A major meteor shower
visible for a week or so before and after peaking on August 12 each year,
the date on which the Earth crosses the orbit. The maximum hourly rate is
about 70 meteors. They appear to radiate from the constellation Perseus,
from which they take their name. This shower is associated with comet
Swift-Tuttle (discovered in 1862, reappeared in 1992) and consists of
debris left by the comet along its orbit. Typical velocity of a Perseid
meteor is about 68 km (42 mi) per second.