Let me share two of the activities I’ve been doing this month with my Chrysalis students. We had a bubble festival which led into why bubbles are round. Bubbles are round for the same reason rocks and planets and skulls are round–minimal surface area. This got me to thinking of the Earth as a bubble. A friend once told me that if you shrunk the Earth to the size of a billiard ball, the Earth would be smoother than a billiard ball.
So I had the kids draw cross sections of the earth’s surface without any vertical exaggeration. The scale we used was 1 millimeter equals 2 kilometers. So we used a pencil at the end of a cord 3.25 meters long as a compass to inscribe the Earth’s curve and then upon that curve we imposed mountains and sea trenches. On this scale, Everest is a little more than 4 millimeters high. Outer space was about 60 – 70 millimeters above the space. It’s an interesting perspective. The smoothness becomes even more dramatic if you change the scale to 1 millimeter equals 4 kilometers but then any deviations from the curve are so slight that the exercise can become boring to any student not captivated by the minuteness of mountains.
This leads to an interesting contemplation for me. When looking at the inorganic world, we see the process of erosion and deposition smoothing the Earth and thereby reducing the amount of surface area. On the other hand, the organic world is busy increasing the amount of surface area by covering bedrock with forests and prairies. The result of this tension is that over billions of years, the surface of the Earth has become less “bumpy” but more “fuzzy”. The exposure of rock at the surface has diminished but the exposure of plant surface has increased. It would be revealing to be able to somehow make a graph of the change in the ratio of biological surface area to geological surface area and how that ratio has changed over time.
Second activity was robin droppings. Every winter, robins drop down from the mountains into the Central Valley. Each evening, small flocks fly to a common roosting areas. One of these roosting areas is right next to Chrysalis. Each evening, around 5 – 10,000 robins congregate in the cottonwoods, converse in great exultation for 20-30 minutes, and then, as it grows dark, drop into the blackberry brambles.
One result is lots of robin droppings on the ground. The Rule of Flow makes me think about what is going on. The robins fly out each morning and forage for miles around throughout the day. When they come together in the evening, they don’t feed. But they do defecate. There might be a potentially massive inflow of robin-transported nutrients being concentrated on these woods. How significant is the flow?
The kids and I figured the way to find out was to take some sort of “tray”, weigh it, place it under the trees, and then weigh it again a day later. We cut out 1 square foot pieces of cardboard. The weight increase ranged from 0 to 2.4 grams with an average of 1.035 grams (dry weight) of droppings per square foot per day. (The squares were not distributed randomly. Most students sought to put them in areas that looked well-pooped.) Given that the robins are here for about 100 nights, that comes out to about 100 grams per square foot per year. That’s a lot of fertility flowing into some areas.
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Last week I helped a teacher do a class walk through a scale solar system. An 8 inch playground ball modeled the Sun. On that scale, the average distance of Pluto was a 1/2 mile away (which we walked). On that scale, the nearest star from our ball in Northern California would be in New York City. I have done these kinds of walks before and they are a good way to help the mind start grappling with the relative size of things. While we were standing at Pluto, I started calculating what our 100,000 light year diameter galaxy would be at this scale. The results shocked me. On the scale of our sun scrunched down to an 8″ ball and Pluto being 1/2 mile away, our galaxy would be about 80 million miles wide, almost as wide as the distance from the Sun to the Earth. Totally different order of scale than solar systems.
There are gradients of space and time. We are sensitive to those areas closest to our scale of existence. Part of science’s progress has been discovering the events and objects happening further away from us on these gradients. Part of our work is expanding our awareness of the miracle we live within by locating the visual clues that help us see the more remote realms of these gradients of space, time…
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