No. 125: Sep-Oct 1999
Around November 17 every year, meteorwatchers strain to see the Leonids dart through the night sky. The Leonids are meteors that radiate from a point in the constellation Leo. The millimeter-size bits of debris that create this annual light show are tiny fragments discarded by the comet Temple-Tuttle that burn up high in the atmosphere. Astronomers are secure and comfortable with this explanation of the mid-November spectacle. Perhaps they shouldn't be.
In November 1998, an intriguing anomaly cropped up -- way up, 120 miles up! Leonids were seen to burn up at this altitude where there is not enough atmosphere to create the friction required to vaporize the space debris. Perhaps the cometary fragments from comet Temple-Tuttle are unusually volatile. Perhaps there is something else going on at the outer fringes of the atmosphere. Who knows?
(Witze, Alexandra; "Scientists Gain Insights into Meteors," Northwest Florida Daily News, May 27, 1999. Cr. B. Reid)
Comments. Sometimes, comets flare up so far from the sun that solar heating is negligible. This poorly understood phenomenon may be related to the highaltitude flare-ups of the Leonids.
Some people claim they can sometimes hear meteors hiss as they streak through the sky at altitudes so high that there is not enough air to convey sound! Such "electrophonic sounds" may have an electromagnetic origin; that is, some people perceive electromagnetic bursts as sounds.