Category: Hands-On Science

On Aisle 42, Universe Components: One Will Make You SmallerOn Aisle 42, Universe Components: One Will Make You Smaller

May 26, 2017| cometary| 0 Comment | 2:25 am

A Top-Down Search for the Strange Charm of Putting Up With Those Quarks at Bottom of the Universe

For part two of our universe-construction project, while the helium models dry, it’s time to delve into the depths of the sub-sub-atomic universe.

Consider those carefully-constructed model atoms. Each contains protons, neutrons, and electrons.

As it turns out, with electrons, there are (so far as physics can determine at present) no smaller particles needed to build an electron. Electrons are part of a group of six elementary particles called leptons. Some of these leptons–the neutrinos–were predicted to not even have any mass, but experiments have shown that while they are incredibly low-mass, neutrinos do have some mass. Interestingly, these experiments leading to even more new developments in fundamental physics and the Standard Model theory. Still, electrons are by far the most numerous leptons (at least in our corner of the multiverse.)

In our candy-based model, we have more than one proton crammed into in a nucleus. Each of those protons has a positive charge, but we all know that objects with the same charge repel each other. Why does the nucleus stay together?

In our model, of course, there is all that sticky candy. But in the real atom, there is also something that, in its own way, makes protons stick together. These other particles are one type of another class of matter, called mesons. These strange, essential, particles are stable only inside the nucleus, where (like our sticky marshmallows) they act as a “glue” to hold protons and neutrons close together.

Given that extremely tiny leptons have been observed, as well as tiny mesons inside the nucleus, protons and neutrons may begin to seem too big to be elementary particles. Sure enough, it turns out that protons and neutrons are also made of smaller particles. And those mesons, too, are made of those same even-smaller particles. And, while it took thirty years to search them all out, a total of six more fundamental particles (on top of the six leptons) have been found. Most of the matter we know about only requires two of those particles–plus the electron–but modern physics predicted six, and sure enough, there are six of them.

Meet the QUARKS. Their six kinds are: up, down, charm, strange, top, and bottom. Each kind comes in a matter form and an antimatter form.

Intriguingly, the terminology for “kinds” of quarks is flavors. Other characteristics of quarks and leptons include color, another clue to the pleasure scientists find in these discoveries. For now, we’ll experiment with the flavors of quarks. Unlike real quarks, we will use macroscopic objects that also happen to taste sweet.

As usual, if you’re working with youngsters, begin by reassuring everyone that there will be plenty of time to eat their quarks later. Each person gets one each of the six flavors of candy…quarks. Because the candies will be handled a lot during the first stage, tell them not to open the wrappers yet. Observe the candies. One side has the brand name on it, and the other side is plain. If we put the candy name-side up, we’ll call it a quark, and if it has the plain side up, we’ll call it an antiquark.

Quark vs Antiquark

A meson is formed by pairs of one quark and one antiquark. Give the group some time to see just how many combinations can be made of such pairs. (A few special mesons combine two or three such pairs, in quark combinations.)

A Small Set of Mesons

This will take some cooperation–participants will want to get together and different groups will organize their tests differently. Meanwhile, if you have access to a whiteboard or poster paper, you can sketch out a list of simple mesons shown below. For smaller (or older) groups, you can also pass out copies of this grid and let everyone check off the combinations as they are discovered.

	quark	antiquark	candy (name)	candy (plain)
bottom eta	b	b	pineapple	pineapple
Upsilon	b	b	pineapple	pineapple
charmed eta	c	c	purple	purple
D+	c	d	purple	peppermint
D0	c	u	purple	red
J/Psi	c	c	purple	purple
Strange D	c	s	purple	green
Charmed B	b	c	purple	pineapple
Kaon0	d	s	peppermint	green
B0	d	b	peppermint	pineapple
Phi	s	s	green	green
Strange B	s	b	green	pineapple
pion	u	d	red	peppermint
kaon+	u	s	red	green
B+	u	b	red	pineapple
Charged rho	u	d	red	peppermint
Kaon*+	u	s	red	green

What’s important from this exercise is realizing that all of these two-quark combinations can really happen. Some of the mesons are the ones that help stick nuclei together. Others are found in outer space, as cosmic rays. Others are only found when scientists smash other particles together to find out what they are made of. Recently, the last of the mesons described by this model was detected by an international team of physicists, using the Large Hadron Collider at CERN, in Switzerland. This prompted huge celebrations by physicists and the process inspired a documentary film about the search for the Higgs Boson, Particle Fever.

When I ran this project at BayCon in 2017, one of the young participants scanned the list above and said, “What about the top quark?” Trust a science-fiction fan to spot an anomaly. Indeed, none of the known mesons make use of the top quark, which is the most elusive one of all, and in some ways the most peculiar. The top quark is extremely unstable–even more ephemeral than the strange, charm, and bottom quarks–and it requires a large particle accelerator to observe one. (Fermilab managed it first; now CERN‘s Large Hadron Collider holds the record.) Even then, once produced, a top quark vanishes in 1/1,000,000,000,000,000,000,000,000th of a second. The top quark is also amazingly massive, fueling the deep interest in the nature of mass itself, which many think is one of the functions of the Higgs boson, which itself has only recently been (tentatively) observed. Scientists at CERN hope to use the relatively massive top quark as a test laboratory to verify their (provisional) Higgs boson observations.

Three-quark particles are called baryons–the most common of these are protons and neutrons. The next step for our own quark exploration is to find the combination of up and down quarks that yields the proton and the one that forms a neutron. Each person has 2 peppermint and 2 of one other color to play with. Each group can also pool resources (still keeping those candy wrappers on) to mix and match groups of three using only 2 colors of candy.

