This picture is of the Alpha-Monocerotid meteor outburst in 1995. The Perseid meteor shower, usually the best meteor shower of the year, peaks in August. Over the course of an hour, a person watching a clear sky from a dark location might see as many as 100 meteors. Meteors are actually pieces of rock that have broken off a comet and continue to orbit the Sun. The Earth travels through the comet debris in its orbit. As the small pieces enter the Earth's atmosphere, friction causes them to burn up.
Credit: S. Molau and P. Jenniskens, NASA Ames Research Center