How many Perseids will I see in 2021?

By Bill Cooke, NASA Meteoroid Environments Office

Many Perseid-related news stories and social media posts state that the maximum rate is about 100 meteors per hour, which is a lot. So, folks get excited and go out on the peak night, braving mosquitos and other nightly hazards. But they are often disappointed; we routinely hear, “I went out and only saw a few meteors. Not even 20, much less 100!” And they would be right. The problem is that the 100 per hour is a theoretical number used by meteor scientists and does not convey what people are actually going to see.

In the 1980’s, meteor researchers were searching for a way to compare the meteor shower rates observed by various individuals and groups across the globe. People were reporting the rates, but the differences in sky conditions, radiant altitude and observer eyesight made getting a comprehensive view of shower activity difficult.

So, the meteor researchers put their heads together and came up with the concept of a ZHR, or Zenithal Hourly Rate. The ZHR is what you get after you correct the observed rates for the sky conditions, the altitude of the radiant above the horizon and observer biases. In other words, it is basically what a perfect observer would see under perfect skies with the meteor shower radiant straight overhead – which never happens!

The often-quoted ZHRs overestimate the meteor rates people actually see – sometimes by a lot. Fortunately, we can take the ZHR and invert things to get the hourly rates for certain locations and circumstances – it’s only math, after all. We have done this for select locations in the United States, producing the following maps.

These maps show the hourly rates that can be expected on the night of the Perseid shower’s peak, provided there are no clouds in the sky. (It’s hard to account for partial cloud cover.)

These rates assume you are out in the country, where lots of stars and the Milky Way are visible and no clouds, of course:

Perseids in CountrySo, instead of 100 Perseids per hour, people in the U.S. can reasonably expect to see around 40-ish Perseids in the hour just before dawn on the peak nights. That’s about one every couple of minutes – not bad. However, we are assuming you are out in the country, well away from cities and suburbs.

What rates can you expect if you want to do your Perseid watching from the neighborhood? We also computed that:

Perseids in SuburbsThe brighter skies of the suburbs greatly cut down the rates. We have gone from a Perseid every couple of minutes to one every 6-7 minutes – a factor of three reduction. This explains the great disappointment expressed by many casual Perseid watchers; they go outside, expecting to see at least a meteor a minute and end up with 10 or less in an hour. The brightness of your sky is everything in meteor observing – you have to get away from the lights!

But what about those in cities? The rates are close to zero:

Perseids in CityUgh! City dwellers might see a Perseid or two in an hour. Not very inspiring. Perhaps the only good news is that, if someone in a city sees a Perseid, it has to be really, really bright and spectacular.

Want to see Perseids? Then head out into the dark – it’s worth it!

Check out our previous blog post, The Perseids are on the Rise, for more information on the Perseids and tips on how to observe them.

The Perseids are on the Rise!

It’s time again for one of the biggest meteor showers of the year! The Perseids are already showing up in our night skies—and when they peak in mid-August, it’s likely to be one of our most impressive skywatching opportunities for a while.

Perseid Meteor image
In this 30 second exposure taken with a circular fish-eye lens, a meteor streaks across the sky during the annual Perseid meteor shower on Friday, Aug. 12, 2016 in Spruce Knob, West Virginia. Photo Credit: (NASA/Bill Ingalls)

Our meteor-tracking cameras spotted their first Perseid on July 26, but your best chance to see them will start the night of Aug. 11. With the crescent moon setting early, the skies will be dark for the peak viewing hours of midnight (local time) to dawn on Aug. 12.

Perseid activity
This chart shows expected levels of Perseid activity for July and August 2021, relative to the peak on Aug. 11-13, ignoring the effects of the Sun, Moon, and clouds. All times are in UTC. Credits: (NASA/MEO/Bill Cooke)

If you’re in the Northern Hemisphere, and far away from light pollution, you might spot more than 40 Perseids an hour! (If you’re in a city, you may only see a few every hour; skywatchers in the Southern Hemisphere will also see fewer Perseids, with none visible below about 30 degrees south latitude.) The night of Aug. 12-13 will be another great opportunity to see the Perseids: with a full Moon (and lower meteor activity) during the Perseids’ peak in 2022 and a waning crescent high in the sky for 2023, this might be your best chance to do some summer skywatching for a few years.