To sort out which of these combinations works requires one extra piece of information. We know that an electron has a charge of -1, a proton has a charge of +1, and a neutron is neutral, with a charge of zero. Another cool feature of quarks…and one of the hardest things their discoverers had to come to terms with…is that they have fractional charges. Before quarks, everyone used to think of a charge…equal to the electric charge of an electron…as an indivisible thing. Just like an atom. But just as it has turned out that atoms aren’t indivisible, neither is charge.

Up quark’s charge: +2/3

Down quark’s charge: -1/3

So, with just a little arithmetic, we can find out which of our combinations makes a proton and which makes a neutron. Here’s the cheat sheet:

uuu	2/3 + 2/3 + 2/3 = 2	Positive…but too much for a proton
ddd	(-1/3) + (-1/3) + (-1/3) = -1	Negative, so it can’t be a proton or a neutron. Note: it’s not an electron either–remember, an electron is already an elementary particle.
uud or udu or duu	2/3 + 2/3 + (-1/3) = 1	OK! It’s a proton!
(Just a reminder…the order the quarks are listed in doesn’t matter.)
ddu or dud or udd	-1/3 + (-1/3) + 2/3 = 0	Yes! We have discovered the neutron!

Aha, it’s a proton.

Aha, It’s a neutron!

So, the charge calculations show that protons and neutrons are made of two ups plus one down for a proton and two downs plus one up for a neutron.

It’s possible to have participants glue their protons and neutron quark groups together. A dip on the water cup from the atomic marshmallow project will make a candy piece sticky. However, these sticky messes will need to sit aside for a while to dry. If your participants include young children, you might want to skip that possibility, as a glued-up stack of Life-Savers could be a choking hazard.

Speaking of glue, the same BayCon2017 participants also suggested some ideas for incorporating gluons into our model. To cover the topic of quantum chromodynamics would be a fun challenge, but for the present, those lonely orange LifeSavers we’d set aside as those transient top quarks can be added between the red and white candies in our proton and neutron models to represent the color exchanges among the quarks.

So now we have established that everything in matter is made of tiny (and flavorful) points of dancing energy called quarks and leptons. How can we visualize the true relative sizes of these quarks, protons, nuclei, and atoms?

Poke a pin through a piece of paper and hold it up to the light, then pass it around, so everyone can see how tiny that hole is. Think of that bright speck as an electron or a quark. To be at the same scale, our helium nucleus would be about 3 feet across. A handy meter-stick or yardstick will provide a sense of scale, but for drama, bring out a huge balloon (the 36-inch size). It won’t be edible, but it will be fun to play with afterwards. If that big old balloon is the tiny nucleus, then to build a whole helium atom we’d need a marshmallow about seven miles (ten kilometers) across!

So let’s check back on our atom model from the atomic marshmallow project. It’s mostly nothing, just that airy, fluffy marshmallow. Remember how thin the “shell” of the electron cloud is, and how surprisingly hard it is to notice the tiny nucleus once the two little protons and neutrons were placed inside. Even so, in our model, the protons and neutrons are huge compared with the atom. Imagine how fantastic the resulting candy treat would be–and how many people could enjoy it–if we’d tried to make this marshmallow atom model to scale.

On Aisle 42, Universe Components: The Atomic Marshmallow ProjectOn Aisle 42, Universe Components: The Atomic Marshmallow Project

May 26, 2017| cometary| 0 Comment | 12:12 am

View looking down of supply kit: pink powder (gelatin) in a white up, water in a clear plastic cup, a round red plate, two wooden skewers, two marshmallows, four small candies in a small container. — The Atomic Marshmallow Kit

Now that you have all of your supplies ready, it’s time to guide your group through the construction of a model atom.

Start by handing out the marshmallows and ice-cream topping pieces. With younger participants, it can maintain focus if you mention that there are extra supplies for snacking on afterwards.

Start with the marshmallow. Most of an atom is empty space. And most of a marshmallow is nothing but air frothed into sugar. So this marshmallow represents the “empty” space of an atom. For older participants, you can encourage them to think of the sugar of the marshmallow as representing not only the energy that permeates what we call “empty” space but also the forces that hold the atom together.

For a very long time, the atom was believed to be more-or-less of uniform density, an amorphous mixture of tiny negative particles called electrons swirling around in a positively-charged “pudding.” In 1911, Ernst Rutherford and his team completed a series of experiments that shocked the physics community by revealing that most of the mass of an atom is concentrated in a tiny, central nucleus containing all of the positive charge. For our model, in honor of Rutherford, we’ll build a helium (He) atom, which has a nucleus containing two protons and two neutrons. (Much of Rutherford’s research focused on the alpha particle–which happens to be exactly the same as a helium nucleus.)

Let your dark-colored candies be protons and your light-colored candies be neutrons. (It doesn’t really matter, but textbooks often draw protons as dark dots and neutrons as white dots.)

Assorted small candies in various colors, blue, green, purple, white. — Candy Nucleons

Two dark and two white little candies (close-up) — Candy Nucleons

Using the wooden skewer or toothpick, drill a small hole in the side of the marshmallow. Now use the same toothpick or skewer to push those nucleons (a word which here means “candy pieces representing protons and neutrons”) into the center of the marshmallow.

Close-up of marshmallow with hole poked in center, showing marshmallow-covered tip of wooden skewer. — Pathway for the Nucleus

Close-up of marshmallow, with one dark candy visible inside hole in center, and two white and one dark candy waiting on top. — Pathway for the Nucleus

This is a good time in the activity to stop lecturing and instead gather suggestions from the participants and sketch their ideas on a board if you have one, or to gather around some sketching paper for discussion purposes. You can expect to see pictures that look much like a planetary system, because that’s the way the atom often (still!) is drawn in textbooks. You might have a knowledgeable participant who’ll shout out something like, “Shells! The electrons are in shells!” or “They’re in the Cloud!” Regardless, during the discussion, build on these volunteered suggestions to reach a description of the electrons as whirling around the nucleus in a cloud, going so fast that you can’t really tell exactly where they are, only that you know roughly how far they are from the nucleus.

