They faithfully return year after year. For many, they signal summer holidays and warm nights under the stars. But who—or what exactly—are they? The Perseid meteors, of course!
Each year around mid-August, Earth passes close to the orbit of periodic comet 109P/Swift-Tuttle. The comet’s trail, filled with billions of dust particles, produces the famous Perseid meteor shower.
However, the quality of the celestial show can vary dramatically from year to year, depending not only on Earth’s distance from the densest parts of the particle stream, but also on the presence of the Moon.
The Perseids in 2025
This year’s Perseids will take place under very good astronomical conditions. The “classic” peak of this shower is expected on August 13 from 4 to 8 a.m. EDT—which is early daytime in North America. However, observations from the last few years show there is some variability in when Earth comes closest to the dust stream from comet Swift-Tuttle, which swings through the inner Solar System every 133 years.
Considering the time of expected peak, the most favourable night for observers in Eastern Canada will be August 12 to 13. If weather conditions don’t cooperate, the nights before and after are also worth watching.
This year, the Moon will—unfortunately—be full on August 9, rising around 9:30 p.m. EDT. It will interfere with viewing during the most favourable hours, when the radiant reaches its highest point in the northeast during the second half of the night and just before dawn. Under clear, reasonably dark skies with good transparency, away from light pollution, you could expect to see up to 50 meteors per hour on the evening of August 12. Let’s hope for great weather for the occasion!
Observing over several days
In recent years, secondary peaks have also been observed, including an intense burst of activity that sometimes occurs a day and a half after Earth crosses the nominal centre of the stream. Keep an eye out on the night of August 14 to 15.
Observations spanning several days are needed to study this complex meteor stream, which still holds many surprises.
The Perseids are active from late July through the third week of August, though at much lower rates. The radiant of this meteor shower rises above the northeast horizon in the evening and continues climbing higher in the sky through the night. This is why the number of visible meteors steadily increases over the course of the night, until daybreak puts an end to your observing session.
Don’t forget, if you’re heading out to watch with friends: bring comfy lounge chairs, some blankets, your favourite beverages—and your wish list!