Find somewhere comfortable, avoiding bright lights as much as possible (yes, including your phone), and give your eyes some time to adjust to the dark—up to half an hour if you can. The Perseids will appear as quick, small streaks of light: they get their name because they look like they’re coming from the direction of the constellation Perseus (near Aries and Taurus in the night sky), but Perseids in that area can be hard to spot from the perspective of Earth. So just look up and enjoy the show!

If you can’t see the Perseids where you live, join NASA to watch them on social media! Tune in overnight Aug. 11-12 (10 PM–5 AM CDT; 3–10 AM UTC) on Facebook, Twitter and YouTube to look for meteors with space fans from around the world. If skies are cloudy the night of Aug. 11, we’ll try again the same time on Aug. 12-13. Our livestream is hosted by the Meteoroid Environment Office at NASA’s Marshall Space Flight Center, which tracks meteors, fireballs, and other uncommon sights in the night sky to inform the public and help keep our astronauts and spacecraft safe.

Where do the Perseids *actually* come from?

The Perseids are fragments of the comet Swift-Tuttle, which orbits between the Sun and beyond the orbit of Pluto once every 133 years. Every year, the Earth passes near the path of the comet, and the debris left behind by Swift-Tuttle shows up as meteors in our sky. (Don’t worry, there’s no chance that we’ll run into the actual comet anytime soon.)

Where can I go to learn more?

We’ve got some great space-rock lessons for students, starting with the biggest question: what’s the difference between an asteroid and a meteor? Our NASA Space Place site also has a kid-friendly introduction to meteor showers in general. If you’re looking for something a little more hands-on, try this asteroid-building classroom activity—or, for an older audience, learn how to describe rocks like a NASA scientist.

And, if you want to know what else is in the night sky this month, check out the video below from Jet Propulsion Laboratory’s monthly “What’s Up” video series:

Happy skywatching!

by Brice Russ

Look Up! Perseid Meteor Shower Peaks Aug. 11-12

Make plans now to stay up late or set the alarm early next week to see a cosmic display of “shooting stars” light up the night sky. Known for it’s fast and bright meteors, the annual Perseid meteor shower is anticipated to be one of the best potential meteor viewing opportunities this year.

The Perseids show up every year in August when Earth ventures through trails of debris left behind by an ancient comet. This year, Earth may be in for a closer encounter than usual with the comet trails that result in meteor shower, setting the stage for a spectacular display.

“Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. “Under perfect conditions, rates could soar to 200 meteors per hour.”

An outburst is a meteor shower with more meteors than usual. The last Perseid outburst occurred in 2009.

How to Watch the Perseids

The best way to see the Perseids is to go outside between midnight and dawn on the morning of Aug. 12. Allow about 45 minutes for your eyes to adjust to the dark. Lie on your back and look straight up. Increased activity may also be seen on Aug. 12-13.

For stargazers experiencing cloudy or light-polluted skies, a live broadcast of the Perseid meteor shower will be available via Ustream overnight on Aug. 11-12 and Aug. 13-14, beginning at 10 p.m. EDT.

Read more about the Perseids here.

An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image. Stargazers expect a similar outburst during next week’s Perseid meteor shower, which will be visible overnight on Aug. 11 and 12. Credits: NASA/JPL
An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image. Stargazers expect a similar outburst during next week’s Perseid meteor shower, which will be visible overnight on Aug. 11 and 12.
Credits: NASA/JPL

Perseid Peak Performance

The All Sky camera network captured over 183 multi-station Perseid meteors Saturday night. Some truly spectacular events — see images below.

 The Perseids have been observed for at least 2,000 years and are associated with the comet Swift-Tuttle, which orbits the sun once every 133 years. Each year in August, the Earth passes through a cloud of the comet’s debris. These bits of ice and dust — most over 1,000 years old — burn up in the Earth’s atmosphere to create one of the best meteor showers of the year.