At this point, we have a positively charged ion, because we haven’t added any electrons yet. A helium atom needs two electrons, negatively-charged particles, to balance out the two positively-charged protons. Once it was established that the positive charge is concentrated in the nucleus, where did researchers decide that the electrons belong?

Our helium atom’s two electrons do indeed share an electron “shell”, a layer of electrons a known distance from the nucleus. So let’s put a very thin, energetic, sparkly shell around our atom.

Before setting up the shell supplies, pause to demonstrate the procedure. If you’re working with younger students, you may need to stress that everyone will get their turn. If the “mess” part of the activity is an issue, set up a protected area where the messy activity is OK and let the participants queue up to build their atoms in assembly-line fashion.

To create the “electron shell” skewer the marshmallow firmly on the wooden stick, then very briefly dunk it into the water, then tap off any excess water into the water container. Tapping off excess water is important, because otherwise the marshmallow can get soggy, which makes for a less-attractive candy atom.

Marshmallow on skewer dunked into clear plastic cup half-full of water. — Dunk

Wet marshmallow held by skewer on edge of plastic cup of water, drops of water dripping off. — and un-dunk.

Each group needs a container with about a cup of water in it and another container with a packet of dry gelatin mix emptied into it. (For fun, choose a gelatin color in keeping with whatever events are ongoing, or a local sports team’s colors…anything to drive interest.)

Finally, gently swirl the damp marshmallow in the gelatin mix.

Marshmallow on a skewer, being rolled in pink gelatin in a round white bowl. — Adding the Electron Shell

Set the decorated marshmallows aside on a sheet of waxed paper or a plate.

Two gelatin-coated marshmallows, on skewers, set to dry on a round red plastic plate. — Two Finished Helium Atoms

As time permits, participants can make other atoms…stuffing different numbers of protons or neutrons into marshmallows and adding a shell of electrons.

On Aisle 42, Universe Components: The Shopping List(s)On Aisle 42, Universe Components: The Shopping List(s)

May 25, 2017| cometary| 0 Comment | 8:33 pm

As hinted in the previous post, for our universe-building project we’re doing two construction activities related to elementary particles. So, we’ll have two “Lists of Requirements” this time around. The model atoms use marshmallows, miniature candy chips, and gelatin mix. You’ll need just one packet of mixed-flavor candies for even a fairly large group–in advance, you can separate out flavors into the amounts needed. For sub-atomic particles, we’ll use multi-flavor candies, such as “Life-Savers”…we need six flavors, so you get to buy both peppermint and five-flavor mixtures. Depending on your workspace, you may choose to have participants work in table groups of of 3-4 people or to set up supplies assembly-line style in a relatively mess-friendly zone. The assembly-line method reduces the need for extra supplies, though these are quite inexpensive materials. For pre-preparation, it helps to count out supplies for each participant–small paper cups are ideal and stack neatly once your supplies are set up. Another helpful side item is a roll of waxed paper or a stack of paper plates for setting out the end-products while they dry or for taking them home.

One extra item, for your wrap-up, is highly recommended if your budget permits: pick up one humongous balloon–the 36-inch diameter size, in any color or design that delights you.

The recommended quantities are generous, to allow for after-project treats. Ice-cream sundaes, anyone?

The Atomic Marshmallow Project

	Per person	For a group of 10	For a group of 30
Standard size (not miniature) marshmallows	1	10	30
Miniature candies, dark color*: try candy “decors” or extra-tiny chocolate chip ice-cream topping mixture	2	1 package of mixed candies: count out at least 20 dark-colored pieces	1 package of mixed candies: count out at least 20 dark-colored pieces
Miniature candies: light color*: try candy “decors” or extra-tiny white candy chip ice-cream topping mixture	2	From the same packet of mixed-flavor candies: count out at least 20 light-colored pieces	From the same packet of mixed-flavor candies: count out at least 60 light-colored pieces.
Gelatin mix (choose a variety of fun, colorful flavors)	1 packet (3-ounce size)	3 packets (one per group of 3-4 people)	For groups: 8 packets For an assembly line: 3 packets
Water	1 cup	3 cups (one per group of 3-4 people)	For groups: 8 cups For each assembly line: 1 cup
Wooden skewers (alternative: toothpicks)	1	10	30
10-16 ounce containers (mugs, plastic cups, reused food containers)	2	6	For groups: 16 For each assembly line: 2
Small cups for sorting supplies	2	20	60

* IMPORTANT NOTE: If you’re tempted to use peanut-flavor candies, remember to be SURE to check in advance that none of the participants suffers from peanut allergy. In its worst form, this allergy can trigger anaphylaxis merely through physical contact with peanut oils or proteins, but at the very least, peanut-sensitive people should not eat anything tagged “packed in same location as peanut-handling equipment” or “may contain nuts”. There are lots of different candy chips to choose from; just be sure you end up with two different colors of “chips” for the protons and neutrons.

Sufficient Supplies For Construction of Approximately 40 Model Atoms

The second project’s list is even easier, and doesn’t require a “mess zone”:

One Side Makes You Smaller

A Top-Down Search for the Strange Charm of Putting Up With Those Quarks at Bottom of the Universe

The counts of candies in a mixed bag of five-flavor candies is a bit random, so if buying for a group you may need to grab an extra bag, just in case you need it. The package of sorting cups you purchased for the Atomic Marshmallow Project will have enough for you to sort supplies for this project as well.

