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Peter Brown (Univ. of Western Ontario)
Spectacular meteor storms are among the rarest of astronomical events, being visible only once every 20 years anywhere on the planet. Of the current storm producing showers, the Leonid meteors stand alone in having produced the majority of the recorded meteor storms over the last millennium. The large 1833 storm visible over Eastern North America led to the birth of modern meteor science and the 1931 shower was the first recorded by means of radio. The parent comet of the Leonid stream is 55P/Tempel-Tuttle. The dust density in the Leonid stream is greatest near the Earth for the 3-4 years closest to the comet's perihelion passage, which occurs every 33 years. At the time of the greatest Leonid storms, the number of visible shower meteors may approach many tens per second. This high rate is a direct consequence of the high entry velocity for Leonid meteoroids (71 km/s) which allows smaller (and more numerous) Leonids to be visible to the naked eye as compared to slower sporadic meteoroids. Recent observations of the Leonids will be presented and a numerical model of the stream developed and discussed. By simulating the formation and evolution of the stream we have been able to reproduce several of its macroscopic features. By applying this model to the current stream, a broad interpretation of what might be expected of the upcoming showers of 1998 and 1999 will be given. In particular, the hazard posed to Earth-orbiting satellites by the large increase in flux of fast meteoroids which would accompany a meteor storm in either of these years will be highlighted. The uncertainties surrounding the interaction of Leonid meteoroids with satellites will also be emphasized.