The Perseid meteor shower is the most famous annual display of "shooting stars." It typically occurs between July and August, when it's both dark and warm in the Northern Hemisphere. Depending on conditions, it's an ideal time to plan camping trips, star parties and backyard stargazing sessions, but it pays to know exactly what to do and when to do it.
Here's everything you need to know about the Perseid meteor shower and how to watch it.
What are "shooting stars"?
Shooting stars are not stars. Rather, they're tiny rock particles called meteoroids that strike Earth's atmosphere about 60 miles (97 kilometers) from the ground. As they do, they energize and release that energy as photons, or packets of light, that we call shooting stars. Meteoroids that enter Earth's atmosphere are called meteors, and they streak across the sky at blazing-fast speeds; the Perseids, for example, travel through the atmosphere at 133,200 mph (214,360 km/h), according to the American Meteor Society.
Meteor showers occur when our planet moves through a dense stream of dust and debris left in the inner solar system by a comet or, occasionally, an asteroid.
What is the Perseids meteor shower?
The Perseids are the most famous meteor shower of all. They appear between July 14 and Sept. 1 each year, peaking around Aug. 11, 12 or 13. All meteor showers have a night of peak activity when you can expect to see the most "shooting stars", but while some of these intervals can be very brief, the Perseids' peak is fairly prolonged. That's helpful because if it's cloudy on the peak night you can always look to the skies the night after. During the Perseids' peak, it's possible to see 100 meteors per hour, according to NASA.
What causes the Perseid meteor shower?
The dazzling light show is caused by comet 109P/Swift-Tuttle, which was last in the solar system in 1992 and won't return until 2126. Some comets (like Halley's comet) produce multiple meteor showers, but 109P/Swift-Tuttle produces only one. "The peak occurs when the Earth passes closest to the core of the many comet orbits produced by 109P/Swift-Tuttle as it passes through the inner solar system," said Robert Lunsford, a fireball report coordinator at the American Meteor Society. "We rarely strike one of these debris streams exactly — and if we do, rates will be stronger than normal."
Why the Perseid meteor shower is the most well-known
The Perseids are certainly pretty, but their fame has more to do with their convenience than the sheer number of them.
"It's strictly because they peak during the summertime for observers in the Northern Hemisphere," Lunsford told Live Science. "The other stronger showers all occur in autumn/winter for the Northern Hemisphere." The most prolific meteor showers are the Geminids, which peak around Dec. 13 and 14, and the Quadrantids, which peak around Jan. 3 and 4. However, because of the cold conditions and reduced chance of a clear sky, far fewer folk attempt to watch these showers.
How to watch the Perseids meteor shower
There are two things you need and three things you don't need to see the Perseids meteor shower. Good timing and patience are essential — you need to be outside just after midnight on the night of peak activity and be prepared to do a late shift through 5 a.m. However, clouds, a bright moon and light pollution are your enemies. Clouds aren't something you can change and whether the moon will be bright is also out of your control, but you can find a dark sky by visiting a Dark Sky Place or consulting a light pollution map.
Sit in a lawn chair or lay on a blanket on the ground and look up. Allow about 30 minutes for your eyes to adjust to the dark. Don't use telescopes or binoculars and don't look at your smartphone because its white light interferes with night vision. "Shooting stars" from the Perseid meteor shower can appear anywhere in the night sky. However, they appear to originate from the constellation of Perseus, which is rising in the northeastern night sky during August as seen from the Northern Hemisphere.
The Perseids and "fireballs"
In 2022, the peak of the Perseid meteor shower will be greatly affected by the Sturgeon supermoon, which will blot out all but the very brightest "shooting stars." However, all is not lost. It will still be one of the best nights of 2022 for seeing meteors, especially since the Perseids often feature some particularly bright "fireballs."
A fireball, or "bolide," is a large and consequently very bright meteor — sometimes as bright as Venus — that are relatively rare, but are visible even in a night sky bleached by either man-made light pollution or moonlight.
"The more particles released by the comet, the better chance that some of these will be large enough to produce fireballs," said Lunsford. "It's not the best fireball producer, but the Perseids is certainly one of the most reliable sources." Fireballs can have a wake that lasts about a second, making them an unforgettable sight.
Why the Perseids are so prolific
According to the American Meteor Society, the maximum number of "shooting stars" that the Perseids typically deliver is about 100 per hour, though that's under a perfectly dark sky with a 360º view. But it's not uncommon to see 30 or so "shooting stars" per hour during the Perseids' peak night. The Perseids are so prolific because the parent body, comet 109P/Swift-Tuttle, has such a large nucleus, measuring 16 miles (26 km) in diameter.
"It has made many passes through the inner solar system shedding a lot of debris that now populates the entire orbit of the comet," said Lunsford. "Because of this, each year is guaranteed to produce a decent display with little variation."
The Perseids won't change much in the 21st century, even though its parent body isn't set to return to the solar system for another 100 years. It may wane by about 25% when the comet is farthest from the sun, but since material has spread throughout the entire orbit, the difference won't be that much, according to Lunsford.
Perseid meteor shower 2022, 2023 and 2024
Meteor showers all have peak rates when the rate of activity maximizes, but the exact time and date changes from year to year. That's because Earth takes 365.25 days to return to the exact same spot in its orbit.
"This extra .25 day adds six hours to the time of maximum activity," said Lunsford. That means the Perseid maximum is predicted to occur at different times each year:
- 01:00 UT on Aug 13, 2022
- 07:00 UT on Aug. 13, 2023
- 13:00 UT on Aug 12, 2024
"It flips back to Aug. 12 in 2024 due to the additional day added to February in a leap year," he said. "Observations of the peak times each year helps us determine a more precise prediction for following years."
Originally published on Live Science.
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Jamie Carter is a freelance journalist and regular Live Science contributor based in Cardiff, U.K. He is the author of A Stargazing Program For Beginners and lectures on astronomy and the natural world. Jamie regularly writes for Space.com, TechRadar.com, Forbes Science, BBC Wildlife magazine and Scientific American, and many others. He edits WhenIsTheNextEclipse.com.