	Per person	Per 10 people	For 30-person group
Five-flavor Life-Savers candies	1 of each color, a total of 5	50: each gets 5 total, 1 of each color (2 bags of individually-wrapped Life-Savers)	150: each gets 5 total, 1 of each color (6 bags of individually-wrapped Life-Savers)
1 extra piece of one of the five flavors	1	10 (There should be enough left over from the 2 bags you’ve purchased.)	30 (There should enough left over from the 6 bags you’ve purchased.)
Peppermint Life-Savers	2	20: each gets 2 (1 bag of individually-wrapped peppermints	60: each gets 2 (2 bags of individually-wrapped peppermints)

A Pile of Quarks, Ready for Construction of a Small Universe

On Aisle 42, Universe Components: Notes for Project LeadersOn Aisle 42, Universe Components: Notes for Project Leaders

May 25, 2017| cometary| 0 Comment | 8:04 pm

I have a pair of projects to present this time–together, they are a sugar-based approach to understanding the building blocks of our universe. The goal is to build up a sense of the scale and dynamic relationships among the smallest particles identified to date, and how they combine to form the stuff we call “matter”. By the end of these activities, everyone participating should have a clearer picture of the following:

1. All of the matter in our universe is composed of just a few extremely basic and very tiny building blocks. They’re called quarks and leptons.

2.These building blocks, in the right combinations, make the next-level construction materials. The most common ones are electrons, protons, and neutrons. But there are others, too.

3. Once you have electrons, protons, and neutrons, you can build elements. Each element has particular physical and chemical properties–which arise from its unique physical composition of protons, electrons, and neutrons.

To make this activity fun (besides incorporating sweet treats), it helps to build into the presentation an element of discovery. First, we come to terms with the fact that the familiar atom is not the smallest particle. Second, we wrap our minds around the knowledge that even the tiny particles inside the atomic nucleus are made of even tinier ones. Third, at the conclusion, it’s truly mind-expanding to try to envision each of these in true relative scale.

The atom is still a meaningful idea, so long as we adjust its definition to suit modern understanding. The concept of the atom dates back over 2500 years, to Leucippus of Miletus and his more-famous student, Democritus. They reasoned out that if you keep cutting a material, you’ll eventually reach a particle that cannot be divided further. In Greek, the word “a” means “not” and “tomos” means cut, so when you call something an “atom,” you’re saying you can’t subdivide it. However, even now that we know that the structures we call “atoms” can be broken open, we still use the term. For instance, we’ll talk about “an atom of iron” or “the carbon atom”. But instead of defining the atom as “indivisible”, we now describe it as the smallest unit of a material that still retains those unique physical and chemical properties defined by its combination of electrons, protons, and neutrons.

In this project, we will build atoms from electrons, protons, and neutrons. Energized by our constructions, we will discard our preconceptions about the structure of the universe and descend to the sub-sub atomic scale, where we will capture quarks and leptons, then build ourselves some protons and neutrons and electrons. And then we will eat the lot: atoms, quarks, protons and all. It’s elemental.

We’ll proceed in two parts: “The Atomic Marshmallow Project” introduces the idea of atoms and their components, and “One Side Will Make You Smaller” takes us down into the realm of quarks. As in our other science projects, we’ll include information to share with the participants as you go along. For those who would like to delve into more detail, you’ll find links to good sources with plenty of depth.

Everything You Need to Build A Universe

Walking to Pluto, Step 4Walking to Pluto, Step 4

July 15, 2015| cometary| 0 Comment | 1:22 am

Step 4: Go Farther

Pluto & Charon in Full Color (Image Credit: NASA)

New Horizons has flown past Pluto successfully, and is now on the way to check out other Kuiper Belt objects. Here’s Corwin Wray’s simulation (made with Pixel Gravity, his software for doing multi-body models on your laptop), which concludes with a wistful look back at our Solar System:

Like New Horizons, you can explore further too.

It’s worth your while to start by tracking down Guy Ottewell. Yes, he’s on the web, folks, and you can connect with him! Start with his Home Page, which includes all of his books, including the latest version of the book form of his Thousand-Yard Model as well as innovative ideas in several fields, from voting systems to landscape design: He has a Facebook Page on which he’s been more active as of 2014, sharing art and world news: And he joined Twitter in 2013 and tweets regularly, especially on human-rights topics, which should interest anyone who’s become aware of just how small our human community is in this huge universe: find him as simply @GuyOttewell on the tweet machine. A few of his books are available at Amazon, but take care—the latest updates are best obtained by purchasing directly from the author.

Of course, you might want to follow some of informational links given in the workbook pdf’s for this project:

For more information on both the inner and outer planets: http://solarsystem.nasa.gov/planets/charchart.cfm

For more information on the asteroid belt: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Asteroids&Display=OverviewLong

For more on Kuiper-belt objects and Pluto: http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs and also http://solarsystem.nasa.gov/planets/profile.cfm?Object=Dwarf

And of course we have an active mission beyond Pluto right now. It’s an APL project, so they have a great page on the program: http://pluto.jhuapl.edu/

Read about the Pioneers’ adventures here http://www.nasa.gov/centers/ames/news/2013/pioneer11-40-years.html#.UzDJ44WwX_0 and here http://www.nasa.gov/topics/history/features/Pioneer_10_40th_Anniversary.html#.UzDKb4WwX_0

Discover more about the Voyager missions at: http://voyager.jpl.nasa.gov/where/index.html

And find out where all the system-leaving spacecraft—as well as Earth-orbiting satellites, the planets, and other system objects–are right now: http://www.heavens-above.com/SolarEscape.aspx?lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT

For more on the Oort cloud, see http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs

Lots of other interesting links:

The National Optical Astronomy Observatory presents Guy Ottewell’s original project description from 1989 online:

A wonderful collection of poems and quotes related to astronomy, gathered by Michele Stark, an astronomer with a wonderful page she created while lecturing in physics at the University of Michigan, Flint. l You’ll also find astronomy labs she’s created for non-majors interested in the field, under “Outreach and Education”

A relatively exhaustive listing of scale models in place around the world—most are designed for point-to-point driving or cycling tours, so scroll to the bottom portion of the list for walkable models, several of which are roughly on the same scale as that presented here. Check before you set out—some of these installations were only temporary, as part of larger events and some are virtual (i.e., online). I would like to imagine astronomy fans travelling to all of them, as baseball fans travel to all the major-league parks.

