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Science Frontiers ONLINE No. 81: May-Jun 1992 |
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Auroral Sounds
March 13, 1989. This night on a cattle ranch in South Dakota, L. Hasselstrom was dazzled by waves of blue auroral light sweeping up from the horizon and meeting at a focal point nearly directly overhead. As the sky blazed, with the blue waves and crimson streamers, she heard:
"...a distant tinkling, like bells. It came again, louder, just as a curtain of green light swept the entire width of the sky from north to south. Each time green flushed the sky, the bells rang, the sound softening to a gentle tinkle as the light died."
(Hasselstrom, Linda; "Night of the Bells," Readers Digest, p. 185, April 1992. Cr. J.B. Dotson.)
Comment. Note the correlation of the sound with the green portion of the aurora.
July 29, 1990. On Coll Island in Centennial Lake, 120 kilometers west of Ottawa. Watching an auroral display, L.R. Morris heard the sound of the aurora:
"It was a faint but distant windlike sound; which, by process of elimination, could not be accounted for by any phenomenon other than the aurora."
(Anonymous; "Auroral Sounds," Sky & Telescope, 83:105, January 1992. Cr. D. Snowhook.)
Comment. Auroras have been heard for centuries, but they "shouldn't be." Current theory restricts auroral activity to altitudes above 50 miles, where a fair vacuum prevails, and sound generation and propagation are impossible. One explanation for auroral sounds is that intense electromagnetic waves created by the auroras sweep through the observer's brain and are rendered as sound (electrophonic sound). But perhaps some auroras reach down lower into the atmosphere than theory allows. See GSH3 in our catalog: Earthquakes, Tides, Unidentified Sounds. To order, visit: here.