Cometary Tales Astronomy & Astrophysics Drake & Josh at the Kepler Conference

Drake & Josh at the Kepler Conference

No, this entry has absolutely nothing to do with the old Nickelodeon TV show.  It’s just that while doing my edits on the very few photos I took last night, I found that half of them were titled Drake & Josh 1, Drake & Josh 2a, and Drake & Josh 2b.

No, wait.  Back up.

(Note:  if “Kepler” means nothing to you, go peek at this first:  NASA’s Kepler page.)

Last night was a public session during this week’s Kepler Science Conference at NASA-Ames Research Center.  Frank Drake—does anybody even faintly interested in extraterrestrial intelligence NOT remember the Drake equation?—was the speaker for a ‘sold-out’ evening at the Conference Center.

Drake with a glimpse of Lynette Cook's Art

Frank Drake          (with a glimpse of Lynette Cook’s Galactic Internet)

With the tiniest bit of encouragement, my husband “Clark” had scored a pair of the free tickets offered to the public by the Ames Events Program.  We even managed to arrive early enough to worm our way into decent seats just behind the “reserved for press” row.  Just between you and me, acquiring those seats involved summoning the chutzpah to ask a woman who was clearly saving a seat for her husband if she could shift left or right one seat to make room, either by claiming the aisle seat for her husband or dibsing the middle seats.  She chose the aisle-seat access.  As she moved over, so did the young man next to her, leaving us with one more free seat which was swiftly nabbed by someone in the next wave of arrivals.

So it all works out well.  One more person got a nearly-front seat (without having to ask for favors), we started the evening filled with gratitude, and the college student got to sit with David Morrison—NASA astrobiologist and SETI Institute leader—and his wife.  (Yes, that’s who the tardy husband was.  “Why didn’t you tell me?” I said to Clark.  “Well,” he lamely explained.  “I don’t see him with his wife at the cafeteria.” )  The student had taken Caltrain all the way from San Francisco and then hiked from the train station to Ames.  He was excited to be surrounded by so many astronomers, but instead of being daunted by that, he’d decided to get as many autographs as he could on his printout about the event.  Most people he asked for autographs from also gave him business cards and some asked for his name in return.    His name is Joshua Caltana.

So now you see where that strand is headed.

Meanwhile, there were a fair number of cell-phone photos being requested in the front-row group.  Frank with one Kepler astronomer.  Frank with another.  A photo of someone taking a photo of Frank with someone.  Was it noted that one of the people sitting in the front row a few feet away was Dr. Drake?   Oh, to be an official Press Person.  They really needed a proper camera with a bounce flash in that light.

A free public talk in the heart of Nerd Country is a strong draw, and traffic was backed up at the gate, we heard.  So there was a delaying action.  Kepler staff launched a putatively impromptu quiz game, awarding Kepler memorabilia to audience members who had the correct answers to crucial astro-trivia.  Alas, I was way too slow to raise my hand on the few I knew, Clark was not interested in playing the game, and Joshua’s answer to one question was just close, not correct.  So our Local Group did not win any of the tchotchkes.  Oh, well.  We didn’t come for prizes.  We came to hear “Frank”.

But finally, they tuned up the computer with Drake’s slides and let him speak.  He had a bit of a scratchy throat to cope with, and the Mac was balky about launching the animations on his slides, but he soldiered on with all those rapt faces in attendance.

So yes, I’m going to make you endure a summary of a great talk before looping back to Drake & Josh.  Or you can be lazy and scroll to the end.  Bear with me.  There will be cool links.

Drake does autographs

Drake does autographs (later, later)

So, the talk was entitled “Kepler and Its Impact on the Search for Extraterrestrial Intelligence.”  But Drake put it a little more strongly.  Kepler, he said, is one of the “most important events in the history of science.”   Not only has the Kepler team’s search for habitable planets spotted thousands of planets orbiting stars in the small portion of sky selected for study, their data are useful for sorting through those finds for planets which might fall in the habitable zone.  The sheer impact of numbers is amplified when we realize that Kepler isn’t looking everywhere and that the Kepler results strongly suggest that there are many many more planets out there that the current tools can’t locate just yet.