The National Center for Earth and Space Science’s “Voyage” program has a “somewhat” pricier scale model in Washington D.C. but also offers up lots of useful curriculum materials: http://voyagesolarsystem.org/ Their program is fee-based, not by any means free, but it is very comprehensive and aims to involve parents, teachers, students, and their communities: http://journeythroughtheuniverse.org/home/home_default.html

You can keep track of the Voyager spacecraft in real time at http://voyager.jpl.nasa.gov/where/index.html They’re in rapid motion—Voyager 1 is travelling at over 38 thousand miles per hour (over 17 km per second).

All about the sun (with a wonderful NASA graphic of a solar flare compared with the Earth): http://www.universetoday.com/94252/characteristics-of-the-sun/

A summary page on the Peppercorn Model at SpyHill Research, which also includes some links to interesting places: http://www.spy-hill.net/myers/peppercorn/

Why isn’t an AU exactly the same as Earth’s orbit any more? Sorry academics, the best answer is in Wikiland: http://en.wikipedia.org/wiki/Astronomical_unit

More about our Moon: http://www.universetoday.com/19677/diameter-of-the-moon/ By the way, Universe Today is a good site to follow!

Asteroid information for Wiki fans: http://en.wikipedia.org/wiki/Asteroid_belt

The Project Astro Notebook used to be sold as a huge expensive bulky (and still wonderful) binder. Soon, you’ll be able download at least some portions in pdf format from the free government-sponsored education resources site eric.gov. However, for now your best bet is to buy the DVD’s at http://astrosociety.org/astroshop/index.php?p=product&id=577&parent=1

While you are waiting for your DVD to arrive, the Astronomical Society of the Pacific has a page full of resources for you, including a few of the Project Astro activities. http://www.astrosociety.org/education/astronomy-resource-guides/

If you actually need to shop for marbles, by all means the best place for working on this project would be “Moon Marbles”, at http://www.moonmarble.com/c-78-shooters-approx-19mm-or-34.aspx

Astronomer Phil Plait summarizes the latest estimates on stars with planets beyond our own system: http://www.slate.com/blogs/bad_astronomy/2013/11/04/earth_like_exoplanets_planets_like_ours_may_be_very_common.html

Why use a FIFA 4 or 5 ball? Well, the dimensions are good for it. But any similar-sized ball will do for this project…like the tennis-ball-patterned playground ball I have. Guy Ottewell likes to use a bowling ball—but notes that it’s kind of heavy to lug around. http://www.achallenge.com/t-faq.aspx

A seemingly unrelated topic—watching for the bright flare of reflected sunlight from certain Earth-orbiting satellites: http://www.washingtonpost.com/wp-srv/washtech/features/iridiumqa.htm The interviewer on that page is talking to Chris Peat, whose website contains a wealth of information on satellites, the solar system, and the positions of the Pioneer and Voyager spacecraft. http://www.heavens-above.com/?lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT

Just to show how established walkable solar system models have become, here’s a typical promotion for a talk by Eric Myers of SUNY (see the GoogleMaps list below) and another talk summary that may inspire you to think about other ways of building a model https://nightsky.jpl.nasa.gov/event-view.cfm?Event_ID=44693 and http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&ved=0CGcQFjAG&url=http%3A%2F%2Fregionalaaptmeeting2013.weebly.com%2Fuploads%2F2%2F2%2F9%2F3%2F22939768%2Faapt_meeting.docx&ei=jaU5U5rvCqiIyAGK0YHwBw&usg=AFQjCNHl4_6jyF2UU_JJ7H9SrD6suXOhjA&sig2=MBKeDxFBGjHlVB2rk8n3wA&bvm=bv.63808443,d.aWc

A few places (courtesy of SpyHill Research’s page) where you can use GoogleMaps to follow a model:

> SUNY College at New Paltz, New York: Map, KML

> Dutchess County Rail Trail, Morgan Lake, Poughkeepsie, New York: Map, KML

> Riverfront City Park, Salem, Oregon: Map, KML

> Walkway over the Hudson, between Poughkeepsie and Highland, NY: Map, KML

> Marist College, Poughkeepsie, NY: Map

For an insanely delicious solar-system project for any mad bakers in your circle, visit Rhiannon’s recipe on her cakecrumbs blog: http://cakecrumbs.me/2013/08/01/spherical-concentric-layer-cake-tutorial/ with some extra photos and video on waitwow http://www.waitwow.com/make-scientifically-accurate-cake-planets/

If you need more reassurance that science and math are not only fun but also funny, visit http://www.xkcd.com (but do prescreen before sharing with students—this webcomic does sometimes use “PG-13” language.

If you have already memorized all of Gary Larson’s Far Side comics, visit the science cartoon webring at http://jcdverha.home.xs4all.nl/scihum/webring.html

And of course, don’t forget to visit Science Cartoons Plus (http://www.sciencecartoonsplus.com/pages/gallery.php)

Materials shopping tips:

Pins with small round heads—look for beading pins—however, be aware that beading pins aren’t sharp, so pick up some ordinary pins as well. http://smile.amazon.com/Beadaholique-20-Piece-Ball-21-Gauge-1-5-Inch/dp/B00BBAXXYS/ref=sr_1_1?s=arts-crafts&ie=UTF8&qid=1396515591&sr=1-1&keywords=pins+2mm+head For pin tips, any small sewing pin with a nice sharp tip will do. (Note that beading pins are not that sharp.)

