Leonids are ancient history

Most of the shooting stars in the annual Leonid meteor shower are the result of tiny bits of material, the size of sand grains or peas, blown off a comet and wafting through space for centuries. The Leonids are spawned by the comet Tempel-Tuttle. Every 33 years, it rounds the Sun and then goes back to the outer solar system. On each passage across Earth's orbit, Tempel-Tuttle lays down another trail of debris, each in a slightly different location than previous trails. Over time, the debris trails spread out. Each year, Earth passes through different streams, and different parts of the streams, creating bursts of activity and slack periods in the nights surrounding the event's peak.