For one thing, Kepler’s detection technique relies on occultation—spotting a planet passing in front of its star.  Only planets fairly close to a star are likely to be sighted this way, because the farther out a planet’s orbit lies, the more likely that a slight tilt of its orbit relative to our plane of view would make the planet pass ‘above’ or ‘below’ the star—making it invisible to us.  For example, even just at Earth’s orbital distance, 99% of such planets would be missed.

But for now, the numbers are big enough to give us plenty of data to study and inspire us.  Drake’s presentation included a snippet of the Kepler Orrery in which all the planets discovered as of early 2011 dance their way through Kepler’s mission period.  If you’re not too hypnotized by that, you can try Fabryky’s 2012 updated edition.

Kepler results include information about the planets’ orbital distances, and the stars’ characteristics are well-known, so the likelihood of there being planets in their respective habitable zones is becoming accessible.  For instance, with a cooler star, the habitable zone is close.  But what affects the habitable zone other than the star and the orbital distance?  From studying our own solar system, even just our own planet, we know that the characteristics of the planet affect habitability.

The Habitable Zone:  Colorado University

So, then Drake moved into Phase II of his talk, which he later revealed should have its own title

Everything I Ever Needed to Know

I Learned in

Kindergarten   

The Solar System

Aiming for that laugh, he led us on a tour of our own locale.  On Planet Earth, habitability changes markedly if we go up in altitude or down into the ocean.  So the topography and water on a planet affect its habitability.  In the deep atmospheres of the outer planets, it’s been proven that there are altitudes at which temperatures—even so distant from the sun—are about what they are on the Earth’s surface.  He shared an image by Lynette Cook illustrating Carl Sagan’s notion of “floaters” evolving and living in the clouds of Jupiter.   Comb jellies accustomed to the arctic seas of Earth—or alien life evolved to a similar design—would be well-suited to the deep, dark ocean beneath Europa’s insulating icy crust.  Our focus on the traditional Habitable Zone defined by certain distances from each star, based on stellar conditions, means that these alternate conditions for life finally need to get some attention so that the Habitable Zone can be redefined to include these non-Earthly, yet potentially life-supporting situations.   He foresees the narrow band illustrated above being widened to include most of the outer planets…and even those wandering ‘rogue’ planets warmed by nuclear decay.

Next, Drake turned to the conundrum of M-type stars and their planets.  He’s now convinced—thanks to Kepler—that there are likely to be planets around most of these stars as well—and those cool M-types (more familiarly known as Red Dwarfs) are far and away the most common stars.  There are more of them than of all the other star types combined.  Until recently, most astronomers were convinced that a planet anywhere in the narrow old-style Habitable Zone of an M-Type would be so close that it would be tidally locked—with one face permanently facing sunward, dooming the planet to be boiling on one side and frozen on the other.   But those convictions are faltering in the face of new understandings about how orbital eccentricities—such as that of our own planet Mercury—can prevent tidal locking and instead force a planet into a resonance pattern.   (Is this breaking news—did you still think Mercury keeps one face to the sun?  Take a break with Universe Today’s article on resonance.)

Even for a planet that ‘succeeds’ in achieving a tidal lock, atmospheric scientists have decided (provided the planet does have an atmosphere), that mixing by the currents of gas moving over the surface, driven by the heat of a star, would more or less normalize the planet’s temperature, establishing stable conditions in a range of habitation zones.  Drake mused that residents of such a predictable planet would consider it nothing more than “wretched circumstances” to endure life on a rock which rotates constantly and varies its temperature patterns hourly, daily, and seasonally.

Drake never directly brought his famous equation into his talk.  But one critical factor is the length of time that a civilization might be communicating—the likelihood of our finding one another falls if our conversational eras fail to overlap sufficiently.   However, he reported “good news for people who afraid that we have been advertising our presence” and are worried about aliens being “about to invade.”  Our own passive “communication” to the Universe has been dropping off precipitously as our use of technology and energy has shifted.   We used to beam many megawatts of television broadcasts into space.  No more—we’re going with digital, satellite, cable TV now, meaning thousands of times less energy expended accidentally broadcasting to the stellar neighborhood.  Soon, the only signature of our technological civilization to a far-off society could be the lights of our night-lit cities—something we aren’t yet capable of looking for ourselves.  A very patient observer might notice our atmosphere heating up over time and deduce that we have been subjecting our planet to global warming.

