On the Fine Structure in the Fireballs Peak of the 1998 Leonids
  The Leonids meteor shower of November 1998 has shown a double activity. An unexpected shower of fireballs occurred about 16 hours before the expected maximum of the meteor activity. The activity profile of the fireball shower revealed also a fine structure. The hypotesis of tidal origin of such sub-structures is discussed. The close encounter of the meteoroid stream with the Earth in 1366 and the encounters with Saturn (in 1630) and Jupiter (in 1732), are identified as the cause of the main features of the structure. Such analysis can be applied to the incoming 2000 Leonids' display. 
Costantino Sigismondi (Yale University, Dept. of Astronomy,   Astronomical Observatory of Rome and ICRA, International Cente...