The Leonid meteor shower occurs each year in mid-November when the Earth passes through a stream of debris left over by the comet Tempel-Tuttle. The comet orbits the sun once every 33 years and its meteor shower appears to radiate out of the constellation Leo, hence the shooting star display's name.

"We're predicting 20-30 meteors per hour over the Americas, and as many as 200-300 per hour over Asia," Bill Cooke, of the Meteoroid Environment Office at NASA's Marshall Space Flight Center.