Drake enjoys a chat about astronomy

Drake enjoys a chat about SETI

Drake said he is beginning to feel that it may be our moral obligation to start an intentional broadcast, to try to share what we have learned with unknown aliens in the far-off planetary systems.  His reading leads him to believe that altruism is a part of our evolutionary heritage and to hope that evolution elsewhere has instilled enough of that same drive to cooperate so that eventually we may be able to do the one thing that we can do over interstellar distances—talk.

What about the Fermi paradox?  Where are those others?  One audience member was convinced that visitors have been here already, but Drake sadly told him he’d checked out those same stories when he was younger, too, and was disappointed to find they were all dead ends, that the fantastic accomplishments of early civilizations on Earth didn’t rely on helpful aliens but on ordinary humans performing great feats.  Interstellar travel is too expensive, in energy terms, he thinks.  When pressed, Drake’s line is that the reason we haven’t seen alien interstellar travellers is that “the only ones who would try are the dumb ones—and they don’t know how.”

So after the Q&A, there was a little bit of meet-and-greet.  Yes, I got to shake Drake’s hand and tell him I enjoyed the talk and always like it when I hear something new.  He said, “well, I try.”  Our new acquaintance, Joshua, roamed the crowd collecting a few new autographs and working up to saying hello to Drake.  By that time, he was one of the last well-wishers.  Drake was surely pining for dinner (his companions were already talking about food), but he listened to this young student, gave his autograph, and then instead of grabbing his bag and dashing away, he stood up and chatted with him for a few minutes.  Ergo:  Drake & Josh 1, 2a, and 2b:

Drake & Josh 1

Drake & Josh 1

Drake & Josh 2a

Drake & Josh 2a

Drake&Josh 2b

Drake&Josh 2b

 

 

 

 

 

 

 

Coda:  Clark was starved, I was hungry.  So we went in search of dinner.   We randomly selected an open restaurant, placed our orders.  And then Frank Drake and his entourage arrived.  (Well, is 2 people an entourage?  Let’s just say yes.)  So I conclude my report with a mention that Frank Drake finished his long day of Keplering with an omelet plate at Crepevine.  I hope he survived—the portions there are well on the way to having detectable gravitational effects.

 

 

 

 

You might also like to read:

Walking to Pluto: Step 1Walking to Pluto: Step 1

 

Compare the sizes of Earth and Pluto & Charon Image Credit: NASA

Compare the sizes of Earth and Pluto & Charon (Pluto’s shadow isn’t that big on Earth!) Image Credit: NASA

It’s been a super-fantastic #PlutoFlyby day (see the video for a Pixel Gravity simulation of New Horizons’ close approach path on 7/15/2015), and I can’t resist going to one of my favorite astronomy projects:  building a scale model of the Solar System that takes you out of the house, out of the classroom, and under the sky.  (Where maybe Pluto’s shadow, cast by a distant star, will pass over you.)

As a reminder, you can look for the following in any Messy Monday project:

  1. A set of notes for project leaders, sketching the key elements of the project and the science topic it is meant to address
  2. A detailed supply list, structured to make it simple to purchase supplies for either a one-shot demonstration or for a classroom-sized group activity.
  3. A set of instructions for working through the project with students, including commentary to help cope with common classroom-management issues, questions that are likely to arise, and issues to keep in mind from safety to fairness.
  4. A rough estimate of the cost to run the project.

 

As before, I’ll break down the presentation into four postings, to spare readers trying to scroll through a 5000-word document, but I’ll post them quickly, so you can jump ahead if you are raring to go or want to access the reference materials first.  In other projects, we built our own comets. In this project, we travel out into the solar system, hoping to reach the source of that comet.

 

Step 1: Space is Big

It’s a long way to Pluto. But as far as the Universe is concerned, Pluto’s in our condo’s tiny back yard. What would it be like, though, to take a hike to Pluto? Like the New Horizons Spacecraft spacecraft buzzing past Pluto and its cluster of moons, but, well, maybe taking a bit less time about it. Nine years (the explorer was launched in early 2006) is longer than even the above-average student’s attention span. What if we could shrink the Solar System down to a reasonable size for nice walking field trip?

