Tag Archives: Asteroids

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.

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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.

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.

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.

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!

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.

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