Monday Science Links
This week's science:
- Dr. Isis at On Becoming a Domestic and Laboratory Goddess posts on Cairo, the Pyramids, and air: The first and last stops on our trip were to Cairo and Giza. Cairo is the most populous city in Africa. Including the surrounding metropolitan area, it is home to more that 17 million Egyptians. While tourism is certainly a staple of the local economy, Cairo is also an important manufacturing and financial center. Over the last several decades, population growth in Cairo has far exceeded available resources, a phenomenon known as hyperurbanization. As a result, Cairo is a patchwork of middle to upper middles class neighborhoods and neighborhoods with with no running water or electricity. In some places people have sought shelter in the crypts of local, ancient cemeteries. The people of Cairo generate more than 10,000 tons of trash each day, but only half of it is picked up and disposed of.
- Emily at The Planetary Society has the scoop on those ring shadows: What's that jaggedy dark stuff behind the brightest ringlet in the image? We're only a few months away from Saturn's equinox, the day when the Sun will pass through the plane of Saturn's rings. So to an observer standing on Saturn's rings, the Sun is beginning to set, and casting long shadows. We're seeing shadows cast from structure within Saturn's rings. COOOOOOOL. Once the first shock of amazement has worn off, questions start to arise. What's casting those shadows? Are those moons? Well, the first thing to ask is, how tall are the things that are casting the shadows?
- Ethan at Starts With A Bang blogs on pink galaxies: A number of these galaxies happen to be "face-on" to us, so we can really get a good glimpse of what's going on in their individual spiral arms. Many of them, like the Pinwheel Galaxy (M101), are pretty unremarkable, and are just a dusty whitish-blue color. But if we take other, similar galaxies, like NGC 3184, we find something interesting. Specifically, we find a few areas in these spiral arms that are pink.
- Darren at Tetrapod Zoology blogs on Asian cattle: Cattle are another of those groups of animals that, while they're familiar and while we take them for granted, are really pretty incredible. The size, power and awesome appearance of many wild cattle never fails to amaze me. Markus Bühler (of Bestiarium) has been good enough to share these photos he took of Banteng Bos javanicus and Gaur B. gaurus at Berlin Zoo.
- Kim at All My Faults Are Stress Related blogs on hot rocks, thermal insulation, and why magma doesn't always act as we expect: The cores of mountain belts formed by continental collisions often contain metamorphic rocks, formed when sediments were buried in the collision and transformed by heat and pressure. But the heat and pressure don't happen simultaneously - rocks can be buried (and increase in pressure) much faster than they can heat up. When the rocks are not allowed to heat up significantly, this process can create blueschists, the high pressure/low temperature metamorphic rocks formed in subduction zones. In continental collisions, subduction stops, and the metamorphic rocks sit around at depth, heating up until a new geothermal gradient forms. When I first read Philip England and Alan Thompson's 1984 paper that modeled the temperature-pressure evolution of rocks in a continental collision, metamorphic rocks suddenly made sense. (And I understood why my interpretation of my senior thesis rocks was simplistic and wrong. Oh, well.)
Enjoy!
Labels: links, science, sciencelinks
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