Paths of the nine planetary objects orbiting the Sun for many years.

Paths of the nine planetary objects orbiting the Sun for many years (A Pixel Gravity simulation result.)

No surprise here: it’s been done. Six ways to Sunday, in fact. While no one person claims to own the idea of building a scale model of the solar system, my favorite advocate of such models is Guy Ottewell, who likes a scaling factor that makes the model a reasonable size for the average person to walk. You can buy his book on the subject (now with cartons!) at the books page on his website. As a bonus, you’ll also find the most current editions of all of his other books on astronomy and much more.   (He self-effacingly describes his annual Astronomical Calendar as “widely used”; a more-accurate description would be “fanatically used by serious amateur astronomers”.)  No disclaimer necessary;  we’re not friends, I’m just one of his (many) Twitter followers.

The goal of this project is for everyone involved to obtain a personal sense of the feature of Outer Space that is hardest to conceptualize by reading books and trolling the internet: Space is BIG. (Yes, you may pause to reread the opening to The Hitchhiker’s Guide to the Galaxy, by Douglas Adams.)  Indeed. Really Really Big.

Our neighbor galaxy, Andromeda (Image Credit:  ESA/Hubble)

Our neighbor galaxy, Andromeda (Image Credit: ESA/Hubble)

On top of that, the places you can stop—the non-empty bits—are few and very tiny compared with the distances between them.  And it takes a long time to get from one stop to another.

So, when assembling materials and presenting this project, keep these two key goals in mind. It’s not important whether you model Earth as a peppercorn (Ottewell’s model) or an allspice seed (easier to find in my own kitchen) or a spitwad from the ceiling that happens to be about a tenth of an inch across.   What’s important is that the Earth is not only extremely teensy compared to the Sun, but you can’t even fit the Sun and Earth into an ordinary classroom. And you have to hike at least a half a mile (a kilometer) if you want to make it to Pluto. With any luck, you can make practical use of the excess energy in a classroom-full of kids and also amaze them. If you’re doing this as a classroom helper and the teacher is used to taking advantage of the time to catch up on infinite paperwork, this is a time to persuade that teacher to shove the paperwork aside and join the expedition. There will be no regrets!

The objects used to represent planets and other bodies should be chosen for familiarity, because you want the participants to absorb the scale comparisons effortlessly. “Everyone knows” how big a jellybean is, a pin is familiar—both the pushing end and the painful poking end—a soccer ball is a known object, and so on. It doesn’t matter if the object you use is not exactly the design diameter—and no one is going to care that jellybeans or coffee beans are bumpy ovoids, not spheres. The next time you’re eating a jellybean (or slurping a Starbucks), at the back of your mind will be “I had to hike a half-mile just to get to this little Neptune here”.   Plus, “Yum, astronomy is delicious.”

If you’re interested in the underlying concepts, I encourage you to stop by the National Optical Astronomy Observatory’s website and read Guy Ottewell’s original 1989 description of his Thousand Yard Model; however, if you consider yourself a mathphobe, don’t let the arithmetical computations worry you. I’ve made you an Excel worksheet to do that task. Running a mind-expanding science project should help relieve that condition, not make it worse.

If you have visited a museum’s scale model, read Ottewell’s book, or done a similar project in the past, there are a few differences you may encounter in this project. In particular, I suggest you avoid having planets represented by peanuts. Including nuts in school projects, can be problematical if any student (or parent helper) with nut hyper-allergy could possibly be affected. (I have relatives with this allergy, and there is nothing quite like coping with anaphylactic shock to ruin a day’s outing.)

Dwarf Planet Ceres Image Credit:  NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dwarf Planet Ceres Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

I’ve included a few more “destinations”—such as the ever-popular asteroid “belt” and my personal favorite of Pluto’s fellow dwarf planets. The number of steps taken between planets (and other destinations) is greater, because kids take shorter steps than grown-ups. (Also, other models I’ve seen assume a stride length more typical of men—and the majority of teachers and parent volunteers are still women, with shorter strides than men.) And I’ve included the current (for now, at least) locations for a few more distant “destinations” that we can look out towards from our turnaround point at Pluto.

