A loud boom and bright light seen in the sky Sunday night over Vancouver Island was likely a meteor, says a seismologist with the Geological Survey of Canada.
John Cassidy, also a professor at the University of Victoria, often investigates loud “booms” associated with mining blasts or blomides—exploding meteors—even though his specialty is studying ground-based factors like earthquakes.
“It’s really just an airwave or sound wave” that rattles the windows when a meteor enters Earth’s atmosphere, much like how an airplane breaking the sound barrier creates a boom, he explained.
Sean Baxandall was driving south in the Willow Point area of Highway 19A south of Campbell River when his dashcam caught a bright light moving through the sky. “From where we were it looked like it landed in the ocean, but it was hard to tell,” he said.
Numerous people south of Nanaimo said they heard a loud bang that rattled their windows. Constance Leverton was making dinner in her Maple Bay home Sunday night when she heard a big boom. “It was loud with all the windows closed,” she said.
Other neighbours quickly chimed in on a local Facebook page about their experiences hearing the noise too.
Reports started hitting social media after 5 p.m. from as far south as Victoria and as far north as Campbell River on the Island from people who either heard the boom, saw a bright light travelling through the sky or both. Alberni Valley News reporter Elena Rardon was driving back to Port Alberni from Beaver Creek when she saw a bright yellowish light, moving fast in the direction of Mt. Arrowsmith.
“I assumed it was a firework, but it was travelling down instead of up,” she said. “It was very bright and moved fast.”
Cassidy said the first-hand accounts point to a classic exploding meteor, or bolide. “An exploding meteor makes the most sense, seen and heard over a large area—but no significant group shaking,” he said. “We see these types of events—exploding meteor—every now and then. They are often associated with loud booms, flashing lights and rattling windows from the air wave.”
The reason some people in the North Island saw a bright flash of light and others down-Island heard the boom at a slightly delayed time is the same principle with lightning, Cassidy said: the speed of light is faster than the speed of sound. “It’s like lightning: there’s quite a delay from seeing the flash and hearing the explosion (thunder).”
He said the event also likely happened kilometres up in the air.
One possible reason for the meteor appearing on Sunday was the expected Geminid meteor shower estimated to occur Dec. 13–14. Astronomy educator and Royal Astronomical Society of Canada columnist Gary Boyle explained that meteor showers occur at the same time every year because they are usually produced by a comet that rounds the sun.
The Geminids, according to Boyle, are not caused by a comet but rather by debris from a 5.8-kilometre diameter asteroid named 3200 Phaethon. He called the Geminid meteors “earth grazers” because they typically don’t enter the atmosphere.
A meteor is a “space rock” or meteoroid that enters Earth’s atmosphere at a high speed and burns up, causing a “shooting star” in the sky. A meteorite, according to NASA Science, is a meteoroid that survives a trip through the atmosphere and hits the ground. It is not common for meteorites to make it all the way to the Earth’s surface.
Cassidy and his seismology colleagues meanwhile will be looking at ground recordings from many different reporting sites to see whether Sunday’s “boom” registered.
“If it’s big enough to generate any sort of ground shakes, which is going to be minute compared to an earthquake…it gets complicated because it’s coming from a sound wave.”
Cassidy said he studied seismic recordings a few years ago when pieces of a meteor actually landed in northern Alberta—a rarity. “We had one that generated some really large seismic waves,” he said. Scientists were able to look at the recordings and determine an approximate location where the meteorite landed, and material was actually recovered.
“They’re really interesting events,” Cassidy said of meteor sightings. “If a chunk of rock survives they’re really important for our astronomy colleagues to better understand the universe.”
— With files from Aaron Hinks, Black Press