A meteor streaks past the Milky Way during the annual Perseid meteor shower on Aug. 12, 2015.Fred Lum/The Globe and Mail
The Perseid meteor shower, one of summer’s most pleasing celestial rituals, reaches its annual peak on Saturday night. If the weather co-operates, those who can escape the glare of street lights have an excellent chance of spotting meteors as they dart across the night sky. In addition to falling on a weekend, this year’s shower coincides with a new moon, which ensures there will be an especially dark sky to help the meteors shine.
“It doesn’t get much better than that for convenience,” said Peter Brown, a meteor specialist and professor of physics and astronomy at Western University in London, Ont.
Working in conjunction with NASA, Dr. Brown and his colleagues have just introduced a real-time “meteor meter.” It harnesses data from cameras around the globe to measure the changing intensity of meteor showers.
On Thursday, Dr. Brown said data were already showing thousands of Perseids entering the atmosphere on the night side of the planet, over Europe. That number corresponds to between 50 and 60 meteors an hour visible to an observer under ideal conditions.
“We’re just in the ramp up right now,” Dr. Brown added. “In the next couple of days the Perseids are really going to take off.”
Meteors – also called shooting stars – are small specks of interplanetary dust that glow to incandescence as they tear through our atmosphere at speeds exceeding 100,000 kilometres an hour. Earth routinely sweeps up these particles, which collide with the atmosphere and generally burn up between 80 and 120 kilometres above the ground.
While meteors are falling steadily, both day and night, there are certain times when their incoming rate spikes dramatically.
The Perseids are the best known example of this. They originate as dust grains released by Comet Swift-Tuttle, first observed in 1862. The comet’s path cuts across Earth’s orbit and remains littered with dust, which sets the stage for the annual spectacle.
This year, the peak of the shower is projected to occur around 4 a.m. ET on Sunday morning, an ideal situation for North American viewers, who will be on the hemisphere that is facing Earth’s direction of motion at that time.
Under clear, dark skies, the rate of meteors could exceed one a minute near the peak, with dozens visible over the course of a few hours.
Though familiar to amateur stargazers, the shower is also an object of scientific study. The changing meteor flux helps researchers map the three-dimensional structure of the particle stream and improves predictions for future years. This is of interest not just to astronomers but to space agencies and satellite owners who want to know when their spacecraft are most at risk from collisions with dust particles moving 60 times faster than a bullet.
Dr. Brown said he invites citizen scientists who are able to set up online automated cameras that can spot meteors to join his network. The growing data stream is what allows the meteor meter to calculate the state of the shower from one minute to the next.
For those who are content to simply look up and enjoy the show, the best way to watch is find a comfortable spot, lie back and take in as much of the sky as possible. A view of the northern sky is preferred, since the meteors will appear to radiate from the general direction of Perseus, a northern constellation, but meteors may appear in any direction.
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