The Perseid meteor shower is one of the finest annual meteor showers that's almost always reliable and produces a flux of fast and bright meteors. This year's maximum occurs on August 12th at 19 UT, although the 75% illuminated waning gibbous Moon in Pisces will interfere. The best time to look for meteors is during the early morning hours. The Perseids usually produce up to 80 meteors per hour at peak time. In addition, reasonable activity is also expected on the nights of August 11th/12th and August 13th/14th from all Northern Hemisphere locations. Recent analysis by NASA has rated the Perseids as the best meteor shower when it comes to fireballs.
For those at southern locations, the radiant remains low down or never even rises above the horizon. This considerably reduces the amount of visible meteors, although it's possible to spot a few of them coming up above the northern horizon.
Discovery and Parent Body
The Perseids meteor shower is associated with comet 109P/Swift-Tuttle (Swift-Tuttle), a Halley-type comet with an orbital period of 133 years. It's believed that most of the dust in the meteor cloud today is about 1,000 years old although some parts may be considerably younger. When the Earth passes through a replenished dust region the meteor rate often dramatically increases.
Chinese observers first recorded the Perseids in 36 AD. Lewis Swift discovered comet Swift-Tuttle on July 16, 1862 followed independently by Horace Parnell Tuttle three days later. Computations made by Italian astronomer Giovanni Schiaparelli between 1864 and 1866 revealed a strong resemblance between the meteor stream and the cometary orbit, providing a definite association for the first time.
The radiant is the point in the sky where the meteors appear to originate from. The Perseid radiant is in Perseus at Right Ascension (RA) = 02hr 27m, Declination (DEC) = +58 degrees. This is close to the Double Cluster (NGC 869/NGC 864) and the Cassiopeia constellation border.
What to expect
The meteors are visible from about July 17th to August 24th. Rates start slow but then shoot up from August 8th until the peak date after which they fall off quite dramatically. To spot as many Perseids as possible find an observing site with an unobstructed view of the sky. Then scan a large area surrounding the radiant without looking directly at it. The reason is although the meteors originate from the radiant they often appear many tens of degrees from it. On maximum night, the Moon rises about an hour before midnight. Try to keep the Moon out of view either behind a building or some trees or with your back to it. This will minimise the interference.
Perseids Data Table 2017
|Meteor shower name||Perseids|
|Activity||July 17th -> August 24th|
|Peak Date||August 13th|
|RA (J2000)||02hr 27m|
|Notes||Prolific meteor shower that was first recorded in 36 AD|
Comet 109P/Swift-Tuttle Data Table (at epoch April 18, 2013)
|Classification||Halley-type comet (NEO)|
|Discoverer||Lewis Swift / Horace Parnell Tuttle|
|Discovery date||July 16th, 1862|
|Aphelion distance (AU)||51.2246|
|Perihelion distance (AU)||0.95952|
|Orbital period (years)||133.285|
|Last perihelion||December 11th, 1992|
|Next perihelion||March 26th, 2126|
|Notes||Also known as Comet Swift-Tuttle|