Cowering beneath a parked car, we were witnesses to a Leonid meteor shower at its peak. The phenomenon occurs when the earth crosses the orbit of comet Temple-Tuttle, which spends most of its time in deep space in a highly elliptical orbit around the sun. Every 33 years it returns, making a close, fast encounter with the solar system, only to be flung into deep space again. As far out as it travels, it is still under the influence of the gravity of the sun, hence its periodic return. The debris cloud, mostly particles ranging in size from house dust to sand, lags behind the comet throughout its orbit, being replenished with each solar encounter.
Earth experiences several meteor showers per year, many with calendar precision.
The famous Perseid showers of August occur every year because their parent comet is very old, and the debris cloud fills its entire orbit. However Temple-Tuttle is quite young, only about 200,000 years. Its cloud hasn't had time to fill the entire orbital path. Although earth crosses its path every year, for many years the showers are absent. The tiny Temple-Tuttle was rediscovered last January, and made a close pass by earth and sun in February, replenishing its short but dense debris field.