Archive for July, 2010

Printable paper Earth globes

2010 July 22, Thursday

cube globe

Map Projections: Polyhedron Maps contains printable paper Earth globes. Paper craft world maps. In a variety of numbers of sides.  Fewer sides mean easier construction, but a less round and more distorted “globe”.

Tetrahedron, octahedron, cube, dodecahedron, icosahedron, truncated icosahedron, cuboctahedron, rhombicuboctahedron, and soccer ball Earth globes.

Because the site is poorly keyworded, people find my Making globes of the planets instead, when this is what they really want. Thanks to the most recent and enthusiastic correspondent, who prompted this post.

I encourage comments with links to similar sites.
One is JAXA AMSR Paper Craft [via Earth Science 3D Paper Models and Toys ]

Other ideas:
– The blank globes available for assembly practice could instead be used for “draw or paint your own globe” art and geography projects.
– It would be nice to have a suite of topical globes, so any time one is teaching a science topic (global winds, currents, biomes, rainforests, population density, crustal plates, geologic periods, etc) it would be easy to print out and assemble a little “globe” to make it tangible.
– If you are teaching polyhedra in maths class, or projection, why not have some pretty examples like these?

Helium balloon – heading for the stars!

2010 July 19, Monday

My wiki project (“Extreme-effort descriptive content for K-grad science education”, aka “Science content doesn’t have to suck”) is on hold, that I might focus on getting a job. Sigh. But folks keep saying I should blog more (like, at all), and this dreadful quote just went by, so here goes…

At that point, in accordance with the familiar, enduring magic of helium, it will weigh less than nothing at all.
[From The Man Who Would Fall to Earth, on page 2. The author does better later.]

My usual reaction to dreck is to think “There are so many wonderful stories which might be told instead.  We sooo need a wiki.  Stories like…”.


Escape! Free at last!
Helium heads for interstellar space!
Alpha particles going home!

What’s the story of this balloon? Or, punting the rubber, of the helium bit?

It’s impossible to do this for real. That would take weeks, or months, not the few hours I have for this post. Thus the need for a wiki. But some highlights are clear.

Briefly, the big picture includes:

  1. atmospheric He is headed out of the solar system,
  2. and it is alpha particles from the decay of heavy nuclei,
  3. which were synthesized in the supernova which triggered solar system formation.

In slightly greater detail,

  • Escaping the balloon. I’m unclear whether it’s a rise and pop, or a float and leak. Both stories have nice linkage to others, including weather and superpressure balloons, surfacing divers, H and He sneaky leakiness, etc.
  • Near-term journey. Atmospheric outgassing; blowing in the solar wind; termination shock; entrainment; and ISM.
  • Long-term journey.  I don’t know the numbers.  What’s a free He going to do around here for the next few Gyr? What are the odds of getting into another star?

Then, looking backwards…

  • Industrial extraction, storage, distribution, and economics.
  • Long-term experience of a heavy nuclei on earth. Living in the decay chain, waiting for your turn to go. Neutralization; diffusion; reservoir caps.
  • Supernova: unstable nucleosynthesis; hell; trigger shock. Solar system formation.
  • Getting from big bang to nova. Filament flow; galaxy mergers. I’m unclear on whether an earlier stellar experience is likely or not.

The hard part is gathering the information.  Only then, the very much not as hard part of generating correct and fun and enlightening end-user content.  Here faked carelessly for crude illustration.

ME: So, you’re a Helium atom?
He-p: Yep, that’s us.  Two protons, two neutrons, and some electrons we picked up.
ME: And you’re headed for space?
He-n: We are headed for the stars, man!  By tomorrow we’ll be mixing with the atmosphere.  Odds are an Myear from now, we’ll be out of the atmosphere and into space.  Wind at our back, blazing along, half a Mm per second.  A century to the wind wall,
ME: heliopause?
He-n: yeah, and then depending on what time of year we leave earth, we’ll either surf the bow wave for time, or wave sayonara.  Bye bye Sol.
ME: A million years? That seems a long time, no?
He-n: We’ve stuck on this rust ball in unstable nuclei for the last 4.6 Gyear. Another 0.001 Gyear?  No problem.  Way better than say waiting 8 Gyear for earth to vaporize.
ME: What are your long term plans?
He-p: We don’t know yet.  Hang out in the local interstellar cloud for a bit, of course.  Or maybe one a little more dense, depending on when we get off earth.  But long term?  Hang out, orbit the galaxy for a few Gyear, maybe do another planet or star someday.
ME: So, tell us about your life.
He-p: Well, we we’re all born 13 Gyear ago,
He-n: just like everyone else
He-p: well, us nucleons, yes, but fluffy ‘nuclei suspended in electrons’ human over there,
He-n: oh, never mind, no offence intended,
He-p: yes, well.
ME: …


Once upon a time, a large star exploded.

Well, sorry, that’s it for this evening, and for this post.  Comments encouraged.