For the jacks ball, you can pick up a jacks set anywhere. Online (e.g., www.orientaltrading.com , they’re often sold in party packs of a dozen sets. But any bouncy ball bigger than ¾” and no bigger than 1” in diameter will do the trick.

If you decide to buy a playground ball or soccer ball online, locate an air pump before your shipment arrives—they’re often shipped uninflated.

And if you buy on Amazon, be sure to sign up for smile.amazon.com first, so your purchases can support your favorite charity.

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

July 15, 2015| cometary| 0 Comment | 1:02 am

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.

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 1/10^th 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

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.

Walking to Pluto: Step 2Walking to Pluto: Step 2

July 15, 2015| cometary| 0 Comment | 12:57 am

Step 2: The List of Requirements:

Don’t worry. This is one of the least expensive major science projects you’ll put together.

You’ll need:

I found a sunny yellow ball for my Sun.

1) Any ball roughly 8” (19mm) in diameter—a basic playground ball is likely to work, as will a standard soccer ball. FIFA size 5 works for the English-units model; the SI model is slightly smaller, so a youth-sized FIFA size 4 is appropriate—but don’t get bogged down in the details. Visually, when compared with the planet models, all of these ball sizes look the same. It’s most likely that you already own or can borrow a ball for this project; if you simply must buy a ball, you should be able to find one for under $10.

2) A set of eleven objects to represent each of the eight planets, our Moon, and two of the dwarf planets:

Mars or Venus

Pluto or Ceres

a) four pins (two pin heads represent Mars and Venus, two pin points represent Ceres and Pluto),

The Moon Is Made Of Green Candy

b) one tiny candy nonpareil (cake décor or “sprinkle”) for the Moon

Earth Gets Spicy

c) two peppercorns or allspice seeds for Earth and Venus

Having a Ball with Jupiter

d) one jacks-size ball (Jupiter)

This jellybean could be Uranus or Neptune

e) two jelly beans (or coffee beans) for Neptune and Uranus

Saturn represented by a large swirly peppermint

f) and a ¾” (19mm) “shooter” marble or a big round piece of candy (also 3/4″ or 19mm) for Saturn. (It’s just so nice to have something extra-cool and colorful for our most spectacular planet.)

Total cost: less than a dollar US; ideally, rummaging about an average home or allowing participants to bring contributions should turn up most of these objects for free. To splurge, pick up a whole jar of fresh peppercorns for around $5 and share them out among the students.

2) Eleven inexpensive holders for your objects, with the object names written on them. Empty clear yogurt containers or plastic drink cups work very well (see photos), as the pins can be pushed through the cups and others attached with glue to the cup bottoms…such that the cups then serve as mini-pedestals for the model objects. However, don’t feel bound by guidelines here—a set of index cards will do the job if that’s what you have handy. It does help to secure each object to its support. However, be sure that students can see the actual object clearly so that everyone has a feel for the scale. Cost: as much as 10 cents

3) A few signs printed on regular-sized paper to leave with objects that will be waiting for your return, such as: “Please Leave This Experiment Undisturbed — (Teacher’s Name).” Cost: 10 cents

4) Weights to keep each sign from blowing away in a breeze—anything from a handy rock to a water bottle to an actual sports-field marker from your supply closet. Cost: negligible

5) Your basic first-aid kit and/or other equipment required by local protocols for a field trip.

6) Water as needed (Up to $10 if you need to buy each student some bottled water; negligible if students can bring refillable water bottles.) You may choose to make the walk as short as a half-mile (kilometer) or as long as twice that. For a short walk, you should only need modest supplies; for a long walk, snacks and water will be welcome.

7) A printout of your “Cheat Sheet” for either the English-units or SI-units version of the project Walk to Pluto, Miles or Walk to Pluto, km (Just click to download the desired document) Whichever measurement system you’re using, it’s just one sheet, front & back, and includes short comments you can make as you take your trek. Cost: 15 cents, if your printer ink is expensive, because it does have colors.

Total cost of essential supplies: normally about a dollar, assuming most items can be gathered at home or borrowed. For bottled water, if needed, budget an additional 50 cents per student

If you purchase all new supplies, you could spend as much as $40 for a brand-new soccer ball, a jar of nonpareils, a jar of peppercorns, a packet of pins, a jacks game, a bag of marbles with a shooter, and a package of jellybeans.

Interested in more details about the project calculations? Here are copies of the complete worksheets: Walk to Pluto Databank, miles and Walk to Pluto Databank, km

(For workbook copies in Excel format, ready for editing, I can send you a copy via Facebook messaging. Just connect to one of my pages, Pixel Gravity or Cometary Tales. Say, while you’re there, “like” the page. Either way, you’ll receive the file in a return message. The beauty of this approach is that you don’t even need a copy of Excel to use the workbook—Facebook will prompt you to choose whether to open it in Office Online or to download it. The alternative is to email me via cometary@cometarytales.com.)

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

July 15, 2015| cometary| 0 Comment | 12:52 am

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:

A set of notes for project leaders, sketching the key elements of the project and the science topic it is meant to address
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.
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.
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 (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)

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

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

Chasing Comets: Supplies & ResourcesChasing Comets: Supplies & Resources

May 14, 2014| cometary| 0 Comment | 1:18 am

Supplies and Materials

Below, you’ll find a handy supply document you can download, with shopping lists for small and large groups and a range of cost estimates, depending on how much of the supplies you can acquire from available supplies or donations by participants. With a minimal outlay, you and your group can experience being comet chasers–observers of comets.

