Stars align to make the annual Perseid meteor shower one of this year's best

The Perseid meteor shower is always one of the year's most anticipated celestial events.

As the Earth plows through Comet Swift-Tuttle's 133-year orbital path around our sun, the comet's shed debris streaks through our planet's atmosphere at a screaming 210,000 kilometres per hour. That's 59 kilometres per second. The debris, sometimes just specks of dust and pea-sized gravel, heats up to between 3,000° F and 10,000° F.

Most often, between 50 and 60 meteoroids per hour—almost one per minute—will turn into searingly bright streaks (meteors) across the night sky during the Perseids, so called because they appear to originate from the vicinity of the constellation Perseus. (Any part of a meteor that survives the vapourizing ride through the atmosphere is called a meteorite, although that would be very rare with comet debris, with much larger asteroid remnants being more common.)

Only December's Geminids shower is more anticipated by sky watchers in terms of numbers of meteors per hour (along with the three-times-per-century cyclic increase in November's Leonids),

The show actually happens during a five-week period every year from mid-July to late August, but the peak meteor-viewing time is usually three days in August, which this year takes place in the predawn mornings of August 11, 12, and 13.

Sometimes the Earth will pass through a cluster of debris in Swift-Tuttle's orbital path, which can result in a significant increase in the hourly rate of meteors, but there is no way of predicting if or when this will happen. These spectacular "outburst years" can see upwards of 200 meteors per hour, or one every 20 seconds or so.

Some Perseid meteors have been sporadically visible for weeks. mixing with stragglers from late July's Delta Aquarids shower, but the early morning (midnight until dawn) of August 12 is the real peak, with good viewing predicted for another day on either side. The waning crescent moon will present little interference in the night sky (and will set before the best viewing hours), and although some rain and clouds are predicted for Saturday (August 11), the weather is expected to clear up quickly from that point onward.

Remember to look for a close and visibly (to the naked eye) orange-red Mars in the southeast sky for a few hours after midnight (Saturn will also be hanging around). 

As always, try to get out of the city or as far away from strong lights as you possibly can, with broad sweeps of unobstructed sky where obtainable, and give your eyes at least 20 to 30 minutes to adjust to dark viewing conditions. Bring a folding chair, relax, and enjoy.

Metro Vancouver is cohosting (along with Science World, H.R. Macmillan Space Centre, and others) a meteor-watching event from 8 p.m. to 11 p.m. at Aldergrove Regional Park on Saturday night (August 11). Admission is $2 and it is an all-ages evening, with lots of family activities. Camping is allowed, with a midnight "quiet" time. Motorists should go to the Aldergrove Bowl entrance on Lefeuvre Road.

Happy viewing!