal-bonded polyurethane foam insulation.  After the end of Apollo, this same foam was used to insulate the Alaskan Pipeline, keeping the oil temperature high enough that it remains fluid on the long journey from Prudhoe to Valdez.  This has allowed the production and delivery of 16 billion barrels of oil since 1977, with a gross revenue of $710 billion.  In the almost forty years since the end of Apollo, this single piece of technology has returned to the US economy more than 25 times the entire decade long cost of the Apollo program.

These are only two examples out of many technologies that have quietly infiltrated everyday life since the last walkers left the Moon.  The technology derivatives from the space shuttle program are just as numerous and have borne just as much economic benefit.  The ultimate return from America’s space program is probably incalculable, both in terms of dollars and in terms of the less tangible threads of common memory.  It has yet to be understood what the absence of an American manned spaceflight program will do to our future.  Forty thousand generations of our ancestors have led us to this place in history.  We have demonstrated the ability to transcend the limitations of the tools Nature gave us to climb trees and walk the savannah and instead journey beyond the confines of Earth using the foresight and computational power of our brains.  But that same mental tool is squandering all of our long and proud heritage, forgoing the memory of all that could be attained in favor of short term political gains without regard to the wider consequences of those actions.

On the voyage home from the Moon in April of 1972, mission commander John Young remarked, “We have seen more in 10 days that most people would see in 10 lifetimes.”  In the past 10 days, how much of your life has flashed before your eyes?  How deeply has your memory of what you did yesterday changed the world?  As the Apollo astronauts slowly succumb to time’s inevitable march, what becomes of those memories of walking on the Moon?  When the last Apollo astronaut dies, no longer will the voyage from the Earth to the Moon be relayed through the eyes of those who saw it.  Instead, we leave to our children images of the fantastic voyage from the pages of a history book, hoping fervently that their imaginations and creativity will be inspired by the memory of 12 pairs of boots that once walked the surface of another world.