Basically, you need a bunch of badminton birdies for your comet heads—keep in mind you don’t need performance-grade shuttlecocks or even new ones. If your high school has a badminton team, they will have worn-out birdies you can take off their hands. A grungy, beat-up birdie makes a more realistic comet head.

Birdies for Comets

And you need a bunch of ribbon—curling ribbon for the comet tails. The supply sheet estimates ribbon packages at around $8, but if you look at this photo, you’ll see the last time I bought supplies, it was out of the clearance bin at $2. And if you can get one in five of your participants to bring in a roll to share, it won’t cost you a dime.

Zoom Out–Yes! Here’s All You Need To Make Comets

The one oddball item is that tulle fabric ribbon for the big comet. This you might have a hard time finding in your junk drawer unless you’ve been helping a bride make wedding tchochkes. But for $10 you can buy enough to make three huge comets. Cut five-yard lengths and tie one end of each to a vane of a single birdie, allowing a few inches of extra length to fan out as the comet’s “coma”. Tulle scrunches up easily, so even a six-inch-wide ribbon will feed through the holes between the birdie’s vanes.

Detail–How To Tie Fabric Tails

You should be able to borrow a portable fan and a playground or soccer ball. If you can’t, it will take a roughly $25 expenditure to get those items in stock—a cost you can recoup in part by either donating it to the group you’re working with or simply deducting the expense as part of your cost of volunteering.

And it is presumed you can find a pencil, which makes holding the small model a little easier when you’re doing the demo with the fan; here’s the trick for hooking the pencil to the comet head:

Holder For Fan Experiment

Depending on how good you are at scrounging supplies and locating soccer balls, your costs will range from $10 to $85 for typical group sizes. The spreadsheet I use has a calculation column to adjust the requirements list for other class sizes So, if you want a copy of this fully-functional workbook, “like” the Facebook page & I’ll send you one via a Facebook “message”. (You can also try emailing me through the “contacts” page here, but you’ll get a faster response on FB.) Your FB contact will be used for nothing other than sending you a file and boosting the “likes”-count on my page. [Insert maniacal laughter, if desired.]

Meanwhile, you can get the static workbook as a pdf right away:

Just Supplies Chasing Comets

Resources and References

Now that you are all excited about comets, here are some fun places to go where you can find more cometary material:

A lovely one-page summary from the Spaceguard Program (sponsored by the European Space Agency) gives a clear description of comet tail structure and dynamics, including a neat animation of what both tails look like as the comet proceeds around the sun. The ion tail streams straight back, while the dust tail is curved a bit as the particles within the dust tail blend movement due to their individual orbits about the sun and the forces of the radiation pressure. Net, both tails roughly point away from the sun, as in our demonstration.

Sweet page from NASA with helpful animations and clear descriptions.

Follow the European Space Agency’s comet-chasing spacecraft, Rosetta, as it aims for the first robotic landing on a cometary nucleus.

Read this: a “real” science article with a good set of detailed discussions of the types of comet tails and how they work.

Or, try this excellent piece by freelance science writer Craig Freidenrich on the inner workings of comets.

The Swinburne Centre for Astrophysics and Supercomputing’s educational site helps with details on the structure of comets.

Explore a public-domain catalog of Solar System images, from Hubble and other spacefarers.

Discover how Oort clouds may be one way star systems interact directly with one another, because the Oort clouds project so far out.

See the invisible part of a comet.

Find out all about radiation pressure.

Plan to catch sight of the meteor shower sponsored by Comet Halley.

Explore the origins of comets at this UC Berkeley site.

Check out NASA’s solar system photo gallery, with images from NASA and European Space Agency exploration missions and telescopes.

Visit the Lunar and Planetary Institute’s educational site, with even more hands-on activities for young astrophysicists. Roam their site for educator workshops and more.

OK, seriously, I’m not the only science blogger keen on comets.

A new comet is incoming this month (May 2014).

Our guy Euler was the first one to suggest that light exerts pressure, but we had to wait over 100 years to get to Maxwell, who proved it, and then another quarter-century went by before some Russians managed to measure radiation pressure. (Also, gotta love Google Books.)

Oh, and by 1915 the proof of radiation pressure made it into Scientific American.

Chasing Comets: Notes for Project Leaders #2Chasing Comets: Notes for Project Leaders #2

May 12, 2014| cometary| 0 Comment | 5:54 pm

OK, we’re back for part 2. Remember that our goal is to impart an intuitive, long-term understanding of how comet tails work. I’ll give you an observation worksheet that students can use during the Comet Running game, but if time or attention-spans are too short for a worksheet, dispense with that element in favor of learning through movement and Socratic dialogue. (What? You think an engineer wouldn’t have read the Greek philosophers?)

If you have time and enough outdoor space for the “Game” version of this simulation, move right along to “Stage 2” now. The promise of a chance to make their own models is what will entice the students back to the classroom. Otherwise, save the great outdoor model for another time or place and move directly to “Stage 3,” building the individual models.

Stage 2: The Game

That’s One Big Comet

This is an outdoor game, and it works to best advantage with a nice BIG comet model. Four five-yard lengths of white fabric streamers attached to a single badminton shuttlecock (“birdie”) make our Comet Chase model. A playground ball or a soccer ball (around 8” in diameter) stands for the sun. Sort the participants into groups of no more than five and no fewer than three, and move to the great outdoors. A grassy area is safest, because this game involves some complicated running; if you’re stuck with pavement, tone down the running to “jogging” and allow a little extra time.

Start by laying out the ground rules for the game. First, each group will get to play every role. There are three parts: being the sun, being the comet, and being observers back on Earth. Remind everyone of your local rules for behavior outside. It’s harder to listen to instructions out in the sunshine and fresh air!

