The Leonids are named for the constellation of Leo and make an annual appearance over the Earth's skies in November. They are believed to be the remnants of the comet Temple/Tuttle. In most years, the Leonids produce a maximum of 10 to 15 meteors per hour. However, in 1966, observers saw as many as thousands of meteors per hour, according to EarthSky Communications. When a meteor enters the Earth’s atmosphere, the American Meteor Society notes, its “high level of kinetic energy rapidly ionizes” in the atmosphere, causing the light show that we observe from Earth.