The tables I’ve provided are in both English and SI units. The scales are slightly different between the two, in order to yield intuitively-scaled results in either set of units. And I’ve provided a “cheat sheet” of the key data for a teacher or other presenter to carry as a reference source on the walk. If anyone would like to get completely precise and build their own model matching their pace length exactly, or adjusting to a different scale, you can request a copy of my Excel workbook for this project to create your individualized pace-off. Or if you know a Senior Girl Scout or Boy Scout in need of a Gold Star or Eagle project, a community solar system model would be a very cool service project. (C’mon, Scouts, do you really want to build another park bench?)

Speaking of space, and coolness, and peanuts, and bigness, by the time your group finishes this project—everyone who participates should wholeheartedly agree:  Space is Big

A Sign From NASA

A Sign From NASA

 

 

 

Gravity & EnergyGravity & Energy

This category of the blog is dedicated to science & technology topics that I think may interest my fellow nerds.

(Note: Original post: 2012. A few updates were made during site reorganization in January, 2021.)

Tracking Movement In the Solar System

For starters, I’ll be posting in the blog regularly under Astronomy & Astrophysics. (In some of these older posts the category is tagged Pixel Gravity.)  To jump straight to those posts, visit the PG Archive–readily accessible in the menu.  For some time now, I’ve been running the social-media support for the program that made the picture you see here.  I’ve been posting about robots, space exploration, astronomy, big steps in physics, and so on.  Sometimes, the space available for a posting on Facebook is too restrictive.   So those kinds of discussions will move here.

What qualifies me to write about this stuff?  Well, I’ve admitted elsewhere that we are a family of hypernerds.  That’s not my term.  It was invented and applied by one of our charming (adult) offspring.  It’s not a misnomer As a family, we are 40% engineers and 60% scientists.

I’m a power systems engineer, which in my case means I’ve made a career out of simulating how power plants and electric and gas networks operate.

My husband is a computational physicist, specializing in solar physics.  Want to know what’s going on inside the sun?  He’s your guy.

Our youngest son is too busy for now, building catapults and robots on his way to a mechanical-engineering degree at UC Santa Barbara. (Update: graduated, with honors. Currently open to job offers.)

After two summer internships in NASA’s astrobiology group, our middle son is working on an honors thesis project on metabolic processes of microbes in deep serpentine wells, attracted by the prospect of doing biology fieldwork in extreme ecosystems right here on planet Earth. (Update: he’s now nearly done with his Ph.D.)

And the oldest escaped from UC Berkeley’s astrophysics program with a degree and a desire to never return to academia.  He built Pixel Gravity instead.

What’s “Pixel Gravity“?  It’s a detailed, graphical astrophysics simulator with real-time controls.  It looks sort of like a game, and it’s fun to play with, but it’s also a serious science tool  As an “n‑body” simulator, it lets users model complex groups of many objects, from the solar system to galaxies.  Most of the other easy-to-use programs available online limit the number of objects or lack physical accuracy, so (for example) relativistic effects on motion near a black hole are not handled properly, if at all.  University researchers have access to extremely-detailed models, but those require supercomputers.  Pixel Gravity provides accurate modeling on personal computers and is priced low so that even students can explore gravity in action.  In addition to Newtonian gravity, Pixel Gravity models the additional effects of atmospheric drag, general relativity, and dark-matter, as well as user-defined forces.  Plus, the software package includes helpful tools for curriculum development such as a tutorial-builder and video-production capability. (Update: Pixel Gravity is at present a retired product–contact us if you’d like a copy to play with.)

So, in short, the topics under this heading are just the kind of things we talk about at our house.  So if you come to dinner, you don’t need to bring a foodie specialty.  But you might scan the latest issue of Scientific American.

Walking to Pluto: Step 3Walking to Pluto: Step 3

Step 3: Making the Journey

If you skipped Part 1, then you need to know know that in this activity, you will build a scale model of the Solar System as far as Pluto. You will use familiar objects and easy, approximate measurements—mostly simply pacing off distances. This is not a project about being extremely precise; the goal is to develop a strong perception of just how big the solar system is and how small the planets are within that system.

For preparation, you need only to assemble the collection of properly-sized objects listed in the requirements table (See Step 2) and print out the “cheat sheet” you’ll carry on the Walk. A glance at a map of your local area will help you decide which way to take your expedition and to identify some landmarks to stand in for more-distant things like the far edge of the Oort Cloud.  To build your own interest and enjoy some discoveries of your own, check out some of the links I’ll include in the references section (Step 4).

