Leonid meteor shower. Artwork of a major Leonid meteor shower over Stonehenge, England. Meteors are fragments of interplanetary debris that burn up as they fall through the Earth's atmosphere. The shower is caused by the Earth passing through the debris left behind in space by comet Tempel- Tuttle. It happens for two days around November 17 each year, but peaks in intensity every 33 years. The shower gets its name from the meteors appearing to emanate from the constellation Leo, seen at upper right.