The Perseids — the shooting star spectacular that peaks tonight — produces more fireballs than any other annual meteor shower, NASA says.
The Perseid meteor shower can be viewed early- to mid-August every year. Its peak officially occurred around mid-day on Aug. 12 in North America, which means that early on the morning of Aug. 13 is one of the best time to view the meteors. The meteor rate will be highest before sunrise when the constellation Perseus, where the meteors appear to originate, is high in the sky, NASA says.
The U.S. space agency recommends watching for the meteors between 10:30 p.m. and 4:30 a.m. local time, with the expectation that the rate of meteors will start off low and increase toward dawn.
In rural and remote areas where the sky is dark, sky watchers may be able to see more than 100 meteors or "shooting stars" per hour, although a rate of 50 to 60 is more typical.
And with the Perseids, people are particularly likely to see spectacular meteors called fireballs that are as bright or brighter than the planets Jupiter or Venus, NASA says.
568 Perseid fireballs since 2008
In July, the U.S. space agency released counts of all the fireballs seen from Earth between 2008 and 2013 from a network of meteor cameras across the southern U.S. It found that the Perseid meteor shower produced 568 fireballs over that period. The runner-up, the Geminid meteor shower in December, produced 426, and other meteor showers produced far fewer.
The Perseids beat out the Geminids not just in quantity, but also quality, said Bill Cooke who heads NASA's Meteoroid Environment Office, on the NASA Science News website: "On average, Geminid fireballs are about a magnitude fainter than those in the Perseids."
The Perseid meteor shower is caused by the Earth passing through debris left behind by the Comet Swift-Tuttle. As pieces of the comet hit the atmosphere, they burn up, producing a bright glow.
Most other meteor showers are caused by comets much smaller than the 26-kilometre wide Swift-Tuttle. Cooke suggested that is why the Perseid meteor shower produces more fireballs.
Calgary astronomer Don Hladiuk told CBC Radio's Calgary Eyeopener program that when viewed from Calgary, the constellation Perseus will be just starting to clear the horizon at 10:30 or 11, so the optimal viewing time won't be until 3 or 4 a.m. MT.