Saturday, May 30, 2009

Black Aurora

The Aurora Borealis is a fascinating sight to behold perhaps because,  for most humans, it does not appear in their sky.  I recall one crisp evening of my youth being called outside to witness a wisp of odd colored light in the evening sky and was told that it was the Aurora Borealis or Northern Lights.  I don't know if it was, but it sparked some primeval meme inside of me- one of those awe moments.
One can imagine the grand awe of early humans who ventured into the northern latitudes suddenly coming upon a bright reddish-green glow in the sky above in the dark of night.  Surely it must have conjured up thoughts of ghosts, monsters, and gods.

Yet one can only speculate what their reaction would have been to a black aurora- an even rarer type of anti-aurora.  Surely, demons and the Devil himself must have caused such an ominously odd-colored sky.  No doubt, at the first sight of such a baleful sight fires would have been lit and chanting would have begun to ward off those evil spirits.  Of course, the fire and song always worked; soon the blackness faded away.

How could early humans know anything other than sinister speculation regarding their darkening nighttime skies?  A clever shaman could enhance his reputation by incanting the 'good spirits'during this time, knowing full-well that, no matter what strange babble came from his mouth, soon the darkness would fade away.

Using data from four Cluster Spacecraft orbiting the Earth has now likely found the secret: black auroras are actually anti-auroras. In normal auroras, electrons and/or predominantly negatively charged particles fall toward Earth along surfaces of constant magnetic field. They ionize the Earth's atmosphere on impact, causing the bright glows. In black anti-auroras, however, negatively charged particles are sucked out from the Earth's ionosphere along adjoining magnetic field lines. These dark anti-auroras can climb to over 20,000 kilometers and last for several minutes.

It must have been frightening to have been a child living during those 'dark' times with myth, superstition, ghosts and odd and dangerous spirits floating all around, waiting to take hold of of you if you were not cautious.  I wonder if parents then did the 'Santa' trick on these children, suggesting that, if they didn't kowtow to the exact demands of their parents, the sky-goblins would grab them and take them away into the dark beyond.

Lucky for us we live in times of enlightening science.  Each day, scientists bring us new insights into the 'scary' world in which we live and, with each new discovery, our fear, our anxiety, our superstitious thoughts subside.

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