(pûr'sē-ĭdz) is a prolific meteor shower
associated with the comet Swift-Tuttle
. The Perseids are so called because the point they appear to come from, called the radiant
, lies in the constellation Perseus
. Meteor showers occur when Earth
moves through a meteor stream. The stream in this case is called the Perseid cloud and it stretches along the orbit of the Comet Swift-Tuttle
. The cloud consists of particles ejected by the comet as it passed by the Sun
. Most of the dust in the cloud today is approximately a thousand years old. However, there is also a relatively young filament of dust in the stream that boiled off the comet in 1862. The rate of meteors originating from this filament is much higher than for the older part of the stream.
The Perseid meteor shower has been observed for about 2000 years, with the first known information on these meteors coming from the Far East. In early medieval Europe, the Perseids came to be known as the "tears of St. Lawrence
The shower is visible from mid-July each year, with the greatest activity between August 8 and 14, peaking about August 12. During the peak, the rate of meteors reaches 60 or more per hour. They can be seen all across the sky, but because of the path of Swift-Tuttle's orbit, Perseids are primarily visible in the northern hemisphere.
The shower peaked on the new-Moon night of Sunday–Monday, August 12
and had an observed ZHRmax
The Perseids were active from July 17 to August 24, 2008. On August 13th, the observed ZHRmax
was 116 (at 20:10 UT)