You can feel free to substitute alternate model planets, using the scaled sizes as a guide; however, most of the items called for can be found in an average family home, borrowed from classroom parents, or purchased at a very modest outlay. While modern kids may not find the contents of kitchen spice jars terribly fascinating, using an allspice or peppercorn seed as your “Earth” model will give them a lifelong reference point–they’ll be smelling pumpkin pie or watching a chef grind pepper and that spark of memory will remind them of this project.

Because the scaled planets range from the size of a pin point to the size of a jacks ball, it also makes sense to attach each object to something larger, such as an inverted cup or a 4 by 6 index card. If you have access to sports equipment, the bright-colored cones often used for laying out a temporary playing field are helpful. You can position the planet-holder and also tape a “Please Leave Our Experiment Here” sign to the top of the cone. And the bright colors and signs help the explorers to look back and spot the distant planets. Again, be creative! There is no need to run out and buy sports equipment—any handy rock or a brick will do to keep your objects and notes in place.

Here's my Walk kit, ready to go.

Here’s my Walk kit, ready to go.

When reviewing the Cheat Sheet, you’ll see that this model describes our solar system as far as the outer edge of the Oort Cloud. However, to go all the way to the Oort Cloud in this model is a journey of 75 miles (100 km), so don’t expect to travel that far. Instead, as part of your preparation, identify a few local landmarks 1 or 2 miles from your start point and also pick some regional and further-off destinations to match the scaled distances for such key locales as the Oort Cloud, the heliopause, the estimated positions of the Pioneer and Voyager spacecraft, the far edge of the Kuiper belt, and our further neighbors in the Universe. If you’re too short on time, the Cheat Sheet includes some general destinations, but your own localized ones will be much more meaningful to the group. If your group won’t have time to walk all the way to Pluto, find out where Pluto would be in that locale and point ahead to that location before you do turn back.

Once in the classroom, before launching your exploratory mission, start with a quick review of the concept of scale. Regardless of your target age group, toys which are also scale models of cars or airplanes or trains are helpful examples. Quickly walk through a sample of numerical proportions to give a sense of how it goes when you are creating your own scale model: for instance, sketch on the board or a sheet of poster paper a rough scale drawing of the classroom room at 1 inch per foot (5 cm per m). Rather than slowing down the project with extra work, prepare for this session by making your own rough measurements of the classroom dimensions in advance—simply pace off the length and width and note any additional features to the room. Remember, the idea is to illustrate your point, not to create an architectural drawing.

Moving on to the Solar System, start with the Sun…an 8-inch-diameter playground ball or an ordinary soccer ball fits our scale. Ask if anyone can guess what size the Earth should be to go with this “Sun”. The guesses are very likely to be way off, because most “models” used in classrooms and the pictures in the textbooks are not at all to scale. In those, Earth is shown as a recognizable ball appearing as much as a tenth the size of the Sun.

Once you have a few guesses on record, share the key data. Write on the board or a flip chart as you go, to keep the presentation lively. (Nothing kills attention like a PowerPoint!) The Sun’s diameter is about 800,000 miles (1400 thousand km), and we’re using an 8-inch (18 cm) ball, so each inch stands for 100,000 miles (or, a cm stands for 75,000 km). The Earth’s diameter is only 8,000 miles (12,700 km). So how big will the model Earth be? It turns out we need something less than 1/10th of an inch across, only 0.08 inches (0.17 cm). So now you can pass around your “Earth”…a peppercorn will work, so will an allspice seed. (And, yes, you can get away with crumbling up a bit of paper and claiming it’s a spitwad you found.) If you have a spice-jar worth of seeds, everyone can have their own Earth to keep. Let the students take a moment to actually compare the sizes of Earth and Sun. It’s a dramatic difference, nothing like what their textbooks show.

