2015年1月2日 星期五

An Icy Volcano and the Cosmic Cycle of Life

Living on the edge of the Rocky Mountains in the winter means getting up every morning and seeing those snow-capped peaks poking out over the nearer foothills. It’s a magnificent view to occupy me as I wait for my coffee to steep.


Seeing the mountains from the side is endlessly fun, but I sometimes wish I could see them from above. After all, when Landsat 8 does it, the view is simply incredible:


[You really want to see this image in all its high-definition glory, too.]


Now, to be fair, those aren’t the Rockies; those are the eponymitic Islands of the Four Mountains, a collection of islands in the Aleutian archipelago curving west off of Alaska. There are actually seven islands in the group, but these four volcanoes stand tall: Herbert (lower left), Cleveland (center), Carlisle (upper left), and Tana (the rugged one to the right).


The Landsat image shows them on June 8, 2013. As you can see, even in summer there’s snow on them thar hills, kindof. What’s funny to me is that Cleveland is the tallest of the four volcanoes (1730 m at its peak, about 5700 feet) but it’s the only one without snow on it. Weather can be weird sometimes.


I love the cloud patterns here, too. North is up, so the wind is clearly blowing north, and the volcanoes punching up into the sky break that flow. The wind blows around the islands, creating that lovely ship-wave effect. Note how the lower flanks of the volcanoes are relatively clear, but then clouds form higher up; as the wind blows up the windward face of the mountains it cools, and clouds form as water condenses out.


Herbert has no records of eruptions in modern times, but Cleveland erupted in 2006 (and again in subsequent years). Get this: That first eruption was actually discovered by astronauts on the International Space Station who happened to be flying over it at the time! They apparently caught it right after the eruption started, too:


It’s a pretty stark (and frankly gorgeous) reminder that we live on a planet that’s not nearly done cooking yet. We live on the cool, solid skin of a vast ball of superheated rock and iron, still roiling inside with energy leftover from its formation (as well as from the decay of radioactive elements and other forces). It’s slightly terrifying to think that all that separates us from all that is a thin veneer of rock just a dozen or two kilometers thick, but we owe our existence to all that heat. It generates tectonic forces that in turn have created the land we live on, and continental drift has pressured life into changing over the eons—allopathic speciation—evolving into us.


As always in the Universe, life and death hang on the same thread; creation and destruction are two sides of the same coin.


That may not be the first thought you have, looking at a pretty picture of Alaskan islands from space. But it’s not a bad one. One of the things I love about science is how it gives us perspective.






from Bad Astronomy http://ift.tt/1BnPtjk

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