So we are approaching the predicted time for the next storm. The odds favor 1999, but predicting the Leonids is harder than predicting the weather, and there is no way to tell for certain which part of our planet will get to see the peak when it does happen. This year, the first-quarter moon will set around 1 a.m. local time, leaving the sky clear in the early morning hours when the constellation Leo the Lion will rise in the east. The Leonid meteor shower seems to come from a point in Leo, which gives the meteors their name. This is when Earth will cross the orbit of Comet Tempel-Tuttle, the comet that provides the particles from which the Leonid meteors come.
Most meteor showers happen when Earth crosses the orbit of a comet.
The meteors are caused by tiny particles of dust and other debris that were released from the comet's nucleus and left behind in space as the comet got closer to the sun. As Earth plows through this stream of particles, each one collides with our upper atmosphere at tremendous speed and burns up almost instantly from friction with air molecules. Comet Tempel-Tuttle passed by Earth's orbit in March 1998, so there is a chance that thousands of meteors and fireballs will appear to stream from Leo as in the great Leonid storms of the past. However, any meteor storm will last no more than a few hours and perhaps less than one hour. Only observers in the region of the planet that is facing into the particle stream and also in darkness will be able to see the storm when it hits.