Leonid meteors occur each year as the Earth, in its annual journey around the sun, passes through the dust trail left by the Comet 55P/Tempel-Tuttle. The dust grains enter the atmosphere at high speed - 44 miles per second- and flare as they heat the air around them and vaporize. More than half will leave persistent trails. The shower, such as it is, will continue for the next few nights, with diminishing intensity. Good luck, and dress warmly.