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Science Frontiers ONLINE No. 12: Fall 1980 |
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Anomalous Sounds From An Australian Fireball
On April 7, 1978, a very large fireball passed through the atmosphere above the east coast of New South Wales. Seen by hundreds, it generated many high quality reports. Fifteen of the written reports mentioned anomalous sounds -- hisses, hums, swishes, and crackling sounds heard simultaneously with the visual sighting. Such sounds are anomalous because the meteor is tens of kilometers high and real sound would take a minute or more to reach the ground. (The sound from a detonating meteor is often heard several minutes later.)
Keay is convinced of the reality of the anomalous sounds and suggests that the highly turbulent plasma in the meteor wake generates powerful electromagnetic radiation at audio frequencies. This intense radio energy reaches the earth at the same time the visible light does. It may be converted into sound as it interacts with the surface and the observer.
(Keay, Colin S.L.; "The 1978 New South Wales Fireball," Nature, 285:464, 1980.)
Reference. Sounds from high-altitude meteors ("electrophonic" sounds) are covered in GSH2 in our Catalog: Earthquakes, Tides, Anomalous Sounds. Information on this book is posted here.