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The Perseid meteor shower is among the finest annual meteor showers, always reliable, producing a flux of fast and bright meteors. This year's event peaks on the nights of August 11-12 and August 12-13. The best time to look is during the early morning hours, and on this occasion it's extremely favourable as the new Moon will not interfere. At peak of about 60 meteors per hour are predicted. Recent analysis by NASA has rated the Perseids as the best meteor shower when it comes to fireballs.

The Perseids favour northern based observers. For those at southern locations, the radiant remains close to or never rises above the horizon. This considerably reduces the amount of visible meteors, although it's possible to spot some of them coming up above the northern horizon.

A Perseid flashes through the sky (credit - Andreas Möller via wikimedia.org)

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 1000 years old, although some parts may be considerably younger. When the Earth passes through a replenished dust area the meteor rate often increases dramatically.

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.

Radiant

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, which is close to the famous Double Cluster (NGC 869/NGC 864) and the Cassiopeia constellation border.

Perseids Radiant and Star Chart (credit - freestarcharts)

Perseids Radiant and Star Chart - pdf format (credit - freestarcharts)

Perseid radiant as seen early morning during August from mid-northern temperate latitudes (credit - stellarium/freestarcharts)

What to expect

The meteors are visible from about July 17th to August 24th. Rates start slow but then shoot up from August 8th/9th until the peak date, after which they fall off quite dramatically. To spot as many Perseids as possible find a dark observing site with an unobstructed view of the sky. Then scan a large area surrounding the radiant without directly looking at it. The reason being that although the meteors originate from the radiant they often actually appear many tens of degrees from it.

Perseids Data Table 2018

Meteor shower namePerseids
Radiant constellationPerseus
ActivityJuly 17th -> August 24th
Peak DateAugust 12th
RA (J2000)02hr 27m
Dec (J2000)+58d
Speed (km/s)59
ZHR 100
RatingBright
Parent body109P/Swift-Tuttle
NotesProlific meteor shower that was first recorded in 36 AD

Comet 109P/Swift-Tuttle Data Table (at epoch April 18, 2013)

Name109P/Swift-Tuttle
TypeComet
ClassificationHalley-type comet (NEO)
DiscovererLewis Swift / Horace Parnell Tuttle
Discovery dateJuly 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
NotesAlso known as Comet Swift-Tuttle