Brian Cox explains (on the BBC) explains how electron shells are like standing waves, and how that relates to the sizes of atoms, and explains why atoms are mostly space.
Category: Natural World
Trebuchet
Last fall, the Good Shepherd Lutheran Church had a pumpkin patch with a trebuchet. They launched a few pumpkins for the kids.
Their design was simple — not for competition, but something I’d like my students to emulate sometime.
Coal Seam
Although it was high in sulfur, the quarry company mined the thin coal seam that cut across the limestone quarry/landfill.
The layer of coal is pretty impervious to water, so it blocks vertical infiltration of water, which forces the water to the surface as springs.
At the surface, when the water is exposed to oxygen in the atmosphere, dissolved iron precipitates to produce a red mineral that stains the quarry walls.
The iron gets into the water when pyrite crystals (FeS2) in the coal dissolves. While the iron precipitates, the sulfur remains in the water, making it more acidic. Dealing with the acid can be a huge problem in large coal and metal mines.
Not all the pyrite is dissolved however, and since this particular coal seam has a lot of pyrite, it is not economical to burn since the burnt sulfur (as sulfur dioxide gas) would have to be captured — otherwise it produces acid rain.
Personal Ceramic Project
I have a neat little tea strainer that sits inside my almost perfect teacup, yet I’m usually at a loss about what to do with it when I take it out of the cup. When the lid is upside down, the strainer can sit nicely into a circular inset that seem perfectly designed for it; however, if I want to use the lid to keep my tea warm — as I am wont to do — I have to move the strainer somewhere else.
One option is to just put the strainer in another cup, but then air can’t circulate around it, and instead of drying, the used tea leaves stay wet and, eventually, turn moldy. A flat saucer would be better, but not perfect.
Of course, I could just empty out the strainer, wash and dry it as soon as I’m done steeping the leaves, but there are a few ancillary considerations with respect to time that make this a sub-optimal solution.
So, since we have a kiln on campus that sees regular use, I thought I’d sit in on the Middle School art class and make my own ceramic tea strainer holder. Since I’ve also been thinking about Philip Stewart’s spiral, and de Chancourtois‘ helictical periodic tables, and been inspired by Bert Geyer’s attempts at making sonnets tangible, it eventually occurred to me that an open helictical form would work fairly well for my purposes.
I’ve cobbled together a design using Inkscape, and layered it onto a cylinder in Sketchup to see what it would look like.
So far the reactions from students has been quite diverse. I have one volunteer who’s wants to help, and I’ve sparked some discussion as to if what I’m doing actually qualifies as art. There is a lot of curiosity though. The middle-schoolers will probably be doing some type of physical representation of the periodic table, so I’m hoping this project gets them to think more broadly about what they might be able to do.
Terraforming Mars
Jason Shankel has an article on how we could go about changing the surface of Mars into something humans can live on. He does an excellent job of condensing the not insignificant literature on terraforming the red planet.
Starting with an explanation of Mars’ geologic history, Shankel addresses Martyn Foggs’ list of critical challenges:
- The surface temperature must be raised
- The atmospheric pressure must be increased
- The chemical composition of the atmosphere must be changed
- The surface must be made wet
- The surface flux of UV radiation must be reduced
— Shankel (2011): How We Will Terraform Mars on io9.com.
The article is expansive in its detail, provides a wonderful primer on the red planet, and demonstrates an excellent application of planetary system science (as opposed to Earth system science) to what would be an enormous geoengineering project. For example, to warm up the planet, Shankel starts with several approaches:
so how do we warm up the Martian poles? Several approaches have been suggested, from spreading dark material on the poles to lower their albedo, to industrial ice farming to good old fashioned thermonuclear detonations.
— Shankel (2011): How We Will Terraform Mars on io9.com.
He then goes into detail. Lots of detail, in a quite readable form.
Human Evolution: A Family Tree
The Smithsonian has an excellent, interactive, family tree for humanity that goes back 6 million years.
io9 has a neat image of key primate and homonid skulls that show the story of human evolution, and how we know about it.
Visit to the Quarry/Landfill
A single, half-day, visit to the landfill and quarry brought up quite the variety of topics, ranging from the quarry itself, to the reason for the red colors of the cliff walls, to the uses of the gases that come out of the landfill. I still have not gotten to the details about the landfill itself, but I’ve put together a page that links all my posts about the quarry and landfill so far.
- Quarry
- Water Cycle
- Methane Gas (CH4)
- Hydrogen Sulfide (H2S)
- Density (and freshwater lens)
- Iron staining on the cliffs.
- The Coal Seam.
There was so much information that we spent the better part of the following week debriefing it in the middle-school science class.
The map below gives a good aerial view of the site.
View Landfill and Quarry (as of 11/26/2011) in a larger map
The Water Cycle … at the Quarry
The water cycle is intricately tied to all the other topics that came up on our visit to the quarry/landfill. For some things, the tie to water is direct and inextricable.
- It’s groundwater that dissolves the pyrite in the coal seam and then precipitates an orange iron stain on the quarry cliffs.
- Rainwater seeping into the landfill leaches out chemicals that have to be prevented from getting into the groundwater, rivers or lakes.
- Gases like hydrogen sulfide can react with water (and oxygen) in the air to produce acid rain. Not to mention that water is needed for the decaying processes that produce the hydrogen sulfide, and other landfill gases like methane, to begin with.
For other things the link to water is not necessarily so obvious:
- The sediment that was compressed into the limestone that is being quarried, was formed beneath the shallow seas that once covered this region in the geologic past. Limestone is also dissolved by rainwater to create caverns, underground rivers and spaces for geodes.
- Methane gas not only requires water for it to be released via decomposition of garbage, but also produces carbon dioxide when burned. Carbon dioxide is a greenhouse gas, so it affects the global temperature and contributes to the melting glaciers, rising sea levels and changes in climatic patterns such as the amount of rain we’re going to receive in the midwest.
The water cycle picture starts simply, but gets complicated very quickly.