Now it’s time to figure out where the Earth and Sun should be to fit in with this scale. Start by inviting students to guess…they will likely assume you can fit the Earth-Sun model easily inside the room. So now, add the distance data they need and we can “step” through the necessary calculation:

  • The Earth is roughly 93 million miles (150 million km) from the sun.
  • In our scale model, that’s 930 inches (2000 cm)
  • or 78 feet (20 m),
  • or 39 steps of about 2 feet (40 steps of 0.5 m)

Notes:

  • In our model we’re using a pace distance reasonably close to the average woman’s step length and not too far off the step length of a child who is supposed to be walking but can’t resist running. If your group is adult men or tall women, you can use the worksheet to adjust the number of steps accordingly.
  • Our scale in SI (Système international, or metric) is slightly different than in English units, so that those using the SI version can also use simple round figures.

At this point, try to keep a straight face while pretending to start building the model inside the classroom. Dramatically place the “Sun” at one end of the room and try to pace off 39 or 40 steps. Unless you’re doing this activity in a large lecture hall or a cafeteria, you will quickly run out of space (pun intended). By now, it should be clear to the students that this is to be an outdoor activity.

If the group is not too insanely anxious to get outdoors, you can take one more minute to assemble a part of the model which will fit in the room—the Earth-Moon system. Our Moon is nearly ¼ the diameter of Earth, so it’s actually an important body in its own right. And it’s close by. In our scale model, the Moon—which can be represented by a single nonpareil or cake “décor” candy—is 2 3/8” or 5 cm from Earth—so Earth & Moon can be stuck to a card or piece of paper. Keep in mind that if your group is too anxious to get outside, you can choose to save this step for your arrival at the Earth’s position in the model outside.

Earth and Moon are stuck together

Earth and Moon are stuck together

Set the very few ground rules for the mission plan. The model is built by counting steps—the students will be the ones to do the counting and you (the project leader) will expect them to try hard and in return will not be too fussy about precision or how the measurement accuracy may be affected when leadership shifts from short to tall students.   The group will remain cohesive, so no-one misses out on any important discoveries—and no one will charge ahead lest they get “lost in space”. And everyone should understand the time constraints.

When the group is large, I’ve had success assigning small subgroups to accompany one adult leader as the “vanguard” to each planet, leaving the rest behind until they have “landed,” then allowing the followers to run full-speed to catch up. If you do this, it’s important to ensure everyone has a turn to be in the vanguard at least once. If the students have been studying the planets, the vanguard students can also be asked to provide just a few key bits of information to the other explorers as features they have “discovered” about the planet they just reached. However, resist the urge to turn each stop into a seminar—the goal is to travel as far as possible across the system quickly enough to return before class time ends.

Remind the group that it’s a long walk across the solar system and then get started for real. Carry your Sun to a central location outside. If you can park Sol near a tall landmark (such as a flagpole), you’ll find it easier to point back to the “center of the Solar System” as you move further away. Take your Cheat Sheet in hand (the page from the resource kit listing your step-off distances) and read out the number of steps from the sun to Mercury. Send the Mercury explorer team ahead to place Mercury in its position, and quickly join them with the rest of the group. If the vanguard has some cool facts to share about Mercury, give them time to speak. And move on to Venus and the rest of the inner planets.

The asteroid belt portion is the first region containing many objects. If you pause at Ceres, the biggest dwarf planet in the inner Solar System, it helps reduce the stigma of Pluto being “only” a dwarf planet. The fun part in these “belt” regions is to pretend to dodge the small asteroids or other objects—while you may mention that there really isn’t any significant risk of running into an asteroid, that is no reason to turn down the chance to pretend you’re in a crowded mess of obstacles just like in the movies. Even Neil deGrasse Tyson, in his reboot of Cosmos, includes a sequence in which his Ship of the Imagination zigs and zags through, first, a crowded Asteroid Belt and later a densely-packed Oort Cloud.

If time is short or you are working with younger children, it is reasonable to make it to Jupiter (don’t forget to dodge the asteroids on the way out) point out roughly where the outer planets, Pluto, and the further objects would be found and then head back to Earth.

In any case, carry some ordinary first-aid supplies and be sure to have extra adults on hand to slow down those who want to jump to lightspeed. Don’t worry if you don’t have a straight route to use…twisting and turning your way around the streets of a neighborhood is equally impressive. If time will permit, participants can bring lunches and picnic in the Kuiper Belt before returning. And remember, as you return to collect the planet models, it is just as fun to rediscover the distances on the way back.

 

 

 

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