Every November, Earth plunges headlong into a cloud of dust. The upcoming encounter could produce the most intense interplanetary dust storm observed in 33 years. A souped-up version of the annual Leonid meteor shower, this storm could put on a brilliant light show when it strikes this Nov. 17 and again on the same date in 1999. Several Web sites feature information about the Leonid storm, including predictions of its severity and graphics showing Earth's path and that of the comet Tempel-Tuttle, parent of the Leonids' dust.