Take a moment to review the lesson so far. Place the model Sun on the ground, at least ten yards away. Ask an adult helper or one of the students to stand about halfway between the class and the Sun and to hold the head of the comet

Large Comet Head With Coma

while you extend the tail’s long white streamers. This model is much more evocative of the scale of a real comet, which has a tail tremendously longer than the diameter of its coma, or head—but it’s still not a scale model. Allow for some oohs and aahs, but move on to your query: which direction should the comet’s tail point? Don’t move yet; both you and your helper just stand in place.

Large Comet: Incoming or Outbound?

Don’t be concerned if it takes more than one answer to get the right one! Some may still want to know which way your comet is moving. But in a few moments, you should achieve the consensus that the tail should point towards the class and away from the sun.

Now, add the movement and ask everyone to call out which way for you to move. Ask your helper to start walking (slowly, please!) towards the sun and then to loop around the sun. You will need to move quickly to keep the comet’s tail pointing away from the sun. In fact, even if your helper cooperates by walking slowly, you will need to break into a run! As you run, if the students aren’t already hollering directions to you, tel them to keep reminding you which way to point the tail: away from the Sun!

Pause partway and while you catch your breath you can demo a technique for helping to align the tail while in motion. With your outside hand, hold the streamers. With your inside hand, point at the Sun. The tail-runners should always find that pointing at the Sun also means pointing at the comet’s head.

Now, it is finally the students’ turn. Run as many iterations as necessary to ensure that each group does each job at least once. For instance, for a class of 20, allow time to run the game at least four times.

The Comet Group: The comet group needs one Head and up to four Tail-Runners. Name the comet after the person who’s serving as the Head. Comets are always named according to the last name of the comet’s discoverer. So if you have Robin Williams as the comet’s head, then this will be Comet Williams. Getting the comet named after him/her may compensate for the fact that the “head” only gets to walk slowly around the sun.

Meanwhile, the tail-runners get to hold the ends of the tail streamers and run to keep the comet’s head between themselves and the Sun. In the normal course, the “tail” group will tend to lag a little and spread out, but that actually serves to more-accurately represent the shape of the dust tail. If you’re working with a two-tails group, designate one especially determined runner to represent the ion tail by taking one ribbon and maintaining a straight line from the ribbon end through the comet head to the sun.

The Sun Group: The sun group stands in the middle of your running space. One or two group members hold the model sun overhead. This makes it easier for the Comet group to see if they have successfully aligned the comet head and the sun. If the tail-runners stray out of line, members of the sun group need to to shout out “Got you! Got you!” or “Solar Wind Coming!” to warn them that the solar forces are blasting the tail.

The Astronomer Group: The people who are not part of the sun-comet demonstration still have a critical role. They are not just watching other people play the game, but they are tracking the shape of the comet’s tail as it passes around the sun, as observers on Earth. Depending on their perspective at each point in the comet’s orbit, the tail will appear longer or shorter. For example, if the comet is roughly between Earth and the Sun, the tail may look short, because it is stretched towards us. If you have time for writing, ask the Observers to sketch the comet as they see it. (See the handout.) In an average class, each student will get to observe the comet at least twice, which is very helpful for catching the unexpected views.

When every group has had a chance to play every role, take a few minutes to review one more time. As a comet is orbiting around the sun, which way does its tail point? By now, everyone should be willing to state that the tail always points away from the sun.

Still, you may still have a few hold-outs who are not quite sure this can be true. If you are lucky and it’s a sunny day, you have a hole card to play. Invite the students to each imagine that they are comets. “Guess what? You can see exactly where your tail would be. Who can point at it? Where’s your tail, Comet Human?”

If you are not saved by the insight of a student who’s totally absorbed the lesson, it is OK to resort to hints. “Everyone has one. It’s easy to see. Yes, you can see your comet tail! Where is it? Which way does a comet’s tail point? Right: away from the sun. Where’s the sun right now? What do you have that’s pointing away from the sun? It’s not bright and shiny like a comet’s tail. It’s dark, because there are no sunbeams there.

“Yes! Your shadow is your comet tail. It points away from the sun, always, no matter what direction you run.”

Stage 3: The Reward

Finally, everyone needs a model comet of their own to take home and show off and share with family members everything about how comet tails work. This is not an art project; it’s an opportunity to review and experiment individually. If some students are fussy about carefully arranging their streamers to make a colorful pattern, that is all right, but the point is to assemble a working model.

Each participant needs 24 feet of curling ribbon and a birdie (remember what I told you earlier about calling it by its proper name—be prepared for lots of giggling and teasing if you insist on that) . Cut the ribbon into eight lengths of roughly 3 feet. It is perfectly all right—and in fact more realistic—if the streamers come out various lengths. And depending on the students’ social skills, it is also all right for them to exchange colors once the cutting is done. (There are always some who prefer to discover a multi-color comet and others who prefer monotone.)

Once each student has six streamers, have them tie one end of each streamer to the head of the birdie.

Detail–Attaching Ribbon For Comet Tail

Your meticulous planners will distribute them evenly around the netting; others will be clumped randomly. Either is fine. Every comet is unique and most are quite non-uniform.

Be real. This project is not done when it the comets have been only built. Everyone needs a chance to try them out. They will, of course, want to toss them around the classroom; if this is not acceptable, make some provision for them to try out that technique outdoors. More scientific, of course, as time permits, is to allow the participants to take turns trying out their comets in the pretend “solar wind” of the classroom fan. As long as they willing and able to mind safety rules about working around a fan, by all means have everyone try out the tail position approaching, passing, and retreating from the Fan Sun. But don’t get all hot under the collar if other comets are flying through the room while you monitor the fan users. Just imagine you’re in the Oort Cloud and you’ll be OK.

Up next: Supplies You Need and Resources You Can Use

A Cluster of Comets, Incoming & Outbound