Peak of the beloved Perseid meteor shower will dazzle skywatchers: NPR

The Perseid meteor streaks across the sky above desert pines on Aug. 13, 2015, in Spring Mountains National Recreation Area, Nevada.

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The annual Perseid meteor shower – the most popular of the year – has already begun, with most of the meteors expected to fall around August 11 when the shower peaks.

The Perseid meteor shower occurs every year when Earth passes through a stream of space debris left behind by a large comet called Swift-Tuttle. The debris, traveling at speeds exceeding 100,000 miles per hour, slams into the planet’s atmosphere, creating rapid streaks of light and sometimes dramatic fireballs.

Here’s what you need to know, and how to attend the show.

Aim for the dark sky, and adjust your eyes.

The greatest activity this time is expected to occur on the night of August 11 and into the early morning hours of August 12, he says. Hunter Millera public observing instructor at the Adler Planetarium in Chicago, notes that viewing is best under a dark sky, away from artificial light and a bright moon.

“This year isn’t necessarily the best year when it comes to the moon, but it’s not too bad because the moon will be far from where the Perseids are in the sky,” Miller says.

He added that the moon will set around midnight on the day when the cloud cover reaches its peak.

“The later you go out, the better the views, the darker the sky,” he says. “With the moon setting, the sky will be quite dark.”

He recommends looking north and giving your eyes at least 30 minutes to adjust to the dark — and warns that looking at a bright phone screen “will basically undo all the time you spent trying to let your eyes adjust to the dark.”

“You want to get as wide a view of the sky as possible,” Miller says. “Sit down, pull out your lawn chair. My favorite part about meteor showers is that they don’t really require much.”

If clouds prevent people from seeing the Perseids at their peak, views should also be good in the days immediately before and after, he says. Peter Browna researcher at the University of Western Ontario who studies meteorites.

The Perseid meteor shower is seen over the Ulan Bum Grassland in Chifeng City, Inner Mongolia, China, on August 14, 2023.

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“With some meteor showers, if you miss the night of peak or even an hour or two away from peak, there’s nothing. But that’s not the case with the Perseids,” he says. “The Perseids are so big and so extended that you can see them within a day or two of peak, and still see a really dazzling display.”

Small rocks, big flash

Almost all of the debris falling from a comet is tiny. However, anything the size of a grain of sand can create a streak of light that can be seen from Earth, about 60 miles below, because it is falling at such high speed.

“You don’t see the rock itself, you see all the light and heat that is produced as it passes through the atmosphere,” Brown says.

He says the largest incoming rock anyone can see during a Perseid impact is typically on the order of a few grams and less than half an inch across.

But this meteorite shower sometimes includes larger rocks.

To see the full range of sizes that hit Earth during the Perseids, Brown and some colleagues recently used a lightning mapping tool on a satellite to monitor the flashes of light that occurred during these meteor showers.

“We detected very bright Perseid fireballs over the entire Earth,” Brown says.

He and his colleagues calculated that the largest Perseid meteors ever recorded could weigh about 20 pounds. Given the meteorites’ density, these space rocks could be smaller than soccer balls.

“This is the largest ever,” he says, adding that rocks that size would burn up completely in the atmosphere, creating a meteor streak brighter than a full moon.

However, most of the larger Perseids go unobserved, because they are rare and because much of the planet is covered by water and uninhabited land.

“People rarely see something this bright, but it’s not unusual,” Brown says. “If you go out and watch year after year, you might eventually see Perseids that rival the full moon. But these meteors are rare.”

Typically, the decent-sized meteor shower we see during the Perseids comes from a rock weighing about one gram, or about the weight of a raisin. These meteors can rival the brightness of Venus.

“There are quite a few of these meteors,” Brown says. “In fact, at the peak of the Perseids at night, you might see a few of them — three, four, five — per hour.”