Perseids facts for kids

Quick facts for kids Perseids (PER)
Perseids in 2017 as seen from the White Desert, Egypt
Pronunciation	/ˈpɜːrsi.ədz/
Discovery date	AD 36 (first record)
Parent body	Comet Swift–Tuttle
Radiant
Constellation	Perseus and Cassiopeia (near HD 19557)
Right ascension	03h 13m
Declination	+58°
Properties
Occurs during	July 14 – September 1
Date of peak	August 12 (August 13 for 2023)
Velocity	58.8 km/s
Zenithal hourly rate	100
See also: List of meteor showers

The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle that are usually visible from mid-July to late-August. The meteors are called the Perseids because they appear from the general direction of the constellation Perseus and in more modern times have a radiant bordering on Cassiopeia and Camelopardalis.

Etymology

The name is derived from the word Perseidai (Greek: Περσείδαι), the sons of Perseus in Greek mythology.

Characteristics

The radiant point for the Perseid meteor shower

A meteoroid of the Perseids with a size of about ten millimetres entering the Earth's atmosphere in slow motion (x 0.1). The meteoroid is at the bright head of the trail, and the recombination glow of the ionised mesosphere is still visible for about 0.7 seconds in the tail.
(Variant of the animation in real time)

The stream of debris is called the Perseid cloud and stretches along the orbit of the comet Swift–Tuttle. The cloud consists of particles ejected by the comet as it travels on its 133-year orbit. Most of the particles have been part of the cloud for around a thousand years. However, there is also a relatively young filament of dust in the stream that was pulled off the comet in 1865, which can give an early mini-peak the day before the maximum shower. The dimensions of the cloud in the vicinity of the Earth are estimated to be approximately 0.1 astronomical units (AU) across and 0.8 AU along the Earth's orbit, spread out by annual interactions with the Earth's gravity.

The shower is visible from mid-July each year, with the peak in activity between 9 and 14 August, depending on the particular location of the stream. During the peak, the rate of meteors reaches 60 or more per hour. They can be seen all across the sky; however, because of the shower's radiant in the constellation of Perseus, the Perseids are primarily visible in the Northern Hemisphere. As with many meteor showers the visible rate is greatest in the pre-dawn hours, since more meteoroids are scooped up by the side of the Earth moving forward into the stream, corresponding to local times between midnight and noon, as can be seen in the accompanying diagram. While many meteors arrive between dawn and noon, they are usually not visible due to daylight. Some can also be seen before midnight, often grazing the Earth's atmosphere to produce long bright trails and sometimes fireballs. Most Perseids burn up in the atmosphere while at heights above 80 kilometres (50 mi).

Peak times

The 2010 Perseids over the ESO's VLT

Historical observations and associations

A Perseid in 2007

Some Catholics refer to the Perseids as the "tears of Saint Lawrence", suspended in the sky but returning to Earth once a year on August 10, the canonical date of that saint's martyrdom in 258 AD. The saint is said to have been burned alive on a gridiron. His manner of death is almost certainly the origin of the Mediterranean folk legend claiming that the shooting stars are the sparks of Saint Lawrence's martyrdom. The legend holds that during the night of August 9 to 10, cooled embers appear in the ground under plants; these embers are known as the "coal of Saint Lawrence."

The transition in favor of the Catholic saint and his feast day on August 10 and away from pagan gods and their festivals, known as Christianization, was facilitated by the phonetic assonance of the Latin name Laurentius with Larentia.

In 1836 Adolphe Quetelet wrote: J'ai cru remarquer aussi une fréquence plus grande de ces météores au mois d'août (du 8 au 15) "I think I noticed also a greater frequency of these meteors in the month of August (from 8 to 15)." After studying historical records, he predicted a peak on 10 August. He then wrote to other astronomers, who confirmed this prediction on the night of 10 August 1837. Quetelet missed the shower due to bad weather.

In 1866, after the perihelion passage of Swift-Tuttle in 1862, the Italian astronomer Giovanni Virginio Schiaparelli discovered the link between meteor showers and comets. The finding is contained in an exchange of letters with Angelo Secchi.

Observation from the International Space Station at Earth orbit

See also

In Spanish: Perseidas para niños

• Leonids, associated with the comet Tempel–Tuttle
• Asteroid impact prediction
• Earth-grazing fireball
• List of asteroid close approaches to Earth
• Meteoroid