Apples and You
Posted by DrJeff on May 21st, 2009
Filed under 1.5. Dr. Jeff's Jeffisms, 1.6. Dr. Jeff Speaks Out, 4. The Earth, 4.1. Environment and Climate Change, 4.2. General Biosphere
Copyright 2009 | About this blog
This post is a ‘Jeffism’ by Dr. Jeff and a Dr. Jeff Speaks Out.
Last time on the blog, I used astronaut John Grunsfeld’s recent Business Trip to the Hubble Space Telescope to show you that the perceived limitless ocean of air we live under is really not limitless. At an altitude of 62 miles (100 km) above Earth’s surface, you’re effectively at the top of the atmosphere (since 99.99% of it is beneath you.) So let’s really put this in perspective with a Dr. Jeff Jeffism:
Earth’s atmosphere compared to Earth is thinner than
the skin of an apple compared to an apple.
I truly hope that makes an impression on you. Read it again and let it sink in. Then take a moment and reflect on what you are thinking.
Now … for the rest of the story—
Our atmosphere is nothing more than a slender veil surrounding our planet. It supports all life on spaceship Earth. It is fragile. It is clearly changing at a frightening pace. Next time you’re in a discussion about global warming, pull this Jeffism out of your pocket—regardless of which side of the debate you might be on (is it induced by human activity or not). It speaks to what we ALL have to lose—’we’ the human race; and ‘we’ the other countless species of Earth.
My view? We humans are the agents of global change, and all of humanity needs to consider the consequences head-on and collectively define a response RIGHT NOW. And all those countless other species—their future is in our hands. Look to the birds in flight. Look to the diversity of life on the savannas of Africa, in the rain forests of Central and South America, and in the worlds’ oceans. They are voiceless in this debate, and powerless to intervene.
Look deeply into your children’s eyes and ask what is our responsibility to them, to their children—and to Earth. I have—and when Jordi and Jada look back at me, I get a sense of purpose and a deep resolve—to educate. This blog is one result.
For a powerful educational essay on global warming as an outgrowth of human activity, read A Day in the Life of the Earth here at Blog on the Universe, or at the Huffington Post. It includes a foreword by Dr. James Hansen, Director of NASA’s Goddard Institute for Space Studies in New York.
Teachers and parents:
Before reading the Jeffism above to your class or children, use a familiar model to identify preconceptions and misconceptions about the atmosphere. Get a classroom globe of the Earth and ask them how high above the Earth globe they think the atmosphere extends. You’ll be amazed (or maybe not) at the depth of the misconceptions. Then read them the Jeffism, and see if they are shocked. Ask them to reflect on the difference between their perception of the atmosphere and reality.
Here’s more to consider:
• Have a thoughtful and interdisciplinary discussion as a class or as a family considering the larger and inter-connected issues we face on global warming in terms of: science, technology, politics, economics, funding, the need for global partnerships, ethics, and morality. Science should not be taught in isolation from all other manner of human considerations. The world is interdisciplinary, so why would we want to teach about the world only subject by subject?
• Visit my Favorite Quotes page and read the quotes by astronaut Ulf Merbold and cosmonaut Yuri Artyukhin. How are their words relevant to the discussion?
• The Jeffism above is so effective because it builds a bridge to the familiar using a model—in this case using an apple as a conceptual model to understand Earth. Read my Power of Models page to gain deeper insight into how to use modeling in learning environments, and to realize that YOU surround yourself with countless models every day to make the world understandable.
The Experiment
Don’t let your students and children just assume my Jeffism is correct. Help them to insist on testing it. That’s what science is all about. Scientists (your kids) should put ideas to the torture test—and own the process. So assume my Jeffism is a hypothesis, and have them test it for themselves. And let them frame the experiment with guidance from you.
Here’s the concept: the atmosphere is 62 miles (100 km) thick and the Earth’s diameter is 7,900 miles (12,700 km). So how does Earth’s diameter compare to the thickness of the atmosphere? That’s just the ratio: 12,700 / 100 = 127. So the diameter of Earth is 127 times the thickness of the atmosphere!
What about the apple? The skin of the apple is what I’m going to define as the peeling you get when you peel an apple with a good potato peeler (one that does not dig deeply into the apple). Here’s the creative thinking part of the experiment—your students/children need to propose how to measure the thickness of an apple skin. One of a bunch of approaches is to use a peeler and carefully peel a really long strip from an apple. Then tear off reasonably sized pieces and stack them in layers until you have a thickness you can measure with a ruler with millimeter divisions. Measure the thickness of the stack, then count the layers, and divide the thickness of the stack by the number of layers to get the thickness of a single layer. That’s the thickness of the apple skin!
Finally, measure the diameter of the apple and calculate the ratio of apple diameter to skin thickness. This ratio is what you compare to the 127 we got for the ratio of Earth’s diameter to the thickness of the atmosphere.
I just did it with a trusty golden delicious apple. My stack of 10 layers had a measured thickness of 11 mm, corresponding to 1.1 mm for a single layer–which is the thickness of the apple skin. The apple has a diameter of 80 mm. So the diameter of the apple is only 80 / 1.1 = 72 times the thickness of the skin! Comparing that to Earth’s diameter being 127 times the thickness of the atmoshere means—the Jeffism (at least with my apple) is confirmed!
A final thought—you can ask your students or children to go back to the classroom globe of Earth and calculate the thickness of the atmosphere on the globe. It’s just the diameter of the globe divided by 127.
Science—it’s fun, it’s a team effort, it’s eye-opening.
-Dr. Jeff
A word from our sponsor:
• I have the title for next Monday’s Weekly Challenge that is sure to intrigue: A Pound of Ants and the Capabilities of Intelligent Biomass (how do I come up with this stuff). It is a powerful post on how we humans are affecting Earth’s environment.
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