Science

Attention stargazers! It's time for one of the best meteor showers of the year — the Perseids

This year, the Perseid meteor shower runs from July 17 to Aug. 23, but it peaks on the night of Aug. 12-13 when, under ideal conditions, the shower could produce roughly 100 meteors per hour. However, you're unlikely to see that many or even half of them this year due to one major problem: the moon.

While a nearly full moon will make seeing faint meteors difficult, there could still be some stunning streaks

Streaks of light are seen against a starry sky.
This composite image shows several Perseid meteors streaking against the night sky, with some fireflies, right, in 2021 from eastern Ontario. (Malcolm Park)

You know that summer is winding down when it's time for the Perseid meteor shower.

The shower is considered one of if not the best of the year, mainly due to it being summer in the northern hemisphere, when the skies tend to be clear (unless there's smoke) and the weather is warmer.

This is contrary to the Geminid meteor shower, which rivals the Perseids in terms of how many meteors can be seen per hour, but occurs in December when it tends to be cloudier and much colder.

You can catch a meteor on any given night, particularly if you're outside of a city, away from light pollution. But meteor showers are special. Instead of the periodic streak against the starry sky, you can potentially see a dozen or more an hour.

When to watch 

We get this stunning and typically reliable shower each year thanks to debris left over from Comet 109P/Swift-Tuttle, which has an orbit of 133 years and was last in the inner solar system in 1992. 

Every year, Earth plows through the comet's debris, which in turn enters Earth's atmosphere, burning up as beautiful streaks in the sky.

Try this interactive map that shows how Earth passes through the meteor shower: 

Most meteor showers get their name from the constellation from which the meteors seem to originate, called the radiant. In this case the radiant is the constellation Perseus, which begins to rise in the northeast around 9 p.m. local time. 

But it's important to note that you don't have to look directly at the constellation. Just look up.

This year, the shower runs from July 17 to Aug. 23, but it peaks on the night of Aug. 12-13. On this night, under ideal conditions — dark, cloud-free, smoke-free, clear skies — the shower could produce roughly 100 meteors per hour.

However, you're unlikely to see that many or even half of them this year due to one major problem: the moon.

Down but not out

The moon will be roughly 84 per cent illuminated, which means it will wash out all but the brightest meteors.

"This year, the moon just kills them," said Peter Brown, Canada Research Chair in Planetary Small Bodies and professor at Western University's department of physics and astronomy in London, Ont. 

The other issue is smoke from wildfires. 

"It's just like cloud. It's going to decrease the the amount of light that gets through," Brown said. "So, you know, if you have the full moon and there's still quite a bit of smoke or high cloud, you're probably only looking at a handful of meteors an hour."

But the great thing about the Perseids is that they tend to produce very bright meteors and even some fireballs. As well, you can get some really good "earth grazers" — meteors that skim our atmosphere. These last longer than a typical meteor streaking across the sky.

"On the 12th, and even better, on the 13th, there'll be an hour or two right after sunset where the moon either won't be there [or] it'll be low and the radiant is low, but the activity is high enough and you'll see the grazers," Brown said. 

WATCH | An earth grazer over Missouri skies:

"You're not going to see 50 of those an hour, but you might see a handful, and they last a long time. They're super spectacular. If ever a meteor looks like fireworks, it's a grazing Perseid meteor."

So, the message is, don't give up. Grab a blanket, lie down — with the moon behind you — and look up. The Perseids rarely disappoint.

"Yes, the moon will be up. It'll be bright, but there'll be so many meteors and bright ones, you'll still see a pretty decent show," Brown said.

ABOUT THE AUTHOR

Nicole Mortillaro

Senior Science Reporter

Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at nicole.mortillaro@cbc.ca.