For many years astronomers have been pretty certain that the Aurora Borealis is caused by something, presumably hydrogen, that is shot out of sunspots. For one thing, bright auroras generally appear about 15 hours after a sunspot has moved to a point on the sun directly opposite the earth. But proof was lacking; even the brightest auroras were too faint and diffuse to be studied spectrographically by existing instruments. Last week the proof was in hand: a few smudged bands on two photographic plates.
For four years Astronomer Aden B. Meinel of the University...
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